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191.
Pentachlorobenzene (PeCB) in simulated flue gas was destructed by a commercial V2O5-WO3/TiO2 catalyst in this study. The effects of reaction temperature, oxygen concentration, space velocity and some co-existing pollutants on PeCB conversion were investigated. Furthermore, a possible mechanism for the oxidation of PeCB over the vanadium oxide on the catalysts was proposed. Results show that the increase of gas hourly space velocity (GHSV) and the decrease of operating temperature both resulted in the decrease of PeCB removal over the catalyst, while the effect of the oxygen content in the range of 5-20% (v/v) on PeCB conversion was negligible. PeCB decomposition could be obviously affected by the denitration reactions under the conditions because of the positive effect of NO but negative effect of NH3. The introduction of SO2 caused the catalyst poisoning, probably due to the sulfur-containing species formed and deposited on the catalyst surface. The PeCB molecules were first adsorbed on the catalyst surface, and then oxidized into the non-aromatic acyclic intermediates, low chlorinated aromatics and maleic anhydride. 相似文献
192.
Tao Tang Kun QianTianyu Shi Fang WangPingliang Li Jianqiang LiYongsong Cao 《Chemosphere》2012,89(11):1419-1425
Quinestrol is synthetic estrogen used in contraceptive and hormone replacement therapy and occasionally for treating breast cancer and prostate cancer. It can make its way into the environment through sewage discharge and waste disposal produced by human excretions. In this study, the photodegradation kinetics of quinestrol in various conditions was investigated by UV and solar irradiation. The affecting factors were studied including concentration of hydrogen peroxide, different water types, and the initial concentrations of quinestrol. Concurrently, the transformation products and presumed pathways of quinestrol in distilled water by UV irradiation were identified and proposed. The results showed that the degradation of quinestrol in both irradiation conditions followed the pseudo-first-order kinetics. More rapid degradation was observed by UV irradiation (k = 0.018 min−1) than solar irradiation (k = 0.004 h−1), and the photodegradation rate of quinestrol depended on the concentration of hydrogen peroxide, the initial concentration of quinestrol and water types. The transformation products of quinestrol in distilled water were identified by gas chromatography/mass spectrometry. When exposed to UV irradiation, quinestrol in aqueous solution was rapidly degraded, giving at least ten photodegradation products. The chemical structures of ten degradation products were identified on the basis of mass spectrum interpretation and literature data. 相似文献
193.
Fang H Tang FF Zhou W Cao ZY Wang DD Liu KL Wu XW Yu YL 《Journal of environmental science and health. Part. B》2012,47(2):104-110
The effects of repeated applications of the fungicide triadimefon in agricultural soil on the microbial functional diversity of the soil and on the persistence of the fungicide in the soil were investigated under laboratory conditions. The degradation half-lives of triadimefon at the recommended dosage, simulated by a first-order kinetic model, were 23.90, 22.95, and 21.52 days for the first, second, and third applications, respectively. Throughout this study, no significant inhibition of the Shannon-Wiener index (H') was observed. However, the Simpson index (1/D) and the McIntosh index (U) were obviously reduced (p ≤ 0.05) during the initial 3 days after the first triadimefon application and thereafter, gradually recovered to or exceeded the level of the control soil. A similar trend in variation but with a faster recovery in the 1/D and U was observed after the second and third triadimefon applications, respectively. Taken together, the above results indicate that the repeated application of triadimefon enhanced the degradation rate of the fungicide and the recovery rate of the soil microbial functional diversity. It is concluded that repeated triadimefon applications in soil have a transient or temporary inhibitory effect on soil microbial communities. 相似文献
194.
Tian Z Cao G Shi J McCallum I Cui L Fan D Li X 《Environmental science and pollution research international》2012,19(5):1364-1374
Purpose
The aim of this paper is to understand the sustainability of urban spatial transformation in the process of rapid urbanization, and calls for future research on the demographic and economic dimensions of climate change. Shanghai towards its transformation to a metropolis has experienced vast socioeconomic and ecological change and calls for future research on the impacts of demographic and economic dimensions on climate change. We look at the major questions (1) to explore economic and demographic growth, land use and land-cover changes in the context of rapid economic and city growth, and (2) to analyze how the demography and economic growth have been associated with the local air temperature and vegetation.Method
We examine urban growth, land use and land-cover changes in the context of rapid economic development and urbanization. We assess the impact of urban expansion on local air temperature and vegetation. The analysis is based on time series data of land use, normalized difference vegetation index (NDVI), and meteorological, demographic and economic data.Results and discussion
The results indicate that urban growth has been driven by mass immigration; as a consequence of economic growth and urban expansion, a large amount of farmland has been converted to paved road and residential buildings. Furthermore, the difference between air temperature in urban and exurban areas has increased rapidly. The decrease of high mean annual NDVI has mainly occurred around the dense urban areas. 相似文献195.
