Adsorption Potentials of binary metal aqueous solution by Moringa oleifera seeds biomass

Abstract

This study was based on the evaluation of the efficiency and applicability of Moringa oleifera seed biomass (MOSB) as adsorbent in the removal of lead (Pb) and cadmium (Cd) heavy metals in water. The study was justified by the toxic nature of the study metals as the current conventional processes of heavy metals’ removal are not ecosystem friendly and chemical coagulant very exorbitant.  Fourier transform Infrared (FTIR) analysis was used to identify the Moringa oleifera seeds biomass functional groups that may be present in the adsorption of metal ions. The observed components were the carboxylic acid and amine functional groups (-COOH and -NH). *The maximum adsorption capacity at pH 5, room temperature and 0.8 g dosage were 90% and 81.77% for Pb(II), Cd(II) respectively. The order of biosorption preference was found as Pb(II) > Cd(II) in binary sorption and there is consistent correlation between physiochemical properties of metal ions and selective biosorption of MOSB functional groups. The data was fitted to the Langmuir and Freundlich models but the adsorption data fit better with the Langmuir isotherm models. From the Langmuir model, the sorption capacities (q_m) of MOSB of Pb(II) and Cd(II) were 6.19 mg/g and 5.03 mg/g respectively. The separation factor (R_L) are within the range of 0 to 1. The significance of this study is that it evaluated the potential and efficiency of a natural adsorbent (MOSB) in removal of Pb and Cd in binary-metal systems. This shows that the Pb(II) and Cd(II) biosorption processes were favourable for Moringa oleifera biosorbent. The results showed that M. oleifera seed biomass is an effective adsorbent in the removal of the studied heavy metals in water. The adsorption kinetics which describes the relationship of solute uptake rate of the adsorption, and the adsorption time is recommended to be studied.