Abstract：
The removal of trace amounts of antibiotics from water environments while simultaneously avoiding potential environmental hazards during the treatment is still a challenge. In this work, green, harmless, and novel asymmetric mesoporous TiO2 (A-mTiO2) was combined with peroxodisulfate (PDS) as active components in a controlled-release material (CRM) system for the degradation of tetracycline (TC) in the dark. The formation of reactive oxygen species (ROS) and the degradation pathways of TC during catalytic PDS activation by A-mTiO2 powder catalysts and the CRMs were thoroughly studied. Due to its asymmetric mesoporous structure, there were abundant Ti3+/Ti4+ couples and oxygen vacancies in A-mTiO2, resulting in excellent activity in the activation of PDS for TC degradation, with a mineralization rate of 78.6%. In CRMs, ROS could first form during PDS activation by A-mTiO2 and subsequently dissolve from the CRMs to degrade TC in groundwater. Due to the excellent performance and good stability of A-mTiO2, the resulting constructed CRMs could effectively degrade TC in simulated groundwater over a long period (more than 20 days). From electron paramagnetic resonance analysis and TC degradation experiments, it was interesting to find that the ROS formed during PDS activation by A-mTiO2 powder catalysts and CRMs were different, but the degradation pathways for TC were indeed similar in the two systems. In PDS activation by A-mTiO2, besides the free hydroxyl radical (·OH), singlet oxygen (1O2) worked as a major ROS participating in TC degradation. For CRMs, the immobilization of A-mTiO2 inside CRMs made it difficult to capture superoxide radicals (·O2-), and continuously generate 1O2. In addition, the formation of sulfate radicals (·SO4-), and ·OH during the release process of CRMs was consistent with PDS activation by the A-mTiO2 powder catalyst. The eco-friendly CRMs had a promising potential for practical application in the remediation of organic pollutants from groundwater.
摘要：
在处理期间从水环境中去除痕量抗生素同时避免潜在的环境危害仍然是一个挑战。在这项工作中,绿色,无害,和新型不对称介孔TiO2（A-mTiO2）与过氧二硫酸盐（PDS）结合在受控释放材料（CRM）系统中作为活性成分，用于在黑暗中降解四环素（TC）。深入研究了A-mTiO2粉末催化剂和CRM在催化PDS活化过程中活性氧（ROS）的形成和TC的降解途径。由于其不对称的介孔结构，A-mTiO2中存在丰富的Ti3+/Ti4+对和氧空位，从而在活化PDS降解TC方面具有优异的活性，矿化率为78.6%。在CRM中，ROS可以在A-mTiO2的PDS活化过程中首先形成，然后从CRM中溶解以降解地下水中的TC。由于A-mTiO2具有优异的性能和良好的稳定性，因此所构建的CRM可以在长时间（超过20天）内有效降解模拟地下水中的TC。从电子顺磁共振分析和TC降解实验，有趣的是，A-mTiO2粉末催化剂和CRM在PDS活化过程中形成的ROS是不同的，但在两个系统中，TC的降解途径确实相似。在A-mTiO2的PDS活化中，除了自由基（·OH）外，单线态氧（1O2）是参与TC降解的主要ROS。对于CRM，A-mTiO2在CRM中的固定使其难以捕获超氧自由基（·O2-），并不断产生1O2。此外,硫酸根(·SO4-)的形成，和·OH在CRMs的释放过程中与A-mTiO2粉末催化剂对PDS的活化一致。生态友好型CRM在修复地下水中的有机污染物方面具有实际应用的潜力。
