A novel efficient cationic flocculant prepared through grafting two monomers onto chitosan induced by Gamma radiation

Abstract

Two monomers, acrylamide (AM) and (2-methacryloyloxyethyl) trimethyl ammonium chloride (DMC) were grafted onto chitosan simultaneously in acid-water solution initiated by the highly efficient and environmentally friendly gamma ray radiation at ambient temperatures. The copolymer obtained was analyzed using Fourier-transform infrared, X-ray powder diffraction and thermogravimetric analysis. The cationic degree of the copolymer was determined by the colloid titration method. Its flocculation properties were evaluated in 0.25% (wt) kaolin suspensions and its significant superiority over PAM (polyacrylamide) and chitosan was observed. The results of zeta potential measurement demonstrated that the flocculation mechanism of the copolymer was distinct when it was used as a flocculant under different conditions. The images and the settling rate test of the floccules after treating by the flocculant showed that the capacities of bridging and charge neutralization of the graft copolymer were improved after the grafting of AM and DMC. Jar tests with pulp mill wastewater demonstrated that the flocculation efficiency of the graft copolymer was much better than that of PAM.