Photocatalytic mineralization of hydroperfluorocarboxylic acids with heteropolyacid H₄SiW₁₂O₄₀ in water

The decomposition of hydroperfluorocarboxylic acids [H-PFCAs; HC_nF_2nCOOH (n = 4 and 6)] induced by heteropolyacid photocatalyst H₄SiW₁₂O₄₀ in water was investigated, and the results are compared with the results for the corresponding perfluorocarboxylic acids (PFCAs; C_nF_2n+1COOH). This is the first report on the photochemical decomposition of H-PFCAs, which are being developed as alternative surfactants to environmentally persistent and bioaccumulative PFCAs. H-PFCAs were not decomposed by irradiation with UV-Visible light (>290 nm) in the absence of H₄SiW₁₂O₄₀. In contrast, UV-Visible light irradiation of H-PFCAs in the presence of H₄SiW₁₂O₄₀ efficiently decomposed H-PFCAs to F⁻ and CO₂. The decomposition reactions showed pseudo-first-order kinetics, and the decomposition rate constants were 1.8-2.5 times higher than those for the corresponding PFCAs. The reaction mechanism can be explained by elimination of H⁺ from the ω-H atom of the H-PFCAs by the excited catalyst, followed by formation of perfluorodicarboxylic acids.     

Solvent tolerant marine bacterium Bacillus aquimaris secreting organic solvent stable alkaline cellulase

The organic solvent tolerant bacteria with their physiological abilities to decontaminate the organic pollutants have potentials to secrete extracellular enzymes of commercial importance. Of the 19 marine bacterial isolates examined for their solvent tolerance at 10 vol.% concentration, one had the significant tolerance and showed a relative growth yield of 86% for acetone, 71% for methanol, 52% for benzene, 35% for heptane, 24% for toluene and 19% for ethylacetate. The phylogenetic analysis of this strain using 16S rDNA sequence revealed 99% homology with Bacillus aquimaris. The cellulase enzyme secreted by this strain under normal conditions showed an optimum activity at pH 11 and 45 °C. The enzyme did show functional stability even at higher pH (12) and temperature (75 °C) with residual activity of 85% and 95% respectively. The enzyme activity in the presence of different additives were in the following order: Co⁺² > Fe⁺² > NaOCl₂ > CuSO₄ > KCl > NaCl. The enzyme stability in the presence of solvents at 20 vol.% concentration was highest in benzene with 122% followed by methanol (85%), acetone (75%), toluene (73%) and heptane (42%). The pre-incubation of enzyme in ionic liquids such as 1-ethyl-3-methylimidazolium methanesulfonate and 1-ethyl-3-methylimidazolium bromide increased its activity to 150% and 155% respectively. The change in fatty acid profile with different solvents further elucidated the physiological adaptations of the strain to tolerate such extreme conditions.     

Influences of redox transformation, metal complexation and aggregation of fulvic acid and humic acid on Cr(VI) and As(V) removal by zero-valent iron

This study investigated the removal kinetics and mechanisms of Cr(VI) and As(V) by Fe(0) in the presence of fulvic acid (FA) and humic acid (HA) by means of batch experiments. The focus was on the involvements of FA and HA in redox reactions, metal complexation, and iron corrosion product aggregation in the removal of Cr(VI) and As(V) removal by Fe(0). Synthetic groundwater was used as the background electrolyte to simulate typical groundwater. The results showed faster Cr(VI) removal in the presence of HA compared to FA. Fluorescence spectroscopy revealed that no redox reaction occurred in the FA and HA. The results of the speciation modeling indicate that the free Fe(II) concentration was higher in the presence of HA, resulting in a higher removal rate of Cr(VI). However, the removal of As(V) was inhibited in the HA solution. Speciation modeling showed that the concentration of dissolved metal-natural organic matter (metal-NOM) complexes significantly affected the aggregation of the iron corrosion products which in turn affected the removal of As(V). The aggregation was found to be induced by gel-bridging of metal-NOM with the iron corrosion products. The effects of metal-NOM on the aggregation of the iron corrosion products were further confirmed by TEM studies. Larger sizes of iron corrosion products were formed in the FA solution compared to HA solution. This study can shed light on understanding the relationships between the properties of NOM (especially the content of metal-binding sites) and the removal of Cr(VI) and As(V) by Fe(0).     