污泥转移SBR工艺处理低浓度生活污水 总被引:1,自引:0,他引:1
污泥转移SBR工艺是一种通过内部污泥回流实现污泥在不同SBR隔室间转移,从而增加污泥利用效率,提高系统除污效能的新工艺。以设计规模为240 m3/d、处理低浓度生活污水的工艺系统为对象,研究了新工艺在不同泥转移量(污泥回流比)下的除污性能,并与系统以传统SBR方式运行的情况进行了对比。结果表明,新工艺可以有效提高SBR反应器的容积利用率;采用30%的污泥回流比进行污泥转移,新工艺的处理能力比传统SBR工艺提高近1/2,除磷效率从46%提升至85%。出水各项水质指标均能达到国家排放标准的要求。 相似文献
196.
分别采用苦土、纯氧化镁为沉淀剂对模拟高浓度氮磷废水(N/P=0.8)进行了脱氮除磷研究,比较了沉淀剂投加量、pH对2种沉淀剂处理氮磷废水的影响,对沉淀产物进行XRD分析,并进行了经济效益比较。结果表明,pH是影响2种沉淀剂处理氮磷废水的主要因素,随着pH的增加,脱氮除磷效果提高,在平衡pH为9~10之间时氮磷处理效果最佳,pH继续增加,由于磷酸镁沉淀的形成使得氨氮去除率降低。此外,处理相同的废水,苦土的最佳投加量要大于纯氧化镁,但是经济效益比较结果表明,以苦土为沉淀剂处理氮磷废水可大大降低处理成本。 相似文献
197.
以γ-Al2O3为载体,以MnxCe1-xO2为催化活性组分,采用浸渍法制备了一系列负载型MnxCe1-xO2/γ-Al2O3催化剂(x=0、0.2、0.4、0.6、0.8、0.9、1),在固定床反应器中评价了催化剂对甲苯的催化燃烧性能。结果表明,MnxCe1-xO2/γ-Al2O3催化剂的催化活性与催化剂的焙烧温度、活性组分MnxCe1-xO2的负载量以及Mn、Ce摩尔比有显著关系,其中焙烧温度550℃、负载量为20%、Mn、Ce摩尔比为4:1时,即MnxCe1-xO2/γ-Al2O3催化剂对甲苯的催化性能最佳,反应温度为180℃时,甲苯的转化率达到95%。并在连续100h的稳定性操作后,催化剂的活性基本无变化。采用XRD、BET以及SEM等分析测试手段对催化剂的结构以及表面进行了表征。 相似文献
198.
Ning Hou Fengzhao Feng Yan Shi Huiming Cao Chunyan Li Zhi Cao Yi Cheng 《Environmental science and pollution research international》2014,21(17):10386-10398
A highly efficient demulsifying strain, LH-6, was isolated from petroleum-contaminated soil and identified as Bacillus cereus by 16S rDNA gene analysis. It achieved 95.61 and 95.40 % demulsifying ratios within 12 h for water-in-oil (W/O) and oil-in-water (O/W) model emulsions, respectively. Fourier transform infrared spectroscopy (FT-IR) and thin-layer chromatography (TLC) detections indicated that the LH-6’s extracellular biodemulsifiers were different types of lipopeptides for the W/O and O/W emulsions. Optimization of the culture medium composition was conducted to improve the biosynthesis and demulsifying efficiency of the biodemulsifier. The optimal carbon source was liquid paraffin, while waste frying oil could also be an alternative carbon source. The optimal nitrogen sources were ammonium sulfate and yeast extract. To further enhance the biodemulsifier efficiency, the optimal cultivation conditions were determined using response surface methodology (RSM) based on central composite rotation design (CCRD). Using the optimized cultivation conditions, the demulsifying ratios increased to 98.23 and 97.65 % for the W/O and O/W model emulsions, respectively. 相似文献
199.
采用ClO2氧化法预处理联苯胺类染料中间体生产废水,探讨了影响COD和联苯胺去除率的主要因素,并采用GC/MS技术对ClO2氧化前后废水中的有机组分进行了分析。实验确定了较佳的工艺参数:ClO2加入量为45~55 mg/L,ClO2与联苯胺的化学计量比控制在(3.0~3.5)∶1,反应时间为 30~35 min。在此条件下,ClO2氧化后出水中联苯胺去除率达到80%以上,联苯胺类污染物含量得到有效降低,废水BOD5/COD由原水的0.18提高到0.40。该方法能提高废水的可生化性,是一种较好的生化预处理技术。 相似文献
200.
分别采用沸水浸泡、酸浸、碱浸和加热的方法对粉煤灰进行改性处理,利用FTIR仪和XRD仪对改性粉煤灰的成分和官能团进行了分析,并利用改性粉煤灰对模拟刚果红废水进行脱色。实验结果表明:碱改性粉煤灰中含有大量官能团,以及NaPl型沸石类物质,能够明显提高粉煤灰对刚果红的吸附性能;与活性炭相比,碱改性粉煤灰具有更高的性价比;在初始刚果红质量浓度为20mg/L、碱改性粉煤灰加入量为50g/L的条件下,废水的脱色率可达87.52%;碱改性粉煤灰对刚果红的吸附过程遵循二级反应动力学,较好地符合Langmuir等温式和Freundlich等温式。 相似文献