Stable carbon isotope fractionation during enhanced in situ bioremediation of trichloroethene

Time-series stable carbon isotope monitoring of volatile organic compounds (VOCs) atthe Idaho National Engineering and Environmental Laboratory's (INEEL) field site Test Area North (TAN) was conducted during a pilot study to investigate the treatment potential of using lactate to stimulate in situ biologic reductive dechlorination of trichloroethene (TCE). The isotope ratios of TCE and its biodegradation byproducts, cis-dichloroethene (c-DCE), trans-dichloroethene (t-DCE), vinyl chloride (VC), and ethene, in groundwater samples collected during the pilot studywere preconcentrated with a combination of purge-and-trap and cryogenic techniques in order to allow for reproducible isotopic measurements of the low concentrations of these compounds in the samples (down to 0.04 microM, or 5 ppb, of TCE). Compound-specific stable isotope monitoring of chlorinated solvents clearly differentiated between the effects of groundwater transport, dissolution of DNAPL at the source, and enhanced bioremediation. Isotope data from all wells within the zone of lactate influence exhibited large kinetic isotope effects during the reduction of c-DCE to VC and VC to ethene. Despite these large effects, the carbon isotope ratio of ethene in all these wells reached the carbon isotope ratios of the initial dissolved TCE, confirming the complete conversion of dissolved TCEto ethene. Conversely, the carbon isotope ratios of t-DCE were only marginally affected during the study, indicating that minimal biologic degradation of t-DCE was occurring.     

Stable carbon isotope evidence for intrinsic bioremediation of tetrachloroethene and trichloroethene at area 6, Dover Air Force Base

Area 6 at Dover Air Force Base (Dover, DE) has been the location of an in-depth study by the RTDF (Remediation Technologies Development Forum Bioremediation of Chlorinated Solvents Action Team) to evaluate the effectiveness of natural attenuation of chlorinated ethene contamination in groundwater. Compound-specific stable carbon isotope measurements for dissolved PCE and TCE in wells distributed throughout the anaerobic portion of the plume confirm that stable carbon isotope values are isotopically enriched in 13C consistent with the effects of intrinsic biodegradation. During anaerobic microbial reductive dechlorination of chlorinated hydrocarbons, the light (12C) versus heavy isotope (13C) bonds are preferentially degraded, resulting in isotopic enrichment of the residual contaminant in 13C. To our knowledge, this study is the first to provide definitive evidence for reductive dechlorination of chlorinated hydrocarbons at a field site based on the delta13C values of the primary contaminants spilled at the site, PCE and TCE. For TCE, downgradient wells show delta13C values as enriched as -18.0/1000 as compared to delta13C values for TCE in the source zone of -25.0 to -26.0/1000. The most enriched delta13C value on the site was observed at well 236, which also contains the highest concentrations of cis-DCE, VC, and ethene, the daughter products of reductive dechlorination. Stable carbon isotope signatures are used to quantify the relative extent of biodegradation between zones of the contaminant plume. On the basis of this approach, it is estimated that TCE in downgradient well 236 is more than 40% biodegraded relative to TCE in the proposed source area.     

絮凝-Fenton氧化处理E段漂白废水的研究

采用絮凝-Fenton氧化处理E段漂白废水。通过正交实验确定了最佳操作参数。Al2（SO4）5-Fen％on氧化配合处理E段漂白废水的最佳操作条件为：Al2（SO4）3用量0．6g／L,氧化反应的pH值为5,H2O2用量1．Og／L,FeSO4用量0．8g／L,在此条件下废水COD的去除率可达90．64％。CPAM-Fenton氧化配合处理E段漂白废水的最佳操作条件为：CPAM用量0．8mg／L,氧化反应pH值6,H202用量1．5g／L,FeSO4用量1．2g／L,在此条件下废水COD的去除率可达82．43％。     

破乳-混凝-光催化化学氧化法处理废切削液新工艺

先硝酸破乳,再用聚合硫酸铁(PFS)和阳离子聚丙烯酰胺(PAM)复合处理废切削液,当pH为8.0,PFS和PAM的用量分别是1 800mg.L-1和8mg.L-1时混凝效果较好.混凝上清液用UV/H2O2/Fe2 系统氧化,当pH=3,分4次加入H2O2,紫外照射6.5h,结果令人满意.采用该工艺处理废切削液,其COD去除率为99.5%,脱色率100%,出水达到了国家《污水综合排放标准》(GB-8987-1996)一级标准.     

