Chemical modification of cashew gum with acrylamide using an ultrasound-assisted method

A flocculant based on cashew gum (CG) grafted with polyacrylamide (PAM) was synthesized using potassium persulfate as the chemical initiator and ultrasound energy. The intrinsic viscosity, hydrodynamic radius, and grafting efficiency of the grafted copolymers (CG-g-PAM) were investigated at different monomer and initiator concentrations. The CG-g-PAM copolymers were evaluated in kaolin suspension and river water by using jar test procedure comparatively to a commercial flocculant (Flonex-9045). Ultrasonication resulted in reduced reaction time and high grafting efficiency. The reaction gel point was reached within 10 min and the grafting efficiency was dependent on the acrylamide concentration. The grafted copolymer CG-g-PAM-15(285) obtained with 0.285 mmol of initiator showed higher hydrodynamic radius, with flocculation efficacy of 96% comparable with the flocculant Flonex-9045. (C) 2016 Wiley Periodicals, Inc.