Abstract

Zinc bacitracin (Zn-Bc) belongs to the group of nonribosomal peptide antibiotics (NRPA), comprising a mixture of non-biodegradable congeners characterized by complex structures containing cyclic, polycyclic, and branched chains. However, reports on the use of AOPs for the degradation of NRPA are non-existent. In this context, the present work investigated the photodegradation of Zn-Bc in aqueous solution by direct photolysis and the UVC/H₂O₂ process. The effects of the specific UVC photon emission rate and initial H₂O₂ concentration were studied following a Doehlert-design response surface approach. The results showed that all congeners photolyzed at the highest UVC doses in the absence of hydrogen peroxide, with a calculated quantum yield of 0.0141 mol Zn-Bc mol photons⁻¹. However, no TOC removal was observed after 120 minutes of irradiation, suggesting the disruption of the peptide bonds in the antibiotic molecules without significant changes in the amino acid residues. The addition of H₂O₂ substantially accelerated Zn-Bc photodegradation, resulting in a remarkable removal of up to 71% of TOC. Most importantly, the antimicrobial activity against Staphylococcus aureus could be completely removed by both treatments. These findings point out that the UVC/H₂O₂ process can be straightly engineered for the treatment of metalloantibiotics-containing wastewater in pharmaceutical facilities.

摘要

杆菌肽锌（Zn-Bc）属于非核糖体肽抗生素（NRPA）组，包括不可生物降解的同类物的混合物，其特征是含有环状，多环和支链的复杂结构。但是，没有关于使用AOP降解NRPA的报道。在此背景下，本工作研究了直接光解和UVC / H ₂ O ₂工艺对水溶液中Zn-Bc的光降解作用。特定UVC光子发射速率和初始H ₂ O _2的影响按照Doehlert设计的响应面方法研究了浓度。结果表明，在没有过氧化氢的情况下，所有同类物均以最高的UVC剂量进行光解，计算出的量子产率为0.0141 mol Zn-Bc mol光子^-1。但是，照射120分钟后未观察到TOC去除，表明抗生素分子中的肽键被破坏，而氨基酸残基没有明显变化。H ₂ O _2的添加大大促进了Zn-Bc的光降解，从而显着去除了高达71％的TOC。最重要的是，对金黄色葡萄球菌的抗菌活性两种治疗都可以完全清除。这些发现指出，UVC / H ₂ O ₂工艺可以直接设计用于制药厂中含金属抗生素的废水的处理。