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

Abstract 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 to 7.0), adsorbent dose (1.0 to 5.0 g/L) and time (1 to 60 min) at a temperature of 40oC 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.