CHROMIUM REMOVAL FROM WASTEWATER USING MORINGA STENOPETALA SEED POWDER AS AN ADSORBENT

Finding an environmentally safe, cost effective method which is efficient enough to meet the regulatory standards of potable and industrial wastewater presents unique challenges. In this work, Moringa stenopetala seed powder which had particle size of 300 µm was characterised; ash content 4.7%, bulk density 0.531/cm³, particle density 0.88 g/cm³, colour yellowish and pH 4.5. FT-IR (Fourier Transform Infrared Spectroscopy) analysis showed the multi-functionality of the Moringa stenopetala seed powder. Moringa stenopetala seed powder was assessed for percentage chromium removal and mg/g chromium uptake as a function of contact time, pH, and dose of the adsorbent and initial concentration. The maximum percent removal was 99.74%. Sorption kinetics of chromium adsorption by Moringa stenopetala seed powder was predicted reliably using a pseudo-second order model. An intra-particle diffusion model revealed that the bio-sorption of metals proceeds via through various processes. Equilibrium uptakes were evaluated using Langmuir, Freundlich, Temkin and the Dubinin-Radushkevich (D-R) adsorption isotherm models. Even though the correlation coefficient was not as high as the Langmuir and Ferendulich models for Temkin adsorption isotherm model, the metal uptake which was predicted by the model is comparable with the experimental value. Generally, the seed powder of Moringa stenopetala was found to be effective in the removal of chromium from tannery wastewater.