Bioremediation of Cd(II), Pb(II) and Cu(II) from industrial effluents by Moringa stenopetala seed husk.

In the current study, the removal of Cd(II), Pb(II) and Cu(II) ions from industrial effluent was investigated using powdered Moringa stenopetala seed husk. The surface functionality, morphology, crystallinity, thermal stability, the surface charge and surface area of the powdered Moringa stenopetala seed husk was studied using FTIR, SEM, XRD, TGA, zeta potential and BET, respectively. Processing parameters, namely contact time, adsorbent dosage, concentration, pH, agitation speed, temperature and particle size were investigated using the batch adsorption method. The maximum adsorption percentage for Cd(II), Pb(II) and Cu(II) ions from synthetic wastewater was found to be 99.1, 99.4 and 99.1%, compared to 95.3, 95.5 and 94.1%, respectively, for adsorption of these metal ions from real wastewater. The maximum adsorption capacity was found to be 52.63, 47.62 and 31.25 mg/g adsorbent for Cd(II), Pb(II) and Cu(II), respectively. The Freundlich isotherm provided a better fit for the adsorption equilibrium data than the Langmuir isotherm, while the kinetics were well defined by the pseudo-second-order model (R2 = 1). Furthermore, the positive value of the enthalpy change (ΔH) indicated that the adsorption of metal ions on the adsorbent was endothermic. The negative values of the Gibbs free energy change (ΔG) confirmed that the adsorption process on the surface of the adsorbent was spontaneous.