Efficient removal of Cr(Ⅵ) by thermal-modified layered double hydroxides (LDHs): adsorption behaviors, effect parameters and comparison with original LDHs
ZHANG Yingxin, ZHOU Tao, MAO Juan, et al. Efficient removal of Cr(Ⅵ) by thermal-modified layered double hydroxides (LDHs): adsorption behaviors, effect parameters and comparison with original LDHs[J]. CIESC Journal, 2015, (S1): 228-236.
ZHANG Yingxin, ZHOU Tao, MAO Juan, et al. Efficient removal of Cr(Ⅵ) by thermal-modified layered double hydroxides (LDHs): adsorption behaviors, effect parameters and comparison with original LDHs[J]. CIESC Journal, 2015, (S1): 228-236.DOI: 10.11949/j.issn.0438-1157.20150134.
The pollution of hexavalent chromium (Cr(Ⅵ)) is of particular environmental concern because of its toxicity and carcinogenic effect. In this study
Mg-Al layered double hydroxides (Mg-Al LDHs) were prepared by the co-precipitation method. It was found that a thermal modification process of the Mg-Al LDHs (calcined LDHs
C-LDHs) could improve obviously the adsorption capacity of Cr(Ⅵ). The equilibrium isotherms showed that the adsorption of Cr(Ⅵ) using either LDHs or C-LDHs could be well fitted with the Langmuir model. The maximum Cr(Ⅵ) uptake capacity of C-LDHs and original LDHs was 105.26 and 20.66 mg·g-1 at 30℃
respectively. The pseudo-second-order model could be used to describe the adsorption of Cr(Ⅵ) on both C-LDHs and LDHs. Effect of important parameters such as reaction temperature
pH and initial Cr(Ⅵ) concentration was also investigated
and it was found that the reaction temperature has slight effect on the adsorption capacity of the C-LDHs. This could be ascribed to the nature of the Cr(Ⅵ) adsorption reaction by the C-LDHs. Characterizations of the LDHs and C-LDHs by XRD
SEM
FT-IR and TG-DTG evidenced that the surface properties of LDHs particles could be successfully varied by the calcined treatment of LDHs.