1. Maliha Parvin M.Sc. Program Department of Chemistry, UAE University
Adsorption of Dyes on Activated Carbon from Agricultural Wastes. (Literature Review)
Maliha Parvin
M.Sc. Program
Department of Chemistry, UAE University

2. Outline
Introduction
Review
Conclusion
References

3. Introduction
Dyes are natural or synthetic compounds that make the world more beautiful .
Dyes are also considered as pollutants.
Dyes are used to add or change the color of something.
They have a wide range of applications in : 1. textiles, 2. leather, 3. cosmetics, 4. paper, 5. pharmaceuticals,6. plastics,7.printing inks, 8. alimentary industry, 9. graphics industry and advertising,10. construction industry.

4. Effects on Human
Triple primary cancers involving kidney, urinary bladder and liver of dye workers have been reported.
Textile dyes can cause allergies such as contact dermatitis and respiratory diseases, allergic reactions to eyes, skin irritation, and irritation to the mucous membrane and the upper respiratory tract.
On the molecular level, azo dyes have toxic effects. They can be carcinogenic and/or mutagenic, are metabolized by intestinal microorganisms causing DNA damage.
allergies
skin irritation

5. Effects on the Environment
Dyes lead to low biochemical oxygen demand (BOD), high chemical oxygen demand (COD), altered pH, changed color and salinity of the water.
Very small amounts of dyes in the water are highly visible, seriously affecting the quality and transparency of water and damaging the aquatic environment.
The highly toxic and mutagenic dyes decrease light penetration and photosynthetic activity, causing oxygen deficiency and seriously influencing the food chain.

7. Different Methods for Dyes Removal
From above discussion, dyes must be separated and eliminated from industrial wastewaters by effective and possible treatments.
Separation processes are based on
Fluid mechanics (sedimentation, centrifugation, filtration and flotation).
Synthetic membranes (micro-, ultra- and nano-filtration, reverse osmosis).
Physico-chemical processes (i.e. adsorption, chemical precipitation, coagulation-flocculation, and ionic exchange).

8. Precipitation, coagulation-flocculation have some limitations
Precipitation, coagulation-flocculation have some limitations . Not all dyes agglomerate. Also, the processes have selected operating conditions.
Ion exchange is not effective for all dyes . It has specific application.
Membrane filtration have high running costs. Concentrated sludge production and dissolved solids are not separated in this process.
Activated carbon is good to remove a variety of dyes. It is very expensive, if industrially produced carbons are used, and can lead to a cost intensive regeneration process.

9. However, activated carbon is the most operational adsorbent for dyes.
There is a great interest to find low cost sources for activated carbon derived adsorbents for dyes.
Industrially prepared activated carbon for the dye removal is environmentally costly.
Availability is the most important factor to choose biomass for biosorption.
Locally available and low-priced agricultural wastes such as date palm leaflets (Phoenix dactylifera) could be one solution.
activated carbon

10. Adsorption capacity of the activated carbon depends on surface functionalities, surface area and pore characteristics of the pores formed during the activation process.
Pore size
Micropores
(<2 nm)
Macropores
(>50 nm).
Mesopores
( nm)

11. Types of Adsorption experiments commonly carried out
Batch experiments
Dynamic adsorption experiments
capped plastic flask
automatic sample collector
Determine the adsorption isotherm .
Observe pH , temperature, contact time, adsorbent, particle diameter, etc.
Dye adsorbed per gram of adsorbent at equilibrium is expressed by
qe=(C0 − Ce)V/m
mechanical shaker

12. Characterization of Activated Carbon
surface functionalities surface area(SBET) and pore size surface structure
Fourier transformed infrared (FT-IR) Brunauer–Emmett–Teller(BET) SEM
Ashing of the carbon will lead to ash content analysis. Important is the determination of the inorganic salts, some of which will have changed during the activation(XRD).