电化学氧化法处理阴离子表面活性剂废水的实验研究

采用小型电化学反应器，利用不同的电极材料，对阴离子表面活性剂(DBS)的电化学氧化行为及各种工艺条件对降解效果的影响规律进行了实验。结果表明，在无隔膜复极性固定床电解槽内，以不锈钢为阴极,以钛基RuΩ2电极为阳极,以活性炭颗粒为填充电极。在合适的工艺条件下，阴离子表面活性剂废水具有较好的降解效果，降解率可达到96％以上，CODCr去除率大于84%。     

DFT study of trichloroethene reaction with permanganate in aqueous solution

The mechanism of the environmentally important reaction between permanganate anion and trichloroethene (TCE) has been studied theoretically using modern DFT functional. It has been shown that IEFPCM/M05-2X/aug-cc-pVDZ theory level yields activation parameters and carbon isotopic fractionation factor in excellent agreement with the experimental data. Obtained results indicate that this reaction proceeds via the 3+2 mechanism with a very early transition state, in which the new C-O bonds are formed only in about 20%. An alternative, stepwise mechanism that involves initial formation of a single new C-O bond and a C-Mn bond, followed by rearrangement to the permanganate-TCE adduct, has been found to be more energetically demanding and in disagreement with the experimental isotopic fractionation.     

Reactive transport modeling of trichloroethene treatment with declining reactivity of iron

Evolving reactivity of iron, resulting from precipitation of secondary minerals within iron permeable reactive barriers (PRBs), was included in a reactive transport model for trichloroethene (TCE) treatment. The accumulation of secondary minerals and reactivity loss were coupled using an empirically derived relationship that was incorporated into an existing multicomponent reactive transport code (MIN3P) by modifying the kinetic expressions. The simulation results were compared to the observations from long-term column experiments, which were designed to assess the effects of carbonate mineral formation on the performance of iron for TCE treatment. The model successfully reproduced the evolution of iron reactivity and the dynamic changes in geochemical conditions and contaminant treatment. Predictions under various hydrogeochemical conditions showed that TCE would be treated effectively for an extended period of time without a significant loss of permeability. Although there are improvements yet to be made, this study provides a significant advance in our ability to predict long-term performance of iron PRBs.     

超声微波双辅助提取葡萄籽低聚原花青素的研究

以新疆吐鲁番的赤霞珠葡萄籽为研究对象,利用超声微波双辅助法提取其中的低聚原花青素.以低聚原花青素提取率为考察指标,研究固液比、微波功率、微波辐照时间、作用次数、乙醇体积分数5个单因素对葡萄籽低聚原花青素提取率的影响.并采用响应面分析法对提取结果进行优化.结果表明,采用超声微波双辅助萃取技术得到的低聚原花青素提取率较单独采用超声或微波辅助得到的原花青素提取率高.在以70.3％vol的乙醇为提取溶剂、固液比为1∶14.6 (g∶mL)、超声处理30min、微波功率400W、微波时间30s的条件下,得到的低聚原花青素提取率最大为7.62mg/g.     

