The University of Queensland , Advanced Water Management Centre (AWMC), St Lucia, Brisbane, Queensland 4072, Australia.
Environ Sci Technol. 2013;47(21):12366-73. doi: 10.1021/es402967e. Epub 2013 Oct 22.
The disposal of ferric phosphate (FePO4) sludge, routinely generated in wastewater and drinking water treatment, has a major impact on the overall treatment cost. Iron sulfide (FeSx) precipitation via sulfide addition to ferric phosphate (FePO4) sludge has been proven to be an effective method for phosphate recovery. Electrochemical oxidation of FeSx can then be utilized to recover ferric iron for reuse back in the phosphate removal process. In this study, the reactivity of FeSx particles for anodic oxidation at pH 4 was studied as a function of time after FeSx precipitate generation at a S/Fe molar ratio of 1.75. Cyclic voltammetry showed high reactivity for fresh FeSx particles, but the reactivity diminished significantly over a period of 1 month. X-ray absorption spectroscopy (XAS) revealed that this reduced reactivity with time is a consequence of the transformation of the FeSx particles in suspension from mackinawite (FeS) to pyrite (FeS2).
铁磷酸盐（FePO4）污泥是废水和饮用水处理过程中常见的废物，其处理方式对整体处理成本有重大影响。向铁磷酸盐（FePO4）污泥中投加硫化物以生成硫化铁（FeSx）沉淀，已被证明是一种有效的回收磷酸盐的方法。然后，可以利用电化学氧化的方法将 FeSx 回收为铁离子，重新用于磷酸盐去除过程中。本研究以 S/Fe 摩尔比为 1.75 时生成 FeSx 沉淀后不同时间的 FeSx 颗粒作为阳极氧化的反应性作为研究对象，在 pH 值为 4 时进行了研究。循环伏安法表明，新鲜 FeSx 颗粒具有很高的反应活性，但在 1 个月的时间内，反应活性显著降低。X 射线吸收光谱（XAS）表明，这种随时间降低的反应活性是由于悬浮液中的 FeSx 颗粒从磁黄铁矿（FeS）向黄铁矿（FeS2）转变所致。
