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.
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