13. Modeling isotherms for Biosorption
Thermodynamic Equilibrium Kinetic Equilibrium
Linear adsorption isotherms Non-linear isotherms
Langmuir Freundlich Temkin Fritz–Schlunder
single-component isotherms multi-component
An isotherm describes the relationship between the amount of dye adsorbed and the dye concentration remaining in solution.
Kinetic models are used to investigate the controlling mechanism of the sorption process such as chemical reaction, diffusion control and mass transfer.
The thermodynamic parameters for the adsorption process are obtained by carrying out the adsorption experiments at different temperatures

14. Agricultural residue : orange (Citrus sinensis) peel
Pretreatment
(washing, cutting, drying ,sieving…)
Chemical activation with H3PO4
Soak for 2h at 110 ◦C
Temperature 4750 C,
heating rate 3 ◦C/min ,0.5h
Rinse with distilled water and drying
“Activated carbon developed from orange peels:Batch and dynamic competitive adsorption of basic dyes.” (2014), Argentina

15. High specific surface area (1090 m2/g)
Activated carbon from orange peels was used as an adsorbent to remove two basic dyes, methylene blue (MB) and rhodamine B (RhB).
High specific surface area (1090 m2/g)
Mesopores and acidic character of the carbon surface.
The activated carbon was found to have high adsorption capacity for both dyes in batch and dynamic modes.
Experimental equilibrium isotherms fitted the Langmuir–Freundlich model.
rhodamine B (RhB).

16. Agricultural residue : coffee husk
Pretreatment
(washing, cutting, drying at 378K for 12 h, sieving.)
Carbonization at 673K, heating rate 10 K/min
Char produced at 973 K with NaOH pellets
Washed with hot deionized
water and 0.1M HCl and dried
“Equilibrium, kinetics and thermodynamic of Remazol Brilliant Orange 3R dye adsorption on coffee husk-based activated carbon.” (2011), Penang, Malaysia

17. Adsorption of RBO3R was favorable at acidic pH.
Coffee husk based activated carbon (CHAC) was used to remove Remazol Brilliant Orange 3R (RBO3R) dye from aqueous solutions.
Adsorption of RBO3R was favorable at acidic pH.
The adsorption uptake was found to increase with increase in initial RBO3R concentration, contact time and solution temperature.
Langmuir isotherm model fitted well the adsorption equilibrium data with maximum adsorption capacity of mg/g at 303 K and follow the pseudo-second-order kinetic model.
Chemical structure of RBO3R dye
C20H17N3Na2O11S3 with molecular weight of g/mol.

18. Agricultural residue : rambutan (Nephelium lappaceum) peel
Pretreatment
(washing, cutting, drying at 1050C for 24h ,sieving…)
chemical activation by KOH under microwave heating
Carbonization at 7500C, heating rate 100 C min-1 for 2h
Rinse with distilled water and drying
“Preparation of activated carbons from rambutan (Nephelium lappaceum) peel by microwave-induced KOH activation for acid yellow 17 dye adsorption.” (2014), Kelantan, Malaysia

19. Rambutan peel was used to prepare activated carbon to remove acid yellow 17 (AY 17).
AC characterized by pore structural analysis, zero-point-of-charge (pHpzc), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM).
Mesoporous texture( average pore diameter lies between 2 and 4 nm)
The experimental adsorption isotherms were modeled using the Langmuir, Freundlich and Temkin equations and pseudo-second-order kinetic model was better described for the adsorption process.
The best fit was obtained with the Langmuir isotherm model, proceeds by a monolayer formation.
Maximum monolayer adsorption capacity of AY 17 was mg g-1.
Chemical structure of AY 17

20. Agricultural residue: sugarcane bagasse pith
Pretreatment
(washing, cutting, drying at 1050C for 24h ,sieving…)
chemical activation with 28% H3PO4 (AC1), 50% ZnCl2 (AC2)& by physical activation in absence of air (AC3)
pyrolysis at 600°C
Rinse with distilled water and drying
“Removal of reactive dye from aqueous solutions by adsorption onto activated carbons prepared from sugarcane bagasse pith.” (2007), Alexandria, Egypt.