Evaluation of ABC efflux transporters genes expression in kidney of rainbow trout (Oncorhynchus mykiss) fed with melamine and cyanuric acid diets

Gene expression experiments were targeted in order to monitor the ABC efflux transporters, which is potentially involved in cellular detoxification/defense. Changes in expression levels of different ABC genes in kidney of Oncorhynchus mykiss fed with melamine and melamine + cyanuric acid enriched diets were recorded in both treated groups by mRNA ΔΔ_CT relative quantification method. Expression profiles of eight different ABC genes basically showed low alterations in melamine group and more consistent changes in melamine + cyanuric acid treated fish, compared with own control. In the last group ABCC2 gene over expression was the more evident alteration. These results suggest that ABC efflux system could be involved in mobilization of hydrophilic molecules in the forcing condition of chronic exposure.     

铁炭-混凝沉淀-生化处理强酸性染料废水的中试研究

采用铁炭-混凝沉淀-水解酸化-生物接触氧化工艺对强酸性染料废水进行中试处理研究。在铁炭微电解单元主要考察了铁炭比、HRT和曝气量大小对处理效果的影响;在水解酸化单元主要考察了进水pH和HRT对处理效果的影响。通过铁炭微电解和水解酸化,在大幅改善废水的可生化性的同时,还可以有效去除废水的色度、削减有机负荷,以保证后续的生物接触氧化工艺的高效稳定运行。在生物接触氧化单元主要考察了进水浓度、HRT对处理效果的影响。经过组合工艺的处理,最终的出水COD〈75 mg/L,出水色度〈40倍。     

阴极氧还原产电生物可渗透反应栅的研究Ⅱ.酸蚀处理对不锈钢丝电极性能的影响

不锈钢毛虽然用作阴极氧还原产电生物反应栅（CORE—PRB）的电极材料虽然有很多优点,但是反应电流较小。尝试对不锈钢毛进行酸蚀处理后用作电极材料,并分别研究比较了4种不同电极组合的产电反应性能。酸蚀处理显著提高不锈钢毛阳极的反应性能,并对提高不锈钢毛阴极的反应性能有一定作用。酸蚀的作用主要是使不锈钢毛表面变得粗糙,有利于提高电极表面积和材料的生物亲和性。虽然生物产电反应对COD降解的直接贡献不到10％,但是不同电极组合下COD的去除率与它们生物产电反应的贡献率呈现高度正相关性。     

废弃锂离子电池中金属的回收及钴酸锂的湿法合成

采用湿法回收并合成锂离子电池中钴酸锂。考察了不同的有机溶剂溶解粘结剂PVDF、不同酸浸条件对钴酸锂浸出效果的影响、碳酸钴和碳酸锂共沉淀物的焙烧条件,并对所获得的钴酸锂进行结构分析。结果表明,N-甲基吡咯烷酮（NMP）作为溶解PVDF的溶剂效果最佳;当硫酸浓度6％、固液比1：30、30％的H2O：1．4mL／g、温度80℃、反应120min时为硫酸浸出最佳条件,此时钴的浸出率为92．3％,锂的浸出率为92．0％;合成LiCoO2时的焙烧温度在750℃较为合适。SEM分析表明,颗粒粒度小,分散性好。     

东莞地下水邻苯二甲酸酯分布特征及来源探讨

在广东东莞地区采集了59组地下水水样和9组地表水水样,采用气相色谱-质谱联用技术进行测定,结果表明,地下水中邻苯二甲酸酯(PAEs)的检出率为39.0％,6种PAEs的质量浓度在未检出～6.70 μg/L.其中,邻苯二甲酸双(2-乙基己基)酯(DEHP)检出率最高,为22.O％,最大值为6.20 μg/L;邻苯二甲酸二...     

模拟酸雨淋溶条件下紫壤淋出液中溶解性有机质的三维荧光特性

运用三维荧光技术分析了模拟酸雨淋溶紫壤淋出液中溶解性有机质（dissolved organic matter,DOM）的组分与酸度及淋溶量的关系.研究结果表明,模拟酸雨淋溶紫壤淋出液中DOM荧光峰主要为类胡敏酸和类富里酸,荧光峰的中心位于Ex/Em=305—370 nm/420—450 nm和Ex/Em=260—270...     

石油烃厌氧生物降解代谢产物研究进展

石油烃厌氧生物降解代谢产物的分析对于石油烃厌氧降解机制的研究、功能微生物的筛选以及微生物活动的原位监测具有指示性作用.综述了近年来石油烃厌氧生物降解代谢产物的研究进展.石油烃厌氧降解的初始活化方式主要包括脱氢羟基化、加延胡索酸以及羧化等.其中,加延胡索酸是不同种类的微生物通常采用的代谢方式.同时,将代谢产物按照气体、无机离子和有机酸进行分类,并针对各类物质特别是瞬时性、低浓度的有机酸类产物常采用的分析方法进行归纳.通过实例强调了代谢产物作为潜在生物标记物的应用,并对石油烃厌氧降解代谢产物分析方法的发展提出展望.图3参58