Influence of some organic ligands on the adsorption of lead by agricultural soil

The adsorption of lead onto agricultural soil in the presence of organic compounds such as, humic acid, gallic acid or phenol was studied. The study included the factors affecting the adsorption process such as contact time, pH, adsorbent dose, metal concentration and organic ligands concentration. The experimental isotherm data were found to fit both Langmuir and Freundlich isotherms. The results show that the pseudo second-order equation provides the best correlation for the adsorption process. The results indicate that both humic acid and phenol increase the adsorption of lead while gallic acid slightly decreases the adsorption.