Adsorptive Removal from Aqueous Solution of Cr(VI) by Green Moringa Tea Leaves Biomass

Abstract

Hexavalent chromium, Cr(VI), is a toxic metal present in industrial effluents. The study was carried to test the use of green Moringa leaves biomass as adsorbent for Cr(VI) from aqueous solutions. Batch adsorption method was used and the concentration of Cr(VI) measured using an ultraviolet-visible (UV-Vis) spectrophotometry. The effects of the adsorption contact time, adsorbent dosage, pH, initial adsorbate concentration and temperature were studied. Results show maximum removal of Cr(VI) of 99% ± 1%, with maximum adsorption capacity of 33.9 mg/g at a pH 2, 60 minutes contact time and 100 mg/l initial Cr(IV) concentration. The Langmuir and Freundlich adsorption isotherm models were used to fit the experimental data. The data showed that adsorption on green Moringa oleifera leaves tea biomass fitted well to Freundlich isotherm (r2 = 0.9432) compared to the Langmuir isotherm (r2 = 0.9122). M. oleifera leaves biomass can be used in water purification systems. The sludge of M. oleifera leaves is biodegradable, cost effective and environmentally friendly and therefore attractive in hexavalent chromium removal in water.