Chemical Technology, Luleå University of Technology, SE-97187 Luleå, Sweden.
Environ Sci Technol. 2012 Dec 18;46(24):13152-9. doi: 10.1021/es300729m. Epub 2012 Dec 3.
Addition of iron oxide to arsenic-contaminated soil has been proposed as a means of reducing the mobility of arsenic in the soil. Arsenic and zinc are common coexisting contaminants in soils. The presence of zinc therefore may affect the adsorption properties of arsenic on iron oxide, and may thus affect its mobility in the soil. The influence of Zn(II) on the adsorption of arsenate ions on iron oxide was studied. Batch adsorption experiments indicated that Zn(II) increased the arsenate removal from a solution by ferrihydrite at pH 8. However, ATR-FTIR spectroscopy showed that no adsorption of arsenate on a ferrihydrite film occurred at pD 8 in the presence of Zn(II). Precipitation of zinc hydroxide carbonate followed by arsenate adorption onto the precipitate was found to be a plausible mechanism explaining the arsenate removal from a solution in the presence of Zn(II) at pH/pD 8. The previously suggested mechanisms attributing the enhanced removal of arsenate from solution in the presence of Zn(II) to additional adsorption on iron oxides could not be verified under the experimental conditions studied. It was also shown that at pH/pD 4, the presence of Zn(II) in the system did not significantly affect the adsorption of arsenate on ferrihydrite.
向砷污染土壤中添加氧化铁被认为是减少土壤中砷迁移性的一种方法。砷和锌是土壤中常见的共存污染物。因此，锌的存在可能会影响砷在氧化铁上的吸附特性，从而影响其在土壤中的迁移性。研究了 Zn(II)对氧化铁吸附砷酸盐离子的影响。批吸附实验表明，在 pH 8 时，Zn(II)增加了针铁矿从溶液中去除砷酸盐的能力。然而，ATR-FTIR 光谱表明，在 pD 8 时，Zn(II)的存在下，针铁矿膜上没有发生砷酸盐的吸附。发现锌氢氧化物碳酸盐的沉淀，随后是砷酸盐吸附到沉淀物上，这是一种可以解释在 pH/pD 8 时 Zn(II)存在下从溶液中去除砷酸盐的合理机制。在研究的实验条件下，先前提出的归因于 Zn(II)存在下从溶液中增强去除砷酸盐的机制不能得到验证。还表明，在 pH/pD 4 时，系统中 Zn(II)的存在并没有显著影响砷酸盐在针铁矿上的吸附。
