光催化氧化苯酚中间产物的分析与降解途径探讨

采用光催化氧化法降解苯酚溶液,利用液相色谱对苯酚及其中间产物进行了定性、定量分析。考察了投加H2O2对中间产物浓度变化的影响。根据中间产物的产生情况及浓度变化,推测了苯酚光催化降解的反应途径。     

铁元素对有机物厌氧降解的影响研究

不同价态的铁元素氧化还原性不同,对有机物的厌氧生物降解过程的影响也不同。以邻氟苯酚和硝基苯为目标污染物,投铁量为20～100mg／L的条件下,单质铁能加速硝基苯的厌氧降解,对2-氟酚降解的影响则很小;二价铁和三价铁对两种物质都表现出一定的抑制作用,投加浓度越高,抑制作用越明显。     

超声辅助电催化氧化降解水杨酸的研究

通过对水杨酸降解的UV扫描吸收光谱的研究表明,在水杨酸的电催化氧化和超声辅助电催化氧化降解过程中,都有吸收紫外光的中间体生成,对吸光度峰值随降解反应时间的变化关系进行非线性最小二乘法拟合(NLSF),发现其衰减均符合表观一级反应动力学规律;而COD值的衰减也都符合表观一级反应动力学规律。GC-MS检测到水杨酸超声辅助电催化氧化降解60 min后,有中间产物甲酸、乙酸、苯酚,认为是水杨酸在.OH的作用下,开环氧化降解生成乙酸和甲酸等小分子有机物,最后降解为二氧化碳和水。     

超声波降解苯酚溶液的研究

以20mg/L的苯酚为研究对象,在超声波槽中对超声波作用于苯酚的降解效率和降解规律进行了初步研究。实验表明:单一的超声波对苯酚的降解率是很低的,不超过6.3%;而在苯酚溶液中加入H2O2后,降解率提高了大约3倍;酸性条件利于苯酚的降解,而在碱性条件下苯酚几乎没有降解。     

苯酚降解菌Y_1的分离与鉴定

旨在从微生物降解的角度出发,解决苯酚大量应用带来的含酚废水对环境污染问题.采用富集培养、驯化筛选和平板划线等方法,从某化工厂废水中分离得到4株苯酚降解菌.利用4-氨基吡啉分光光度法测定其苯酚降解能力,筛选出降解率较高的菌株Y_1.经形态学观察、生理生化鉴定和16S rDNA序列分析,将该菌初步鉴定为苏云金芽孢杆菌(Ba...     

一株降解苯酚微生物的研究

从污泥中分离出可在舍100mg/L苯酚的LIB培养基上生长的菌株，其中JF-2生长情况最好。通过逐级驯化，JF-2的降解苯酚能力明显提高，可在以苯酚为唯一碳源的培养基中降解苯酚并生长。在接种量为1％时，JF－2在24h内将300mg／L的苯酚完全降解。该菌的最适生长和降解温度为30℃，并能在pH5．5～9内降解苯酚。河水中的天然微生物降解苯酚的能力弱，需7天才可将200mg/L的苯酚完全降解。     

吸附-双催化氧化降解苯胺、硝基苯废水

苯胺、硝基苯废水利用吸附树脂吸附后,再利用过氧化氢作氧化剂,在亚铁离子和紫外光的双催化下氧化降解。通过对亚铁离子浓度、过氧化氢浓度等因素对光降解影响的考察,结果表明,在实验条件下,本氧化体系对苯胺、硝基苯废水有明显的降解效果,苯胺、硝基苯废水经该体系处理12h后,去除率最高分别达到99.7%和95.3%。     

P-25纳米TiO2在含酚废水处理方面的应用

采用室内模拟研究,以P-25纳米TiO2作为光催化剂进行了苯酚水溶液的光催化降解性能探讨,初步考察了溶液的pH、P-25纳米TiO2用量对光催化降解苯酚过程的影响,以获得P-25纳米TiO2光降解含酚废水的较好反应条件.实验结果表明,当溶液pH=8时,降解水体中苯酚效果最佳,强酸和强碱条件均不利于苯酚的降解;在pH 8的反应体系中,当光催化剂用量为0.4g/L时,催化水体中苯酚降解的效果最好.     

