Effect of Turbidity and Contact Time on the Rate of Biosorption of Ni2+, Pb2+, Cr3+ and Cu2+ from Wastewater Using Moringa oleifera

Abstract

Heavy metals in water have been a major preoccupation for researchers for many years due to their toxicity towards aquatic life, human beings and the environment. As they do not degrade biologically like organic pollutants, their presence in industrial effluents and drinking water is a public health problem. Consequently, there is need to come up with novel methods of heavy metals remediation which are more effective and reliable. The biosorption processes using biosorbents like Moringa oleifera have been found to be affected by various physical and chemical factors. Therefore, the present study sought to determine the effect of turbidity and contact time on the rate of biosorption of Ni2+, Pb2+, Cr2+ and Cu2+ from wastewater using Moringa oleifera. Atomic absorption spectrometer (AAS) was used to analyse samples for levels of massive metal species; Pb2+, Cr3+, Cu2+ and Ni2+ before and after treatment with oleifera biosorbent. The effect of turbidity and contact time on the biosorption of the heavy metals by the Moringa oleifera biosorbent was studied by varying these parameters.  Results obtained in the study showed that percentage adsorption decreased from 99, 96, 95 and 87% in 20 ml of turbid solution to 70, 92, 93 and 60% in 50 ml cloudy solution for Pb2+, Cr3+, Cu2+ and Ni2+ respectively. Sixty minutes of equilibration time was found to be adequate for adsorption of the considered metal ions. Several kinetic models were applied to the adsorption data, and it was found that pseudo-second order fitted well with the adsorption data.  It was therefore concluded that M. oleifera could be used as a low-cost adsorbent for the removal of heavy metals from aqueous solutions.