The investigation of the effectiveness of the removal of copper, nickel, chromium and zinc ions from
synthetic waste water by using Moringa aptera Gaertn (MAG) was studied. The effect of biosorption
experimental parameters such as initial metal concentration, contact time, temperature and adsorbent
dose has been presented and discussed in details. The equilibrium data for biosorption were analysed by
using Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherm models to define the best
correlation for each metal.
Among the four isotherm models, both Freundlich and Temkin models were
fitted with the equilibrium
isotherm for copper, while Temkin and Dubinin–Radushkevich models best correlated for nickel and
Langmuir isotherm model best describe the experimental data for chromium. The adsorption capacity for
each studied heavy metals is reported as follows: copper qe = 6.07 mg Cu/g MAG, nickel qe = 5.53 mg Ni/g
MAG and chromium qe = 5.497 mg Cr/g MAG with a removal percentage of 90%, 68% and 91%, respectively
for each ion at 1 g dose of biosorbent. Results also show that MAG pods are not a good biosorbent for the
removal of zinc from wastewater. Kinetics results were best described by pseudo-second order model for
all metals.