School of Environmental Science and Engineering, Shanghai Jiao Tong University, No. 800, Dongchuan Road, Shanghai, 200240, PR China.
School of Environmental Science and Engineering, Shanghai Jiao Tong University, No. 800, Dongchuan Road, Shanghai, 200240, PR China.
Chemosphere. 2021 Feb;264(Pt 1):128398. doi: 10.1016/j.chemosphere.2020.128398. Epub 2020 Sep 24.
Adsorption is a simple and efficient way for arsenic contamination purification in water, with a pressing challenge to find a cheap and efficient adsorbent. As a poorly crystalline Fe(III)-oxyhydroxy sulfate mineral, schwertmannite can be As(V) adsorbent because of its tunnel structure and low cost. However, the schwertmannite synthesized commonly by HO rapid oxidation suffers from the low Fe utilization and limited As(V) adsorption capacity. In this research, the schwertmannite is synthesized by KMnO. The results show that the Fe utilization can be improved from 40% to 56%, with the As(V) adsorption capacities double times better than those synthesized by HO at pH 7 and 2. The As(V) adsorption mechanisms at different pHs and the reason for the improvement of As(V) adsorption capacity are thoroughly investigated. The FTIR and EDS images confirm that As(V) adsorption exchange with SO is the dominant mechanism at pH 7 and 2. At pH 11, the As(V) is mainly removed by surface complexation because the surface SO is exchanged by OH. The intraparticle diffusion model fitting and XPS results further reveal that the tunnel structure built by Fe-SO in the KMnO oxidized schwertmannite is more stable, possibly resulting in the better As(V) adsorption performance.
吸附是一种简单有效的水中砷污染净化方法，迫切需要找到一种廉价高效的吸附剂。水铁矿是一种结晶度较差的 Fe(III)-氧羟基硫酸盐矿物，由于其隧道结构和低成本，可作为 As(V)的吸附剂。然而，HO 快速氧化合成的水铁矿普遍存在 Fe 利用率低和 As(V)吸附容量有限的问题。本研究采用 KMnO4 合成水铁矿。结果表明，Fe 的利用率从 40%提高到 56%，在 pH 7 和 2 时，As(V)的吸附容量提高了两倍。深入研究了不同 pH 值下的 As(V)吸附机制以及吸附容量提高的原因。FTIR 和 EDS 图像证实，在 pH 7 和 2 时，As(V)主要通过与 SO 的吸附交换来实现，而在 pH 11 时，由于表面 SO 被 OH 取代，表面络合是主要的去除机制。颗粒内扩散模型拟合和 XPS 结果进一步表明，KMnO4 氧化合成的水铁矿中的 Fe-SO 隧道结构更稳定，可能导致更好的 As(V)吸附性能。
