Qing-Zhou Zhai * Pages 123 - 132 ( 10 )
Background: In recent years, with the progress of human civilization, the environmental pollution is aggravating. Among them, heavy metal pollution is one of the greatest harmful water pollution problems. As a global pollution problem, heavy metal pollution, such as lead, has been paid more and more attention by scientists. How to solve this problem, is an interesting issue.
Objective: The aims of the current study are to develop the optimized adsorption of Pb2+ by MCM (Mobil Composition of Matter)-48 mesoporous molecular sieve material and study the properties of this adsorption study.
Method: First, MCM-48 mesoporous molecular sieve was prepared by hydrothermal method by using cetyltrimethyl ammonium as template and tetraethyl orthosilicate as silica source. The prepared sample was characterized by powder X-ray diffraction and scanning electron microscopy. Then, harmful heavy metal Pb2+ was adsorbed by MCM-48, the effects of acidity, contact time, temperature, the initial concentration of lead(II) and the dosage of adsorbent on the rates of adsorption were studied, and the optimum adsorptive conditions were obtained.
Results: The results show that when pH value was 4.5, temperature was 18 ℃, contact time was 40 min and m(MCM-48) : m(Pb2+) = 2.5 (mass ratio), the adsorptive effect was the best, the adsorption rate was reached to 96.71% and the adsorptive capacity was 386.84 mg/g. After the kinetic calculation, it is shown that process of the adsorption of Pb2+ by MCM-48 conforms to the pseudo-second-order kinetic equation. Thermodynamic calculation shows that the adsorption is an exothermic process. The adsorption obeys the Freundlich adsorption isotherm equation. Nitric acid, hydrochloric acid and acetic acid were respectively used to study the effects of desorption, indicating that the desorptive effect was the best using 0.1 mol/L of nitric acid as a desorptive agent. At the time of desorption 6 h, its desorptive ratio was the highest and reached to 71.11%.
Conclusion: This method provides a possible and alternative one for removing lead ions harmful substance, which has a potential applied value in processing lead polluted waters.
Pb(ę ), adsorption, MCM-48, mesoporous molecular sieve, harmful heavy metal, hydrothermal method.
Research Center for Nanotechnology, South Campus, Changchun University of Science and Technology, 7186 Weixing Road, Changchun 130022, Jilin Province, P. R