Department of Marine Environmental Engineering, National Kaohsiung University of Science and Technology, Kaohsiung City, Taiwan.
Department of Civil and Environmental Engineering, University of Delaware, Newark, USA.
Sci Total Environ. 2019 Dec 15;696:133973. doi: 10.1016/j.scitotenv.2019.133973. Epub 2019 Aug 19.
This study investigated the degradation of phthalate esters (PAEs) in marine sediments by sodium persulfate (NaSO, PS) activated by a series of iron-cerium (Fe-Ce) bimetallic catalysts (FCBCs). The surface structure and chemistry of the FCBCs were characterized by TEM, HRTEM, XRD, FTIR, BET and XPS. Results show successful synthesis of FCBC catalysts. Factors such as PS concentration, Fe to Ce molar ratio, catalyst dosage, and initial pH that might affect PAEs degradation were investigated. Results revealed that PAEs was degraded more effectively over FCBC with a Fe-Ce molar ratio of 1.5:1. Increase in Ce improved the catalytic activity of FCBC due to increase in oxygen storage capacity (OSC). Acidic conditions enhanced PAEs degradation with a maximum degradation of 86% at pH 2 and rate constant (k) of 1.5 × 10 h when the PS and FCBC concentrations were to 1.0 × 10 M and 1.67 g/L, respectively. Di-(2-ethylhexyl) phthalate (DEHP) was a salient marker of PAE contamination in sediments. Dimethyl phthalate (DMP) and diethyl phthalate (DEP) were easier to degrade than DEHP, diisononyl phthalate (DINP), dioctyl phthalate (DnOP) and diisononyl phthalate (DIDP). The synergistic catalytic effect of Fe/Fe and Ce/Ce redox couples, in addition to electron transfer of oxygen vacancies, activated SO to generate SO and HO radicals, which played the major role of PAEs degradation. 5,5-dimethyl-1-pyrroline N-oxide (DMPO) spin trapping EPR studies verified the crucial role of SO and HO in the oxidative degradation process. FCBC/PS oxidation exhibited high-performance for the remediation of PAEs-contaminated marine sediments.
本研究采用过硫酸钠（NaSO，PS）作为氧化剂，在一系列铁铈（Fe-Ce）双金属催化剂（FCBC）的作用下，研究了海洋沉积物中邻苯二甲酸酯（PAEs）的降解情况。采用 TEM、HRTEM、XRD、FTIR、BET 和 XPS 对 FCBC 的表面结构和化学性质进行了表征。结果表明成功合成了 FCBC 催化剂。考察了 PS 浓度、Fe 与 Ce 的摩尔比、催化剂用量和初始 pH 等可能影响 PAEs 降解的因素。结果表明，当 Fe 与 Ce 的摩尔比为 1.5:1 时，FCBC 对 PAEs 的降解效果更显著。Ce 的增加提高了 FCBC 的催化活性，这是由于其氧存储能力（OSC）的增加。在酸性条件下，PAEs 的降解效果增强，当 PS 和 FCBC 的浓度分别为 1.0×10-2 M 和 1.67 g/L 时，最大降解率为 86%，速率常数（k）为 1.5×10-2 h-1。邻苯二甲酸二（2-乙基己基）酯（DEHP）是沉积物中 PAE 污染的显著标志物。与 DEHP 相比，二甲基邻苯二甲酸酯（DMP）和二乙基邻苯二甲酸酯（DEP）更容易降解，邻苯二甲酸二异壬酯（DINP）、邻苯二甲酸二正辛酯（DnOP）和邻苯二甲酸二异癸酯（DIDP）则较难降解。Fe/Fe 和 Ce/Ce 氧化还原对的协同催化作用，以及氧空位的电子转移，激活了 SO 生成 SO 和 HO 自由基，这些自由基在 PAEs 的降解过程中发挥了主要作用。5,5-二甲基-1-吡咯啉 N-氧化物（DMPO）自旋捕获 EPR 研究证实了 SO 和 HO 在氧化降解过程中的关键作用。FCBC/PS 氧化法在修复 PAEs 污染的海洋沉积物方面表现出了优异的性能。
