Removal Of Pb(?)?Cd(?) By Sorbent DFT: Adsorption Behavior And Mechanism

Nowadays, as the enhancement of the environmental awareness in public, water pollution, especially those caused by heavy metal ions, has been paid more and more attention. Developing cheap, practical and high efficient methods and technologies for heavy metal pollution is the key to solve water pollution.In this paper, two kinds of sorbent(DFT) were synthesized in water phase, which its requirement for equipment and process conditions was relatively lower. The synthesized DFTs were characterized by FT-IR, XRD, XPS and other methods systemically. The adsorption removal ability for common heavy metal ions Pb(?), Cd(?),which has strong biological toxicity, was studied and the effect of Ca(?) and Mg(?),which are common in both natural water and industrial and mining waste water, on the above adsorption was also studied. The adsorption kinetics of two above heavy metal ions on the DFTs and the thermodynamics and adsorption mechanism were studied.Based on above study, the main conclusions are as the following ones: Firstly, the main crystal phase of the DFTs synthesized by above method was ?- DFT and ?- DFT, respectively. The degree of their crysallinity was poor and both of them had large specific surface area and there were plenty of hydroxyl groups on both DFTs surface. Secondly, both DFTs had strong adsorption removal ability for Pb(?), Cd(?), especially for Pb(?). The present of Ca(?) and Mg(?) had little influence on the above adsorption process, which was related to the formation of relatively stable inner complexes on the surface of the DFTs. Thirdly, the adsorption of these two heavy metal ions on the DFTs could be better fitted by the second-order kinetic equation, so the above adsorption processes were mainly controlled by chemical adsorption. Fourthly, the adsorption on both DFTs was spontaneous and exothermic, so higher temperature was not conducive to it. Finally, comparing with DFT-1, DFT-2 had a stronger removal ability for Pb(?), Cd(?), which may be the result of its larger specific surface area and percentage of higher valent manganese on the surface.