[Effect of humic acid and coexistent cation on the adsorption of Pb (II) in wastewater onto bentonite].

Both the physical-chemical properties and adsorption performance for lead of Na-bentonite have been studied in this paper. The results showed that the removal of lead in solution by use of bentonite was effective. The pH, concentrations of coexistent cations and humic acid, which could influence the adsorption process were also studied. The results indicate that the sorption of lead (II) on Na-bentonite increased as pH value increased, and increased with increasing humic acid concentration, while decreased with increasing coexistent cation concentration. The adsorption mechanism was investigated from thermodynamics, and it was founded that the sorption of lead (II) on Na-bentonite increased with increasing temperature and the Freundlich adsorption equation fit to the experimental data excellently. The thermodynamic parameters were calculated: deltaH = 0.959 4 kJ/mol, deltaS = 16.6113 kJ/(mol x K).