This document discusses dyes and their adsorption using orange peel extract. It provides information on types of dyes and their harmful effects on wastewater. The document then describes an experiment where Congo red dye and methylene blue dye were adsorbed using orange peel extract over different time intervals. The percentage removal of Congo red dye was highest (23.25%) at 100 minutes, while methylene blue dye reached the highest removal rate (11.25%) at 20 minutes. In conclusion, the percentage dye removal increased with contact time and further experiments could explore additional dyes and adsorbents.

1. - Ajay Singh

2. Dyes-
 Organic compounds that can provide bright and lasting color to other
substances.
 Dyes absorb wavelengths in the visible
spectrum (400nm-720nm)
TYPES
NATURAL
SYNTHETIC
 Used in the textile, leather, paper, rubber, plastic, pharmaceuticals, food
industries, etc.
 Difficult to biodegrade because of their complex aromatic molecular
structure which makes them more stable.
 Treatment process involves use of chemicals which lead to secondary
pollution.

3. Wastewaters
Features
High BOD
High COD
Visible Pollutant
Hot, alkaline and contain
high amounts of
dissolved solids
Harmful effects
Toxic
Carcinogenic
Mutagenic
Teratogenic
Retards photosynthetic activity
Inhibits growth of aquatic biota
Adsorption- Adhesion of atoms, ions, or molecules from a gas, liquid, or dissolved solid
to a surface.
Types
Physisorption (characteristic of weak van der Waals
forces)
Chemisorption (characteristic of covalent bonding).
It may also occur due to electrostatic attraction.

4. ADSORBATE ADSORBENT
 Congo red dye
 Methylene blue dye
 Orange peel extract

5. Preparation of stock (1g/L) of dyes.
Addition of 0.25g absorbent in 25ml sample
Removal of sample at different time intervals
Calculate percentage removal
Colorimetric reading congo red at 497 nm and
methylene at 590 nm.

6. CONGO RED DYE ADSORPTION
METHYLENE BLUE DYE ADSORPTION

7. (1) Congo red: The percentage removal was obtained by calculating the
difference between initial and final optical density of dye solution at 497nm.
Optimum percentage removal was found to be 23.25% at 100mins.
Time in
minutes
Percentage
Removal of
Congo Red
dye
20 5.62
40 10.12
60 14.50
80 18.75
100 23.25

8. (2) Methylene blue: The percentage removal was calculated by calculating the
difference between initial and final optical density of dye solution at 590nm.
Optimum percentage removal was found to be 11.25% at 20mins.
Time in
minutes
Percentage
removal of
methylene blue
dye
2 -
4 0.87
6 1.63
8 3.25
10 1.63
12 2.75
14 3.25
16 7.50
18 7.75
20 11.25
Percentage removal of Methylene Blue dye solution (%)

9. The percentage
removal of dye
from congo red
solution by orange
peel was found to
be
5.62%,10.12%,14.5
%,18.75% and
23.25% at time
interval of
20,40,60,80 and
100mins
respectively.
Congo
red
Percentage removal
was found to be
0.87%,1.63%,3.25
%,1.63%,
2.75%,3.25%,7.50
%,7.75%,11.25% at
time interval of
2,4,6,8,10,12,14,16,
18 and 20mins
respectively.
Methylene
blue
 Batch absorption method was used for dye absorption study.
 Percentage removal of both the dye increases with increase in time.
 To try and find various other waste materials to be used as adsorbents.
 To test adsorbent activity of other group of azo dyes such as azo violet,
Janus green B, Erichrome Black T, etc.