Equilibrium, Thermodynamic and Kinetic Studies for Removal of Copper (II) from Aqueous Solution by Onion and Garlic Skin
Avisha Chowdhury1, Avijit Bhowal2*, and Siddhartha Datta3
1Department of Environmental Science, University of Calcutta, Kolkata 700019, India
2School of Advanced Studies in Industrial Pollution Control Engineering, Jadavpur University, Kolkata 700032, India
3Department of Chemical Engineering, Jadavpur University, Kolkata 700032, India
*Correspondence E-mail: avijit_bh@yahoo.co.in
Key Words: Onion skin, Garlic skin, Copper (II), Biosorption, Remediation
Received December 14th, 2011; Accepted April 25th, 2012; Published October 21st, 2012; Available online November 15th, 2012
Summary
Removal of Cu2+ from aqueous solution by onion skin and garlic skin was studied as a function of various experimental parameters. FTIR analysis and Boehm titration were used to identify and estimate the surface functional groups. Point of zero charge for the onion and garlic skin was between 4.25 to 4.45 and 4.55 to 4.75 respectively. Compared to garlic skin (66.7 mg/g), the maximum adsorption capacity of onion skin (76.9 mg/g) was slightly higher (pH = 5.3, T = 303K). The pseudo second order kinetic model fitted the batch data adequately. The rate constant for onion and garlic scale in the absence of diffusional resistance was estimated to be 0.07 and 0.075 mg/g/min respectively at 303 K. The thermodynamic studies showed that the Cu2+ adsorption on the onion and garlic skin was spontaneous and endothermic.