Assessment of shea nut shell activated carbon in biochemical oxygen demand removal: a kinetic approach

Abstract

The production of activated carbons from shea nut shell, with H3PO4 and ZnCl2 as activating agents using the two step activation process was studied. Results of physicochemical variables followed a inverse relationship between percentage burn off and yield. The highest Biochemical Oxygen Demand (BOD) removal from industrial dye wastewater were 31.79, 52.28, 14.84, 28.61, 26.85 and 28.26% for the series of sorbents labeled as SS/H3PO4/5, SS/H3PO4/10, SS/H3PO4/15, SS/ZnCl2/5, SS/ZnCl2/10 and SS/ZnCl2/15 respectively and thus implies that acid catalyzed shea nut shell biosorbents are more effective than the corresponding salt modified sorbents. Evaluation of the sorption dynamics via kinetic studies revealed that BOD uptake was governed by the pseudosecond– order kinetics with more appreciable R2 > 0.5, least % SSE and high precision between the calculated and experimental qe values. Sorption rate was faster for acid catalyzed biosorbent, while the overall analysis competed favorably with those reported in literature and demonstrated the feasibility of using shea nut shell for removal of organics from textile effluent.

Keywords: Activated carbon, shea nut, dye, biochemical oxygen demand, sorbents