Thesis.pdf

Microwave Solution Combustion synthesis of Visible light-
responsive Photocatalyst for degradation of Reactive
turquoise Blue (RB21) dye
By
RAHUL JARARIYA
Enrolment No.: 200170730001
Under Guidance of
DR. FEMINA J. PATEL
Professor and Head of Chemical Engineering Department
VGEC, Chandkheda, Gujarat
A Thesis Submitted to
Gujarat Technological University in Partial fulfilment of Requirements for
the Master of Engineering Degree in Chemical Engineering
May 2022
Department of Chemical Engineering
VISHWAKARMA GOVERNMENT ENGINEERING COLLEGE
Nr. Visat three roads, Sabarmati-Koba highway, Chandkheda,
Ahmedabad, Gujarat, India-382424
Affiliated to
GUJARAT TECHNOLOGICAL UNIVERSITY

ix
ACKNOWLEDGEMENT
It gives me great pleasure and honor to express my sincere gratitude to my guide Dr Femina J.
Patel, Head of the department at Department of Chemical Engineering, Vishwakarma
Government Engineering College, and Chandkheda for her excellent guidance, constant
support, encouragement, valuable suggestion, and affection throughout my career. Without his
motivation, it would have been difficult to complete the task. As a teacher, she has always
encouraged me to realize my potential and to pursue and accomplish things that I alone could
have only imagined.
I will grab this opportunity to extend my sincere gratitude to all other teaching and non-teaching
faculties of the department for providing me necessary help, support, and suggestion. During my
project work. I would like to thank the Faculty of Chemical Engineering Department at
M.A.N.I. T (Maulana Azad National Institute of Technology), Bhopal, for allowing me to
utilize their facilities such as Centrifuge, Muffle furnace, FTIR, XRD, Magnetic stirrer,
Glassware and chemicals etc. I'd like to thank Dr K Suresh for his assistance with the dissertation
portion of my work. I would like to express my gratitude to the HOD of the Chemical
Engineering Department at MANIT, Bhopal. Who understands me and my practical job and has
provided me with a supportive mentor, Thank you to everyone at MANIT, Bhopal who helped
me get on the correct track.
RAHUL JARARIYA
200170730001

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TABLE OF CONTENTS
 Title page……………………………………………………………...…………...........i
 Certificate………………………………………………………………..………….......ii
 Compliance certificate……………………………………………………..………........iii
 Publication certificates…………………………………………………….…………....iv
 Thesis approval certificate……………………………………………..….……............vii
 Declaration of originality certificate……………………………………..………..……viii
 Acknowledgement…………………………………….………………….………....…..ix
 Table of Contents…………………………………….………………………...……......x
 List of Figures……………………………………….……………………….…….…...xiii
 List of Tables……………………………………….……………………………..…….xv
 Abstract………………………………………… …….……………………..………....xvii
CHAPTER 1: Introduction…………………………………………………..………………...1
1.1 Background of work…………………………………………………..…….............1
1.1.1 Dye wastewater and its environment effects……………………..…..…….....1
1.1.2 Dyes and their structure, properties, and application……………..….…….....3
1.1.3 Dye removal technologies from waste water……………..………..................5
1.1.3.1. Physical Methods……………………………………………….........6
1.1.3.2. Chemicals Methods……………………………………………..........7
1.1.3.3. Others method…………………………………………………..……8
1.1.4 Standards for discharge effluents………………………………………..........9
1.1.5 Textile industry's standards for water pollutants in the U.S………................10
1.2 Scope of work…………………………………………………………………...…12
1.3 Objective of work……………………………………………………….………....12
1.4 Organization of the thesis…………………………………………………….........13

xi
CHAPTER 2: Literature review………………………… ……….…………………………...14
2.1 Wastewater sources…………………………………………………………….…..15
2.1.1 Wastewater………………………………………………..……….….........15
2.1.2 Sources/Types of Waste water…………………………………………..15
2.1.3 Effects of Wastewater……………………………………………….…...17
2.2 Spinel ferrites and their structure………………………………………….............18
2.3 Spinel doping effect for dye degradation.…………………………………...……....19
2.4 Dye degradation by photocatalytic activity………………………………...…..........20
2.4.1 Photocatalytic activity………………………………………………...………20
2.5 Catalyst preparation methods………………………………………………....……..22
2.5.1 Microwave solution combustion method……………………………....……..22
2.5.2 Solution combustion method………………………………………..............23
CHAPTER 3: Materials and Methods …………………..…………………….…………........36
3.1 Synthesis of Spinal ferrites…………………………………………………...……..36
3.1.2 Material………………………………………………………………………............36
:
3.2 Required equipment……………………………………….………………........…...37
3.2.1. Microwave reactor…………………………………….…………………………….37
3.2.2 Muffle furnace………………………………………….……………………............37
3.2.3 Magnetic stirrer with Hot plate……………………….………………..................38
3.2.4 Photoreactor…………………………………………….…………………..............39
3.3 Microwave solution combustion method………………………………...…............40
3.3.1 Spinel Ferrite production …………………………………………….............40
3.3.2 Spinel ferrite preparation by Solution combustion method…………..............41
3.4 Stoichiometry equations………………………………………………….…….…...42
3.5 RB21 Dye degradation set up………………………………………………….........44

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3.6 Dye Solution Preparation…………………………………………………..………..45
CHAPTER 4: Characterization…………,,,,,…………………………………….……..............46
4.1 X-ray Diffraction (XRD)………………………………………………....….….........47
4.2 Fourier transforms infrared (FTIR) …………………………………...……..............49
CHAPTER 5: Results and discussion………………….………………..……...………............52
5.1 Dye degradation analysis (UV-visible spectrophotometer)….…...………................52
5.2 Effect of dye concentration……………………………………...…………..…........52
5.2.1 Effect of pH………………………………………………...…………….……........56
5.2.2 Effect of H2O2 Dosage…………………………………..……………..…............59
5.3.3 Catalyst Effect Without H2O2 ………………………..……………….……….….60
5.3.4 Effect of Catalyst Dosage……………………………..…………………...….…..61
5.3.5 Different Catalyst Effects on 100 ppm dye wastewater
Concentration…………………………………………..………………………..…62
CHAPTER 6: Conclusion…………………………………...………..………….……….........66
 References…………………………………..…………..……..….…………….……........68
 Appendix I List of Abbreviation…………………………….….………………….….......77
 Appendix II Calculations………..…………………………..………………..…….….......79
 Appendix III Review cards…………..………………….….………………………...........82
 Appendix IV Achievements…………………………….…………………..……..........…86
 Appendix V Letter to use the facilities……..…………….…………….……………....….90
 Appendix VI Plagiarism Reports………………………….…………….……………..…..91

xiii
LIST OF FIGURES
Figure 1.1: List of the various dye removal techniques……………………………………..…6
Figure 2.1: Waste water soruces……………………………………………………................16
Figure 2.2: Photocatalysis reaction solution of dye wastewater……………………………....21
Figure 2.3: Photocatalysis reaction solution of dye wastewater………………………….…...22
Figure 2.4: Methods for producing spinel ferrites and their applications…………….…….23
Figure 2.5: Solution combustion synthesis of spinel ferrite preparation……………….…..24
Figure 3.1: The microwave reactor system (Raga’s scientific preparation)………..............37
Figure 3.2: Muffle furnace…………………………………………………….………….....38
Figure 3.3: Magnetic stirrer with the hot plate………………………………………….…..39
Figure 3.4: the photoreactor for dye degradation experiment………………………….…...39
Figure 3.5: Preparation of spinel ferrites (CoFe2O4, MgFe2O4, Mg0.5Co0.5Fe2O4)…….…….41
Figure 3.6: Preparation of spinel ferrites (Ni0.5Co0.5Fe2O4)……………………………….…..41
Figure 3.7: Dye degradation procedure……………………………………………………..…44
Figure 3.8: Centrifugation steps for dye degradation……………………………………….…44
Figure 3.9: The prepared Rb21 dye solution in distilled water (100ml)………………………45
Figure 4.1: XRD Pattern OF MgFe2O4 with Excel graph……………………………………..47
Figure 4.2: XRD Pattern OF CoFe2O4 with Excel graph…………………………….………..47
Figure 4.3: XRD PATTERN OF Mg0.5Co0.5Fe2O4 with Excel graph……………………….…48
Figure 4.4: FTIR Spectra for MgFe2O4………………………………………………………..49
Figure 4.5: FTIR Spectra for Mg0.5Co0.5Fe2O4………………………………………...............50
Figure 4.6: FTIR Spectra for CoFe2O4………………………………………………………...51
Figure 5.1: (a) Initial Dye absorbance in multiple concentration (b) Calibration curve at
620nm…………………………………………………………………………………………..53

xiv
Figure 5.2: Calibration curve (concentration vs absorbance)………………………………….54
Figure 5.3: Rb21 Dye degradation by MgFe2O4……………………………………………....54
Figure 5.4: Pseudo first-order kinetic graph……………………………...……………………55
Figure 5.5: Dye removal in multiple concentrations with MgFe2O4 dosage in presence of visible
light/H2O2……………………………………………………………………………………….56
Figure 5.6: pH solution at (4.0,6.0,8.0) with MgFe2O4………………………………….……..59
Figure 5.7: Rb21 % removal in absence of Hydrogen peroxide with 20 mg
MgFe2O4……………….……………………………………………………………………..…61
Figure 5.8: MgFe2O4 Dosage effect with time on Rb21 dye solution on 60 ppm (a) 0.02g (b)
0.04 g (c) 0.06 g(d) 0.08 g………………………………………………….………………...…62
Figure 5.9: Catalyst Effects on 100 ppm Rb21 dye concentration……………………………..64
Figure 5.10: Graph shows different catalysts (ferrite spinel ferrites vs doped spinel ferrites)
effectively work Rb21 dye to degrade from waste water. Parameters (100 ppm, 20 mg dosage
each catalyst, with 30 min. interval, 30 % w/v of H2O2 (5ml-drops)…………………………...64
Figure 5.11: Catalyst reusability parameters (λ = 620 nm, Volume = 100 ml, Concentration =
100 ppm, Dosage = 60 mg.)……………………………………………………………..………65

xv
LIST OF TABLES
Table 1.1: Classification of dyes………………………………………………………………….2
Table 1.2: Properties of dyes and their applications……………………………………………5
Table 1.3: Standards of water quality by CPCB (Central Pollution Control
Board)………………………………………………………………………………………..…..10
Table 1.4: Textile industry's standards for water pollution…………………….…………...…..10
Table 1.5: Emission standards for gross printing and dyeing wastewater………………………11
Table 1.6: Emission standards for fabric printing and dyeing wastewater…………………...…11
Table 2.1: Difference between UV and visible light…………………………….……………...21
Table 2.2: Literature review based on different methods with the suitable spinel ferrites for dye
degradation………………………………………………………………………………………26
Table 2.3: Literature review based on different methods with the suitable Spinel ferrites and
doped spinel for dye degradation…………………………………………….……………....27-28
Table 2.4: Literature review based on different methods with suitable catalysts for dye
degradation…………………………………………………………………………....................29
Table 2.5: Literature review based on magnetic properties with suitable spinel……………30-31
Table 2.6: Litera ture survey on Types of Photocatalyst used for dye degradation…………....32
Table 2.7: Literature survey for Different Catalyst processed by solution combustion synthesis
method……………………………………………………………………………………….33-34
Table 2.8: Magnesium ferrites synthesis method and its applications……………….………...35
Table 3.1: List of all Chemicals Required for Experimentation……………………….………36
Table 3.2: Calculated table for spinel ferrite by stochiometric evaluation…………….……...43
Table 3.3: Stochiometric calculations of Doping spinel ferrites………………..……………...43

xvi
Table 3.4 Oxidizing and reducing valances and quantities of the different chemical reagents used
to prepare the different catalysts………………………………………………………………..43
Table 4.1: XRD patterns parameter for MgFe2O4, CoFe2O4, Mg0.5Co0.5Fe2O4………….…….46
Table 5.1: Pseudo first-order absorption kinetics…………………………………………....…55

