Removal of erythrosine dye in aqueous solution using chitosan beads and chitosan-tripolyphosphate beads

Abstract

Chitosan (CHS) and chitosan-tripolyphosphate beads (CTTP) were used for the removal of Erythrosine dye in batch adsorption experiments. The initial pH, agitation period, and adsorbent dosage were studied to determine the influence of these parameters on the adsorption capacity of the beads. Based on the initial pH study, the adsorption capacity for both adsorbents were found to be at pH 6. As the initial pH was increased, the adsorption capacity reduced for both beads. Based on the agitation period study, the kinetics of the adsorption process was determined. It was found that both CHS and CTPP followed the pseudo-second-order kinetic model with the highest adsorption capacity were attained at 50 and 60 minutes, respectively. An additional parameter on the adsorbent dosage was studied for CTTP beads to further improve on the removal capacity. The optimum adsorbent dosage for CHS and CTTP was achieved at 0.05 g and 0.6 g, respectively. An isotherm study was carried out on Erythrosine dye at the concentration of 20 mg/L – 100 mg/L for CHS and 20 mg/L – 150 mg/L for CTPP. It was found that the experimental data for CHS fitted the monolayer Langmuir model. Meanwhile, CTPP favored the multilayer Freundlich model. The CTPP was found to be effective in adsorbing a high concentration of dye, whereby the percentage of removal obtained was 92.6 % at the initial concentration of 150 mg/L of Erythrosine. Meanwhile, for CHS, the percentage of removal attained was 90.0% at the initial concentration of 60 mg/L of Erythrosine.