Adsorptive Characteristics of Chromium(VI) Ions from Aqueous Phase by Iron(III) Coordinated Amino-Functionalized Poly(glycidyl methacrylate)-Grafted Cellulose: Equilibrium Kinetics and Thermodynamic Study

Abstract

A novel sorbent, Iron(III)-coordinated amino-functionalized poly(glycidyl methacrylate)-grafted cellulose (Fe(III)-AM-PGMACell), was prepared through graft copolymerization of glycidyl methacrylate (GMA) onto cellulose (Cell) in the presence of N,N′-methylenebisacrylamide (MBA) as a cross linker using benzoyl peroxide initiator, followed by treatment with ethylenediamine and ferric chloride in the presence of HCl. The surface features of the adsorbent were characterized using FTIR, XRD, and SEM, N₂ adsorption, and potentiometric titration. The contact time to attain equilibrium and the pH value for maximum adsorption were found to be 90 min and 4.0, respectively. A two-step pseudo-first-order kinetic model agreed well with the dynamic behavior for the adsorption process. Equilibrium data were fitted with the Langmuir, Freundlich, and Sips isotherm equations with the latter giving the best fit to the experimental data with maximum adsorption capacity of 72.05 mg/g at 30°C. A simulated industry wastewater sample was treated by the Fe(III)-AM-PGMACell to demonstrate its efficiency in removing Cr(VI) from wastewater. The adsorbed Cr(VI) ions were desorbed effectively by 0.1 M NaCl solution and hence can be reused through many cycles of water treatment and regeneration without any loss in the adsorption capacity.

Keywords:

• adsorption
• cellulose
• chromium(VI)
• glycidyl methacrylate
• graft copolymerization
• thermodynamics

ACKNOWLEDGEMENTS

The authors are thankful to the Head of the Department of Chemistry, University of Kerala, Thiruvananthapuram, India, for providing the laboratory facilities.