油污土壤的生物处理技术及其影响因素分析

生物处理技术可以用于转化和去除土壤中的石油类污染物,微生物对油污土壤产生降解作用,其降解的最终产物是CO2和水,不产生二次污染。重点分析了影响微生物降解的主要因素,包括pH值、温度、湿度、供氧情况、营养素、表面活性剂加入量、油污染强度,论述了各种影响因素的调整和控制方法。     

对铁碳处理硝基酚废水的研究

铁碳降解水中难降解有机污染物的影响因素、最佳工艺参数及处理效果;初步探讨了氧化降解污染物的作用机理;通过分析污染物降解的中间产物,提出了污染物降解的可能途径.探讨了pH、铁碳用量、温度以及锰矿物的粒径等对处理效果的影响,在最佳的工艺条件下,CODCr的去除率达到95%以上,TOC测定表明：大部分硝基酚被氧化降解为H2O和CO2.对硝基酚的降解途径主要是微电解将对硝基酚还原为对氨基酚,对氨基酚在酸性条件下被软锰矿氧化为H2O和CO2做探索性研究.     

黄腐酸的萃取和性质研究

黄腐酸是腐植酸中最具活力的组成部分,蕴藏量丰富,萃取方法简便。研究了从红原1#泥炭中萃取黄腐酸和降解物。它的分子量较小,易溶于水,抗絮凝性能好,分子内含有较多的活性官能团,具有很高的化学活性和生物活性,用途广泛。     

The effect of the activation of carboxyl group and hydrogen migration on reaction pathway during the pyrolysis of triglycerides

ABSTRACT

This study investigated the activation of carboxyl group and hydrogen migration on the pyrolysis products of triglycerides. It was found that the activation of carboxylic group determined the efficiency of the decarboxylation reactions. The activation of carboxyl group influenced the pyrolysis products. The glycerol mono-stearate and glycerol mono-oleate were used as the model compounds to analyze the cracking of the ester bond. It was found that the first intermediate formed was RCOO·, but not RCO·. Large amount of ketone was found in the pyrolysis of stearate, while not in that of oleate. In comparison, alcohol was found in pyrolysis products of oleate, while not in stearate. The results indicated that during the pyrolysis process, the carbon-carbon double bond influenced both the cracking of the C-C bond and the transformation of the oxygen-containing functionalities. The activation of carboxyl group and hydrogen migration played essential roles in the determination of the formation of the pyrolysis products. In addition, the mechanism for the evolution of the acid, ester, ketone, aldehyde, alcohol, and other heavy compounds during the pyrolysis was also proposed.     

Accidental organochlorine pesticide contamination of soil in Porrino, Spain

In the 1960s at Porri?o, Spain, soil from a pesticide factory dump was placed in an uncontrolled land infill during demolition. Since then, organochlorine pesticides have degraded and migrated from their original location. Concentrations of lindane, DDT, dicofol, and related side products or degradation products were determined at depths of 0 to 20, 20 to 60 and 60 to 100 cm along a 300-m transect running between the land infill and a nearby river. Depthwise nonmonotonicities (lowest concentrations of DDT and dicofol were found in the 20- to 60-cm layer) were attributed to the occurrence of several successive spill episodes; in general, concentrations were highest or near-highest in the 0- to 20-cm layer. At the dump site, the analyte contents of the 0- to 20-cm layer were as follows: alpha-hexachlorocyclohexane (alpha-HCH), 25 mg kg-1; beta-HCH, 15 mg kg-1; gamma-HCH (lindane), 1.3 mg kg-1; delta-HCH, 0.5 mg kg-1; DDT, 2.5 mg kg-1; dicofol, 0.05 mg kg-1; DDD+DDE, 2.2 mg kg-1. The alpha-HCH/gamma-HCH ratio was higher than in commercial products, and the DDT/(DDD + DDE) ratio lower, suggesting the degradation of lindane and DDT with time. In general, the concentrations of HCH isomers, DDT, and dicofol fell with increasing distance from the dump site; in particular, the rapid fall in HCH concentrations illustrates the marked immobility of these species in the soil. By contrast, the combined concentration of the DDT degradation products DDD and DDE rose with distance from the dump site, which is attributed to their higher mobility.     

