Investigation of locust bean husk char adsorbability in heavy metal removal

Abstract

he column adsorption study examines irrigation water treatment prior to its application in order to ensure water-crop-consumer heavy metal transfer reduction to the safe level using locust bean husk char (LBHC) as biosorbent. Char structural pattern was investigated with SEM-EDX machine. Contaminated surface water was introduced simultaneously into the bioreactors containing 100 and 200 g of LBHC and collected after 30, 60, 90 120 and 150 min of detention time. Removal efficiency, isotherm and kinetic sorption model were the evaluation tools for the study. Percent of Cr, Cd and As removal at 150 min retention time were 83.33, 100 and 100%, respectively for 100 g biosorbents. A similar trend was observed for Cr and As removal at the same retention time for 200 g of LBHC. Metals sorption conforms to the Freundlich isotherm with correlation coefficient values greater than 0.92. Experimental kinetics had a good fit for pseudo second order (R2 > 0.94 for most cases). Removal efficiency is a function of contact time, biosorbent dosage and metal concerned. Locust bean husk char has good and effective treatability for some heavy metals in mildly polluted water.

Keywords

• locust bean husk char
• biosorption
• heavy metal
• removal efficiency
• isotherm, kinetic sorption