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Biosorption of cadmium metal ions on raw and chemically modified walnut shells
Author(s) -
Gondhalekar Sachin C.,
Shukla Sanjeev R.
Publication year - 2015
Publication title -
environmental progress and sustainable energy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.495
H-Index - 66
eISSN - 1944-7450
pISSN - 1944-7442
DOI - 10.1002/ep.12161
Subject(s) - biosorption , adsorption , freundlich equation , enthalpy , desorption , chemisorption , chemistry , nuclear chemistry , cadmium , langmuir adsorption model , langmuir , metal ions in aqueous solution , monolayer , metal , sorption , organic chemistry , thermodynamics , biochemistry , physics
The abundantly available agricultural waste product walnut shells were treated with alkali for enhancement in adsorptive capacity for Cd(II) ions. The raw walnut shells (RWS) and alkali treated walnut shells (AWS) were characterized for functional groups and morphological changes using FTIR and SEM analysis. The adsorption increased drastically between pH 2 and 6. The Langmuir isotherm model provided a better fit with the experimental data than Freundlich by giving high correlation coefficients. The biosorption capacity of RWS and AWS for Cd(II) ions was found to be 4.20 and 14.29 mg g −1 , respectively. Dubinin–Radushkevich (D‐R) isotherm model was used to find out the mean adsorption energy. The adsorption followed pseudo‐second order kinetics, suggesting monolayer coverage and a chemisorption process. The thermodynamic parameters including change in free energy (Δ G ), enthalpy (Δ H ), and entropy (Δ S ) were derived. Negative value of Δ G confirmed spontaneity of biosorption. Desorption efficiency showed no significant decrease till third cycle. © 2015 American Institute of Chemical Engineers Environ Prog, 34: 1613–1619, 2015