【作者】 陈大伟；

【导师】 闫吉昌；

【作者基本信息】 东北师范大学 ， 环境科学， 2008， 博士

【摘要】 本实验选用电离辐射技术,对难处理的有机氯农药苯酚、六氯苯、五氯酚和五氯硝基苯废水进行辐射降解研究:模拟配置每个农药废水溶液,利用气相色谱/质谱联机测量60Co-γ射线辐照前后废水中相应农药的浓度,研究了多个因素(辐射条件、酸碱性、添加剂等)对废水中相应农药降解的影响。研究结果表明:1. TiO2粒子光催化主要依赖·OH自由基降解苯酚,其·OH自由基的产额与TiO2粒子结构有关,其降解能力是通过光催化产生·OH自由基实现的。60Co产生的γ射线和TiO2光催化均能够有效的降解苯酚。在10 kGy辐射吸收剂量下,苯酚降解率达96 %,辐射降解苯酚水溶液中,·OH自由基起主要作用,e–aq次之,辐照产生的·OH、水合电子、氢自由基等与苯酚发生开环的氧化反应,降解产物最终矿化为二氧化碳、水和气体;中性溶液中自由基活性强,有利于苯酚的降解。2. 60Co产生的γ射线能够有效的降解六氯苯。在10 kGy辐照吸收剂量下,六氯苯(HCB)降解率达90 %,在17 kGy辐照吸收剂量下,六氯苯降解率达95 %;辐照降解HCB水溶液中,·OH自由基起主要作用,·OH与六氯苯发生开环和脱氯的氧化反应,降解产物最终矿化为小分子物质、二氧化碳和气体,溶液的酸、碱性对HCB水溶液辐照降解有重要影响,碱性溶液中自由基活性强,有利于HCB的降解;加入的Na2CO3、NaNO3、H2O2和TiO2能影响参与降解反应的自由基:Na2CO3和TiO2能提高六氯苯的降解效率,NaNO3和H2O2的加入降低了六氯苯的降解效率;添加TiO2粒子,可得到协同作用的降解优于单一的降解结论。3. 60Co产生的γ射线能够有效的降解典型的有机氯农药五氯酚。在10 kGy辐照吸收剂量下,PCP降解率达90 %,在17 kGy辐照吸收剂量下,PCP降解率达96 %;在辐照降解PCP水溶液中,·OH自由基起主要作用,辐照产生的·OH自由基与五氯酚发生开环和脱氯反应,辐射降解产物最终矿化为二氧化碳和气体逸出;溶液的酸、碱性对PCP水溶液有重要影响作用,在酸性溶液中自由基活性强,有利于PCP的降解;溶液中加入Na2CO3、NaNO3、H2O2和TiO2能影响参与降解反应的自由基:Na2CO3、H2O2和TiO2能提高PCP的降解效率,NaNO3的加入降低了PCP的降解效率;添加TiO2粒子,PCP水溶液降解率提高,可得到协同作用的降解优于单一的降解结论。4. 60Co产生的γ射线能够有效的降解典型的有机氯农药五氯硝基苯。在8.5 kGy辐照吸收剂量下,PCNB降解率达95 %,在17 kGy辐照吸收剂量下,PCNB降解率达96 %;辐照降解PCNB水溶液中,e–aq电子起主要作用,辐照产生的水合电子与PCNB发生开环和脱氯反应,辐射导致了脱氯或脱硝的结果,降解产物最终矿化为二氧化碳和气体;溶液的酸、碱性对PCNB水溶液有重要影响作用,在碱性条件下自由基活性强,有利于PCNB的降解;在PCNB水溶液中加入Na2CO3、NaNO3、H2O2和TiO2能影响参与降解反应的自由基:Na2CO3和TiO2能提高PCNB的降解效率,NaNO3和H2O2的加入降低了PCNB的降解效率。它们作用的原因均为促进或抑制了e–aq、·OH和·H自由基的数量或活性;添加TiO2粒子,可得到协同作用的降解优于单一的降解结论。5.本研究还同时配制了含五氯硝基苯、氯氰菊酯、氰戊菊酯各5mg/L的混合溶液,进行60Co-γ辐照降解,结果表明在多种农药同时存在的情况下,辐射降解方法对每种农药的降解都有明显效果,可以同时达到多种农药污染同时消除的目的。6.结论:60Co-γ辐照对苯酚、六氯苯、五氯酚、五氯硝基苯等有较好降解效果,针对这些极难降解的持久性有机污染物的治理,辐照是一种较有应用前景的方法。更多还原

