State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin, Heilongjiang, 150090, China.
School of Environmental and Material Engineering, Yantai University, Yantai, 264005, China.
Water Res. 2020 Jun 15;177:115752. doi: 10.1016/j.watres.2020.115752. Epub 2020 Apr 3.
As a common animal feed additive, p-arsanilic acid (p-AsA) is thought to be excreted with little uptake and unchanged chemical structure, threatening the environment by potentially releasing more toxic inorganic arsenic. We herein investigated the removal of arsenic by in situ formed ferric (oxyhydr)oxides with the promotion of p-AsA degradation in Fe(II)/peroxydisulfate (PDS) system. Results showed that under acid conditions, p-AsA degraded very quickly and over 99% of p-AsA (5 μM) was degraded within 10 min at the optimal dosage of Fe(II) (100 μM) and PDS (150 μM) at pH 3, while less than 66.4% of arsenic was removed at pH 3-5. Higher pH (3-7) would inhibit the degradation of p-AsA but promote the arsenic removal. At pH 6-7, over 98.5% of total arsenic was removed, while the degradation efficiency of p-AsA was lower than 52.4%. HPLC-ICP-MS results indicated that the arsenic group was cleaved from p-AsA in the form of As(III) and then rapidly oxidized to As(V). FTIR and XPS analysis indicated that both As(V) products and residual p-AsA were bonded to ferric (oxyhydr)oxides via hydroxyl groups. Common cations (e.g., Na, Ca, Mg) and anions such as Cl, SO, CO had no significant influence on arsenic removal, while SiO, PO and HA inhibited the removal of total arsenic, mainly by affecting the zeta potential of iron particles. In summary, the Fe(II)/PDS process, as an efficient method for partial oxidation and simultaneous adsorption of p-AsA under near-neutral conditions, is expected to control the potential environmental risks of p-AsA.
作为一种常见的动物饲料添加剂，对氨基苯砷酸（p-AsA）被认为排泄量少且化学结构不变，有可能释放更多毒性无机砷，从而威胁环境。本研究通过原位形成的铁（氧）氢氧化物，促进 p-AsA 在 Fe(II)/过二硫酸盐（PDS）体系中的降解，来去除砷。结果表明，在酸性条件下，p-AsA 降解速度非常快，在最佳 Fe(II)（100 μM）和 PDS（150 μM）剂量下，5 μM 的 p-AsA 在 10 min 内几乎完全降解，而在 pH 3-5 时，只有不到 66.4%的砷被去除。较高的 pH（3-7）会抑制 p-AsA 的降解，但会促进砷的去除。在 pH 6-7 时，超过 98.5%的总砷被去除，而 p-AsA 的降解效率低于 52.4%。HPLC-ICP-MS 结果表明，砷基团以 As(III)的形式从 p-AsA 中被裂解，然后迅速被氧化为 As(V)。FTIR 和 XPS 分析表明，无论是 As(V)产物还是残留的 p-AsA，都是通过羟基键合到铁（氧）氢氧化物上的。常见的阳离子（如 Na、Ca、Mg）和阴离子（如 Cl、SO、CO）对砷的去除没有显著影响，而 SiO、PO 和 HA 则抑制了总砷的去除，主要是通过影响铁颗粒的动电电位。总之，Fe(II)/PDS 工艺作为一种在近中性条件下部分氧化和同时吸附 p-AsA 的有效方法，有望控制 p-AsA 的潜在环境风险。
