DSA类电极催化降解硝基苯动力学及机理的研究

用新兴的电化学催化系统,以特殊工艺自制的DSA类电极作阳极,对模拟硝基苯废水进行了降解处理,得出了该试验范围内的最佳条件,降解过程符合一级反应模型.根据分析,推测硝基苯分子主要先被阴极产生的H还原为亚硝基苯、苯胺等,然后再扩散到阳极附近被HO*氧化为偶氮苯、氧化偶氮苯等,最后进一步氧化开环,生成苯基丁二酸等酸类物质以至二氧化碳,同时硝基苯分子也可以直接在阳极附近得到氧化生成2-硝基苯酚.最后,对硝基苯的降解途径进行了描述.      

全氟辛酸和全氟辛基磺酸的光降解技术及机理研究进展

目前,普遍存在于各种环境介质中的全氟辛酸(PFOA)和全氟辛基磺酸(PFOS)造成的环境污染问题已引起全球的广泛关注.PFOA和PFOS具有稳定性、持久性和生物累积性等特点.常规的方法如:超声降解法、电化学氧化法和微生物降解法等,很难将其彻底降解,因此开发有效的PFOA和PFOS降解技术成为了环境领域的研究重点.近年来...     

OH自由基降解二英OCDD的反应机理及动力学研究

采用量子化学计算研究了OH自由基降解八氯代二苯并对-二英（OCDD）的微观反应机理,计算分析了微观反应进程,结果表明该反应存在两条途径：①α-氯取代：1,4,6,9位置氯取代,该路径反应活化能较高,反应难以进行,并以中间产物积聚,无法使OCDD的毒性消失;②β-氯取代：2,3,7,8位置氯取代,该路径的反应能相对较低,且能使OCDD的毒性消失,是有效降解OCDD的主要途径.结合过渡态理论,计算获得动力学参数：反应活化能为8.32 kJ·mol^-1（B3LYP/6-311G++（d,g）//B3LYP/6-31G（d））,阿仑尼乌斯表达式为k=1.29×10¹⁴exp（-1049.6/T）（cm³·mole^-1·s^-1）.这与文献实验结果取得了很好的吻合,说明本文对OH自由基降解OCDD的反应机理及动力学研究是合理且可靠的.本文的计算结果可为催化氧化降解二英的进一步研究提供理论参考.     

土霉素降解菌TJ-1在猪粪无害化处理中的作用

利用普通理化分析结合Biolog微平板技术研究了土霉素高效降解菌Staphylococcus sp.TJ-1在新鲜猪粪无害化处理中的作用.结果表明,土霉素高效降解菌的接种能显著提高猪粪中土霉素的降解效率(p＜0.05),21d堆肥结束时可将土霉素降解率从62.7％提升至82.0％.堆肥结束后,不接种降解菌的普通堆肥工艺和接种降解菌的高效堆肥工艺中NH+4-N含量分别为189.34、42.36 mg·kg-1,NO-3-N含量分别为439.38、238.06 mg·kg-1.Biolog结果显示,土霉素降解菌TJ-1对土霉素中碳源的代谢有利于堆体中氨基酸类及芳香族化合物等氮源的降解,缓解了堆体中有毒有害物质对其他微生物的损伤,保证了微生物群落的多样性和活性,对维护堆体生态系统的稳定性具有良好作用.因此,接种高效降解菌进行堆肥是一种良好的消除抗生素残留的猪粪无害化工艺.     

三唑酮在油菜-土壤生态系统中的降解与建模

为评价三唑酮可湿性粉剂在土壤-油菜生态系统中使用后的残留行为和环境安全性,进行了2 a大田试验,并比较了指数模型、GM(1,1)灰色模型、阻滞动力学模型对三唑酮降解规律的描述。结果表明:3种模型的拟合结果均达到统计学意义上显著相关;对三唑酮在土壤和油菜中降解行为模拟结果最好的分别为GM(1,1)模型和阻滞动力学模型;三唑酮在土壤中2 a的半衰期分别为3.48和4.38 d,油菜植株中分别为1.98和3.78 d,其降解受温度影响较大。     

Effect of sulfate on the methanogenic activity of a bacterial culture from a brewery wastewater during glucose degradation

The maximum specific methanogenic activity （SMA） of a sludge originating from a brewery wastewater treatment plant on the degradation of glucose was investigated at various levels of sulfate on a specific loading basis. Batch experiments were conducted in serum bottles at pH 7 and 35℃. A comparison of the values indicates that the SMA of this mixed culture was increased and reached its highest level of 0.128 g CH4 gas COD/（g VSS.d） when biomass was in contact with sulfate at a ratio of 1：0.114 by weight.     

