LAUSR

The efficiency of chromium removal from tannery effluents using prepared crab shell chitosan was studied. Adsorption of Cr by chitosan was investigated at various contact times, pH values, adsorbent dosages, and temperatures. The amount of Cr adsorbed under different conditions was evaluated using atomic absorption spectroscopy. Subsequently, the changes in the physicochemical parameters were also examined. It was found that the total dissolved solids, electrical conductivity, and turbidity of the tannery effluent decreased significantly after treatment with crab shell chitosan. No significant changes were found after different soaking times; in most cases, the best adsorption was achieved within the first hour of treatment. On the other hand, the total organic carbon and pH increased significantly after treatment with chitosan, possibly owing to dissolution of organic compounds from the adsorbent materials. The concentration of Cr was significantly reduced after treatment with chitosan under different treatment conditions. However, the highest amount of Cr was adsorbed within the first hour of contact. After studying different treatment conditions, it was found that maximum Cr removal from the tannery effluent was achieved at pH 3 (60 $${^{\circ }}$$∘C) using an adsorbent dose of 5 g/100 mL.