臭氧深度氧化处理制浆造纸废水的研究

研究了用臭氧法深度处理制浆造纸废水的工艺条件。包括臭氧与废水量的比与处理效果的关系,臭氧接触反应时间与处理效果的关系以及臭氧脱色机理的初探。结果表明：臭氧与废水接触时间为5min、pH值8左右、臭氧的浓度为42.55mg/L时,废水CODCr的去除率为80%以上,色度的去除率为93.34%。     

Enhanced sorption of trichloroethene by smectite clay exchanged with Cs+

Trichloroethene (TCE) is one of the most common pollutants in groundwater, and Cs+ can be a cocontaminant at nuclear facilities. Smectite clays have large surface areas, are common in soils, have high affinities for some organic contaminants, and hence can potentially influence the transport of organic pollutants entering soils and sediments. The exchangeable cations present near smectite clay surfaces can radically influence the sorption of organic pollutants by soil clays. This research was undertaken to determine the effect of Cs+, and other common interlayer cations, such as K+ and Ca2+, on the sorption of TCE by a reference smectite clay saponite. Cs-saturated clay sorbed the most TCE, up to 3500 mg/kg, while Ca-saturated smectite sorbed the least. We hypothesize that the stronger sorption of TCE by the Cs-smectite can be attributed to the lower hydration energy and hence smaller hydrated radius of Cs+, which expands the lateral clay surface domains available for sorption. Also, Cs-smectite interlayers are only one or two water layers thick, which may drive capillary condensation of TCE. Our results implicate enhanced retention of TCE in aquifer materials containing smectites accompanied by Cs+ cocontamination.     

介体电化学氧化法测定制革废水COD

考察了在室温下经电化学活化的PbO2 阳极电生Co(Ⅲ)用于测定COD的条件及其应用。阳极电生Co(Ⅲ)的库仑效率可达97%以上,Co(Ⅲ)在溶液中的稳定时间达3 0min。电生的Co(Ⅲ)能氧化适量的葡萄糖和邻苯二甲酸氢钾。方法用于测定2种制革废水的COD ,测定值与重铬酸钾法测得值基本一致     

氧化还原法表面改性羊毛的理化性能

采用高锰酸钾（KMnO4）-二氧化硫脲（TD）氧化还原法对羊毛织物进行剥鳞片处理。应用扫描电镜（SEM）、X-射线光电子能谱（XPS）和衰减全反射红外光谱（FTIR-ATR）等现代表面分析技术研究剥鳞处理后羊毛织物和剥鳞前羊毛织物表面的化学和物理结构特性。SEM研究结果表明,经剥鳞处理后的羊毛织物表面整体较为光滑,织物边缘的阶梯状结构也不再明显。XPS和FTIR-ATR研究表明,上述氧化还原法使羊毛表面的二硫键氧化断裂和表面类脂物质改性/除去,从而促使剥鳞片后的羊毛织物润湿性能有了显著的提高,且在强力保留、白度、纤维细化等方面也获得良好的效果。但剩炭率、氧指数均比未经剥鳞处理的羊毛织物有所下降,热稳定性下降。     

Enhanced water absorption of wheat gluten by hydrothermal treatment followed by microbial transglutaminase reaction

BACKGROUND: The water absorption of wheat gluten plays an important role in the weight, volume and form ratio of the breads. In this paper, hydrothermal treatment and microbial transglutaminase (MTGase) modification were combined to improve the water absorption ratio (WAR) of wheat gluten. To understand the increases in WAR, the changes in MTGase reaction after gluten hydrothermal treatment were also investigated. RESULTS: The sole hydrothermal treatment improved the WAR of gluten. The gluten treated at 100 °C for 30 min exhibited the highest WAR value (2.03 g g^?1 gluten) while the WAR of the control without hydrothermal treatment was 1.5 g g^?1 gluten. When gluten was exposed to 90 °C for 30 min followed by incubation with MTGase for 5 h, its WAR reached 2.48 g g^?1 gluten. In contrast to control gluten, the surface hydrophobicity of the gluten preheated at 90 °C for 30 min increased and fluctuated in a different way during the following MTGase reaction. Meantime, the trend in the amount of soluble protein of preheated gluten was also changed in the progress of MTGase reaction. CONCLUSION: Hydrothermal treatment followed by MTGase reaction is an efficient approach to improve the WAR of wheat gluten. The analysis of catalytic process, including determination of ammonia, gluten surface hydrophobicity, soluble protein and SDS–PAGE, suggested that hydrothermal pretreatment accelerated the cross‐linking reaction and may alter the ratio of gluten deamidation catalysed by MTGase, which induced an increase in the WAR. Copyright © 2010 Society of Chemical Industry     

