Functionalized polyacrylamide by xanthate for Cr (VI) removal from aqueous solution

Hexavalent chromium [Cr (VI)] has long been considered as a highly toxic substance that will impact water quality. In this study, a modified polyacrylamide (MPAM) was prepared by grafting a xanthate group onto polyacrylamide (PAM), which was characterized by the Fourier transform infrared (FT-IR) spectrum, X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray spectrometry (EDS). The performance of the new metal chelating agent, MPAM, was assessed by measuring Cr (VI) removal efficiency from an aqueous environment. FT-IR spectroscopy demonstrated that the MPAM is a xanthate functionalized PAM with functional groups of (sic). MPAM is a crystal material, and its main phase is similar to Na2CO3 center dot!H2O, which was not significantly changed in the chelation process. However, there was a significant increase in the intensity of the phase, which was possibly attributed to an increase in the size of ligand group. EDS results demonstrated that the chelation product was the result of a complex MPAM formation process, and Cr. MPAM had better yields with CS2/NaOH molar ratio of 1:3 during the preparation. Cr (VI) removal efficiency increased with the increase of MPAM dosage. With an appropriate dosage, aqueous Cr (VI) could be almost completely removed. An acidic environment was conducive to Cr (VI) removal with better removal efficiency achieved at pH 5. Further illustration indicated that with 4.7 mg/L of MPAM dosage for treatment of solution containing 10 mg/L Cr (VI), a Cr (VI) removal efficiency of over 98% could be achieved. The presence of the cations, such as K+, Na+, and Ca2+ had an inhibiting effect on Cr (VI) removal; thus, there was a need to use a higher MPAM dosage. Overall, the functionalized polyacrylamide exhibited good Cr (VI) removal efficiency from aqueous solution with tested Cr (VI) concentrations. (C) 2015 Elsevier B.V. All rights reserved.