Study of ionic charge dependent salt resistant swelling behavior and removal of colloidal particles using reduced gum rosin-poly(acrylamide)-based green flocculant

Abstract

Present work reports the under pressure preparation of reduced gum rosin and acrylamide-based GrA-cl-poly(AAm) green flocculant. Characterization of the synthesized product was carried out by different techniques such as Fourier transform infrared spectroscopy, X-ray diffraction method and scanning electron microscopy. In addition, several variables such as time, physiological pH, solvent, pressure, monomer, cross-linking agent and initiator were examined to obtain maximum flocculation efficiency and explore the salt resistant swelling of the system. The maximum percentage swelling (P s) at pH 7.0 and pressure 8.0 psi was found to be 578 %. Thermal behavior of the flocculant was investigated and the synthesized sample showed higher thermal stability than the gum rosin. The effect of ionic strength and charges of various cations (Na+, Ba+2, Fe+3, Sn+4) on salt resistant swelling of GrA-cl-poly(AAm) flocculant, in different salt solutions such as sodium chloride, barium chloride, ferric chloride and stannic chloride (NaCl, BaCl2, FeCl3 and SnCl4), was also studied. The synthesized sample was found to show ionic charge and salt concentration related behavior. Further, the removal of colloidal particles from wastewater through flocculation showed that GrA-cl-poly(AAm) exhibited significant flocculation efficiency (95.18 %) at a dose rate of 55 mg at 30 °C and pH 5.0. Flocculant capacity in saline medium was found to be maximum (99 %) at 1 % concentration. Further, increase in saline concentration resulted in decreased flocculant capacity. The kinetics of the aggregation of particles, deflocculation and reflocculation was analyzed through the Smoluchowski classical model based on first-order and second-order kinetics.