Zwitterion-chitosan bed for the simultaneous immobilization of Zn(II), Cd(II), Pb(II) and Cu(II) from multi-metal aqueous systems

The present paper reports the synthesis, surface characterization, and application of a grafted adsorption bed material namely carboxylate functionalized chitosan copolymer (CFCCP-COOH). The functionalized copolymer prepared by expanding the landscape of chitosan through co-grafting glycidyl methacrylate with methacrylic acid. The -COOH group introduced through grafting imparted a zwitterionic nature to chitosan copolymer which results in increasing the adsorption capacity. The surface of CFCCP-COOH was profiled by XPS, XRD, CHNS Analyzer, Surface Area Analyzer, Zetasizer, and FTIR. A wide spectrum of batch-adsorption studies carried out for optimizing the conditions for effectively removing heavy metals using CFCCP-COOH from water and industrial wastewaters. In a multi-metal system, for an initial concentration of 150 mg/L of each adsorbing ions, CFCCP-COOH maintains an adsorption capacity values of 92.27, 108.42, 127.91 and 123.50 mg/g in removing Zn(II), Cd(II), Pb(II) and Cu(II) at pH of 6.0. Conditions of Pb(II) adsorptive removal was optimized through response surface methodology (RSM) considering pH (4.0-7.0), adsorbent dose (1.0-5.0 g/L) and time (1-60 min) at a temperature of 40 degrees C and initial concentration (25 mg/L). The equilibrium and kinetic-data showed good regression with Langmuir isotherm and pseudo-second-order kinetic models. The CFCCP-COOH was feasibly applied in the treatment of wastewater streams. (C) 2020 Elsevier Ltd. All rights reserved.