Abstract
Removal of heavy metals including Pb, Co, Cr and Zn from an aqueous solution was investigated using modified clinoptilolite zeolites as adsorbents. The adsorbents were characterized by X-ray, FTIR, SEM and BET. The central composite design defined under response surface methodology was applied for design of experiments. According to the results, clinoptilolite/MgO showed higher capacity for absorption of lead (98.38 %) in comparison to clinoptilolite/NaOH. The removal percentage of Co, Cr and Zn was obtained 89.51 %, 81.07 % and 78.24 %, respectively, using clinoptilolite/MgO. Moreover, the equilibrium experimental data well fitted the Freundlich isotherm model, as compared with the Langmuir isotherm. The results show that the complete regeneration of adsorbents can be achieved at room temperature using NaCl (0.35 M).
Highlights
Environmental pollution by hazardous materials including heavy metals has attracted the attention of scientists
It can be concluded that the ability of magnesium oxide (MgO)/clinoptilolite zeolite in adsorbing lead was higher than that of NaOH/ clinoptilolite zeolite
4 Conclusion The present study showed that clinoptilolite zeolite modified with NaOH and MgO had much potential as adsorbents for the removal of heavy metal ions from the aqueous solution
Summary
Environmental pollution by hazardous materials including heavy metals has attracted the attention of scientists. The influences of effective parameters including heavy metal ion concentration in aqueous solution, temperature, contact time and adsorbent dosage were simultaneously investigated for removal percentage of heavy metals including lead, cobalt, chromium and zinc over the modified clinoptilolite zeolite by designing an experiment using the RSM. The process was stopped and the products were withdrawn from the vessel and centrifuged at 3600 rpm for 30 min to separate the remaining adsorbent In these experiments, pH of initial solutions before addition of adsorbent were determined 4.7-4.3 for solutions at concentration of 3001500 mg/L respectively. First, the optimum condition of the adsorption of lead from the aqueous solution using clinoptilolite zeolite modified with NaOH was obtained by designing an experiment using the RSM. The design of the experiments was done by Design Expert version 7.0.0
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