xvii
ABSTRACT
Currently, colour removal dye degradation from synthetic wastewater of RB21 dye using
photocat alysis with numerous spinel catalysts created in different methods. The reactive
turquoise blue (RB21) dye, which belongs to the phthalocyanine group and has a strong azo link
and a Cu2+
metal complex, is a very stable molecule that is difficult to degrade. Textile, paper,
and leather sectors all employ reactive dyes. Spinel ferrites are oxides with the general formula
AB2O4, where A and B are rare earth, alkali metal, and transition metal cations. Researchers
have used spinel catalysts in photocatalytic degradation technology to combat wastewater
pollution caused by dyes. The present research is focused on the creation of Magnesium and
Cobalt ferrites spinel catalysts for the breakdown of RB21 dye. The most efficient photocatalyst
was chosen, and the catalyst dosage, pH, dye concentration, reactor temperature, irradiation time,
and other parameters were optimized. In the present work spinel catalysts (CoFe2O4, MgFe2O4,
Mg0.5Co0.5Fe2O4, Ni0.5Co0.5Fe2O4) were prepared by different methods. The operating conditions
for spinel synthesis were observed at 146˚C commencing combustion of spinel ferrites. The
experiments were performed under varying light sources like a 700W microwave system, and a
Visible-Light photocatalytic reactor. The photocatalytic activity was carried out using a light
source (two 9W LED bulbs, Halonix) and stirring the sample (400 rpm, 25°C). The best-
screened spinel catalyst was doped spinel prepared by MSC and SCS without heat treatment.
Spectroscopic analysis of catalyst and analysis of wastewater sample before and after treatment
has revealed that MgFe2O4, CoFe2O4, and Doped spinel catalyst were in rhombohedral phase
with unconverted oxides or impurities with crystal size 13.34 nm comparable. It exhibited a
narrow band-gap 2.0 eV to degrade RB21 dye with 93% removal in 180 min with MgFe2O4 and
80% removal with H2O2 after 7 hours. The different photocatalysts used for Rb21 dye to
degradation with 100 mg/L concentration (100ml), the efficiency will decrease as concentration
increases around 70% with MgFe2O4, 73% CoFe2O4, 90.91 % with Magnesium doping in
cobalt, Nickle doping in cobalt gives 90.36 % dye removal.
KEYWORDS: Spinel ferrites, Photocatalytic process, Reactive Turquoise Blue-21, Visible-
light, Doped spinel, Microwave solution combustion method.

1
CHAPTER 1
INTRODUCTION
1.1 BACKGROUND OF WORK
1.1.1 DYE WASTEWATER AND ITS ENVIRONMENTAL EFFECTS
Wastewater is a big concern in India for the past decades. Solid particles in water impact
harmful to our environment, humans and Aquatic life. It causes several effects like
respiratory diseases, asthma, heart attack, other diseases etc. Due to impure water
consumption, thousands of deaths happen. In India, rural areas cause acids and heavy
metals to enter into body whereas urban sites cause pollutants such as ammonia to enter the
water system. Recent cases from water pollutants like malaria, diarrhoea, eyesight
problems, plague, viruses (epidemic), and bacteria are in front of us. Living beings can’t
live in this havoc nature environment. Dyes are primary effluents in the textile sector, it
discharges through channels into rives, ponds, or outsources. But in industry, dyes are not
directly applied to the fabrics, for colouring clothes is constructed within the fibres to
achieve the properties of dyes in one element of the dye and the other component infused
in fibre. Azo dyes are widely used for colouring fabrics in the textile industry. During the
process of dye inlet in fibre within less energy consumption rates or de facto is all major
dyes are done using water and it is easy, and cheap to avail water even cleaning and
depositing off is simple. Natural dye is the maximum consumption rate in the food industry
but there is no conclusive evidence that food dye is dangerous for most people. Azo dye is
consistent compared to food dyes. It is also heat resistant and difficult to expose to sunlight
and oxygen. The European Commission, on the other hand, has set a goal of limiting the
use of azo dyes, a category of 43 compounds that can cause cancer and are harmful to
human DNA or reproduction [3]. Azo dyes are most commonly found in paints, printing
inks, varnishes, and adhesives. So, it is more important to reduce dye effluent in the
wastewater which is help to get the life cycle back. The major drawback of azo dye does
not dissolve in oil or fat. It causes hyperactivity. However, these matters cannot be ignored
as it is a sensitive issue regarding the health of children. Degradation products of this dye
are carcinogenic and therefore, some dyes have been permanently banned. According to

2
Gujarat pollution control board (GPCB) schedule I and II (odit book gpcb NEW 6102015
final.cdr (gujarat.gov.in)) [59]. Azo dye is the part of Synthetic dyes used in textile due to
their low cost and colour diversity. Every year, up to 50% of dye effluent is dumped
directly into the environment. According to recent reports, colours disseminated from
Tirupur, Tamil Nadu's dying and bleaching units, which provide colour and flare to the
city's garments, have converted the lovely Noyyal river into an inebriated sewer and
damaged agricultural land once the river is sustained. It was darkness river undercover by
toxic dyes. White textiles may appear to be safe owing to their lack of colour, however, the
impact of bleaching causes severe water contamination. The survey on dye concluded that
200 k tons/year of this effluent by improper treatment in textile industries[6]. At present,
the agriculture and textile sectors suffer from dye problems. Major issue from
contamination molecule to be reduced. Azo, anthraquinone dyes or other dyes are
largely effective to the environment. Types of dyes are included in the table below i.e.,
(Classification of dyes).
BASED ON
SOURCE
BASED ON THE
IONIC
STRUCTURE
BASED ON
CHROMOPHORIC
GROUPS
BASED ON THE
CHEMICAL STRUCTURE
OF DYES
Natura dyes
Anionic structure:
Reactive dyes, acid dyes
etc.
Azo dyes, Anthraquinone
dyes, Nitro and Nitroso
dyes, Triaryl methane
dyes, and Indigo dyes.
Read made dyes:
Water-soluble dyes: reactive dye,
Acid dyes, Direct dyes.
Water Insoluble dyes: Vat dyes,
sulphur dyes etc.
Synthetic dyes
Cationic structure: Basic
dyes
Ingrain dyes: Mineral colours,
Azoic dyes, Oxidation colours.
Non-ionic structure:
Disperse dyes
Table1.1: Classification of dyes

3
1.1.2 DYES AND THEIR STRUCTURE, PROPERTIES, AND APPLICATION:
Types of
Dyes
Structure Properties Application
Direct
dyes
Congo Red dye
Water-
soluble and
anionic.
Weak Ionic
bond and
wander walls
forces of
attraction.
Cotton and
Viscose
Reactive
dyes
Water-
soluble and
anionic.
Powder
liquid and
paste form.
Fixed in
fibre easily
by a covalent
bond.
Cotton.
Acid
dyes
Highly
water-
soluble and
anionic.
It creates
ionic bonds
with the
contribution
of Vander
Nylon, Silk
and Wool.

4
walls forces
and H-Bond.
Basic
dyes
Cationic,
readily
soluble in
water, show
good
fastness
properties,
applicable to
jute and
acrylic.
Jute and
Acrylic.
Vat dyes
Not soluble
in water,
Colors and
brilliant
shades,
powder and
paste form,
very
expensive.
Cotton
Sulfur
dyes
Water-
insoluble,
cheap,
shades are
limited.
Cotton and
viscose.

5
Disperse
Dyes
Non-ionic,
Acidic,
mechanically
trapped,
weak
solubilizing
group.
Polyester,
Nylon,
Cellulose
Acetate,
Cellulose
triacetate.
Azoic
Dyes
Not water
soluble,
Bright, red
and orange-
scarlet
shades,
Cheap.
Cotton,
nylon and
polyester.
Mordant
Dyes
Produce dark
shades,
strong ionic
bond,
soluble in
cold water.
Natural
protein
fibres,
nylon, and
modacrylic
fibres.
Table 1.2: Properties of dyes and their applications
1.1.3 DYE REMOVAL TECHNOLOGIES FROM WASTE WATER:
A variety of activities contribute to the creation of wastewater. Domestic wastewater is
produced in homes, restaurants, and companies as a result of activities such as bathing,
washing, and using the toilet. Surface runoff is caused by the combination of waste, grit,
nutrients, and different pollutants. Chemical and manufacturing industry discharges

6
produce industrial wastewater. As a result, wastewater is simply utilised water that has
been contaminated by home, commercial, or industrial usage. Different types of
processes to degrade dyes in water. Like Physical, Chemical and Biological Methods.
Considering the stability of dye compounds, organic effluents and cost efficiency is not
much time-consuming. As per the basis, structure, and nature of dyes consider for
possibility.
Different methods review dye degradation. In physical method consists of Ion exchange,
Adsorption, and Filtration/coagulation. The adsorption method is the most commercial
process among others. It is done by activated carbon. Adsorption of activated carbon is
difficult without pretreatment because suspended particles quickly block the filter.
Figure 1.1: List of the various dye removal techniques.
1.1.3.1 Physical methods:
Ion exchange, both natural and synthetic, is employed where, it is necessary to have a large
treatment capacity, high efficiency, and quick kinetics. To generate stronger resins,
sulphonic and carboxylic groups are utilised. In both cases, aqueous media modification is
common in the case of kerosene solvent extraction and implemented in countercurrent
when oximes are used. Ion exchange resins dye degrade and decrease COD in textile

7
effluent. Ion exchange has not been widely employed for the treatment of dye-containing
effluents, owing to the belief that it cannot handle a wide spectrum of dyes.
Adsorption separation treatments: When two immiscible states of matter, such as gas
and liquid, gas and solid, or liquid and solid, come into contact in heterogeneous systems,
they are separated by a surface layer whose characteristics differ from those of the two
states constituting it. The adsorption process occurs when one or more components present
in one of the two phases (or both) tend to increase their concentration on the surface layer.
Coagulation and flocculation are two procedures that are often employed in water treatment
to remove undesired suspended debris. They may, however, be used to destabilize any
suspension system. Coagulation is the use of a coagulant that has the ability to destabilize
previously stabilized charged particles in a solution. In contrast, de-stabilization in
flocculation is caused by physical procedures such as solution mixing and, in certain cases,
the addition of polymers. This is the primary distinction between coagulation and
flocculation.
1.1.3.2 Chemical methods:
Chemical Treatment methods consist of Fenton Process, Ozonation, and Photocatalytic
reactions to degrade dyes. Currently, maximum points accounted for the photocatalytic
procedure due to removal in the presence of sunlight or visible light. On the other form, the
Fenton process quietly achieved that target for degradation of dye. In the process, low
concentration Fe2+
and H2O2 arrangements are utilized by OH-
radicals including High
oxidation potential which might helpful for de-colorization techniques.
Recently, a technology known as Advance Oxidation Processes was developed for
eliminating color molecules from water (AOP). This approach is thought to have good dye
degradation performance. Fenton, Photo-Fenton, photolysis, ozonation, electrochemical
oxidation, and sonolysis are all examples of AOP. For example, TiO2 is also the best
semiconductor for photocatalytic activity, with a bandgap range of approximately 3.2 eV.
TiO2 is the sole active material in UV light due to its broad bandgap, and its efficiency
decreases with light irradiation. TiO2 does not function for commercial use for a variety of
reasons. To make the photocatalyst phenomenon observable in both UV and visible light to
further future study. As a result, TiO2 gets overlooked. Because of TiO2 large bandgap, we

8
are focusing our study on metallic metals such as cobalt, nickel, magnesium, and so on.
Because of the material's low band gap, it may be used in visible light irradiation, which
accounts for the vast majority of sunlight or visible light.
Photocatalysis is the redox couple of promoting both the reactions like oxidation and
reduction. The term photocatalysts are derived from the word 'photo,' which means 'light,'
and catalysis is defined as a substance that modifies the pace of chemical processes. It is
the phenomenon of chemical reactions in the molecules that trigger the electrons from
valance to conduction band. The metals grab band gap narrow which exhibits to degrade
dye presence of responsive visible light. This is the basic idea of photocatalysts activity and
further in Chapter 2 will elaborate on the experimental result.
The rationale for selecting this method is that it allows for the destruction or disintegration
of dye molecules, and such procedures employ a variety of oxidising chemicals such as
Ozone, Hydrogen peroxide, and Permanganate (MnO4).
1.1.3.3 Other methods:
Due to the high cost of physical treatment methods and disposal problems ascertained.
Biological methods overlapped to degrade dye. In Biological method, consist of Anaerobic,
Aerobic, and Biosorption techniques. Most researchers hard work on azo dye degradation
anaerobically. It is a feasible technique for the large volume of effluents, has low cost and
has good effective properties shown.
Microbial decolourization using appropriate bacteria, algae, and fungus is gaining
popularity; these microorganisms may biodegrade and/or bio absorb pigments in
wastewater. On the other hand, anthraquinone dye serious dose for the environment and is
effective for human health. The route of attention in biological methods to decolourize dye
via enzymatic action of oxidoreductases reviewed the dye effluents and remediation from
dyehouses.
Membrane filtration: Although membrane filtration was shown to be an excellent method
for eliminating basic colours, side effects such as air binding and particulate matter fouling
preclude it from being employed commercially. The choice of membrane selection by their
pore size, layer shape, and capability to oppose certain parameters for separation.
Microfiltration is better used for achieving the target. Its primary use is the separation of