21. Bagasse pith from sugarcane was used to prepare different activated carbons to remove reactive orange (RO) dye.
Adsorption data were modeled using the Langmuir and Freundlich adsorption isotherms. Adsorption kinetic data were tested using pseudo-first-order, pseudo- second-order and intraparticle diffusion models.
Kinetic studies showed that the adsorption followed pseudo-second- order reaction with regard to the intraparticle diffusion rate.
Structure of reactive orange dye.

22. Agricultural residue : coconut shell
Pretreatment
(washing, cutting, dried at 1100C for 24 h ,grinding and sieving)
Chemical activation by H2SO4
Carbonization of dried at 5000C for 2 h
at a rate of 100C/min
Rinse with distilled water and drying
“Kinetics and equilibrium study for the adsorption of textile dyes on coconut shell activated carbon.” (2014), Hilla, Iraq.

23. The adsorbent was characterized with FT-IR, and SEM.
Coconut husk was used to prepare activated carbon to remove textile dyes (maxilon blue GRL, and direct yellow DY 12).
The adsorbent was characterized with FT-IR, and SEM.
Adsorption of both GRL and DY 12 dyes was favorable at acidic pH.
The adsorption was increased with increasing in initial dye concentration and contact time. But, adsorption decreased with the amount of adsorbent, particle size, and temperature of the system.
The equilibrium data were evaluated using Langmuir, Freundlich, Temkin and Fritz–Schlunder isotherms. The Fritz–Schlunder model best describes the uptake of (GRL andDY12) dye, which implies that the adsorption of textiles dyes onto coconut husk activated carbon is heterogeneous with multi-layers.
Chemical structures of dyes maxilon blue (GRL), and direct yellow (DY 12).

24. The pseudo-second order exhibited the best fit for the kinetic studies, which indicates that adsorption of (GRL, andDY12) is limited by chemisorption process.
Thermodynamic parameters such as Gibbs free energy, enthalpy and entropy were determined. It was found that (GRL and DY 12) dye adsorption was spontaneous and endothermic.

25. Dye adsorption performance onto some natural adsorptive materials.

26. Conclusion
In every country , the economy plays a vital role. So, it is better to find out low-cost adsorbents.
All the used agricultural wastes above are environmentally friendly, cost effective and locally available. These can be used as alternative biosorbants for successful removal of reactive dyes from aqueous solutions.
The developed activated carbons from the literature showed high adsorption capacity for reactive dyes .
All the papers described how to make activated carbon but they do not tell us how to recycle the activated carbon. Spent adsorbant must be either regenerated or incinerated .

27. Date palm leaflets are readily available in the Middle East, including in the United Arab Emirates (UAE) and present one of the most abundant agricultural wastes in the area.
The date palm leaflets can be used in the preparation of activated carbons for the removal of dyes and heavy metal ions.

28. References
Maria Emilia Fernandeza, Gisel Vanesa Nunella, Pablo Ricardo Bonellia, Ana LeaCukiermana,(2014), “Activated carbon developed from orange peels:Batch and dynamic competitive adsorption of basic dyes.” Industrial Crops and Products 62(2014)437–445.
Mohd Azmier Ahmad, Nazira Khabibor Rahman,(2011), “Equilibrium, kinetics and thermodynamic of Remazol Brilliant Orange 3R dye adsorption on coffee husk-based activated carbon.” Chemical Engineering Journal 170 (2011) 154–161
V.O. Njoku , K.Y. Foo , M. Asif d, B.H. Hameed ,(2014), “Preparation of activated carbons from rambutan (Nephelium lappaceum) peel by microwave-induced KOH activation for acid yellow 17 dye adsorption.” Chemical Engineering Journal 250 (2014) 198–204
Nevine Kamal Amin,(2007), “Removal of reactive dye from aqueous solutions by adsorption onto activated carbons prepared from sugarcane bagasse pith.” Desalination 223 (2008) 152–161
Aseel M. Aljeboree , Abbas N. Alshirifi , Ayad F. Alkaim ,(2014) “Kinetics and equilibrium study for the adsorption of textile dyes on coconut shell activated carbon.” Arabian Journal of Chemistry (2014) in press.

29. Thank you for your attention