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Adsorption–Desorption of Cd(II) and Pb(II) on Ca-Montmorillonite
journal contribution
posted on 2012-05-09, 00:00 authored by Yan Li, Ji-de Wang, Xiao-jun Wang, Juan-fang WangThe adsorption and desorption of Cd(II) and Pb(II) on
Ca-montmorillonite
have been investigated. The maximum removal efficiency of Cd(II) reaches
98% at the initial concentration of 50.00 mg L–1, while it is about 70% for Pb(II) at the initial concentration of
58.79 mg L–1. Experimental results indicate that
adsorption reactions of Cd(II) and Pb(II) on Ca-montmorillonite agree
well with second-order kinetics and the Langmuir isotherm model. Cd(II)
and Pb(II) on Ca-montmorillonite are successfully desorbed by NaCl
solution of high concentration. Data shows that desorption efficiencies
are mainly influenced by the concentration of NaCl and temperature.
The optimum desorption concentrations of NaCl for Cd(II) and Pb(II)
are 1 mol L–1 and 3 mol L–1, respectively,
where the adsorption efficiencies can reach 93% and 83%. The results
of 4-time consecutive adsorption–desorption show that the method
of desorption by NaCl solution is efficient and practical. Samples
before and after adsorption or desorption have been characterized
by X-ray diffraction, which are consistent with the results mentioned
above.