【Abstract】 In this paper, we studied the radiation degradation of wastewaters contaminated with organochlorine fungicides which were difficult to deal with such as HCB, PCP and PCNB by using ionizing radiation technology. Simulate wastewater containing each pesticide solution was prepared, and the before and after concentration of corresponding pesticide radiated by 60Co-γwas measured by GC/MS. And we studied the impact of a number of factors (radiation, pH, additives, etc.) on the degradation of corresponding pesticide. The results showed that: 1. Photocatalytic TiO2 particles mainly depended on the free radical ?OH to degrade phenol. The yield of ?OH radical was relevant with the structure of TiO2 particles. And its capacity of degradation was achieved through radical ? OH yielded by photocatalysis. The 60Co-γand the photocatalysis of TiO2 all could effectively degrade phenol. When radiation absorbed dose was 10 kGy, the rate of degradation of phenol could reach to 96%; In the process of radiation degradation of phenol solution, ?OH played a major role, and next was e–aq. The ?OH, the hydrated electron and hydrogen radicals produced in the process of radiation could react with phenol, so the phenol opened the loop and happened dechlorination oxidation reaction. The ultimate degradation products of phenol were small molecular substances, carbon dioxide, water and gas. The activity of radical was strong in neutral solution, so it was propitious to degrade phenol.2. 60Co-γcould effectively degrade HCB. When radiation absorbed dose was 10 kGy, the rate of degradation of HCB could reach to 90%; When radiation absorbed dose was 17 kGy, the rate of degradation of HCB could reach to 95%; in the process of radiation degradation of phenol solution, ?OH played a major role. The ?OH, could react with HCB, so the HCB opened the loop and happened dechlorination oxidation reaction. The ultimate degradation products of HCB were small molecular substances, carbon dioxide and gas; the pH of HCB aqueous solution had an important impact on the radiation degradation of HCB aqueous solution. In the alkaline solution, the activity of free radical was strong, so it was helpful to the degradation of HCB. Na2CO3, NaNO3, H2O2 and TiO2 added into HCB aqueous solution could affect free radicals involved in degradation reaction. Na2CO3 and TiO2 could improve the degradation efficiency of HCB, while NaNO3 and H2O2 could reduce the degradation efficiency of HCB; when TiO2 particles were added into, the degradation of synergies was better than the degradation of a single.3. 60Co-γcould effectively degrade PCP which was typical organic pesticide. When radiation absorbed dose was 10 kGy, the rate of degradation of PCP could reach to 90%; When radiation absorbed dose was 17 kGy, the rate of degradation of PCP could reach to 96%; in the process of radiation degradation of phenol solution, ?OH played a major role. The ?OH produced in the process of radiation could react with PCP, so the PCP opened the loop and happened dechlorination oxidation reaction. The ultimate degradation products of PCP were carbon dioxide and gas; the pH of PCP aqueous solution had an important impact on the radiation degradation of PCP aqueous solution. In the acid solution, the activity of free radical was strong, so it was helpful to the degradation of PCP. Na2CO3, NaNO3, H2O2 and TiO2 added into PCP aqueous solution could affect free radicals involved in degradation reaction. Na2CO3, H2O2 and TiO2 could improve the degradation efficiency of PCP, while NaNO3 could reduce the degradation efficiency of PCP; when TiO2 particles were added into, the degradation efficiency of PCP was improved. So the degradation of synergies was better than the degradation of a single.4. 60Co-γcould effectively degrade PCNB which was typical organic pesticide. When radiation absorbed dose was 8.5 kGy, the rate of degradation of PCNB could reach to 95%; When radiation absorbed dose was 17 kGy, the rate of degradation of PCNB could reach to 96%; in the process of radiation degradation of phenol solution, e–aq played a major role. The hydrated electron produced in the process of radiation could react with PCNB, so the PCNB opened the loop and happened dechlorination oxidation reaction. And nitro-group and chloric-group were removed owing to radiation. The ultimate degradation products of PCNB were carbon dioxide and gas; the pH of PCNB aqueous solution had an important impact on the radiation degradation of PCNB aqueous solution. In the alkaline solution, the activity of free radical was strong, so it was helpful to the degradation of PCNB. Na2CO3, NaNO3, H2O2 and TiO2 added into PCNB aqueous solution could affect free radicals involved in degradation reaction. Na2CO3 and TiO2 could improve the degradation efficiency of PCNB, while NaNO3 and H2O2 could reduce the degradation efficiency of PCNB; the reasons of their roles were all promoting or inhibiting the quantity or activity of e–aq, ?OH and ? H radicals, when TiO2 particles were added into, the degradation of synergies was better than the degradation of a single.This study also prepared 5 mg/L mixed solution containing pentachloronitrobenzene, cypermethrin, fenvalerate, and the mixed solution was degraded by 60Co-γradiation. The result showed that the radiation degradation method had obvious degradation effect for each pesticide under the condition of various pesticides existing, and the purpose of a variety of pesticide contamination degraded at the same time could be carried out.60Co-γirradiation had a better degradation effect on the HCB, PCP and PCNB. In response to the treatment of extremely difficult degradation persistent organic pollutants, the radiation was a more promising method.更多还原