【作者】 张静；

【导师】 关小红；

【作者基本信息】 哈尔滨工业大学 ， 市政工程， 2014， 博士

【摘要】 近十年，随着环境检测技术的进步和人类环保意识的增强，水环境中的新兴微污染物(emerging micropollutants, EMs)正日益受到全世界科研人员的关注。目前水质或环境指标中并没有规定多数新兴微污染物在水中或者环境中的最高允许浓度。新兴微污染物种类繁多、性质各异，因此它们的检测和分析也给科研人员提出了很大挑战。常规水处理工艺很难有效去除水中的新兴微污染物，所以寻找和开发更加有效的深度水处理技术或者预处理技术已经成为必然。高锰酸钾氧化工艺在常见水处理pH范围内对水中有机污染物具有较强的氧化能力，其还原产物二氧化锰可以通过吸附、氧化、助凝等与高锰酸钾协同除污染。但由于高锰酸钾在使用过程中容易出现色度超标的问题，因此本文采用钌催化高锰酸钾氧化技术，通过催化过程提高高锰酸钾氧化新兴微污染物的效能，同时降低高锰酸钾的投加量。本文首先证明了在近中性pH范围内均相RuIII催化高锰酸钾氧化技术去除水中新兴微污染物的可行性。RuIII在pH4.0-8.0范围内将高锰酸钾氧化双酚A的反应速率提高了1.2-8.4倍，同时也提高了双酚A的矿化率。虽然RuIII溶液作为均相催化剂可以很好地催化高锰酸钾氧化去除水中新兴微污染，但RuIII溶液投加进水体以后会对水体造成二次污染，并且也不能实现回收利用。为了实现催化剂的回收和重复利用，本文制备了非均相钌催化剂。利用上海光源X射线精细结构吸收光谱(XAFS)探索了其催化高锰酸钾氧化新兴微污染物的机制，具体如下：催化剂表面的RuIII被高锰酸钾氧化为高价态的RuVII和RuVI，而RuVII比高锰酸钾的氧化活性更高，可以快速地将新兴微污染物氧化，同时自身回到RuIII。RuIII可以继续与高锰酸钾反应，开始下一轮催化循环过程。非均相钌催化高锰酸钾氧化的效能受反应条件的影响较大。随着pH从4.0升高至8.0，Ru/CeO2催化高锰酸钾氧化对羟基苯甲酸丁酯的二级反应速率常数从90.4M-1s-1降低至16.9M-1s-1；高锰酸钾浓度较低的时候，Ru/CeO2的催化效果更明显；当催化剂的浓度从0.13g L-1增加至2.0g L-1，相应的二级反应速率常数呈线性增大的趋势，从6.7M-1s-1升高至74.7M-1s-1；另外非均相钌催化剂降低了高锰酸钾氧化对羟基苯甲酸丁酯的表观活化能。本文制备了Ru/CeO2、Ru/TiO2、Ru/ZSM-5A、Ru/ZSM-5B和Ru/MCM-41等一系列不同载体的催化剂，考察了载体对其催化性能的影响。结果表明基于不同载体的钌催化剂其催化效果的差异主要源于催化剂表面钌负载量的不同，与载体自身的性质没有明显关系。载体对催化剂的稳定性有很大影响，载体的比表面积越大，相应载体制备的催化剂在反应过程中就越容易吸附高锰酸钾的还原产物二氧化锰，也就越容易失活。随着非均相钌催化剂的重复使用，催化剂会出现逐渐失活的现象，因此本文采用盐酸羟胺和抗坏血酸分别对非均相钌催化剂Ru/ZSM-5A进行了再生研究。经盐酸羟胺再生后的Ru/ZSM-5A的性能与新制备Ru/ZSM-5A的性能相当，再生后的Ru/ZSM-5A催化高锰酸钾氧化磺胺甲噁唑的去除率可以达到95%；而经抗坏血酸再生的Ru/ZSM-5A氧化磺胺甲噁唑的去除率仅为76.2%。这可能主要是由于抗坏血酸不能够完全将非均相钌催化剂表面堆积的二氧化锰还原为溶解态的离子，而使得催化剂再生不完全。非均相钌催化高锰酸钾氧化技术可以很好地去除水中含有富电子基团的新兴微污染物，也可以同步降低其相应的急性生物毒性。该技术可以同时去除水中共存的多种痕量新兴微污染物(浓度约为g L-1)，并且它们的二级反应速率常数不会因为彼此间竞争催化剂和氧化剂而降低。通过向实际水源水中投加新兴微污染物的标准品，发现在实际水体中Ru/TiO2催化高锰酸钾氧化技术对富电子基团的新兴微污染物具有很好的选择性，并且水源水中微量的腐殖酸可以进一步促进该技术的氧化效能，但当腐殖酸的浓度较高时也会与新兴微污染物形成竞争，进而降低氧化效率。非均相钌催化高锰酸钾氧化过程中不会有溴酸盐等消毒副产物产生。由此可见，RuIII催化高锰酸钾氧化技术是去除水中新兴微污染物非常高效和非常有前景的预氧化水处理技术。更多还原

