Assessment of the Use of Moringa oleifera Seeds for Removal of Manganese Ions from Aqueous Systems

Moringa oleifera seeds were investigated for the removal of manganese ions from aqueous solutions. The seeds utilized were obtained from plants grown in Uberl ndia, Brazil. After being dried and pulverized, the seeds were treated with 0.1 mol L-1 NaOH. Using the optimized methodology (50 mL of 4.0 mg L-1 Mn(II), pH range of 4.0-6.0, contact time of 5 min, and biosorbent mass of 0.5 g) it was found that 100% of Mn(II) could be removed from water samples. In order to remove up to 95% of Mn ions in 50 mL of a laboratory residue produced during biochemical oxygen demand determinations with 112.0 mg L-1 of manganese, the contact time and pH were maintained, but a mass of 3.0 g was used. The kinetic data were fitted to a pseudo-second-order kinetic model. The sorption data were fitted satisfactorily to the Langmuir and Freundlich isotherm models. Evaluation applying the Langmuir equation gave the monolayer sorption capacity as 5.61 mg/g. In this application the method was found to be efficient, fast, simple, and economical.