Utilization of Chitosan and Polyacrylamide Gel to Remove Direct Dyes from Wastewater

Abstract The adsorption of direct blue 78 dye with a commercial (DB78) from synthetic wastewater using a pure chitosan powder and chitosan micro-beads has been studied. The ability of chitosan as a bio-adsorbent to remove dyes from textile wastewater effluent has been investigated in detail. This study aims to achieve the highest removal efficiency with a lower contact and sedimentation time of direct blue dye using chitosan particles enhanced with polyacrylamide polymer. A series of batch experiments were conducted in terms of adsorbent dose, contact time, and pH. The chitosan particles were characterized by physicochemical analysis namely; FTIR and Zeta potential analysis. It was found that the net surface charge was + 6.52 mv and + 28.77 mv respectively for pure chitosan powder and chitosan micro-beads. The adsorption tests showed that the removal efficiency increases with increasing adsorbent dosage and contact time. Removal efficiency decreases at the high initial concentration of direct blue 78 dye. The maximum capacities for removal of dyes were achieved up to 94.2% with an initial concentration of 50 mg/l and pure chitosan dose of 4.5 g/L and an optimal contact time of 60 minutes. Furthermore, the sedimentation time for chitosan powder decreases from 8 hours to 10 minutes by using a polyacrylamide gel dose of 45 mL/L of synthetic wastewater. Studies have shown that equilibrium data followed Freundlich and Langmuir isotherm closely, but the latter isotherm better suited the results with R2 = 0.997. These results revealed that the use of pure chitosan powder enhanced with adding polyacrylamide gel is an effective adsorbent for the removal of direct blue 78 dye. The removal efficiency is considered high with a low adsorbent dose compared to using pure chitosan micro-beads.