9
particles and colloidal colours from discarded washing dye bath output. But in the
Ultrafiltration process less commercial for the textile sector, de facto is ultra-elementary
particles of colour molecules present in the material which is the problem of MWCO
(Molecular weight cut off) will be lower rejection point. From a separation point of view,
Nanofiltration is a unique method utilised between ultrafiltration and reverse filtration
(RO). It maintains its attractiveness in terms of environmental contamination, brine
recovery and reuse.
1.1.4. STANDARDS FOR DISCHARGE EFFLUENTS
Standards for discharge of effluents from textile industries (According to Central
pollution control board, CPCB)
Industry Parameter Standards References:
All integrated textile
units, units of cotton /
Woollen / Carpets /
Polyester, Units having
printing / Dyeing /
Bleaching process or
manufacturing and
garment units.
pH 6.5-8.5
[7]
Suspended solids 100 ppm
Colour (Platinum
cobalt units)
150 ppm
Biochemical oxygen
demand (BOD) [3
days at 27˚C]
30 ppm
Oil and grease 10 ppm
Chemical oxygen
Demand
250 ppm
Total chromium 2.0 ppm
Sulphides 2.0 ppm

10
Phenolic compounds 1.0
Total dissolved solids
Inorganic (TDS)
2100 ppm
Sodium absorption
ratio (SAR)
26 ppm
Ammonical Nitrogen 50 ppm
Table 1.3: Standards of water quality by CPCB (Central pollution control board
1.1.5 Textile industry's standards for water pollutants in the U.S.
The standards are given by Textile Industries for water pollutants and the requirements
using BPT (Best practical control tech.)[7]. It is adjusted by the fabric printing and dying
wastewater, dyeing, resin processing, washing and drying and so on.
S.No. Parameters
The limits of
discharged
concentration
The limits of
discharged
concentration
The special
limits of
discharged
concentration
1 COD 100 mg/l 80 mg/l 60 mg/l
2 BOD 25 mg/l 20 mg/l 15 mg/l
3 PH 6-9 6-9 6-9
4 SS 70 mg/l 60 mg/l 20 mg/l
5 Chrominance 80 60 40
Table 1.4: Textile industry's standards for water pollution

11
S.NO. Parameters
BPT
MAXIMUM
AVERAGE OF 30
DAYS
KG / T (FABRIC)
1 BOD 22.4 11.2
2 COD 163.0 81.5
3 TSS 35.2 17.6
4 S 0.28 0.14
5 PHENOL 0.14 0.07
6 PH 6.0 – 9.0 6.0 – 9.0
Table 1.5: Emission standards for gross printing and dyeing wastewater.
S.NO. Parameters
BPT
MAXIMUM
AVERAGE OF 30
DAYS
KG / T (FABRIC)
1 BOD 5.0 2.5
2 COD 60 30
3 TSS 21.8 10.9
4 S 0.20 0.10
5 PHENOL 0.10 0.05
6 PH 6.0-9.0 6.0-9.0
Table 1.6: Emission standards for fabric printing and dyeing wastewater

12
1.2 SCOPE OF WORK
Advance Oxidation Processes (AOP) are a new developing technology that is based on the
creation of highly powerful oxidizing agents, such as OH- radicals, however, the problem
is that it is very expensive and unappealing. According to certain study studies, it uses a lot
of electrical energy and chemical reagents. Ascertain the catalyst for the quick procedure
since the catalyst speeds up the reaction by decreasing the quantity of energy.
The Microwave Solution Combustion Method (MSCM) is a novel process for the synthesis
of spinal ferrite nanoparticles. A lot of study shows that this method is cost-efficient and
less arduous. So, perfect for catalyst preparation. By this method, self–sustaining solid
flame combustion reaction for internal development of catalyst.
According to a review of the literature, the F/O ration (Fuel to oxidizer ration) can alter the
attributes of nanomaterials such as reaction temperature, rates, time, sample quality,
particle size, magnetization, crystallinity, and so on. Also, the work proposed the
photocatalytic/photo-Fenton activity with ferric ion catalyst to reduce the contamination
and speed up the reaction.
1.3 OBJECTIVE OF WORK
Based on the scope of the study stated in the preceding section, the major goal of the
proposed research is to create a Spinel-based doped photocatalyst that can be employed
successfully for photocatalytic dye degradation from wastewater.
The specific objectives are as follows:
 Preparation of catalyst for dye degradation using method i.e., Microwave Solution
Combustion Method.
 Doping of Spinel (visible light-sensitive) catalysts
a. To reduce band gap.
b. Improve magnetic property of catalyst.
c. Reduce photo-induced electron-hole recombination
d. Catalyst reusability to degrade Reactive turquoise Blue -21 dye from water.

13
 Investigation of the suitability of doped Spinel (visible light-sensitive) catalyst for
degradation of Reactive turquoise blue-21 dye.
 Study effect of operating parameters: pH, contact time, catalyst dose, dye
concentrations, and specified catalyst irradiation time.
 Characterization: TGA, XRD, EDX, VSM, UV-vis, SEM / TEM, FTIR.
1.4. ORGANIZATION OF THE THESIS
A Thesis is divided into parts that include an introduction, a review of the literature,
materials and experimental procedures, findings and discussion, and a summary with a
conclusion that includes the future scope.
The Thesis following the chapters are:
Chapter 1: The background and scope of the research work are explained with specific
objectives of the research.
Chapter 2: Photocatalytic dye degradation mechanism along with the spinel based
photocatalyst is discussed in detail with the effect of doping on the physio-chemical
properties of the catalyst. Even different methods for synthesis of spinel and doped spinels
such as microwave solution combustion and solution combustion synthesis are explained in
detail along with all the steps for these processes and supporting literature. All discussions
are carried out for spinels are Nickel and Magnesium doped cobalt Ferrite, Cobalt Ferrite,
Magnesium Ferrite and more.
Chapter 3: The experimental work after the literature survey is planned as materials and
methods, catalyst synthesis procedure using Microwave solution combustion, and Solution
combustion synthesis. The activity of the catalyst was carried out using visible light to
degrade the dye.
Chapter 4: In this chapter, provides a through discussion of the characterization results of
the various metal oxides catalysts. Deeply investigation of prepared spinel ferrite following
combustion heating using microwave and muffle furnace. Moreover, this chapter reports a
comparative study of the catalyst presenting various compositions and metal contents.

14
Chapter 5: It covers all of the results based on the experimental work outcomes and
discussion.
Chapter 6: The summary and conclusion present a brief Research conducted to reduce
water waste in the environment. This photocatalytic dye degradation method is
ecologically safe and expands the area of future development.

15
CHAPTER 2
LITERATURE REVIEW
2.1 WASTEWATER SOURCES
2.1.1 Wastewater
Water is an essential part of our lives since it is not only necessary for our physical
survival but also for a variety of home and industrial activities ranging from cleaning
and agriculture to cooking and product manufacture. Unsustainable exploitation and
uncontrolled pollution are the "hot topics" in water management right now. To meet the
continually expanding agricultural and industrial demand caused by population increase,
limited water resources must be apportioned and utilized judiciously. The major
approaches to addressing water shortage are prevention, demand management, and water
valorization. According to this viewpoint, industrial effluent should be treated and
utilized. The water that is disposed of from homes and workplaces is known as domestic
wastewater. It was once known as sewage [10,8]. Domestic sources of wastewater are
toilets, sinks, showers, and washing machines.
Domestic wastewater strength and composition vary hourly, daily, and seasonal, with
average strength, influenced by per capita water use, habits, nutrition, living standard, and
lifestyle. The fundamental reason is that residential water use varies. Developed-country
households consume more water than developing-country households. Domestic
wastewater has a grey color, a musty odor, and a solids concentration of roughly 0.1
percent on a physical level. The solids can be dissolved as well as suspended. Chemical
and biological processes can precipitate dissolved solids [8]. When suspended materials are
released into the receiving environment, they might form sludge deposits and anaerobic
conditions.
2.1.2 Sources/Types of Waste water
Domestic Wastewater- It can come from several wastewater sources, including hospitals,
businesses, and other commercial establishments. Water gathered during a storm might be

16
considered household trash. Water discharges from our daily hygiene activities are typical
wastewater sources, such as bathing, cooking, and cleaning meat, vegetables, and textiles.
Domestic wastewater can be properly treated despite being highly polluted.
Figure 2.1: Waste water sources
Blackwater – Blackwater is a kind of residential wastewater typically generated by toilets,
dishwashers, and kitchen sinks. Human feces have been found in this form of effluent. As a
result, effluent from flush toilets and even bidets contribute to this problem. Every
contaminant that enters our toilets, bathrooms, and sink drains is contained in this water.
Greywater – Feces haven’t polluted this kind of wastewater. Non-toilet units such as
baths, washers and dryers, washbasins, laundry, tubs, spas basins, and anything in between
produce this type of effluent. This sewage water hasn’t had any urination or human waste
added to it.
Greywater, unlike blackwater, carries fewer germs. However, it should be noted that it
includes trace levels of dangerous pollutants that might cause sickness if consumed.
Greywater is treated differently from blackwater since it does not contain feces or urine.
Greywater is usually acceptable for re-use following treatment in a proper wastewater
treatment plant.

17
The dye sector and the sectors relevant to dye applications (textile, tannery, paper) are
recognized among the most polluting industries, based on both the volume and the
composition of effluents. [3,4] Effluents released in the water bodies create aesthetic and
environmental issues with a high societal unacceptance. Furthermore, they can cause pipe
corrosion, blockages, and bioaccumulation, and result in the production of hazardous
sludge. The presence of dyes in effluents makes their reuse difficult, as the presence of
color and other substances affects consecutive dyeing cycles.
While for azo dyes, relevant data is easily available, it is difficult to find current or accurate
data for the annual production of anthraquinone (AQ) dyes. Nevertheless, data found from
previous years can be used to roughly estimate a production volume. For the U.S., within a
period of about 15 years (1986−2002), the annual production of anthraquinone (a precursor
for dyes and other chemicals) had a staggering 50% increase (from 500 to 25k tons). Given
the increase in production volume of dyes, it is safe to assume that the production of AQ
dyes increased as well; a rough estimation of about 100 k tons of AQ dyes per year can be
made.
These issues make the monitoring of colored effluents released in the environment quite a
challenge. The problem of the dye contaminated water is especially evident in Asia, which
contributes about 50% of textile exports and more than 50% of world’s consumption of
dyes. However, many of the countries involved lack sufficient legislation about
environmental protection relevant to textile industries [10].
2.1.3 Effects of Wastewater
Industrial wastewaters degrade water clarity and can hinder oxygen dissolution. Many
industrial wastewaters contain oil and grease (O&G). While some of the latter are organic,
the majority are mineral oils.
Organic or mineral, both types cause interference at the air-water interface and hinder
oxygen transfer. The O&G (particularly mineral oils) may be inhibitory and impede the
transport of oxygen from the atmosphere to water.
Industrial discharges, unlike home sewage, can have temperatures that are significantly
higher than ambient temperatures. These increase the temperature of the incoming water
and decrease the oxygen solubility.

