Optimization of the coagulation-flocculation of dye wastewater using hybrid polymer

Abstract

The inorganic-organic hybrid polymer of magnesium chloride-poly(ethylene oxide) (MgCl2- PEO) was prepared, characterized and applied in coagulation-flocculation of Cibacron Blue F3GA (RCB). Conductivity and viscosities of the hybrid polymer with varying ratios were measured. The ratio of MgCl2 to PEO with the lowest viscosity and highest conductivity was chosen to be used in the coagulation-flocculation of RCB. The ratio of MgCl2:PEO which showed the best performance in the treatment of RCB was 90% MgCl2: 10% PEO. The factors that affected the coagulation-flocculation process, namely initial dye concentration, initial pH, agitation speed, agitation time and hybrid polymer dosage, were studied using fractional factorial design and response surface methodology (RSM), and the process optimized. The five factors studied were significant towards the colour removal and chemical oxygen demand (COD) reduction of the dye. The maximum colour removal and COD reduction achieved was 99.76% and 92.09%, respectively. The optimum conditions were, initial dye concentration of 173 mg/L, pH 11.13, agitation speed of 150 rpm, agitation time of 6 minutes and hybrid polymer dosage of 1020 mg/L.