University of Oulu, Fibre and Particle Engineering Research Unit, P.O. Box 8000, FI-90014, Finland; Eawag, Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, Dübendorf CH-8600, Switzerland.
Eawag, Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, Dübendorf CH-8600, Switzerland; School of Architecture, Civil and Environmental Engineering (ENAC), Ecole Polytechnique Lausanne (EPFL), Lausanne 1015, Switzerland.
Water Res. 2022 Sep 1;223:118984. doi: 10.1016/j.watres.2022.118984. Epub 2022 Aug 14.
Peracetic acid (PAA) in combination with transition metals has recently gained increasing attention for organic micropollutant abatement. In this study, aqueous Co(II), Cu(II), and Ag(I) were compared for their capacity to activate PAA. Co(II) outperformed Cu(II) or Ag(I) and the optimum conditions were 0.05 mM of Co(II), 0.4 mM of PAA, and pH 3. However, due to a wider applicability in water treatment, pH 7 (i.e., bicarbonate buffer) was selected for detailed investigations. The abatement of different micropollutant surrogates could be described with a second-order rate equation (observed second-order rate constants, k were in the range of 42-132 M s). For the para-substituted phenols, there was a correlation between the observed second-order rate constants of the corresponding phenolates and the Hammett constants (R = 0.949). In all oxidation experiments, the reaction rate decreased significantly after 1-2 min, which coincided with the depletion of PAA but also with the deactivation of the Co(II) catalyst by oxidation to Co(III) and subsequent precipitation. It was demonstrated that Co(II) immobilized on a geopolymer-foam performed approximately similarly as aqueous Co(II) but without deactivation due to Co(III) precipitation. This provides a potential option for the further development of heterogeneous catalytic Co(II)/PAA advanced oxidation processes utilizing geopolymers as a catalyst support material.
过氧乙酸（PAA）与过渡金属结合，最近在有机微量污染物去除方面受到越来越多的关注。在这项研究中，比较了水相中的 Co(II)、Cu(II)和 Ag(I)激活 PAA 的能力。Co(II)的性能优于 Cu(II)或 Ag(I)，最佳条件为 0.05 mM Co(II)、0.4 mM PAA 和 pH 3。然而，由于在水处理中具有更广泛的适用性，选择 pH 7（即碳酸氢盐缓冲液）进行详细研究。不同微量污染物模拟物的去除可以用二级反应速率方程来描述（观察到的二级反应速率常数 k 在 42-132 M s 范围内）。对于对位取代的酚类，相应酚盐的观察到的二级反应速率常数与 Hammett 常数之间存在相关性（R = 0.949）。在所有氧化实验中，反应速率在 1-2 分钟后显著下降，这与 PAA 的消耗以及 Co(II)催化剂因氧化为 Co(III)和随后沉淀而失活相吻合。研究表明，固定在地质聚合物泡沫上的 Co(II)与水相中的 Co(II)表现相似，但不会因 Co(III)沉淀而失活。这为进一步开发利用地质聚合物作为催化剂载体材料的非均相催化 Co(II)/PAA 高级氧化工艺提供了一种潜在选择。
