Decomposition and mineralization of cefaclor by ionizing radiation: kinetics and effects of the radical scavengers.
Decomposition and mineralization of cefaclor by ionizing radiation: kinetics and effects of the radical scavengers.
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DOI：
10.1016/j.chemosphere.2008.01.020
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发表时间：
2008-05
期刊：
影响因子：
8.8
通讯作者：
Seungho Yu;Byung-Guen Lee;Myunjoo Lee;I. Cho;S. Chang
中科院分区：
文献类型：
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作者：
Seungho Yu;Byung-Guen Lee;Myunjoo Lee;I. Cho;S. Chang
最近，人们越来越关注抗生素在不同环境部门中的存在。一个值得关注的问题是，即使在低浓度下，环境中也可能产生抗药性细菌。头孢克洛是β-内酰胺类抗生素之一，是一种广泛使用的抗生素。进行了动力学研究，以评估使用γ辐射的头孢克洛的分解和矿化。30 mg/l头孢克洛在1000 Gy γ射线照射下完全降解。在30 mg/l浓度下，去除率随累积辐射剂量的增加而降低，其G值随累积辐射剂量的增加而降低。初始水溶液浓度为8.9、13.3、20.0和30.0mg/l的批式动力学实验表明，头孢克洛在γ射线照射下的降解遵循准一级反应，剂量常数随初始浓度的降低而增大。在给定的辐射剂量下，G值随着初始头孢克洛浓度的增加而增加。以甲醇和硫脲为自由基清除剂的实验结果表明，OH自由基与头孢克洛的辐解反应的关系比其它自由基如eaq-或H.在O2和N2 O饱和条件下，考察了自由基清除剂对头孢克洛辐解过程中TOC去除率的影响。在O2饱和条件下，100000 Gy照射，TOC去除率可达90%。众所周知，氧气通过有效的链式反应途径在有机物质的降解中起着相当大的作用。根据有效自由基反应，TOC去除率的提高可能是基于eaq-和H与O2的快速转化反应，分别转化为氧化性自由基，如O2-和HO 2。在20000 Gy的N_2O气体中，由于还原性自由基如eaq-和H被N_2O清除并转化为具有强氧化性的OH自由基，TOC去除率达到100%。研究结果表明，γ射线辐照对水溶液中头孢克洛的去除非常有效。使用O2或N2 O，与辐射，显示出作为有效的自由基清除剂的承诺，用于提高TOC或COD去除效率的制药废水中含有抗生素。然而，生物毒性和辐射处理过程中各种化学品之间的相互作用，以及在更能代表真实的废水的条件下的处理，将需要进一步研究。
There has been recent growing interest in the presence of antibiotics in different environmental sectors. One considerable concern is the potential development of antibiotic-resistant bacteria in the environment, even at low concentrations. Cefaclor, one of the β-lactam antibiotics, is widely used as an antibiotic. Kinetic studies were conducted to evaluate the decomposition and mineralization of cefaclor using gamma radiation. Cefaclor, 30mg/l, was completely degraded with 1000Gy of gamma radiation. At a concentration of 30mg/l, the removal efficiency, represented by the G-value, decreased with increasing accumulated radiation dose. Batch kinetic experiments with initial aqueous concentrations of 8.9, 13.3, 20.0 and 30.0mg/l showed the decomposition of cefaclor using gamma radiation followed a pseudo first-order reaction, and the dose constant increased with lower initial concentrations. At a given radiation dose, the G-values increased with higher initial cefaclor concentrations. The experimental results using methanol and thiourea as radical scavengers indicated that OH radicals were more closely associated with the radiolytic decomposition of cefaclor than other radicals, such as eaq-or H. The radical scavenger effects were tested under O2and N2O saturations for the enhancement of the TOC percentage removal efficiencies in the radiolytic decomposition of cefaclor. Under O2saturation, 90% TOC removal was observed with 100000Gy. Oxygen is well known to play a considerable role in the degradation of organic substances with effective chain reaction pathways. According to the effective radical reactions, the enhanced TOC percentage removal efficiencies might be based on the fast conversion reactions of eaq-and H with O2into oxidizing radicals, such as O2-and HO2, respectively. 100% TOC removal was obtained with N2O gas at 20000Gy, as reducing radicals, such as eaq-and H, are scavenged by N2O and converted into OH radicals, which have strong oxidative properties. The results of this study showed that gamma irradiation was very effective for the removal of cefaclor in aqueous solution. The use of O2or N2O, with radiation, shows promise as effective radical scavengers for enhancing the TOC or COD removal efficiencies in pharmaceutical wastewaters containing antibiotics. However, the biological toxicity and interactions between various chemicals during the radiolytic treatment, as well as treatments under conditions more representative of real wastewater will require further studies.