Remediation of colour from distillery wastewater using orange peels as adsorbent

Abstract

The dark-brown color of Distillery Wastewater (DWW), often termed melanoidin, causes discoloration and turbidity rise in water bodies, restraining water usage and detrimental to aquatic life. This study investigates Orange Peels (OP) efficiency as a low-cost adsorbent for color removal from DWW. The color of Fresh DWW’s was confirmed on platinum-cobalt color scale, its color concentration was measured at 620-nm using UV-visible spectrophotometer. OP was carbonized and characterized for chemical composition, specific surface area, surface functional group and surface morphology. Batch adsorption experiment was performed on Orange Peel Carbon (OPc) and compared with coal-based commercial activated carbon (AC_C) to determine the effects of agitation speed, retention time, carbon dosage, DWW pH on the Maximum Removal Efficiency (MRE) of color.  The adsorption capacity was evaluated using Langmuir, Freundlich, Elovich, Pseudo-first-order and Pseudo-second-order models. OP_c showed good-quality adsorbent. DWW was dark-brown in color (2.030 Abs). A 60.20 % MRE was achieved at 100 RPM agitation speed, 60 mins retention time, 2.5 g/100ml OP_c dosage and pH of 4.0. AC_C showed better performance of 79.46 % color removal. The adsorption followed Elovich isotherm, implying multilayer adsorption with correlation factor of 0.9414. In general, OPc proved effective in reducing color from DWW, and thus, recommended as a suitable adsorbent to replace the costly commercial adsorbents for DWW treatment.