18
2.2 SPINEL FERRITES AND THEIR STRUCTURE
Ferrites are divided into three groups based on their crystal structure Spinal ferrite, garnet
ferrite and hexagonal ferrites. Spinal Ferrite nanomaterials are widely used. It achieved
great attention in several areas like pharmaceuticals, biomedical, electronic devices,
catalyst preparation and wastewater treatment, biosensors and photocatalyst etc. Spinal
ferrite nanomaterials are in the spotlight in current applications because of their excellent
magnetic properties often accompanied by other functional properties such as catalytic
activity [1, 2]. The synthesis, characterization and application of dye degradation are
focused on. Spinal ferrite is from basic science, especially for magnetic property and
crystal characteristics or structure. In recent advances, spinal ferrite nanomaterials for their
useful electrical and magnetic properties with stupendous applications are storage systems,
magnetic bulk cores, magnetic fluids, microwave absorbers, and magnetic diagnostics. It
varies from biomedical to industrial applications. Because of their colloidal stability,
biocompatibility, and magnetic characteristics, magnetite (Fe3O4), maghemite (-Fe2O3),
and hematite (-Fe2O3) are the most studied MNPs in biomedical applications [8]. Due to
their superior magnetic nature, inherent biological interactions, prominent surface area, and
small size, spinel ferrites (M-Fe2O4), a class of superparamagnetic materials at the forefront
of material synthesis and engineering, are being investigated as magnetic nanocarriers for
drugs in biological systems, contrast agents in MRI [40], and arbitrators in hyperthermia
treatment. The typical formula for spinal is AB2O4, where A and B are metallic cations that
are found in two distinct crystallographic locations, tetrahedral (A sites) and octahedral (B
sites) (B sites). Cations have tetrahedral and octahedral coordination with oxygen atoms in
both locations. The formula for common ferrite spinel is M-Fe2O4, where M stands for Fe,
Co, Mn, Zn, Cu, and Ni [8]. Cation distribution at tetrahedral and octahedral sites has an
impact on the physical and chemical composition of ferries. For example, the magnetic
properties of ferrite nanoparticles are directly related to the distribution and kinds of
cations at the vertebral structure's octahedral and tetrahedral sites. The basic reason behind
that is a magnetic moment in two sites. The spinal ferrites are considered magnetic
semiconductors this material is measured in vast applications including recording heads,
antenna rods, loading coils, and microwave devices. Core materials for power transformers
or in electronic and telecommunication achieved popularity. Ni0.5Co0.5Fe2O4 has potential
applications in high temperature integrated circuits, spintronic, chemical catalysts, high
power electronic devices and photocatalysts [9]. Cobalt ferrite (CoFe2O4) is one of the most

19
significant magnetic materials that can be widely used in electronic technologies,
particularly on magnetic and magneto-optical recording media, due to its exceptional
magneto crystalline anisotropy, temperate saturation magnetization, mechanical
inflexibility, and high coercively and chemical stability. The spinel ferrites structures are
three types based on the cation distribution:
 Normal Spinal: M2+
occupies A sites and trivalent cations on B sites.
 Inverse Spinal: Inverse spinal where divalent cations (M2+
) occupy the B sites and
trivalent cations occupy half of the A sites and half of the B sites by equal
distribution.
 Mixed/Random Spinal: Both divalent and trivalent cations occupy A and B sites.
Spinel ferrites' physical and chemical characteristics are determined by the kind and
distribution of cations at distinct locations, as well as their geometrical qualities [8]. The
shape of various spinal ferrites may be adjusted by changing the elemental composition and
synthesis criteria such as sintering temperature, sintering time, rate of heating and cooling,
and so on. As a result, a proper synthetic technique is required to provide the specified
functionality [55].
2.3 SPINEL DOPING EFFECT FOR DYE DEGRADATION:
Spinel doping is shown effective results for photocatalytic activity on basis of physical and
chemical properties. It improved the magnetic properties of the catalyst, and also for the
rate of dye degradation increased with suitably doped spinel. Cobalt, nickel, and
magnesium ferrites [10], as well as their relative doping in that spinel, were studied.
Because of its low bandgap and superior magnetic characteristics, it is often useful for
photocatalytic activity. Spinel ferrite can be used to degrade dyes in wastewater. Dye
discharge, as well as a myriad of other dangerous compounds, are generated by the dyeing
and textile industries (either inorganic or organic). The dye wastewater has a lot of negative
environmental effects. It causes asthma attacks, carcinogenic illnesses, skin irritation,
vision difficulties, and a variety of other issues. The problem of dye-contaminated water is
notably visible in Asia, which accounts for around half of all textile exports and more than
half of all dye usage worldwide. Only water that has been released must deteriorate.

20
According to the CBCP (Central Pollution Control Board) and, the quality of wastewater
has already been declared (Gujarat pollution control board) [2].
Azo dyes, reactive dyes, anthraquinone dyes, and acidic and basic dyes comprise the
majority of industrial dyes that influence the environment. Azo accounts for more than
60% of synthetic colours used in industry, followed by other dyes. Azo (Reactive dyes) are
inexpensive and widely accessible. It has a high level of water stability. Dye the (-N=N-)
chromophore group connections. The sulphonic group is also found in reactive dyes (SO3-
). The following is a survey of the literature on spinel ferrite, doped spinel, and other fuels
utilised in prior publications.
2.4 DYE DEGRADATION BY PHOTOCATALYTIC ACTIVITY
2.4.1 Photocatalytic activity
When photocatalysts absorb visible light radiation or by an illuminated light source
(fluorescent lamps, LEDs, etc.), they will produce electrons and holes. The electrons of the
valance band become excited when illuminated by light. The surplus energy of this excited
electron advanced the electron to the conduction band, resulting in the formation of
negative electron and positive hole pairs. This is known as the semiconductor photo
excitation state. The 'Band Gap' is the energy differential between the valance and
conduction bands. The wavelength of light required for photo-excitation is:
1240 (Plank’s constant, h)/ eV (bandgap energy) = nm
The positive hole splits the water molecules, releasing hydrogen gas and hydroxyl radicals.
A superoxide anion is formed when a negative − electron combines with an oxygen
molecule. When there is light, the cycle resumes. The overall mechanisms of photocatalytic
reaction are given in the figure below.

21
Figure 2.2: Photocatalysis reaction solution of dye wastewater
BENEFITS OF UV LIGHT LOSES IN UV LIGHT
BENEFITS OF VISIBLE
LIGHT
Efficient Photoactivity Large Band Gap Narrow bandgap
High Stability High cost Low cost
Degradation potential of
pollutants
Higher energy Lower energy
Safety for the environment
and humans
Highly efficient
No secondary Pollution
Table 2.1: Difference between UV and visible light

22
2.5 CATALYST PREPARATION METHODS:
Spinel ferrites can be produced via sol-gel, co-precipitation, microemulsion, solid-state,
Hammer's approach, microwave combustion method, sol-gel auto combustion method,
solution combustion method, and other processes. Because of its simplicity, variety, and
low cost, a combustion synthesis is a well-known approach for producing a wide range of
functional and structural activities. The microwave solution approach outperforms other
ways due to its efficient, time-saving, and rapid path for producing spinel ferrites and
doping of spinel ferrite as application, as well as heading to a new generation catalyst for
dye degradation. Solution combustion synthesis, on the other hand, provides satisfaction
for catalyst preparation due to high product yield at a reasonable cost [15]. The combustion
synthesis process is based on a self-propagating exothermic reaction in which the emitted
heat is sufficient for the reaction to proceed.
Figure 2.3: Methods for producing spinel ferrites and their applications
2.5.1 MICROWAVE SOLUTION COMBUSTION METHOD (MSCM):
This method is fast, and energy-efficient for the synthesis of solid materials. It takes less
time duration to the preparation of catalyst even if it needs less equipment at the time of
procedure implementation. A previous study used highly reactive precursors in this
method. MSCM is a solvent-free process so, not take a lot of time during combustion. In
the end, it generates a large number of gases released at high temperatures. Microwaves

23
cannot travel to large areas for large scale production. Different catalysts were prepared in
microwave-based on the literature review tables:
Figure 2.4: Microwave solution combustion synthesis of spinel ferrite preparation
2.5.2 SOLUTION COMBUSTION METHOD:
Because of its magnetic characteristics and the ability to produce extremely pure and
homogeneous structures at a cheap cost and in a short time, solution combustion synthesis
has also synthesized and enhanced the production of ferrites. SCS is also known as another
method of treating ferrites. It is made up of an oxidizer as well as a fuel ration for burning
in an aqueous media. The mixture is heated until it achieves self-sustaining ignition, which
results in rapid and extremely exothermic combustion. The precursor solution is then
combusted by increasing the temperature to the mean temperature (200–500˚C) [4, 8] to
directly generate the end product [8, 12]. It is sometimes necessary to calcine the
combusted products at higher temperatures (700˚C) [8]. The F/O ratio has a significant
impact on the catalyst powder. The F/O ratio is kept constant at one. The amount of
powder used is critical for the turning phase and micro-structured combusted powders. This
article examined both Microwave solution combustion synthesis and solution combustion
synthesis (SCS).

24
Figure 2.5: Solution combustion synthesis of spinel ferrite preparation
Magnetic spinel ferrites have many suitable chemical and physical properties such as
moderate saturation magnetization, electrical properties, morphological and structural
behaviour, and high chemical stability, inspiring many applications in magnetic coils,
antennae, gas sensors etc. The role of various fuels may affect catalyst preparation with
precursor mixture.
The photocatalytic destruction of organic pollutants is now receiving a lot of interest in
photocatalysis employing metal oxide and linked metal oxide nanoparticles. Because of its
superior catalytic activity, non-toxicity, stability, and reusability, spinel magnetic nano-
composites are now frequently employed in environmental applications. Spinel MgFe2O4
(n-type semiconductor) has a narrower band gap (2.0 eV) and can operate as a
photocatalyst for visible light. In recent work, researchers reported that MxMg1-xFe2O4-
TiO2 (0.0 x 0.5) microwave combustion nanocomposites employed as a photocatalyst for
photocatalytic degradation (PCD) of 4-chloro phenol (4-CP) [56].
However, complete research on the structural, morphological, optical, magnetic, and
photocatalytic characteristics of Co2+
doped MgFe2O4 nanoparticles generated by the
combustion technique has yet to be published. In this study, we show how to make spinel
Co-Mg ferrite ceramic nanoparticles using a modified Microwave solution combustion

25
process that results in fewer agglomerated particles. In addition, the impacts of metallic
dopant on the morphological, structural, optical, magnetic, and photocatalytic
characteristics. Also, synthesis of Ni0.5Co0.5Fe2O4 nanoparticles (NPs) was performed by
the SCS method [8].
APPLICATIONS:
 Advanced materials for energy technologies: Batteries, supercapacitors, fuel and
solar cells, as well as various devices for high-efficiency, low-cost energy
conversion and storage.
 Technological applications: Biomedicines, electronics and energy, cancer
treatment and microwave applications.
 Biological applications: Hyperthermia, drug delivery, Magnetic resonance
imaging, photocatalysis, antibacterial agents.

