Eco-friendly decolorization of cationic dyes by coagulation using natural coagulant Bentonite and biodegradable flocculant Sodium Alginate

Abstract

The coagulation performance of Bentonite (BE) aided by Sodium Alginate (SA) to remove basic dyes was investi- gated. Four basic dyes Rhodamine B (RB), Malachite Green (MG), Methylene Blue (MB) and Basic Violet 14 (BV) were used to cover a range of variations in the experiments. It was found that the removal of the dyes increased with addition of SA as the flocculant/coagulant aid. Bentonite as a natural coagulant aided by the biodegradable floccu- lant, SA, is an effective combination for removal of basic dyes (color removal). The effect of coagulant dosage on the overall dye removal efficiency/decolorization rate was explored and followed by the investigation of the mecha- nism of dye removal by coagulation process. Optimum dye removal efficiencies for RB, MG, MB and BV by using both Bentonite and Sodium Alginate combined were, 91.5%, 98.2%, 98.5%, 98.8%, respectively with pH set at 9.0. FTIR was used to characterize the sludge to determine the functional groups. The resultant outcome in this study indicates that using Bentonite as a natural coagulant, aided by a biodegradable flocculant, Sodium Alginate, pro- vides an effective and environmentally friendly coagulation option for removing color from basic dyes.