Abstract：
In-situ chemical oxidation based on sodium percarbonate (SPC) has received much attention for remediation of groundwater contaminated with organic pollutants due to the high efficiency, stable reaction, and sustainability of SPC. Currently, metal ions and their composite materials, are mainly employed for the activation of SPC. However, due to its narrow pH range, slow Fe3+/Fe2+ circulation, and generation of refractory sludge, its application in groundwater is limited. In this study, SPC was activated with natural pyrite (FeS2) to remove tetracycline, which was selected as the target pollutant. FeS2 exhibited excellent catalytic activity and stability towards the degradation of tetracycline. The tetracycline degradation efficiency of SPC/FeS2 system reached 70 % within 10 min, and nearly half of the tetracycline was degraded in the first 5 min of the reaction. The optimum SPC dosage for the tetracycline removal was 8 mM, with FeS2 dosage of 0.5 g/L. The tetracycline removal efficiency remained above 60 % after 4 cycles, indicating its good recycling efficiency of the system. SPC/FeS2 system was not significantly affected by the initial pH or the presence of Cl-, SO42-, NO3- while, HCO3-, Ca2+, Mg2+, and humid acid suppressed the reaction. The electron paramagnetic resonance spectroscopy and quenching experiments demonstrated that OH and O2- played a dominant role in tetracycline removal by the system. S22-, as an electron donor, was able to participate in the Fe3+/Fe2+ cycle. In addition, the 13 transformation products were determined by liquid chromatography-mass spectrometry predicted that the degradation pathway of tetracycline consisted of hydroxylation, demethylation, and decarbonylation reactions. Finally, the dynamic simulation experiments of SPC/FeS2 sand column showed that FeS2 effectively activated SPC and significantly reduced the toxicity in groundwater after the packed column treatment. This study reveals that FeS2 can efficiently activate SPC and has good prospects for tetracycline-contaminated groundwater remediation applications.
摘要：
基于过碳酸钠(SPC)的原位化学氧化技术因其高效修复被有机污染物污染的地下水而备受关注,稳定的反应，和SPC的可持续性。目前,金属离子及其复合材料，主要用于SPC的活化。然而,由于其狭窄的pH范围，缓慢的Fe3+/Fe2+循环，以及耐火污泥的产生，其在地下水中的应用是有限的。在这项研究中,用天然黄铁矿(FeS2)活化SPC去除四环素,被选为目标污染物。FeS2对四环素的降解表现出优异的催化活性和稳定性。SPC/FeS2体系的四环素降解效率在10min内达到70%,在反应的前5分钟内，近一半的四环素被降解。去除四环素的最佳SPC剂量为8mM，FeS2用量为0.5g/L4个循环后四环素去除效率保持在60%以上,表明该系统具有良好的回收效率。SPC/FeS2体系不受初始pH或Cl-存在的显著影响,SO42-,NO3-而，HCO3-,Ca2+,Mg2+,潮湿的酸抑制了反应。电子顺磁共振谱和猝灭实验表明，OH和O2-在该系统去除四环素中起主导作用。S22-,作为电子供体，能够参与Fe3+/Fe2+循环。此外,13种转化产物经液相色谱-质谱联用分析,预测四环素的降解途径为羟基化,去甲基化,和脱羰基反应。最后,SPC/FeS2砂柱的动态模拟实验表明，FeS2有效激活了SPC，并显着降低了填充柱处理后的地下水毒性。该研究表明FeS2可以有效激活SPC，在四环素污染的地下水修复应用中具有良好的前景。