26
S.No,
CATALYSTS
NAME
PROCESS
Catalyst preparation
method
Source
Band
gap
DYE
Dye
concentration
Catalyst
Dosage
Dye
Degradation
References
1. Cr-CeO2
Photocatalyst
assisted H2O2
Deposition-
precipitation method
UV
light
2.52 eV
Methylene
Blue
10 ppm 20mg 59% (100min) [22]
2. Sn-Co3O4 Photocatalyst Co-precipitation
Visible
light
-
Methylene
Blue
50 ml dye sol. 0.1 g 75% (180min) [07]
3. Date pulp- ZnO Photocatalytic Green Synthesis
UV
light
-
Methylene
Blue, Eosin
Yellow
10 ppm 100 mg
90.2%, 90.6%
(180min)
[09]
4. MgFe2O4 Photo-Fenton Reaction sintering
Visible
light
2.25 eV
Rhodamine
B
10 ppm 10 mg 98.55% [13]
5.
LaFeO3-RGO-
NiO
Photocatalytic
Sol-gel and solid-state
method
Visible
light
1.9 eV Congo red - - - [23]
6.
Mg0.5
Zn0.5
FeMnO
4
Photocatalytic Green Sol gel process
Visible
light
1.56 eV
Reactive
blue 21
10 ppm 0.04g 96% [24]
7. Bi2O3 Photocatalytic Microreactor based
Visible
light
2.65 eV
Methyl
Orange
5 ml 20 mg 96% (15min) [25]
8. CuO NPs Photocatalytic
Green Synthesis
(Ruellia tuberose)
Visible
light
-
crystal
violet (CV)
dye
10 ml 10 mg/l 93% [26]
9. MgFe2O4
Fenton like
catalyst
Sol-gel method
Visible
light
-
Methylene
Blue
10 ppm 0.5 g/l 95% [27]
10. MgFeCrO4 Photocatalytic Green sol-gel method
Visible
light
1.57 eV
Direct black
122
(DB122)
20 ppm
(0.01-
0.04 g)
96 % (60s) [28]
11.
Zinc vanadate
NPs
Photocatalytic
Microwave-assisted
precipitation method
UV
light
-
Methylene
blue
10-50 ppm - 83% (160 min) [29]
12.
Zn0.5Ni0.5AlFeO
4
Photocatalytic sol-gel
visible
light
-
Reactive
blue 21
10 – 40 ppm
0.01-
0.04 g
94% (60 min) [30]
Table 2.2: Literature review based on different methods with the suitable spinel ferrites for dye degradation

27
S.No.
Catalysts
name
Method Fuels Source
Band
gap
Dye
Dye
concentr
ation
Catalyst
Dosage
Dye
Degradation
References
1.
ALW/CoFe2O4
Apocynaceae leaf
Auto combustion
method
Urea Visible light - RR 141
100 – 200
ppm
50 mg 94.12% [31]
2. CuFe2
O4
/RGO
Solution
Combustion
synthesis
Citric acid,
urea,
glycine
Visible light
1.7-1.9
eV
Methylen
e Blue
15 ppm 0.1 g 82% [32]
3. MgFe2O4
Solution
combustion
method
Urea Visible light
1.81-1.83
eV
Methylen
e Blue
10 ppm 50 mg 89.73% (240min.) [15]
4. CoFe2O4
Co-precipitation
method
- Visible light -
Methylen
e Blue
50 ml 10mg 74% (80min) [11]
5. CoFe2
O4
Microwave-
hydrothermal
- Visible light -
Bromoph
enol Blue
(BRB)
5 ppm 0.4 g 61.4% [33]
6.
ZnxCo1−xFe2
O4
(X = 0.2 steps)
Green
Combustion
Method
Curd
(Green
fuel)
Visible light 1.67eV
Congo
red
and Evan
s
blue dyes
10 ppm 0.2 g 96% [18]
7. MnFe2O4
co-precipitation,
sol-gel, and
hydrothermal
Citric acid - - - - - - [27]
8. Co:Mn:Fe2O4 Co-precipitation
1.5 M
NaOH
Visible light
2.68 to
2.61 eV
and 2.71
to
2.67 eV
Methylen
e Blue
(5 mg/500 m
L) = 10 ppm
30 mg 95% [34]
9.
Cu1-xNixFe2O4 (0 ≤
x ≤ 0.5)
Microwave
combustion
L-arginine Visible light
2.30-2.63
eV
Rhodami
ne B
3-15 ppm 0.31 g
95.58%, 285 min,
pH =2
[35]

28
10.
CoxMg1-xFe2O4
(x = 0 to 1.0)
Sol gel
combustion
Urea Visible light
2.26 -
2.59 eV
Methylen
e Blue
10 ppm 0.6 g 98.55 % [36]
11.
Ni2+ doped
ZnFe2O4
Auto-combustion
sol–gel
Urea Visible light 1.85 eV
Rhodami
ne B
10 ppm 0.5 g 98% [37]
Table 2.3: Literature review based on different methods with the suitable Spinel ferrites and doped spinel for dye degradation

29
CATALYSTS
NAME
Method Fuels Source
Band
gap
DYE
Dye
concentratio
n
Catalyst
Dosage
Dye
Degradation
References
Zr doped CuFe2O4
Chemical
precipitation
method
Aqueous
ammonia
hydroxide
Visible
light
1.39-
1.97eV
Rose Bengal
(RB), Indigo
Carmine (IC)
20 ppm for
Both
0.1 g 88%, 71% [38]
Ce: CuO NPs
sol-gel auto-
combustion
citric acid
Visible
light
1.42 eV
Methylene
Blue
10 ppm 20 mg
60%, 99% (2%
doping of Ce)
[39]
CoFe2O4/RGO
Solvothermal
synthesis
Isopropanol
Visible
light
-
Methylene
Blue
10 ppm 60mg 73% [40]
Zn/Fe2O4
Solvothermal
synthesis
oleic acid, 1-
pentanol,
oleylamine
Visible
light
1.98 eV
Carbamazepi
ne
25–200 ppm
25–100
mg/100
mL
100% [41]
Ni0.96Cd0.04Gd0.0
4 Fe1.96O4
wet chemical
method
-
visible
light
1.82 eV
Methylene
Blue and
Rhodamine-B
10 mg 92.27%, 53.18% [42]
Sm doped ZnFe2O4
co-
precipitation
method
-
Visible
light
1.47 eV
Cationic dye
(Methylene
Blue )
10 ppm 0.01 g 65% [43]
ZnSeWO3eCoFe2O
4
wet
impregnation
method
Ethanol
visible
light
-
Methylene
Blue
50 ppm 0.05 g 95.97% [44]
CoZnFeO4
solid phase
method
-
Visible
light
2.11eV
Methylene
blue
200 ppm 0.1 g 100% [45]
Co with ZnAlCrO4
solid-phase
method
-
Visible
light
2.02 eV
Rhodamine B
(Rhb)
200 ppm 0.1 g 83% [47]
MIL-101(Fe)/
CoFe2O4
Hummer’s
method
-
Visible
light
1.715 eV
Direct Red 23,
Reactive Red 198
60,100 ppm 0.002g 99% [46]
Table 2.4: Literature review based on different methods with the suitable catalysts for dye degradation

30
S.No. Catalyst Name Synthesis Methods Fuel
Saturation
magnetization
(Ms) – emu/g
Remanence
magnetization
(Mr) – emu/g
Coercivity
(Hc) (Oe)
References
1. CoFe2O4/RGO
Solvothermal
synthesis
- 41.98 25.42 6.41 [40]
2. ZnSeWO3eCoFe2O4 Wet impregnation - 0.6503 - 1000.03 [44]
3. Co-doped ZnAl2
O4
Microwave
combustion method.
Glycine - 0.23 217.39 [48]
4. Zn1−xCoxAl2O4
Microwave-Assisted
Combustion Method
Ethylenediamin
etetraacetic acid
- 0.00137 52.25 [49]
5. 8% Co-doped Fe3O4 NPs Co-precipitation - 29.51 6.48 308.14 [50]
6. MgFe2
O4
(glycine) Solution combustion
method
Urea 27 - 51 [51]
7. NiFe2O4
Solution combustion
synthesis
Glycine 59 13 95 [52]
8.
CoFe2
O4,
Co0.5
M0.5
Fe2
O4
(M=Mn, Ni, Zn)
Solution combustion
synthesis
Oxalyl di
hydrazide
76.1 - - [53]
9. Ni0.50Co0.50Fe2O4
Microwave
combustion synthesis.
Glycine 33.3 14.3 941 [54]
10. NiFe2O4
Auto-combustion sol–
gel
Urea 44.26 11.320 284.53 [37]
11.
Ni0.5CoxCd (0.5-x) Fe2O4
(x=0.02)
Microwave-auto
combustion route
Glycine 21.47 1.1372 61.93 [55]

31
Catalyst Name Synthesis Methods Fuel
Saturation
magnetization
(Ms) – emu/g
Remanence
magnetization
(Mr) – emu/g
Coercivity
(Hc) (Oe)
References
ALW/CoFe2O4 Auto combustion method Urea 38.75 13.78 784.56 [31]
MgFeCrO4 MNPs Green synthesis - 3.67 - - [28]
ZnFe2O4 Sol gel auto ignition Urea 24.05 0.09 - [56]
CoFe2O4
Microwave-hydrothermal
Glycine 66.4 19.1 241
[33]
MnFe2O4 Hydrothermal - 41.89 7.52 93.20 [57]
8% Mn doped Fe3O4 NPs Co-precipitation - 18.72 1.78 72.529 [34]
Ni0.4Zn0.6Fe2O4
Solution combustion
method
Urea 78.42 3.39 16.32 [52]
CoFe2O4 Combustion - 76.08 36.31 1049.6 [52]
CoFeAlO4 sol–gel auto-ignition - 22.65 8.590 800.49
[58]
16% Co doped Fe3O4 NPs Co-precipitation - 49.91 22.78 1469.299 [34]
Cu0.5Ni0.5Fe2O4 Microwave combustion Urea 25.93 5.29 165.70 [35]
Table 2.5: Literature review based on magnetic properties with suitable spinel

32
Materials Dyes
Degradation
efficiency
Irradiation time
(min.)
Light source References
CuFe2O4 Methylene Blue 94% 105 125 W Hg lamp (UV light) [59]
Ni0.8Zn0.2Fe2O4 Rhodamine B 98.48% 120 Visible light [37]
Zn:CuFe2O4 Direct Red 264 55% 120 Xenon lamp (Visible light) [3]
Ag:CuFe2O4 Malachite Green 98% 240 UV light [50]
Ti:CuFe2O4 Methylene Blue 82% 180
500 W Xenon lamp (Visible
light)
[51]
CuFe2O4 / Bi2O3 Methylene Blue 90% 45 Sodium lamp (Visible light) [38]
CuFe2O4 / rGO Phenol 90% 180
400 W Xenon lamp (Visible
light)
[52]
Zr:CuFe2O4 Rose Bengal 88% 120
150 W Tungsten halogen lamp
(Visible light)
[53]
Zr:CuFe2O4 Indigo Carmine 71% 120
150 W Tungsten halogen lamp
(Visible light)
[54]
Ce: CuO NPs Methylene Blue 99% 30 Visible light [33]
Table 2.6: Literature survey on Types of Photocatalyst used for dye degradation

33
Catalyst Materials Fuel Method
F/O
ratio
Calcination Purpose References
SrZnCoFe16O27
Ferric nitrate, strontium
nitrate, cobalt nitrate, zinc
nitrate, citric acid, distilled
water
citric acid
Solution combustion
synthesis
1.5
Molar
ratios
1200˚C
For 2h
Magnetic properties and
absorption
[7]
Ni0.4Zn0.6Fe2O4
Nickel nitrate, zinc nitrate,
iron nitrate, glycine
Glycine
Solution combustion
method
1
600˚C for
3h
Sintered two temperature
conditions 1000˚C to 1100˚C,
planetary ball mill for 12h
crushing to submicron
powder.
[6]
CoAl2O4
Cobalt (II) nitrate
hexahydrate, aluminium
nitrate nonahydrate, urea
and glycine, polyvinyl
alcohol.
glycine, PVA,
Urea
Solution combustion
method
1 -
The study of particle size and
magnetic characteristics of
different fuels
[9]
M-Fe2O4, M = Co and
Ni
Cobalt, Nickle and iron
nitrates
Glycine
Solution combustion
method
1 -
Metallic doping in ferrites and
Cobalt shows good Ms
[4]
Mg0.9Mn0.1CoxFe2xO4,
X= 0.0,0.1,0.2,0.3
cobalt nitrate, ferric nitrate,
magnesium nitrate,
manganese nitrate, and
distilled water.
Glycine
(CH2NH2COOH)
Combustion method 1.5
500C for 4
h
dielectric losses when
increasing frequency
[20]
Cu1-xNixFe2O4
Nickel nitrate (Ni (NO3)2;
98%), Copper nitrate, L-
arginine, ferric nitrate
L-arginine
Solution combustion
method
1 -
Cupper reduce the particle size
and increases the surface area
in doping on nickel ferrites
[5]
CoFe2O4 and
Co0.5M0.5Fe2O4(M =
Mn, Ni, and Zn)
cobalt, ferric, zinc, Nickle
nitrates, oxalyl dihydrazide oxalyl dihydrazide
Solution combustion
method
1
400C for 2
hr
Magnetic property increases
with Doping
[10]
NiFe2O4
Nickle nitrate hexahydrate,
Ferric nitrate nonahydrate,
Glycine, Nitric acid,
Distilled water.
Glycine
(CH2NH2COOH)
Solution combustion
method
1 600 for 1h
EDX Good Saturation
magnetization (Ms)High F/O
ratio
[50]