Enzymatic and chemical oxidation of trihydroxylated phenols

Gallic acid, pyrogallol and gallic acid methyl ester were kinetically characterised as substrates of polyphenoloxidase (PPO) and peroxidase (POD) and their pro- and anti-oxidant capacities were studied. The data obtained are correlated with the chemical shifts of the carbons supporting the vicinal hydroxyls obtained by ¹³C NMR. Pyrogallol showed the highest catalytic constant for both PPO and POD, reflecting its low δ₂ value. This also implies that both enzymes have a high Michaelis constant for pyrogallol.     

电芬顿氧化法处理染料废水的研究进展

文章综述了电芬顿法处理印染废水的基本原理,分析了电极材料、不同类型芬顿反应器对染料废水脱色率的影响,电芬顿法作为一类高级氧化技术,是处理染料废水的有效方法。双氧水(H2O2)是在包含支持电解质的酸性溶液中通过电化学法还原溶解氧制备的,这个氧化过程产生的羟基自由基(·OH)可以与废水中的有机污染物反应产生二氧化碳和水。另外,对阴极材料的优化不仅可以提高(·OH)/(或H2O2)的产率,而且可以节约染料废水的处理成本。因此,通过选择性研究,电芬顿法处理染料废水是经济可行的。     

Competitive uptake of trichloroethene and 1,1,1-trichloroethane by Eucalyptus camaldulensis seedlings and wood

The efficient use of trees for taking up volatile organic compounds (VOCs) from the subsurface for remedial and screening purposes is hampered because many poorly quantified co-occurring processes affect VOC concentrations in the tree, the most basic of which are VOC sorption and uptake by roots. Toward understanding the dominant sorption mechanisms, uptake of trichloroethene (TCE) and 1,1,1-trichloroethane (TCA) by Eucalyptus camaldulensis seedlings was studied in both single-solute and bi-solute experiments. Single-solute and bi-solute sorption experiments on wood from a mature Eucalyptus camaldulensis specimen were also carried out. Competition between TCE and TCA for sorption sites was found in both seedling uptake and wood sorption experiments, indicating that partitioning is not the sole mechanism governing compound interactions in these systems. The nonlinear single-solute sorption isotherms on wood were fit by a dual-mode model including partitioning and Langmuir terms. The dual-mode model calculated parameters were consistent with the results of the bi-solute sorption experiments. As a consequence of competitive sorption processes, uptake of individual compounds may be lower than expected when multiple VOC contaminants are present in the subsurface.     

Fenton试剂氧化深度处理食品添加剂废水

采用Fenton氧化法深度处理食品添加剂经常规二级处理后的废水.研究了H2O2/CODcr投加量比、Fe2 /H2O2投加量比、反应pH和反应时间对废水CODcr去除效果的影响.结果表明,通过Fenton氧化,可使废水中CODcr由393.2mg/L降到64.3mg/L,去除率达83.6%;处理该废水的最适务件为:H2O2/CODcr=3,Fe2 /H2O2=1,pH4,反应时间60min.     

Pyrite oxidation by hexavalent chromium: investigation of the chemical processes by monitoring of aqueous metal species

Pyrite, an iron sulfide, occurs in many soils and sediments, making it an important natural reductant of toxic metal pollutants. This study investigated the processes leading to aqueous Cr(VI) reduction by pyrite in a closed thermostated (25 +/- 0.1 degrees C) system and under an argon atmosphere. Synthetic pyrite suspensions were reacted with a range of Cr(VI) solutions from 0 to 7 x 10(-4) M and at pH 2-8. Metal species concentrations were continuously monitored during a period lasting approximately 20 h. Preliminary experiments carried out in acidic media without Cr(VI) have shown that some pyrite dissolution occurred. Then, metal species concentration changes with time during pyrite oxidation by Cr(VI) solutions exhibited two distinct trends depending on the complete or incomplete Cr(VI) removal. As long as chromate existed in solution, the Cr-(Ill) to Fe(lIl) ratio was found to be an effective parameter to investigate the pyrite reaction stoichiometry with Cr(VI). Experimental values close to 2 suggest that sulfur compounds with oxidation states between 0 and 2 should be formed during pyrite oxidation by Cr(VI). If Cr(VI) was completely reduced from solution, then the pyrite oxidation by Fe(lll) ions took place to generate ferrous ions.     