【Abstract】 With the development of measuring and testing techniques and people’s awareness of environmental protection in this decade, the emerging micropollutans (EMs) in aquatic environment are becoming a new concern to the worldwide researchers. Emerging micropollutants are those that are suspected to have harmful effects-e.g. endocrine disruption and antibiotic drug resistance-but are not routinely monitored or regulated against. Research on emerging micropollutants is further complicated as there is an extensive array of different chemicals entering the aquatic environment, their volume is increasing and new compounds are continually being introduced to the market. Emerging micropollutants have been found in the effuent of wastewater treatment plants, which constitutes a major limitation for their potential reuse. Hence, the development of new strategies to deal with this concern is needed. Permanganate has several obvious advantages, such as relatively low cost, ease of handling, effectiveness over a wide pH range, and comparative stability. Its reductant manganese dioxide can also remove the pollutants by adsoption, oxidation and coagulation. Considering the unpleasant color of permanganate, only very low inlet concentration was allowed to avoid the appearance of chromaticity in the treated water. Thus, catalyzing this process is becoming a necessity to achieve high emerging pollutants removal with lower permanganate dosage.This study proved that the addition of homogeneous Ru enhanced the performance of permanganate oxidation of emerging micropollutant at environmentally relevant pH. The second order rate constants of permanganate oxidation of bisphenol A (BPA) were increased by1.2to8.4fold at pH4.0-8.0in the presence of RuIII. The mineralization rate of BPA was much higher in RuIII catalyzed permanganate oxidation than its uncatalytic counterpart. Ru is rather expensive and the addition of RuIII into permanganate oxidation system is far from practical application, since it is troublesome to remove or/and Ru from the efuents. The heterogeneous catalyst (Ru/CeO2) was prepared for reclamation andrecycling. The catalytic mechanism of Ru/CeO2in permanganate oxidation of emerging micropollutant was explored. The XANES analysis revealed that (i) Ru was deposited on the surface of CeO2as RuIII;(ii) RuIII was oxidized by permanganate to its higher oxidation state RuVI and RuVII, which acted as the co-oxidants in butylparaben (BP) oxidation;(iii) RuVI and RuVII were reduced by BP to its initial state of RuIII. Therefore, Ru/CeO2acted asan electron shuttle in catalytic permanganate oxidation process.The kinetics of BP degradation by Ru/CeO2catalyzed permanganate was determined as functions of pH, permanganate concentration, catalyst dosage and temperature. In the heterogeneous catalysis, the oxidation potential of permanganate increased with decreasing pH over the pH range of4.0-8.0, which would result in more efective RuIII oxidation to RuVII and RuVI and thus more rapid BP oxidation at lower pH. More signifcant enhancement in BP removal rate due to the presence of Ru/CeO2catalyst at lower permanganate concentration was observed. With the increase of Ru/CeO2dosage from0.13to2.0g L-1, the rate constant of BP degradation increased linearly from6.7to74.7M-1s-1.The second order rate constants of Ru catalyzed permanganate correlated well with the loading of Ru on the catalysts, indicating that the performance of heterogeneous catalysts dependented on their coorespounding Ru loading. The stability of heterogeneous catalysts was highly depended on the BET suface area of the support. The higher BET suface area would lead to higher amount of MnO2deposition onto the surface of catalyst, thus the catalytic effect of Ru/CeO2catalyst would decrease due to the masking of the active sites.The regenerated Ru/ZSM-5A by hydroxylamine hydrochloride performed as good as the newly prepared one. But the ascorbic acid could not totally remove the deposited MnO2. It should be noted that hydroxylamine hydrochloride was toxic, thus Ru/ZSM-5A regenerated by hydroxylamine hydrochloride should be flushed for some times before next run in water treatment.Permanganate catalyzed by Ru/TiO2is a selective oxidant, which can oxidize emerging micropollutants containing electron-rich organic moieties. Ru catalyzed permanganate oxidation was effective not only for eliminating emerging micropollutants but also for detoxification.The oxidation rates of these three emerging micropollutants by Ru/TiO2catalyzed permanganate were not decreased due to the presence of other emerging micropollutants, indicating that the oxidation ability of Ru/TiO2catalyzed permanganate was much stronger than permanganate. Therefore, Ru/TiO2catalyzed permanganate could remove target emerging micropollutants effectively in the presence of a variety of other emerging micropollutants at trace concentration.In real water, the oxidative removal of emerging micropollutants by Ru/TiO2catalyzed permanganate is a promising method due to its higher selectivity. In catalytic process, the removal of emerging micropollutants was enhanced in the presence of lower concentration humic acid, while some reductants and higher concentration humic acid in real water may compete for the oxidant with target organics and thus lower the performance of Ru catalyzed permanganate oxidation. No bromate byproduct was formed during the catalytic process. Therefore, Ru-catalyzed permanganate oxidation was an effective and promising peroxidation process in water treatment.更多还原