34
Catalyst Materials Fuel Method
F/O
ratio
Calcination
With time
Characterizati
on
Remarks
Referenc
es
MgFe2O4
Magnesium nitrate,
ferric nitrate, urea
Urea
(NH2CONH2)
Solution
combustion
method
1:5 800 for 3h
TGA, XRD,
SEM, TEM,
FTIR, UV-Vis
DRS, and EDS
Urea also enhances the
combustion, and stability of
the solution. Urea also
provides stable complexes
b/w metal ions.
[15]
NiFe2O4
Nickle nitrate
hexahydrate, Ferric
nitrate nonahydrate,
Glycine
Urea
(NH2CONH2)
Solution
combustion
method
1, 1:3, 0.8 400 for 1h
VSM, SEM,
XRD, Raman
spec, TGA, BET
Crystallinity increases with
Mr or Hc decrease, and
stability against temperature
changes
[16]
CuFe2O4/R
GO
Copper nitrate, ferric
nitrate, glycine, GO
(6-10 layers)
Glycine
(CH2NH2COOH)
Solution
combustion
method
1, 1.5, 2 -
TGA/DTA,
Ramen, VSM,
XRD, SEM, UV
vis
Copper impurity is removed
when fuel is in rich condition
and high surface area
[17]
CoFe2O4
Glycine, Cobalt
nitrate or can use
cobalt acetate
Glycine
(CH2NH2COOH)
Solution
combustion
method
1, 1.5 400 for 1h
TGA/DTA, XRD,
VSM, BET,
SEM/TEM
Surface area decreases with
cobalt ratio increase
[18]
MgFe2O4
Magnesium nitrate,
ferric nitrate.
ethylenediaminete
traacetic acid
(EDTA), citric
acid and glycine
as fuel
Solution
combustion
method
1
400, 600, 800
C
TGA, XRD,
SEM, TEM, VSM
glycine has not shown
stability with Mg2+like other
EDTA, Citric acid
[19]
Magnetite
(Fe3O4)
powders
ferric nitrate, CTAB,
distilled water, citric acid,
ammonia solution
cetyltrimethylammoni
um bromide (CTAB)
and citric acid fuels
Solution
combustion
synthesis
1 400C for 3 hr
TGA, XRD, TEM,
VSM, BET
The higher surface area in citric acid [21]
Table 2.7: Literature survey for Different Catalyst processed by solution combustion synthesis method

35
Spinel ferrite
name
Materials
Mg/Fe
ratio
Preparation
method
Applications Summery References
MgFe2O4
Lemon juice Natural
citric acid, Mg and
Fe nitrate
1:2
Lemon juice assisted
combustion method
Biomedical application
Antibacterial property
investigated
[55]
MgFe2O4/Carbon
Based electrode
MgSO4, HClO4,
Dopamine
Hydrochloride,
Ethanol, NaOH,
Graphite powder
-
Solution-based method Sensors, Biological active
compounds, Injection
samples, transmitters.
Electrochemical
investigation of DA with
detection limit 7.7 * 10-8
M.
[22]
MgFe2O4
Iron and Magnesium
nitrate, N,N-
dimethylformamide,
Ethanol.
1:2 Electrospinning Method
Ferromagnetic nano-
structures, Lithium-ion
batteries, Catalysis, anode
material for nanodevices
and storage devices
Polycrystalline MgFe2O4
NPs (D – 14-24nm).
Applicable to work for
lithium-ion batteries.
[56]
GO/MgFe2O4
MgSO4 (1.2 g) and
FeCl3.6H2O (2.4 g),
3.2 g of NaOH
1:2 Hummer’s method Drug delivery systems
The antibacterial activities
of the prepared
composites toward pure
tetracycline.
[58]
Table 2.8: Magnesium ferrites synthesis methods and their applications.

36
CHAPTER 3
MATERIALS AND METHODS
3.1 Synthesis of Spinal ferrites
3.1.2 Materials:
Commercially reagents catalyst preparation with AR, LR (Laboratory reagent), and ACS grade
chemicals can be used. Ferric Nitrate from ISOCHEM Laboratories was purchased from
Amazon. N-butanol was purchased from Ajanta chemicals, Ahmedabad. Cobalt and Nickle
nitrate were procured from Chem dyes corporation (Extra pure chemical). Mac-dye chem
industries, GIDC, Vatwa, and Ahmedabad graciously contributed Reactive Turquoise Blue
(RB21), a copper phthalocyanine reactive group with (molecular weight=1282.97 g/mol).
Equipment Facilities used from Maulana Azad National Institute of Technology (MANIT),
Bhopal.
List of chemicals Chemical Formulas
Nickle nitrate Hexahydrate Ni (NO3)2.6H2O
Cobalt nitrate Hexahydrate Co (NO3)2.6H2O
Iron nitrate Nonahydrate Fe (NO3)3.9H2O
Magnesium Nitrate Hexahydrate Mg (NO3)2.6H2O
Urea NH2CONH2
Hydrochloric acid HCl
Distilled water H2O
Reactive Turquoise Blue - Rb21 dye C41H25ClCuN14Na4O14S5
Table 3.1: List of all Chemicals Required for Experimentation

37
3.2 REQUIRED EQUIPMENT:
3.2.1. Microwave reactor:
A microwave reactor is used to heat molecules. In this microwave, which has an internal heating
temperature, the temperature controller also played a part (˚C). The purpose is to maintain the
temperature of the reactor's materials under control. It is a completely sealed vessel to keep
radiation from escaping outside of the microwave. The parameter's function is regulated by the
controller located on the right side of the microwave. The microwave reactor has a power output
of 700 W and a frequency range of 2.54 GHz.
Figure3.1: The microwave reactor system (Raga’s scientific microwave)
Energy loss in a dielectric substance owing to delayed polarization or any other dissipative event
is the single loss component in a microwave.
3.2.2 Muffle furnace:
It is the apparatus used to severely heat or burn a material at high temperatures while keeping it
confined to chemicals or other substances. It is frequently lined with stainless steel, which makes
it very corrosive. Various samples were cooked in the furnace at temperatures ranging from 400
˚C to 2000˚C. Depending on the size of the muffle and the various heating elements required
(Kanthal resistive wire, Silicon carbide rods, Molybdenum Disilicate) for a higher temperature of
around 1400˚C. A PID controller is installed in a muffle furnace. There are two elements to the

38
controller: set value and process value (PV). A high-density ceramic fibre blanket is used as
insulation to maintain the outside surface at a low temperature.
Figure 3.2: Muffle furnace (High-temperature furnace 1400˚C)
3.2.3 Magnetic stirrer with Hot plate:
The hot plate is commonly working in the synthesis of combustion with chemical propellants.
With this apparatus, several researchers worked cost-effectively to create high conversion degree
catalysts. To heat the beaker with the liquid within it, a flat surface around or enclosing the
surface of a hot plate is working. The operating temperatures range from 100 to 750 degrees
Celsius, and the voltage range is from 120 to 148 volts.

39
Figure 3.3: Magnetic stirrer with the hot plate
3.2.4 Photoreactor:
The metallic photoreactor is used for dye degradation from synthetic wastewater. The two LED
Blubs is employed as the source of visible light in the areas. The visible colour is highly
monochromatic, emitting a pure colour in a narrow frequency range. Identification of colour by
peak ranges in nanometers. Peak wavelength is the function of the LED chip ranges approx.
600nm is the most sensitive level of light. The perceived colour is yellow and amber from LEDs
than the other one. The magnetic stirrer is placed inside the photoreactor because continuous
stirring is needed for dye solution at the normal temperature seen in the figure.
Figure 3.4: The photoreactor for dye degradation experiment

40
3.3 MICROWAVE SOLUTION COMBUSTION METHOD:
Initially, the components for the Microwave solution combustion technique are combined at the
self-propagating high-temperature synthesis as an alternative route to prepare a wide range of
advanced materials, including metal oxide catalysis. The manufacturing of solid materials is
distinct from the self-sustaining combustion process. In the classic scenario, the reaction is
responsible for both synthesis and heat generation. The majority of the heat is emitted as a
consequence of the oxidation of organic fuel components (e.g., carbon and hydrogen) at certain
temperatures, whereas the target products are largely metal oxides or metals. A large variety of
gases are produced as byproducts of this Novel method. As a result of the gasification, the solid
product expands significantly and cools rapidly after the reaction, resulting in a porous and finely
dispersed solid product.
3.3.1 Spinel Ferrite production -
For the preparation of Spinel ferrites, Stochiometric amounts of oxidizers and fuel (urea) were
combined into a beaker then at 80 °C mixed with continuous stirring for the production. The
solution was then heated on a magnetic stirring and hot plate to enhance the limitation, adding
12M NaOH [8] solution small drop at continuous stirring to modify the pH of the solution. The
pH was adjusted to 7.8, and the contents of the beaker were kept at 80°C for 40 minutes to allow
the precipitates to settle. The Viscous gel formed and was ready for microwave irradiation for 5
mins at 700 W after exothermic reaction and combustion achieved at 146˚C in microwave
heating, during this session a large number of gasses were released CO2 and N2. The materials
were crushed with mortar & pestle. By distilled water three times to assure the elimination of
unreacted ions. In this way, three spinels prepared (CoFe2O4, MgFe2O4, Mg0.5Co0.5Fe2O4)

41
Figure 3.5: Preparation of spinel ferrites (CoFe2O4, MgFe2O4, Mg0.5Co0.5Fe2O4)
3.3.2 Spinel ferrite preparation by Solution combustion method -
Figure 3.6: Solution combustion method for Preparation of Spinel ferrites (Ni0.5Co0.5Fe2O4)

42
To prepare nanomaterials, NixCo1-xFe2O4 (x = 0.5) magnetic nanoparticles were prepared using
solution combustion method. We used analytical grade chemicals such as cobalt nitrate Co
(NO3)2.6H2O, nickel nitrate Ni (NO3)2.6H2O, and iron nitrate Fe (NO3)3.9H2O in this method.
The chemicals were placed in a glass beaker at the determined stoichiometric ratio and swirled
for 1 hour using a magnetic stirrer. The nitrates in this procedure were subjected to a process
known as hydroxide ion production, which was accomplished by introducing NaOH to the mixer
while it was still swirling. The NaOH was taken as 12M NaOH [8] in distilled water; by adding
the NaOH to the solution, it instantly became brown. After 1 hour, the well-stirred solution was
transferred to a 100˚C drier. The nanoparticles generated and reacted particles were then washed
numerous times to clear content in the purification process after the reaction was completed in
the muffle furnace for 5 minutes. Finally, the nanoparticle composition was rinsed with distilled
water and dried again at 100 °C (373 K) for drying and sintering reasons. The fine powder type
sample was collected once the entire procedure was done.
3.4 STOICHIOMETRY EQUATIONS
3Co(NO3)2*6H2O + 6Fe(NO3)3*9H2O + 20NH2CONH2 → 3CoFe2O4 + 112H2O + 20CO2 + 32N2
3Mg(NO3)2*6H2O + 6Fe(NO3)3*9H2O + 20NH2CONH2 → 3MgFe2O4 + 112H2O + 20CO2 + 32N2
3Mg(NO3)2*6H2O + 3Co(NO3)2*6H2O + 12Fe(NO3)3*9H2O + 40NH2CONH2 → 6Mg0.5Co0.5Fe2O4 +
224H2O + 40CO2 + 64N2
3Ni(NO3)2*6H2O + 3Co(NO3)2*6H2O + 12Fe(NO3)3*9H2O + 40NH2CONH2 → 6Ni0.5Co0.5Fe2O4 +
224H2O + 40CO2 + 64N2
3Ni (NO3)2*H2O + 6Fe (NO3)2*H2O + 14NH2CONH2 = 3NiFe2O4 + 37H2O + 14CO2 + 23N2

43
Catalyst
Molecular
weight (M-
Fe2O4)
Weight
(g)
Amount of
M-
(NO3)2.6H2O
(g)
Amount of
Fe
(NO3)3.9H2
O
(g)
Amount of Urea
(used)
(g)
CoFe2O4 234.619 5 6.20 17.21 8.53
NiFe2O4 234.379 5 4.28 8.44 5.97
MgFe2O4 199.991 5 6.41 20.19 10.00
Table 3.2: Calculated table for spinel ferrite by Stochiometric evaluation
Catalyst
Molecular
weight
(M-Fe2O4)
Weight
(gm)
Amount of
M1
(NO3)2.6H2O
Amount of Fe
(NO3)3.9H2O
(gm)
Amount of
Co
(NO3)2.6H2O
Amount of
Urea (used)
(gm)
Mg0.5Co0.5Fe2O4 223.34 5 2.95 18.59 3.34 9.21
Ni0.5Co0.5Fe2O4 234.53 5 3.09 17.22 3.10 8.53
Table 3.3: Stochiometric calculations for Doped spinel ferrites
Reactant Elemental Valences
Total Oxidizing
Valence
Total reducing
Valence
Fe(NO3)3.9H2O
1Fe = +3, 3N= 0, 9O = -18, 9H2O
= 0
-15 -
Ni(NO3)2.6H2O
1Ni = +2, 2N= 0, 6O = -12, 6H2O
= 0
-10 -
Co(NO3)2.6H2O
1Co = +2, 2N= 0, 6O = -12, 6H2O
= 0
-10 -
NH2CONH2 1C = +4, 4H= +4, 2N =0, 1O = -2 - +6
Table 3.4 Oxidizing and reducing valances and quantities of the different chemical reagents used
to prepare the different catalysts.

