光辅助下TiO2-蒙脱土复合材料抑杀蓝藻

以TiCl4和钠基蒙脱土为原料,采用水解法制备了TiO2-蒙脱土复合材料,采用XRD、IR和TEM对其结构和性质进行表征;通过藻细胞的内含物含量、生长代谢活性和形态的变化以及藻细胞膜脂质过氧化分析,研究了TiO2-蒙脱土复合材料在光辅助下去除颤藻的性能.结果表明,TiO2-蒙脱土复合材料中一部分TiO2插入蒙脱层间,增加了蒙脱土的层间距,另一部分以锐钛矿相均匀分散在蒙脱土上;在紫外光辅助下,TiO2-蒙脱土的用量为50.0 mg/L,lh后颤藻的除藻率可达94.58％;TiO2-蒙脱土通过光催化作用破坏藻细胞膜、降解藻细胞内含物、降低藻细胞代谢活性和破坏藻细胞形态,从而产生抑藻作用.     

亚铁氰化铜的制备及其对铯的吸附

以亚铁氰化钠和硝酸铜为原料,采用水热合成法制备出亚铁氰化铜(CuFC)吸附剂,对其进行了表征,并考察了CuFC对模拟放射性废水中铯的吸附性能。表征结果显示:产物的分子式为Cu2Fe(CN)6·7H2O,外观为具有清晰几何形状的颗粒物,粒径约为30 nm。25℃下的静态吸附实验结果表明:当初始铯质量浓度为98.01μg/L、CuFC加入量为0.08 g/L、吸附时间为90 min时,达到吸附平衡,铯的去污系数达到1.13×104;用拟二级动力学模型可准确描述CuFC对铯的吸附过程,相关系数为1.000 0;吸附等温线符合Freundlich等温吸附模型。     

光催化降解内分泌干扰物双酚A的响应面分析与优化

对光催化降解内分泌干扰物双酚A进行了研究,使用响应面方法(RSM)结合中心组合设计(CCD),对光催化过程中的影响因素(光强、Ti O2浓度、初始双酚A浓度)进行了探讨和分析,构建响应面模型,并对反应条件进行了优化。此响应面模型能够较好地模拟实验结果,可以用于探索设计空间。优化的最佳反应条件为:Ti O2浓度1.80 g/L、初始双酚A浓度41.08 mg/L、UV光强6.61 m W/cm2,预测和实验最大双酚A去除率分别为81.5%和82.3%,数值比较接近,说明此响应面模型能够有效描述光催化反应过程,优化光催化反应条件,为光催化技术工程应用和光反应器设计提供技术参考。     

交流变频磁化聚合硫酸铁混凝处理造纸废水

采用交流变频磁场预处理聚合硫酸铁(PFS),用于混凝处理造纸废水。考察了有无磁化作用、PFS加入量、磁化强度、磁化频率、磁化时间等因素对造纸废水的COD去除率和色度去除率的影响。实验结果表明:磁化PFS对造纸废水的处理效果较未磁化时明显提高;在PFS加入量为1 000 mg/L、磁化强度为6 mT、磁化频率为90 Hz、磁化时间为3 min的条件下,处理初始COD为650 mg/L、初始色度为180倍的造纸废水,COD去除率为93.22%,色度去除率为88.89%。     

PCB 77 dechlorination products modulate pro-inflammatory events in vascular endothelial cells

Persistent organic pollutants such as polychlorinated biphenyls (PCBs) are associated with detrimental health outcomes including cardiovascular diseases. Remediation of these compounds is a critical component of environmental policy. Although remediation efforts aim to completely remove toxicants, little is known about the effects of potential remediation byproducts. We previously published that Fe/Pd nanoparticles effectively dechlorinate PCB 77 to biphenyl, thus eliminating PCB-induced endothelial dysfunction using primary vascular endothelial cells. Herein, we analyzed the toxic effects of PCB congener mixtures (representative mixtures of commercial PCBs based on previous dechlorination data) produced at multiple time points during the dechlorination of PCB 77 to biphenyl. Compared with pure PCB 77, exposing endothelial cells to lower chlorinated PCB byproducts led to improved cellular viability, decreased superoxide production, and decreased nuclear factor kappa B activation based on duration of remediation. Presence of the parent compound, PCB 77, led to significant increases in mRNA and protein inflammatory marker expression. These data implicate that PCB dechlorination reduces biological toxicity to vascular endothelial cells.     

