WC/TiO2纳米复合界面光催化剂制备及其光催化降解酚类污染物研究

设计并制备了新型WC/TiO2纳米复合界面光催化剂应用于酚类污染物的光催化降解反应中.采用X射线衍射(XRD)和扫描电子显微镜(SEM)技术分析了WC/TiO2纳米复合界面光催化剂的晶型和表面形貌.结果显示锐钛矿型TiO2纳米颗粒均匀地分散在WC纳米球表面并很好地构筑了WC/TiO2界面.研究了不同WC负载比例的WC/TiO2光催化剂在模拟太阳光照射下降解苯酚的光催化性能.结果表明:WC/TiO2复合界面的形成可以有效地提高TiO2光催化降解性能;其中,3%WC/TiO2(质量分数)光催化降解苯酚的活性最高.利用紫外-可见光谱(UV-Vis)和高效液相色谱-质谱联用技术(HPLC-MS)分析了WC/TiO2纳米复合界面光催化剂降解苯酚的中间产物,提出了苯酚在WC/TiO2界面上可能的降解机理.     

Mechanism and kinetics study on the ozonolysis reaction of 2,3,7,8-TCDD in the atmosphere

The ozonolysis of 2,3,7,8-tetra-chlorodibenzo-p-dioxin(2,3,7,8-TCDD) is an efcient degradation way in the atmosphere. The ozonolysis process and possible reactions path of Criegee Intermediates with NO and H2 O are introduced in detail at the method of MPWB1K/6-31+G(d,p)//MPWB1K/6-311+G(3df,2p) level. In ozonolysis, H2O is an important source of OH radical formation and initiated the subsequent degradation reaction. The Rice-Ramsperger-Kassel-Marcus(RRKM) theory was applied to calculate rate constants with the temperature ranging from 200 to 600 K. The rate constant of reaction between 2,3,7,8-TCDD and O3 is 4.80 × 10 20cm3/(mole·sec) at 298 K and 760 Torr. The atmospheric lifetime of the reaction species was estimated according to rate constants, which is helpful for the atmospheric model study on the degradation and risk assessment of dioxin.     

Comparison of biochemical characteristics between PAO and DPAO sludges

A successful enhanced biological phosphorus removal(EBPR) was observed in both anaerobicaerobic sequencing batch reactor(An-Ox SBR) to induce growth of phosphorus accumulating organism(PAO) and anaerobic-anoxic(An-Ax) SBR to induce growth of denitrifying PAO(DPAO).Although the EBPR performance of An-Ox SBR was higher by 11.3% than that of An-Ax SBR,specific phosphorus release rates in the An-Ax SBR(22.8 ± 3.5 mg P/(g VSS·hr)) and the An-Ox SBR(22.4 ± 4.8 mg P/(g VSS·hr)) were similar. Specific phosphorus uptake rates under anoxic and aerobic conditions were 26.3 ± 4.8 mg P/(g VSS·hr)(An-Ax SBR) and 25.6 ± 2.8 mg P/(g VSS·hr)(An-Ox SBR), respectively, which were also similar. In addition, an analysis of relationship of poly-β-hydroxyalkanoates(PHA) synthesized under anaerobic conditions with phosphorous release(Preleased/PHAsynthesized) and of PHA utilized under anoxic and aerobic conditions with phosphorous uptake(Puptaked/PHAutilized) verified that biological activities of EBPR per unit biomass between DPAO and PAO were similar. An analysis of the specific denitrification rate of DPAO showed that NO-3-N can be denitrified at a rate that does not substantially differ from that of an ordinary denitrifier without additional consumption of organic carbon when the PHA stored inside the cell under anaerobic conditions is sufficiently secured.     

石油污染物对海底微生物燃料电池性能的影响及加速降解效应

海底石油污染物在缺氧环境下导致其生物降解过程缓慢,对海洋环境造成长期危害.本文利用海底微生物燃料电池(BMFCs)原理,尝试通过电催化作用提高海底石油污染物的降解速率.对比测试了含油电池装置(BMFCs-A)与无油电池装置(BMFCs-B)的电化学性能,研究了石油污染物对电池性能的影响;比较了含油通路(BMFCs-A)和断路状态下(BMFCs-C)的石油降解率和细菌聚集量,分析了BMFCs对石油污染物降解的加速作用.结果表明,BMFCs-A和BMFCs-B阳极的交换电流密度分别为1.37×10-2A·m-2和1.50×10-3A·m-2,最大输出功率密度分别是105.79 m W·m-2和83.60 m W·m-2,BMFCs-A装置的抗极化能力增强,交换电流密度提高近9倍,最大输出功率密度提高1.27倍.BMFCs-A和BMFCs-C阳极表面的异养菌数量分别是(66±3.61)×107CFU·g-1和(7.3±2.08)×107CFU·g-1,细菌数量增加了8倍,高的异养菌数量导致石油降解加速进行,BMFCs的石油降解率是自然条件下的18.7倍.BMFCs在电化学性能提高的同时,加速石油污染物的降解.本文同时提出了一种海底微生物燃料电池对石油污染物加速降解的新模式.     

