The ppt. is composed of the nanocatalyst and nanozymes applications.

1. Nanocatalyst and and
Nanozymes in removal
of heavy metals.
BY ARKA DEBNATH
(RA1611009010145)

2. What are Nanomaterials?
• Nanomaterials, structures with at least one dimension with less than
100 nm in size, have been developed in a range of forms such as
nanowires, nanotubes, particles, quantum dots and films.
• Nanomaterials are constantly studied, and numerous applications are
continuously developed in different fields, such as: catalysis,
medicine, sensing, bio-labelling, textile industry, etc
• The application of nanomaterials for the detection and removal of
pollutants from wastewater is constantly gaining importance due to
their small sizes that especially means large specific surface area
and thus strong absorption capacity, strong reactivity and increased
mobility in solutions.

3. Different applications of nanomaterials:

5. What are Nano-Catalysts?
• Nano-catalysts are the second class of nanomaterials used
with good results in wastewater treatment and it mainly
includes metal-oxides and semiconductors. The
degradation process of pollutants in wastewater employs
using different types on nano-catalysts such as
electrocatalysts, Fenton-based catalysts and catalysts that
possess antimicrobial activity.

6. Nanocatalysts in water treatment:
• Nano-catalysts in wastewater treatment are focused mainly
on inorganic materials such as semiconductors and
different metal oxides. Different types of nano-catalysts are
used such as photocatalysts, electrocatalysts and Fenton
based catalysts that increase the chemical oxidation of
organic pollutants
Nanocatalysts
Photocatalysts Electrocatalysts
Fenton based
catalysts

7. Photocatalysts:
• Photocatalysts comprise of semiconductor metals able to degrade
numerous organic pollutants such as dyes, pesticides and volatile
organic compounds . Also, semiconductor nano-catalysts are
effective in removing halogenated and non-halogenated organic
compounds, PCPPs and heavy metals.
Basic Mechanism:
• The mechanism involves the photoexcitation of electrons. Upon
light irradiation, holes (h+) and excited electrons (e-) are
generated in the conducted band. In an aqueous environment, h+
are filled with water molecules to generate hydroxyl radicals (·OH)
that are powerful oxidizing agents against organic pollutants

8. Production of Hydoxyl Ion:
Function of Hydoxyl Ion:

9. Various photocatalysts have been developed and studied and, among
them, TiO2 is the most important and widely applied photocatalyst mainly
because it is highly reactive upon ultraviolet exposure and is chemically
stable. Similarly, ZnO has also been studied as it also contains a wide
band gap. A study published in 2011 revealed that the photocatalytic
degradation efficiency of ZnO decreases when a high calcination
temperature is applied that leads to an increased particle size as a
consequence of agglomeration.
Limitations:
Although nanocatalysts are widely known for their catalytic activity,
they present the disadvantage of being activated only under ultraviolet
light. Therefore, recent researches are focusing of modifying these
catalysts so that their activity is increased upon irradiation with visible
light. In the last decade, different doped nannocatalysts were
developed including ZnO:Co, ZnO:Ni, ZnS:Mn, CdS:Eu, ZnSe:Mn.
Dopants such as Cr, Si, Co, Mg, Mn, In and Ga enhance the surface
area of metal oxide nano-structures while anions (e.g. nitrogen) suites
better in industrial applications.

10. Other processes of sensing and
detection of heavy metals:
•Nanocatalysts also help to detect water-borne contaminants
like heavy metals.
•A new type of nanomaterial called nanostructured silica has
bn found to detect heavy metals.
•It has a large surface area and regular pores, has the
capability of being able to extract heavy metals from
wastewaters.
•Electrodes are seperated with a small atomic gap so a few
ions can be detect.

11. What are Nanozymes?
• A nanozyme is any inorganic nanoparticle (bare or surface
modified) that mimic the catalytic properties of various enzymes.
A typical example is Fe3O4 nanoparticle which is well know for
mimicking the peroxidase
Advantage over Natural Enzymes:
. Nanozyme posses various advantages over natural
enzymes such as
• high stability
• ease of storage
•easy synthesis .
However, turn over numbers and selectivity are not high
enough to compare with natural enzymes.

12. Applications of Nanozymes:

13. Nanozymes :
Nanozymes mimics the properties of certain compounds :
Antioxidant nanozymes-
In the biological system, antioxidants are required to protect the cells/tissues
from damage imposed by the excess of free radicals, generated during the
normal biochemical reactions of the body. Among inorganic antioxidants,
cerium oxide nanoparticles (CeNPs) are reported by Self and colleagues to
exhibit scavenging of superoxide radicals and degradation of hydrogen
peroxide under in vitro, in vivo, and other animal models
• Superoxide Dismutase Mimetic Nanoparticles
• Catalase Mimetic Nanoparticles
Pro- oxidant Nanozymes-
The term “pro-oxidant nanozymes” refers to the action of nanozymes which
induces oxidative stress by producing free radicals in mammalian cells or
inhibiting their antioxidant system.
• Peroxidase mimetic Nanoparticles
• Oxidase mimteic Nanoparticles

14. As such heavy metal removal processes using nanozymes
have not been introduced. In present research is going on
this sector of nanotechnology in bioremidiation.
As mentioned earlier nanozymes, exhibit intrinsic enzyme-
mimetic activity similar to that of natural peroxidases (e.g.,
horseradish peroxidase, HRP), which can catalyze H2O2-
mediated oxidation of peroxidase substrates.
Changes in the colorimetric or fluorogenic response of the
solution are correlated to Hg2+ concentration.

15. Drawback:
• Expensive
• Complicated surface modifications.
• Require sophisticated analytical Instruments for reading out.
Hence more cheap and affordable methods are introduced:
Paper-based devices are a portable, user-friendly, and affordable
technology of analytical tools for inexpensive diagnostic devices. Most
PADs are fabricated by a simple wax printing method to create
hydrophilic/hydrophobic patterns for fluid transport via capillary action,
and are commonly used for colorimetric analysis owing to the high
color contrast on paper substrates21. The assay results can be directly
interpreted by the naked eye and quantified using a mobile camera
instead of bulky instruments, making PADs ideal for onsite monitoring
application

16. • A gold nanozyme-based paper chip (AuNZ-PAD) is
presented for simple, rapid, sensitive, selective, and cost-
effective detection of trace Hg2+ in aqueous systems.
• Gold nanoparticles were present to identify the formation of
Hg-Ag alloy by the formation of blue stain on PAD.

17. CONCLUSION:
• Each technology has its own advantages and specific
efficiency for removing pollutants. Nano-adsorbents are
efficient for the removal of heavy metals (Cr, As, Hg, Zn,
Cu, Ni) from wastewater while nanoparticle photocatalysts
are used for both toxic pollutants and heavy metals.
• Further research on nanozymes are going on which will
help in future in dealing with further issues in the
environment .

18. THANK
YOU