A performance comparison of arsenate removal from water by five iron oxides
5种铁氧化物去除As(V)性能的比较研究

In order to obtain high efficient and low-cost adsorbent for arsenate removal, five iron oxides were evaluated and compared in batch adsorption tests. The results showed that the adsorption capacities decreased in the following order: schwertmannite>akáganite>ferrihydrite>hematite>goethite, and the adsorption process followed a pseudo-second order reaction model. Adsorption approached equilibrium by about 24 h. Due to schwertmannite had a maximum adsorption capacity of 83 mg-As(V)/g-adsorbent at pH 5 among these iron oxides, so it was used in the treatment of simulated groundwater containing high contents of arsenic (1.484 mg/L and 0.850 mg/L, respectively) and TOC at high pH values. It was found that the residual arsenic in both samples could be effectively decreased to 0.01 mg/L at dosages of 500 mg/L and 300 mg/L adsorbent, respectively. Then, schwertmannite was characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR) and surface potential titration. SO2-4 was observed to be existed in the bulk or on the surface of schwertmannite, the site density for proton was about 4.32 sites/nm2, and the protonation constants of pK1 and pK2 were 4.60 and -8.98, respectively.