基于氢氧稳定同位素的黄土高原云下二次蒸发效应

根据GNIP提供的1985年1月至2004年12月黄土高原8个站点的409个降水同位素数据及同期的气象资料,结合HYSPLIT 4.9模型,分析了该区δ18O和d的时空分布特征,计算了二次蒸发的比率,并对不同气象因子影响二次蒸发的程度作了探讨,得到以下结论:1冬季风和夏季风期间,在黄土高原内由南向北δ18O呈上升趋势,d呈下降趋势;自东向西δ18O仅在夏季风期间有上升趋势,而在冬季风期间呈现下降趋势,d总呈现下降的趋势,δ18O和d的变化幅度可以指示季风的路径.2该区全年存在二次蒸发效应,夏季风期间最为明显,蒸发比率介于1.51%~5.88%之间,平均值为3.87%.冬季风期间蒸发比率总体较低,介于1.06%~5.46%之间,平均值也降为3.03%.黄土高原边缘站点蒸发比率受季风变化影响较大,而中部站点受季风变化影响较小.3温度对二次蒸发的影响较大,降水量和水汽压其次,相对湿度较小.此外,风速和海拔对二次蒸发的影响较弱.     

泄爆导管对球形容器内气体爆炸泄放过程影响的试验

设计了球形容器内气体爆炸通过导管泄爆的试验系统,选用体积分数为10%(特殊说明除外)的甲烷和空气预混气体开展试验,研究了泄爆导管长度、容器容积、点火位置、气体体积分数、破膜压力等因素的影响。结果表明:泄爆导管越长,容器内的正压力峰值和负压力峰值越大;密闭爆炸时,球形容器的容积对爆炸压力峰值几乎无影响;不同容积球形容器内气体爆炸通过相同导管泄爆时(导管长度均为6 m,直径均为0.06 m),容积大的容器内的压力锋值为小容器压力值的3.3倍,且大容器内的压力上升速率也明显高于密闭爆炸的情况;有泄爆导管存在时,尾部点火容器内的压力峰值高于中心点火;泄爆导管的存在使得容器内的压力峰值高于直接泄爆时的压力峰值;无论有、无泄爆导管,容器内的压力峰值均随破膜压力增加而增加,但差值越来越小,说明导管的存在对容器爆炸泄爆过程的影响趋向缓和,但导管的存在总是阻碍了泄爆过程,增加了爆炸的严重程度,因此,在泄爆设计时要充分考虑导管的影响,适当提高容器自身的耐压强度。     

地铁火灾场景设计的初步研究

现阶段地铁火灾研究的主要工具是计算机模拟,而模拟计算结果准确与否很大程度上取决于火灾场景选取得是否恰当.本文通过对地铁站内的可燃物状况和已发生地铁火灾情况的仔细调查与分析,设定出了几种典型的地铁火灾场景,为地铁火灾模拟计算提供了依据.     

石化企业伤亡事故率的系统动力学仿真

针对石化企业伤亡事故率的复杂性和与企业运行的系统相关性,为了科学地预测伤亡事故率,提出了利用系统动力学对石化企业伤亡事故率进行仿真试验的方法.在对石化企业伤亡事故率进行了系统动力学分析之后,建立了石化企业伤亡事故率系统动力学仿真模型,对某石化企业进行了仿真试验,并分析了仿真试验的结果.试验应用表明,利用系统动力学对石化企业伤亡事故率进行仿真是科学有效的.     

Application of the health risk assessment of acetochlor in the development of water quality criteria

Acetochlor is a widely used herbicide in agricultural production. Studies have shown that acetochlor has obvious environmental hormone effects, and long-term exposure may pose a threat to human health. To quantify the hazards of acetochlor in drinking water, a health risk assessment of acetochlor was conducted in major cities of China based on the data of acetochlor residue concentrations in drinking water. The approach of the Species Sensitivity Distributions (SSD) method is used to extrapolate from animal testing data to reflect worst case human toxicity. Results show that hazard quotients related to acetochlor residues in drinking water for different age groups range from 1.94 × 10^?4 to 6.13 × 10^?4, so, there are no indication of human risk. Compared to the total estimated hazard quotient from oral intake of acetochlor, the chronic exposure imputed to acetochlor residues in drinking water in China accounts for 0.4%. This paper recommends 0.02 mg/L to be the maximum acetochlor residue concentration level in drinking water and source water criteria.     

哈密市锅炉烟尘控制区监测验收结果分析

对哈密市区锅炉烟尘验收监测结果作了分析阐述，论述了市区烟尘控制区烟尘排放规律及特点，并对监测统计结果进行了小结，为日后的实测工作积累经验。