5种铁氧化物去除As(V)性能的比较研究

A performance comparison of arsenate removal from water by five iron oxides

为了从铁氧化物中筛选得到潜在经济有效的除砷材料,对5种铁氧化物去除As(V)的性能进行了比较研究。吸附实验结果表明,其吸附容量依次为施氏矿物>四方纤铁矿>水铁矿>赤铁矿>针铁矿,其吸附过程均符合准二级动力学,约24 h时吸附达到平衡。其中,pH=5时,施氏矿物的吸附容量达到83 mg/g。分别投加500 mg/L和300 mg/L的施氏矿物,可将含砷1.484 mg/L和0.850 mg/L、高TOC含量和高pH特征的模拟配水砷浓度降至0.01 mg/L以下。鉴于施氏矿物良好的吸附除砷性能,进一步通过SEM、FTIR和电位滴定对其表面特性进行了深入研究,结果显示,本研究中制备的施氏矿物存在结构性或表面吸附的SO42-,其(质子)表面位密度约为4.32个/nm2,表面质子化常数pK1为4.60,pK2为-8.98。

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： schwertmanniteakáganiteferrihydritehematitegoethite,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.