Removal of Toxic Congo Red Dye Using Water Hyacinth Petiole, an Efficient and Selective Adsorbent

Abstract

Congo red (CR), one of the major dyes used in the textile mills of Bangladesh has carcinogenic and chronic effect on living system. Removal of CR was done by using water hyacinth petiole (WHP), an efficient and selective adsorbent. Adsorption experiment was performed through batch process at different pH values, dye concentrations, contact times, particle sizes and dosages of adsorbent. A comparable study was carried out using untreated and sodium chlorite treated WHP at different pH values. Equilibrium adsorption was attained after 240 minutes. The highest removal 94.88% was obtained using sodium chlorite treated water hyacinth petiole (SCT-WH) and 94.51% using untreated water hyacinth petiole (UT-WH) at pH 6. Adsorption increased with the increase of initial dye concentration and after a certain time saturation was attained. Adsorption decreased with the increase of particles size (≤ 75and#181;m, ≤ 150and#181;m and ≤ 300and#181;m) and increased with the amount of adsorbent (0.25g, 0.50g and 0.75g). The equilibrium data were best described by the Freundlich isotherm and adsorption kinetics better fitted to pseudo-second-order kinetic model.