Effects of relative humidity on the characterization of a photochemical smog chamber

A linear relationship between k_NO2→HONO and relative humidity in smog chamber is found in this work.     

Characterization and reactivity of biogenic manganese oxides for ciprofloxacin oxidation

Biogenic manganese oxides （BioMnOx） were synthesized by the oxidation of Mn（II） with Mn- oxidizing bacteria Pseudomonas sp. G7 under different initial pH values and Mn（II） dosages, and were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and UV-Vis absorption spectroscopy. The crystal structure and Mn oxidation states of BioMnOx depended on the initial pH and Mn（lI） dosages of the medium. The superoxide radical （O2） was observed in Mn-containing （III/IV） BioMnOx suspensions by electron spin resonance measurements. BioMnOx（0.4）-7, with mixed valence of Mn（II/III/IV） and the strongest O~- signals, was prepared in the initial pH 7 and Mn（II） dosage of 0.4 mmol/L condition, and exhibited the highest activity for ciproftoxacin degradation and no Mn（II） release. During the degradation of ciprofloxacin, the oxidation of the Mn（II） formed came from biotic and abiotic reactions in BioMnOx suspensions on the basis of the Mn（II） release and O2- formation from different BioMnOx. The degradation process of ciprofloxacin was shown to involve the cleavage of the hexatomic ring having a secondary amine and carbon-carbon double bond connected to a carboxyl group, producing several compounds containing amine groups as well as small organic acids.     

Preparation and characterization of a lipoid adsorption material and its atrazine removal performance

A novel adsorbent named lipoid adsorption material (LAM), with a hydrophobic nucleolus (triolein) and a hydrophilic membrane structure (polyamide), was synthesized to remove hydrophobic organic chemicals (HOCs) from solution. Triolein, a type of lipoid, was entrapped by the polyamide membrane through an interfacial polymerization reaction. The method of preparation and the structure of the LAM were investigated and subsequent experiments were conducted to determine the characteristics of atrazine (a type of HOC) removal from wastewater using LAM as the adsorbent. The results showed that LAM had a regular structure compared with the prepolymer, where compact particles were linked with each other and openings were present in the structure of the LAM in which the fat drops formed from triolein were entrapped. In contrast to the atrazine adsorption behavior of powdered activated carbon (PAC), LAM showed a persistent adsorption capacity for atrazine when initial concentrations of 0.57, 1.12, 8.31 and 19.01 mg/L were present, and the equilibrium time was 12 hr. Using an 8 mg/L initial concentration of atrazine as an indicator of HOCs in aqueous solution, experiments on the adsorption capacity of the LAM showed 69.3% removal within 6–12 hr contact time, which was close to the 75.5% removal of atrazine by PAC. Results indicated that LAM has two atrazine removal mechanisms, namely the bioaccumulation of atrazine by the nucleous material and physical adsorption to the LAM membrane. Bioaccumulation was the main removal mechanism.     

Fenton溶液预处理对TiO2纳米管催化活性的影响

采用Fenton溶液对TiO2纳米管电极进行预处理,研究其对TiO2纳米管催化活性的影响,考察了Fenton溶液的浓度、配比和处理时间等影响因素,研究了Fenton预处理过程中溶液中二价铁和总铁的含量变化,运用X射线光电子能谱仪(XPS)和场发射扫描电子显微镜(FESEM)对TiO2纳米管电极进行了表征,初步探讨了经处理后TiO2纳米管催化活性再生或增强的机理.结果表明,经Fenton溶液处理后的TiO2纳米管催化活性有明显地提高,Fenton溶液浓度越高,TCs降解率越大(相应于TiO2纳米管催化活性的增强);在一定浓度范围内,H2O2的配比高低对TCs降解率影响较大,其所占比例高,则降解率高,而Fe2+配比高低对TCs降解率影响相对较小.在Fenton溶液处理过程中,溶液中剩余的Fe2+含量较为恒定,总铁的含量呈下降趋势.XPS分析表明,经Fenton溶液处理后,TiO2纳米管电极表面C1s含量降低,O1s、Fe2p含量增大;部分含碳官能团含量明显降低,O1s的电子结合能向高能端位移.     

Quantitative characterization of Cu binding potential of dissolved organic matter （DOM） in sediment from Taihu Lake using multiple techniques

Dissolved organic matter （DOM） plays an important role in heavy metal speciation and distribution in the aquatic environment especially for eutrophic lakes which have higher DOM concentration. Taihu Lake is the third largest freshwater and a high eutrophic lake in the downstream of the Yangtze River, China. In the lake, frequent breakout of algae blooms greatly increased the concentration of different organic matters in the lake sediment. In this study, sediment samples were collected from various part of Taihu Lake to explore the spatial difference in the binding potential of DOM with Cu. The titration experiment was adopted to quantitatively characterize the interaction between Cu（II） and DOM extracted from Taihu Lake sediments using ion selective electrode （ISE） and fluorescence quenching technology. The ISE results showed that the exogenous DOM had higher binding ability than endogenous DOM, and DOM derived from aquatic macrophytes had a higher binding ability than that derived from algae. The fluorescence quenching results indicated that humic substances played a key role in the complexation between DOM and Cu（II） in the lake. However, because of the frequent breakout of algae blooms, protein-like matters are also main component like hnmic matters in Taihu Lake. Therefore, the metals bound by protein-like substances should be caused concern as protein-like substances in DOM were unstable and they will release bound metal when decomposed.     

沃特世ACQUITY~超高效聚合物色谱系统

五十年前,沃特世(Waters)与陶氏化学公司合作,对化工材料行业进行了彻底的革新,第一次能够使用实验室仪器对聚合物进行分析和表征.这项技术就是我们熟知的凝胶渗透色谱(GPC),它将分析时间从几天大幅度减少到了几个小时.更重要的是,它促进了新型、创新的化工材料未来几十年的发展.全球各地的化学实验室都在持续使用沃特世液相色谱、凝胶色谱柱和专用的GPC软件以帮助在溶液中     

土壤磷素的流失风险分析进展评述

关于如何评价土壤磷素的流失引起的环境风险这一课题日益成为研究的热点.文章重点探讨了面向环境学意义的用于土壤磷素流失风险分析的常用指标与表征方法.     

隐喻:教师个人理论的表征

一直以来,人们仅仅将教师视为实践者,而忽视了教师也有自己的理论。教师个人理论反映了其对教育教学的认识,是其教学实践的重要支撑。教师个人理论作为经验性的、个体性的认识,具有鲜明的表征形式。隐喻就是其中的一种基本形式。教师创作和使用的隐喻反映了其教学信念以及其对课程、教学和自我的认识。通过教师的隐喻我们可以了解教师的教学思想状况。     

土壤重金属复合污染特点及治理方法探讨

土壤重金属复合污染日趋严重,对其进行研究在预防和治理重金属污染方面具有重要意义。本文首先介绍土壤重金属复舍污染的特点,分析共存重金属之间的相互作用,总结评价土壤重金属复舍污染的表征方法,进而探讨土壤重金属复舍污染问题的解决方法,为土壤重金属复合污染的治理研究提供参考。