A green, eco-friendly and self-supporting geopolymer membrane for Cr (Ⅵ) removal from aqueous solution
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Qing Tang, Chuchu Wang, Changsheng Peng, Shoulian Wei, Peng Hu, Tafeng Tseng, Lianfen Chen
In this study, a self-supporting geopolymer membrane was prepared for the treatment of Cr(Ⅵ) containing wastewater. The membrane has the advantages of low raw material cost, free of sinter-ing, simple preparation process, good removal effect. The phase structure of the membrane was amorphous gel structure with a specific surface area of 34.48 m2/g. The influence of pH and initial concentration on the removal effect of Cr(Ⅵ) were investigated. The Cr(Ⅵ) removal amount reached to 45.56 mg/g and the removal rate reached to 82.69% under favorable conditions. Further mechanism study showed that the removal of Cr(Ⅵ) by the membrane mainly depends on the Donnan effect caused by electrostatic repulsion, which is fundamentally different from the remov-al for positively charged heavy metal ion such as Pb2+, Ni2+ and Cu2+. This study not only provides a membrane material for chromium-containing wastewater, but also broadens the scope of geo-polymer materials in the field of water treatment, and provides theoretical support for its treatment of anionic pollutants (Cr(Ⅵ) presents as HCrO4- and Cr2O72-).
geopolymer; self-supporting membrane; Cr(Ⅵ) removal; water treatment