Removal of Cu and Cr ions from aqueous solutions by a chitosan based flocculant

In this work, carboxylated chitosan and acrylamide are used to synthesize a graft-modified natural polymer flocculant carboxylated chitosan-graft-acrylamide (CCSPAM) by UV-induced polymerization for copper and chromium removal. The effects of total monomer concentration, monomer mass ratio, pH value, photoinitiator concentration, and illumination time on the synthesis performance of CCSPAM were investigated regarding intrinsic viscosity (IV), grafting rate (GR), and grafting efficiency (GE). Various analytical techniques characterize the physicochemical characteristics of CCSPAM. Single factor experiments are used to investigate the effect of dosage, pH value, and reaction time on the chelation and capture of heavy metal ions by CCSPAM. The results show that the optimal IV, GR, and GE of CCSPAM achieved at total monomer concentration 30%, monomer mass ratio 1:4, pH 7.0, photoinitiator concentration 0.03%, and irradiation time 2 h are 1412.2 mL/g, 394.1%, and 84.1%, respectively. The experimental data of flocculation show that CCSPAM has a good total Cu and total Cr removal efficiency of 74.8% and 70.6% at dosage 2.0 mg/L, pH 6.0, and reaction time 2h, respectively. Fom the investigation, it is concluded that the grafted chitosan (CCSPAM) could be a be an effective and eco-friendly flocculant for removal of total Cu and total Cr ions from aqueous system.