44
3.5 RB21 Dye degradation set up:
An experimental setup for degradation of RB21 dye under a visible light source is reported in
Fig.3.4. All the experiments were carried out in a photoreactor with two 9W LED HALONIX
bulbs.
Figure 3.7: Dye degradation procedure
Figure 3.8: Centrifugation steps for dye degradation

45
The photocatalytic activity of MgFe2O4, CoFe2O4, Mg0.5Co0.5Fe2O4, and Ni0.5Co0.5Fe2O4
nanoparticles was investigated with Rb21 dye degradation as a probe reaction under visible light
illumination. To achieve adsorption-desorption stability, 20 mg of nanoparticles were thoroughly
dispersed in 100 ml Rb21 solution (20 mg/l, 40mg/l, 60 mg/l, 80mg/l, 100mg/l) using a magnetic
stirrer in the dark for 2 hours. Under steady stirring, the solution was then illuminated with
visible light from two 9W LED bulbs. After that centrifugation to remove/separate the
nanoparticles, the solution was rechecked using a UV–visible spectrophotometer at each time
interval (30,60,90,120,150,180 min).
After every 30 min up to 180 min irradiation time, 3 ml of the suspension sample was withdrawn
and then the solution and particles are separated by a Neodymium magnet (the strongest
powerful magnet). The photocatalytic degradation process can be investigated by UV-Vis
spectrophotometer for colour removal analysis.
3.6 Dye Solution Preparation:
Initially, the 2g of Rb21 dye was taken and dried at 90˚C for 2 hours. The dye solute was
dissolved in 1000 mL of distilled water. Further dilution is required to obtain a solution
containing 20,40,60,80,100 mg/l. The answer is then fitted for the calibration curve. The largest
absorption peak obtained was at 620 nm, which was analyzed using several wavelengths (nm).
The experiment was carried out at different dosages of 20 to 80 mg of catalyst were doped into
the concentration of dye solution. To check the efficiency, the following formula was used:
Percentage (%) =
𝐶0−𝐶𝑡
𝐶0
× 100
Where C0 is the initial concentration, and Ct is the dye degradation concentration.

46
CHAPTER 4
CHARACTERIZATION
The prepared catalyst dosage characterization is important to know deep analysis. XRD (X-Ray
Diffraction) using Rigaku Japan Mini-flex voltage 60kV, SEM (Scanning Electron Microscopy),
TEM (Transmission electron microscopy), UV visible NIR, FTIR (Fourier transform infrared
spectroscopy) using Shimadzu Affinity, Vibrating sample magnetometer (VSM), Thermo
gravimetric analysis (TGA), UV-vis spectrophotometer etc.
4.1 X-ray Diffraction (XRD)
X-ray diffraction (XRD) utilizing RIGAKU – JAPAN (MINI FLEX) at 60kV and 30 mA using
Cu Kα radiation (λ=1.5406) was used to determine the phase analysis. Spectra were taken with a
0.05° step for 2 between 20° and 90°. The standard JCPDS number (Joint Committee on Powder
Diffraction Standards) data bank was used to identify the crystal phase. The programme was
used to derive lattice parameters from the reflections that appeared in the 2ϴ range. The Scherrer
equation (d XRD =0.9λ/cosϴ) with Warrens correction for instrumental broadening was used to
compute the crystal size of the catalyst (d XRD), where d XRD is crystal size and is the
wavelength of Cu-K radiation (-1.5406) [21].
Table 4.1: XRD patterns parameter for MgFe2O4, CoFe2O4, Mg0.5Co0.5Fe2O4
Spinel name
Angle
(2ϴ)311
Crystalline
size (D)
d-spacing
(Å)
Lattice
parameter
(a)
X – ray
density (Dx)
MgFe2O4
35.62
15.45 2.52 8.34 4.58
CoFe2O4 35.991 13.33 2.49 8.24 4.74
Mg0.5Co0.5Fe2O4 36.052 13.24 2.49 8.24 4.74

47
The phase and structural determination of the spinel MgFe2O4 nanoparticles was confirmed by
the XRD technique. The XRD pattern of the MgFe2O4 Nanoparticles shows in Figure 4.1. the
diffraction peaks 2ϴ at 30.22, 33.38, 35.62, 43.15, 57.17, 62.74 are corresponds to (220), (311),
(400), (422), (511), (440) respectively and matched with [8] previous work. The pattern reveals
single phase cubic spinel after microwave heating distracting Mg – Fe bonds at 146-150˚C. The
diffraction peak radially attracts the rhombohedral structure formed. The crystallinity was
observed at the highest peak 35.63˚ is d= 15.45 nm. The Iron oxide or red hematite catalyst
material formed. To the formation of pure crystals in microwave feasibility shown at low
temperature or materials should be fuel lean condition.
20 40 60 80
Intensity
2ϴ
20 30 40 50 60 70 80 90
Intensity
2ϴ
Figure 4.2: XRD PATTERN OF CoFe2O4 with Excel graph
Figure 4.1: XRD PATTERN OF MgFe2O4 with Excel graph

48
Figure 4.2 depicts P-XRD patterns of cobalt ferrite samples obtained at high F/O ratio For either
cobalt ferrite, the pure phase did not arise in this range of F/O ratio values. The F/O ratio has a
significant influence on structural properties and pure phase formation. The ferrite phase in these
samples is deficient in divalent cations, and the α-Fe2O3 and 𝛽-Fe2O3 phases are probably
present in addition to the spinel phase. However, even under fuel-rich conditions, there is no
evidence of the -Fe2O3 phase being produced in any of the cobalt ferrite samples with a divalent
cation deficit. Because the P-XRD pattern of the 𝛾-Fe2O3 phase is similar to that of spinel, it is
difficult to distinguish this phase's contribution to the P-XRD spectra. As an impurity, the
metallic cubic cobalt phase is present, showing that the Co2+
state is reduced to the Co° state
during the combustion process. This illustrates the presence of a reducing environment during
the burning of urea and metal nitrate. Several metallic cobalt impurities were detected as
impurities in the current investigation under fuel-rich conditions. α=90˚, 𝛽=90˚, 𝛾 ≠ 90˚ as a
rhombohedral structure formed. The crystallinity check at the highest peak 2ϴ = 36.00˚ as
d=13.33 nm was evaluated by the Scherrer formula.
Figure 4.3 shows the XRD spectra of the sample. A series of characteristic peaks in the spectrum
agree with the standard Mg0.5Co0.5Fe2O4 XRD spectrum. Cobalt ferrite doped with magnesium
(JCPDS card no 52-0279). The entire sample exhibits a poly oriented structure with numerous
20 40 60 80
Intensity
2ϴ
FIGURE 4.3: XRD PATTERN OF Mg0.5Co0.5Fe2O4 with Excel graph

49
peaks resembling various crystallite planes (220), (311), (400), (511) and (440), which explains
the single-phase cubic spinel structure of Mg0.5Co0.5Fe2O4 . The strength of the peak (3 1 1)
reduces as the pH value drops. The lattice constant for Mg0.5Co0.5Fe2O4 samples is in the 8.24
range. The lattice constant reduces as the pH value increases. This may be explained using cation
stoichiometry. Because the ionic radius of Mg2+
ions (0.69) is less than that of Co2+
ions (0.82),
the drop in intensity of the (311) plane may be due to the migration of Fe3+
ions from the
octahedral position to the tetrahedral site as Co2+
ions are replaced by Magnesium.
4.2 Fourier transforms infrared (FTIR)
The Fourier transform infrared spectroscopy spectra of the catalyst samples used for the
investigation of functional groups and catalyst confirmation was recorded on a Shimadzu FTIR,
MANIT, Bhopal. The spectra were examined between 400 and 4000 cm-1
.
Figure 4.4: FTIR Spectra for MgFe2O4
For the precursor sample, three broad absorption bands were observed at approximately 3454,
1647, and 1384 cm−1
, respectively, corresponding to the presence of hydroxyl groups (-OH), the
stretching vibration of the carboxyl group, and the presence of NO3–
ions. . Two bands in the
MgFe2O4 spectra, at 557 and 430 cm-1
and 443 and 445 cm-1
, could be paired indexed to the
stretching vibrations of metal-oxygen bonds at tetrahedron and octahedron sites, respectively,
indicating the development of magnesium ferrite. Furthermore, large absorption bands at 3695
400 1400 2400 3400
Transmittaance
%
Wavenumber (cm-1)
MgFe2O4

50
and 3795 cm1 are seen, indicating the stretching mode of H2O molecules and hydroxyl groups,
and, as a result, the presence of H2O molecules on the surface of MgFe2O4 nanoparticles.
Figure 4.5: FTIR Spectra for Mg0.5Co0.5Fe2O4
FTIR spectra confirmed the doping effect of the MNPs. Peak around 417 and 506 cm−1
is related
to the Fe-O bond characteristic of an uncoated spinel ferrite. This band shifted slightly for the
Mg0.5Co0.5Fe2O4 at 608 cm−1
. The primary amine groups are strongly evident in the MNP by
stretching N-H vibration at 1388 cm−1
and 1517.44 cm−1
. The MNPs displayed additional peaks
at 888.50 cm−1
and 1073.18 cm−1
respectively, relating to C=O stretching vibrations. This shift
was more pronounced in Mg0.5Co0.5Fe2O4 at 1062.44 cm−1
. Mg0.5Co0.5Fe2O4 NPs displayed
strong C - H bands at 2876.88 cm−1 and 2309.50, 2357.72 cm−1
while peaks around 3751.72,
3840.28 cm−1
were observed in all the NPs corresponded to the O-H group.
400 1400 2400 3400
Transmittance
%
Wavenumber (cm-1)
Mg0.5Co0.5Fe2O4

51
Figure 4.6: FTIR Spectra for CoFe2O4 with excel graph
Figure 4.6 depicts the FTIR spectra of the samples. The FTIR spectra of spinel ferrites have
peaks that correspond to tetrahedral and octahedral sites. Only peaks related to tetrahedral
stretching vibration and hydrogen-bonded O-H stretching (3400 cm-1
) are seen when the FTIR
spectrometer is used in this study. Although octahedral stretching may be seen, the peaks are not
resolved. The metallic impurity phases lack distinguishing IR vibrations, while the other
impurities, which are metal oxides, have almost identical peak positions and hence are difficult
to distinguish. The FTIR spectra of the samples created fuel in rich circumstances exhibit a
modest nitrate signal at 1384 cm-1
, indicating the presence of residues of precursor metal nitrates
in the sample. At 589.94 cm-1
, the relative Fe-O bond was revealed. At 419.63 cm-1
, the metal
tetrahedral site was discovered. At 1055.74 cm-1
, the Fe-Co bond was detected. The stretching
and bending vibrations of hydroxyl groups cause the absorption bands detected at 3450.41 cm-1
and 1652.87 cm-1, respectively. The anti-symmetric stretching vibration of NO3- caused by
residual nitrate is significantly associated with the band at 1384.89 cm-1
.
400 1400 2400 3400
Transmittance
%
Wavenumber (cm-1)
CoFe2O4

52
CHAPTER 5
RESULTS AND DISCUSSION
5.1 DYE DEGRADATION ANALYSIS (UV-VISIBLE SPECTROPHOTOMETER)
The colour degradation of dye samples was measured using absorbances values. A UV-visible
spectrophotometer at wavelength max = 620 nm was used to measure dye de-colorization. Over
the wavelength range of 340-999 nm, the band-gap investigation was performed using A vis-
double beam spectrophotometer 1203.
5.2 EFFECT OF DYE CONCENTRATION:
The dye was made in various concentrations (20, 40, 60, 80, and 100 mg/l). The absorbance
spectra of various concentrations of solutions were measured, and the maximum absorbance was
recorded. All absorbance measurements were taken at 620 nm, the wavelength with the
maximum equivalent absorption of Reactive turquoise blue - Rb21 dye. A graph of absorbance
against concentration was constructed. As the dye concentration grew, so did the degradation, as
seen by the graph. In addition, a microwave solution combustion approach was used to
synthesize a photocatalyst having a heterojunction structure. When exposed to visible light. UV-
visible spectra of dye degradation (a) as a function of time, (b) as a function of catalyst dose and
(c) at different dye initial concentrations. The deterioration of Reactive turquoise blue (RB21)
dye was proposed in a prior study. The photocatalytic effectiveness of Rb21 photodegradation
has been improved. The heterogeneous catalyst was used to achieve this action. The elimination
of Rb21 has mostly been triggered by the consumption of conduction band electrons and
valence-band holes, both of which play major roles in photocatalytic activity. The spectrometry
of visible light diffusion reflectance was carried out. These results suggest that they are
distributed to form heterogeneous catalytic complexes capable of absorbing visible light. The
degradation of reactive turquoise blue (Rb21) revealed a heterojunction fraction that boosted
visible light absorption for photocatalytic activity with increasing concentration.