Imazaquin degradation and metabolism in a sandy loam soil amended with farm litters

Irnazaquin applied in legume crops has a long residual time in soil, which often impacts safety of the susceptible crops. To increase safety of imazaquin application, two composted litters, bovine manure （BM） and chicken manure （CM）, were used to determine their effects on imazaquin environmental behavior by incorporating each kind of manure into the tested sandy loam soil at 10% （w/w）. The degradation of imazaquin in BM- and CM-amended soil was about 2.4 and 1.5 times, respectively, faster than that in unamended soil. The half-lives of imazaquin in BM-amended soil varied between 6.7 and 15.4 d over the temperature range of 20 to 40℃, and the degradation rate constant （k） increased by a factor of about 1.5 for every 10℃ change. Higher mix ratio did not significantly increase the degradation, and the optimal active degradation of imazaquin was observed approximately at the mix ratio of 10：1 of soil to BM. The different moisture levels had negligible effect on imazaquin degradation. In both unamended and BM-amended treatments, two metabolites were observed at 5, 10 and 30 d after treatment. One metabolite at retention time （RT） of 8.4 rain was identified as 2-（4- hydroxyl-5-oxo-2-imidazolin-2-yl） quinoline acid, originating from the loss of isopropyl group and hydroxylation at the 4-position of imidazolinone ring. The other at RT of 12.9 rain was identified as quinoline-2,3-dicarboxylic anhydride, resulting from detachment of imidazolinone ring and the forming of dicarboxylic anhydride. This finding suggested that the addition of farm litters into soil might be a good management option since it can not only increase soil fertility but also contribute to increase safety of imazaquin application to the following susceptible crops.     

Aerobic degradation of methyl tert-butyl ether by a Proteobacteria strain in a closed culture system

The contamination of methyl ten-butyl ether （MTBE） in underground waters has become a widely concerned problem all over the world. In this study, a novel dosed culture system with oxygen supplied by H2O2 was introduced for MTBE aerobic biodegradation. After 7 d, almost all MTBE was degraded by a pure culture, a member of β-Proteobacteria named as PMI, in a closed system with oxygen supply, while only 40% MTBE was degraded in one without oxygen supply. Dissolved oxygen （DO） levels of the broth in closed systems respectively with and without H2O2 were about 5-6 and 4 mg/L. Higher DO may improve the activity of monooxygemase, which is the key enzyme of metabolic pathway from MTBE to tert-butyl alcohol and finally to CO2, and may result in the increase of the degrading activity of PM1 cell. The purge and trap GC-MS result of the broth in closed systems showed that tea-butyl alcohol, isopronol and acetone were the main intermediate products.     

亚硝酸盐型同步脱氮除硫工艺单质硫产率及特性

采用SBR同步脱氮除硫反应器,设置了化学对照组(灭菌,不添加污泥)和生物试验组(添加污泥),以期研究亚硝酸盐型同步脱氮除硫工艺中S0的产率以及特性.发现化学对照组中NO2--N和S2--S的去除率最高可分别达到25.07％和62.26％,其主要产物为NH4+-N和S2SO32--S,并无S0生成.而在生物试验组中,NO...     

水热法合成SnWO4及其对甲基橙的光催化降解性能

采用水热法合成了光催化剂SnWO4,并研究了其对甲基橙的可见光催化降解性能.实验结果表明:制备SnWO4的最佳反应条件为水热反应pH 3.6,水热反应温度160℃,水热反应时间24 h;采用SnWO4光催化降解甲基橙的最佳加入量为1.5 g/L;甲基橙初始质量浓度越高,其降解率越低;溶液在酸性和中性条件下有利于甲基橙的...