Degradation pathways of low-ethoxylated nonylphenols by isolated bacteria using an improved method

Nonylphenol ethoxylates (NPEOs) with low ethoxylation degree (NP_av2EO; containing two ethoxy units on average) and estrogenic properties are the intermediate products of nonionic surfactant NPEOs. To better understand the environmental fate of low-ethoxylated NPEOs, phylogenetically diverse low-ethoxylated NPEO-degrading bacteria were isolated from activated sludge using gellan gum as the gelling reagent. Four isolates belonging to four genera, i.e., Pseudomonas sp. NP522b in γ-Proteobacteria, Variovorax sp. NP427b and Ralstonia sp. NP47a in β-Proteobacteria, and Sphingomonas sp. NP42a in α-Proteobacteria were acquired. Ralstonia sp. NP47a or Sphingomonas sp. NP42a, have not been reported for the degradation of low-ethoxylated NPEOs previously. The biotransformation pathways of these isolates were investigated. The first three strains (NP522b, NP427b, and NP47a) exhibited high NP_av2EO oxidation ability by oxidizing the polyethoxy (EO) chain to form low-ethoxylated nonylphenoxy carboxylates, and then further oxidizing the alkyl chain to form carboxyalkylphenol polyethoxycarboxylates. Furthermore, Sphingomonas sp. NP42a degraded NP_av2EO through a nonoxidative pathway with nonylphenol monoethoxylate as the dominant product.     

Association of PM2.5 pollution with the pattern of human activity: A case study of a developed city in eastern China

Recently, air pollution has attracted a substantial amount of attention in China, which can be influenced by a variety of factors, but the association between air pollution and human activity is not quite clear. Based on real-time online data (January 1, 2014, to December 31, 2014) of air pollution and meteorology reported by official sites, and demographic, economic, and environmental reform data in a statistical yearbook, the influences of meteorological factors (temperature, relative humidity, precipitation intensity, and wind force) and human activities on PM_2.5 pollution were explored. After correlation analysis, logistic regression analysis, and a nonparametric test, weak negative correlations between temperature and PM_2.5 pollution were found. In most cases, festival and morning peak hours were protection and risk factors of PM_2.5 pollution, respectively. In addition, government actions, such as an afforestation project and increasing financial expenditure for energy saving and environmental protection, could greatly contribute to alleviating pollution of PM_2.5. The findings could help officials formulate effective laws and regulations, and then PM_2.5 pollution related to the pattern of human activity would be ameliorated.

Implications: Most of the time, festival and morning peak hours are protection and risk factors for PM_2.5 pollution, respectively. Increasing the percentage of afforestation area and financial expenditure for energy saving and environmental protection could significantly reduce PM_2.5 pollution. The findings can help officials formulate effective laws and regulations, and then PM_2.5 pollution related to the pattern of human activity, especially government action, will be ameliorated.     

水化深度处理渗滤液尾水中的有机物

利用水泥的水化过程易受有机物影响的特点,采用硅酸盐水泥深度处理了垃圾渗滤液膜生物反应器(MBR)工艺出水,考察了不同因素,如投加量、初始pH、反应时间及振荡速率等对于渗滤液尾水中有机物的去除效果以及最佳工艺条件,并分析了渗滤液尾水中有机物的去除机理。结果表明,水化过程对渗滤液尾水中的有机物去除性能良好,且对不同有机物具有一定的选择性,尤其对具有近紫外区(200～400 nm)吸收峰特征的有机物去除效果更佳,同时发现,当投加量为50 g/L、pH=8.3(原渗滤液pH)、反应时间为24 h和振荡速度为200 r/min时,去除效果最佳,其COD、TOC和UV254的平均去除率分别达到55.6%、62.1%和68.8%。     

Gene expression analysis and classification of mode of toxicity of polycyclic aromatic hydrocarbons (PAHs) in Escherichia coli

Escherichia coli is known to respond to certain toxic chemicals through an increased expression of various stress genes. In this study, therefore, the expression of recA, katG, fabA and grpE genes was used as a representative for DNA, oxidative, membrane and protein damage, respectively, after E. coli was exposed to different polycyclic aromatic hydrocarbons (PAHs), i.e., phenanthrene, naphthalene and benzo[a]pyrene. To accomplish this, the expression levels of these four genes were quantified using a real-time RT-PCR analysis when E. coli cultures were under stressful conditions, such as those caused by an exposure to mitomycin C, hydrogen peroxide and phenol. It was found that the primary toxic effect of each chemical is clearly seen when the expression levels of the different genes are compared. Tests with the PAHs showed naphthalene and benzo[a]pyrene to be genotoxic, while phenanthrene had no clear effect on the expression of any of these genes. Based on these results, the effects due to these toxic chemicals and the extent of each stress can be evaluated with ease using the expression levels of different stress responsive genes.