53
Figure 5.1: (a) Initial Dye absorbance in multiple concentration (b) Calibration curve at 620nm
y = 0,0134x
R² = 0,9901
0
0,2
0,4
0,6
0,8
1
1,2
0 10 20 30 40 50 60 70 80 90 100
absorbance
Concentration (mg/L)
Cablibration curve for Rb21 dye at λ=620 nm
620nm

54
Figure 5.2: Calibration curve (concentration vs absorbance)
The calibration curve between dye concentration (20 mg/L, 40 mg/L, 60 mg/L, 80 mg/L, and 100
mg/L) and absorbance was determined using the Visible spectrophotometer 1203. At 620 nm, the
true straight-line outcomes occurred. R2= 0.9972 was obtained, and data kinetics were recorded
by a 0.0134 value. It is now time to examine the "y" value to determine the final dye
concentration.
Figure5.3: Rb21 Dye degradation by MgFe2O4
20mg/L 40mg/L 60mg/L 80mg/L 100 mg/L

55
Figure 5.4: Pseudo first-order kinetic graph
Rb21 dye C0(ppm) R2
K (min-1
) T1/2 (0.693/k)
20 9796 0.0143 48.46
40 9873 0.0147 47.14
60 9943 0.0093 74.51
80 9771 0.0083 83.49
100 9864 0.0073 94.93
Table 5.1: Pseudo first-order absorption kinetics
y = 0,0143x
R² = 0,9481
y = 0,0147x
R² = 0,9568
y = 0,0093x
R² = 0,9832
y = 0,0083x
R² = 0,9428
y = 0,0073x
R² = 0,9504
0
0,5
1
1,5
2
2,5
3
0 20 40 60 80 100 120 140 160 180
-log(c/co)
time (min.)

56
Figure 5.5: Dye removal in multiple concentrations with MgFe2O4 dosage in presence of visible
light/H2O2.
5.2.1 Effect of pH:
The pH of the system influences the catalytic activity that occurs on the catalyst surface, which
acts as a Lewis acid, and the surface of the dye, which acts as a Lewis base, or vice versa, as the
first step of dye degradation is adsorption, which depends on the electrostatic interaction and
binding affinity between the dye molecule and the catalyst surface, moderate adsorption is
beneficial for dye degradation, and this is affected by the pH of the system, and dyes get
adsorbed on the surface. When the temperature rises, desorption begins, which is not good for
dye degradation because only a small amount of dye must be deposited on the surface;
additionally, rising temperatures increase charge carrier recombination, reducing available
radicles for reactions. As can be observed, when the pH is acidic, the results are much better
since RB21 is a basic dye, and there is an improvement in elimination efficiency in terms of
time. Experiments were carried out at three different pH values, as illustrated in Figure 5.6
above: 4, pH 6, and pH 8.

57
The mechanism of the fluctuation of photocatalytic effectiveness with pH change has been
investigated. The following is a summary of the reaction formula: -
According to Equations (1) – (3), the generation of OH radicals during light stimulation is
mediated by positive holes interacting with H2O and OH' on the photocatalyst surface. If the
concentration of H+ ions is too high or in the acidic state, the excitation of H2O and OH' into
OH radicals is repressed owing to an excess of H+ and a deficiency of OH'. Furthermore, when
the pH exceeds the p Ka, the reaction in Equation (5) proceeds inversely and is therefore
blocked. As a result, the reaction system will contain fewer HO2 radicals with decreased redox
potential and oxidizing capability. Equations (6) – (8) are suppressed by the absence of HO2
radicals, and these reactions will also impede oxidation since they create oxidizing chemicals
that are lower in oxidized. To conclude, the photocatalyst will have more oxidizing activity at
neutral or higher pH levels. For pH values ranging from 4.0 to 8.0, the dye residual
concentrations were measured. This suggests that within this pH range, the photocatalysis
efficiency stays constant. When the pH was raised to 8.0, the final concentration of dye was
lowered to 22%, and the rate constant increased. Phenomena appear to be related to the
hypothesis that photocatalytic performance is better at neutral pH or higher. The correlation
coefficient of degradation findings suited by pseudo-first-order kinetics when pH = 8.0 was 0.95,
but the correlation coefficient of results at other pH levels was greater than 0.9. It is reasonable
to believe that some process other than photocatalysis causes the data to be unfitted by pseudo-
first-order kinetics. Rb21 dye will be destroyed only by visible light irradiation, and the impact
was pH-dependent. The residual concentration of dye after 120 minutes was roughly 60% in a
pH range of 4.0 to 8.0, whereas it was only 23% at pH = 8.0, indicating that visible light
photolysis might induce dye degradation. The absorption spectra of dye redshift as the pH

58
increases. The number of photons absorbed per unit time rose as the absorption spectra shifted to
the visible light area as pH values climbed, resulting in improved photolysis efficiency at higher
pH. At pH values ranging from 4.0 to 8.0, the residual concentrations of the blank test were
greater than those of the photocatalysis tests. Because the adsorption test demonstrated that the
catalyst had a poor adsorption capacity, the beginning concentrations for photocatalysis and the
blank test were almost identical. The turbidity increase is anticipated to impair the photolysis if
additional particles were introduced instead of the photocatalyst. As a result of the increased
degradation efficiency caused by the addition of a catalyst, photocatalysis plays a role in the
degradation. When the pH level was 8.0, the findings of the two tests were essentially equal. The
degradation results given above were achieved with the use of a Spectrophotometer. The findings
reveal that the efficiencies of photolysis and photocatalysis on dye are pH-dependent. It was
challenging to measure the true effect of visible light photocatalysis degradation of dye under
various pH conditions using only a spectrophotometer as the reference. As a consequence,
measurements were utilized to assess changes in photocatalysis efficiency. The difference in dye
concentration levels after photolysis across experimental groups with different starting pH values
was almost non-existent. After 60 minutes of adsorption, the residual dye concentration was
lowest at pH = 6.0. The catalyst's isoelectric point is 6.0. As a result, the repulsive force between
the dye molecule and the catalyst is the weakest at pH = 6.0, and the adsorption capacity is
greatest at pH = 8.0. When it came to residual dye concentration following photocatalysis after
180 minutes, the best result was likewise at pH = 8.0. The phenomenon of optimal adsorption
and photocatalysis removal at the same pH = 8.0 rather than at higher pH may be because dye
adsorption on the photocatalyst decreases with increasing pH, making OH radicals entering the
solution the rate-determining step, which decreased dye degradation at higher pH. According to
the pH values, the best dye degradation efficiency was observed at pH = 8.0. Because visible
light photocatalysis may be difficult to accomplish dye reduction, the measurement may be a
useful technique to eliminate the impact of visible light photolysis and meet the aim of
measuring the real degradation efficiency of visible light photocatalysis. In this investigation, the
dye measurement was used in all of the deterioration experiments.

59
5.2.2 Effect of H2O2 Dosage:
The degradation capacity of the Fenton-like system by Catalyst on dye concentration was
evaluated. The Fenton-like system used an M-Fe2O4 (Mg, Co) dosage of 20 mg and a pH of 8.0.
The initial dye concentration was 20.0 mg/L, and the H2O2 dosages were chosen to be 5 ml from
30% w/v (diluted).
As demonstrated in Figure 5.7, the apparent rate constant fitted by pseudo-first-order kinetics
had the largest apparent rate constant and the lowest residual dye concentration. Figure 5.5
shows the residual dye concentration after 180 minutes of photocatalytic degradation as
measured by a UV-vis spectrophotometer. The final dye concentrations were the lowest at an
H2O2 dose of (5ml quantity consumed) 30 per cent w/v (100 volumes) (diluted). The following
reactions are thought to be involved in the mechanism of the heterogeneous Fenton-like system
triggered by iron-containing catalysts.
Figure 5.6: pH solution at (4.0,6.0,8.0) with MgFe2O4

60
First, in the equation, H2O2 forms a complex with Fe (III) sites on the catalyst surface (1). In
Equation, the Fe (III) sites in this complex are then transformed into Fe (II) sites (2). In
Equations (3) and (4), surface Fe (II) interacts with H2O2 to generate OH and Fe (III) (4). H2O2
in excess will react with O. First, H2O2 forms a complex with Fe (III) sites on the catalyst
surface in equation (1). The Fe (III) sites in this complex are subsequently converted to Fe (II)
sites in Equation (2). In Equations (3) and (4), surface Fe (II) interacts with H2O2 to generate OH
and Fe (III) (4). Excess H2O2 will react with OH to form HO2 with a lower oxidation capability.
This might explain the reduction in oxidation efficiency during the H2O2 overdose in this test.
Figure 5.4 depicts the breakdown of dye by H2O2. H and generate HO2 with a lower oxidation
capability. This might explain the reduction in oxidation efficiency during the H2O2 overdose in
this test. Figure 5.4 depicts the breakdown of dye by H2O2. With a catalyst, the removal rate,
reaction speed, and removal rate all decrease. Catalyst does act as a catalyst in this test.
According to the test, the optimal dose pair of Catalyst and H2O2 was 20 mg and 5 ml diluted, 20
mg/L, respectively. In terms of optimal reaction rate and dye removal, the Fenton-like
photocatalytic degradation system excelled the photocatalysis test. As a consequence, the
catalyst outperformed the photocatalyst as a heterogeneous Fenton catalyst.
5.3.3 Catalyst Effect Without H2O2:
The reported findings are very low when compared to the H2O2 dosage, demonstrating that the
catalyst does not react with aqueous solutions of varying dye concentrations. The solution was
kept in the dark by utilising high voltage visible light bulbs, and no mercury was present. Every
hour, the influence of light energy on dye concentration solutions was investigated. Without

61
H2O2, the dye percentage removal with a certain catalyst dosage was seen after 7 hours, i.e.,
80% degradation. Furthermore, due to the inclusion of visible light energy in the Catalyst
dosage, the concentration will be lowered. Adsorption in Rb21 dye solution is also facilitated by
the Catalyst. Figure 5.7 shows how concentration rises and efficiency declines. The dye is
readily reactive with a catalyst dose of 20mg/l solution. In the presence of a deteriorated or
fractured visible light area, the dye molecules produce better results, as seen in figure 5.5.
Figure 5.7: Rb21 dye % removal in absence of Hydrogen peroxide with 20 mg MgFe2O4
5.3.4 Effect of Catalyst Dosage:
Various levels of MgFe2O4 NPs were investigated to determine the effect of photocatalyst dose
on de-colourization. In this test, 20 to 80 mg of catalyst was employed in a 60 mg/L
concentration of RB21 for 180 minutes. Figure 5.8 depicts the photocatalyst impact of MgFe2O4
on dye de-colourization percentages for 180 minutes. It is possible that raising the catalyst
concentration produces an increase in dye removal. When the catalyst dose was increased, the
number of reactive radicals produced and the number of active reaction sites on the photocatalyst
increased, resulting in a higher percentage of degradation. As a result, 80 mg was observed as an
appropriate catalyst dosage for this test.
0
10
20
30
40
50
60
70
80
90
1 2 4
Removal
percentage
Time (hrs.)
20 ppm
40 ppm
60 ppm
80 ppm
100 ppm

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