Change in surface chemistry of the cuticle of human hair by chemical and photochemical oxidation

This is a multifaceted study on the characterization and quantification of damage to the hair fiber surface caused by photochemical and cosmetic chemical oxidative processes. Unique techniques were used, including a microfluorometric method that had been adapted to characterize and quantify the delipidation and acidification of the human hair surface during light exposure and cosmetic chemical grooming processes such as bleaching. During photochemical and chemical oxidation, breakdown of the lipid domains (also called the F‐layer) of the outer b‐layer occurs on the exposed scale faces and cysteic acid groups are generated on the cuticle cell surface. The newly formed acid functionalities can be tagged with the cationic fluorochrome Rhodamine B, allowing not only quantification of the level of progressive acidification but also localization of the newly formed acid functionalities. On the other hand, the negative charges generated on the hair surface by oxidation can also bind low molecular weight quaternary cationic conditioning compounds such as cetyltrimethylammonium bromide. This process can be considered a relipidation by adsorption. We have shown that the entire process of delipidation/acid formation and subsequent relipidation by adsorption on the scale faces can be quantified by X‐ray photoelectron spectroscopy. Since X‐ray photoelectron spectroscopy analysis is highly sensitive and able to detect atomic species at the very surface of the hair fibers, receiving signals from an escape depth as shallow as 25 Å, it appeared ideal for the characterization of treatment‐induced changes in the hair surface. However, X‐ray photoelectron spectroscopy provides an average elemental composition of the hair surface including scale faces and scale edges. The microfluorometric technique, on the other hand, can distinguish progressive delipidation of the scale faces from changes occurring at the broken scale edges. This distinction was shown and characterized in detail by slow speed microfluorometric scanning of the hair surface. Chemical and photochemical oxidative processes at the hair surface result in certain collateral effects. Particularly changes in surface wettability and fiber friction are of significance to the cosmetic chemist because they affect the spreading and wicking of products in hair as well as the managability and the body of hair assemblies. Methods of characterizing these effects are discussed briefly.     

热处理延长油茶籽油氧化稳定性研究

研究了油茶籽经过不同条件加热后其压榨油氧化稳定性的变化规律,并通过测定压榨油过氧化值、酸值、水分、脂肪酸、油脂伴随物等指标探讨影响油茶籽油氧化稳定性变化的主要因素。结果表明,油茶籽经过不同温度加热20 min后,其压榨油的氧化稳定时间显著延长,30、60、90、120、150℃加热条件下分别比初始延长了1.1、4.2、5.2、3.5、3.9倍,随着加热时间的延长,60、90℃和120℃的加热温度下油茶籽油的氧化稳定性变化趋于平缓,30℃和150℃下加热40 min后氧化稳定性仍有提高,在加热60 min时,5种温度氧化稳定时间分别比初始延长了4.4、5.0、4.4、3.1、5.8倍。水分、酸值、过氧化值、角鲨烯含量、β-谷甾醇含量与油茶籽油的氧化稳定性的变化呈现负相关,说明水分、酸值、过氧化值低的油茶籽油的氧化稳定性好,角鲨烯和β-谷甾醇等抗氧化物质并不是提高油茶籽油氧化稳定性的活性成分。总酚、5-丁基二氢-2(3H)-呋喃酮、3,4-二甲基-2,5-二氢呋喃、正辛醇、苯甲醛、戊酸、辛酸、苯乙醛、壬醛等物质的含量与油茶籽油的氧化稳定性呈现正相关,说明总酚和美拉德反应产物可能是延长油茶籽油氧化稳定性的主要因素。