Seasonal greenhouse gas emissions (methane, carbon dioxide, nitrous oxide) from engineered landfills: daily, intermediate, and final California cover soils

Compared with natural ecosystems and managed agricultural systems, engineered landfills represent a highly managed soil system for which there has been no systematic quantification of emissions from coexisting daily, intermediate, and final cover materials. We quantified the seasonal variability of CH, CO, and NO emissions from fresh refuse (no cover) and daily, intermediate, and final cover materials at northern and southern California landfill sites with engineered gas extraction systems. Fresh refuse fluxes (g m d [± SD]) averaged CH 0.053 (± 0.03), CO 135 (± 117), and NO 0.063 (± 0.059). Average CH emissions across all cover types and wet/dry seasons ranged over more than four orders of magnitude (<0.01-100 g m d) with most cover types, including both final covers, averaging <0.1 g m d with 10 to 40% of surface areas characterized by negative fluxes (uptake of atmospheric CH). The northern California intermediate cover (50 cm) had the highest CH fluxes. For both the intermediate (50-100 cm) and final (>200 cm) cover materials, below which methanogenesis was well established, the variability in gaseous fluxes was attributable to cover thickness, texture, density, and seasonally variable soil moisture and temperature at suboptimal conditions for CH oxidation. Thin daily covers (30 cm local soil) and fresh refuse generally had the highest CO and NO fluxes, indicating rapid onset of aerobic and semi-aerobic processes in recently buried refuse, with rates similar to soil ecosystems and windrow composting of organic waste. This study has emphasized the need for more systematic field quantification of seasonal emissions from multiple types of engineered covers.     

9,10-Phenanthrenequinone photoautocatalyzes its formation from phenanthrene, and inhibits biodegradation of naphthalene

Polycyclic aromatic hydrocarbons (PAHs) have earned considerable attention due to their widespread environmental distribution and toxicity. In the environment, PAHs decompose by a variety of biotic and abiotic pathways. In both polar and nonpolar environments, phenanthrene (Phe, a common, three-ring PAH) is converted by sunlight to more polar products such as 9,10-phenanthrenequinone (PheQ) and subsequent oxidation products such as the corresponding open-ring dicarboxylic acid product. Biodegradation of phenanthrene also usually leads to oxidative metabolites, and eventually ends in mineralization. Our experimental objective was to investigate the photodegradation of phenanthrene and determine the effect of reaction products such as PheQ on microbial biodegradation of two- and three-ring PAHs. Abiotic experiments were performed to examine the photolytic breakdown of Phe; Phe was converted to PheQ, which catalyzed its own formation. In biodegradation experiments PheQ (0.04-4 mg/L) caused marked inhibition of naphthalene (Nap) biodegradation by a Burkholderia species; Phe did not. Only 20% of the naphthalene was degraded in the presence of PheQ compared with 75% in the control culture with no PheQ added. No PAH-degrading cultures were able to use PheQ as sole carbon source; however, the Phe-degrading enrichment culture dominated by a Sphingomonas species was able to degrade PheQ cometabolically in the presence of Phe. These results may explain why photooxidized phenanthrene-containing mixtures can resist biodegradation.     

Biodegradation of pentyl amine and aniline from petrochemical wastewater

The objectives of the project were to isolate a bacterial strain capable of degrading pentyl amine and aniline and to define the optimal pentyl amine and aniline degradation conditions for this bacterial strain. The bacterial strain was isolated from activated sludge obtained from a Northeastern China treatment facility for petrochemical wastewater rich in pentyl amine and aniline. Once the strain was isolated, five triplicate (5) batch tests were used to establish the conditions for maximum pentyl amine and aniline degradation, by varying one at a time the following five factors: temperature, pH, reaction time, pollutant concentrations and aeration rate. In a final test, oil refinery sludge was inoculated with the strain and tested for the degradation of pentyl amine and aniline under optimal conditions, while observing the degradation pathway of pentyl amine and aniline. The isolated strain, PN1001, is a member of the Pseudomonas species and it was capable of degrading pentyl amine and aniline. The optimal reactor conditions for the degradation of a mixture of pentyl amine and aniline, at a concentration ranging between 150 and 200mg/L, were found to be 30 degrees C at a pH of 7.0, under a reaction time of 24h and a maximum solution dissolved oxygen level of 6 mgO(2)/L. Under such conditions, the strain PN1001 degraded 93% and 89% of the pentyl amine and aniline, respectively, aniline being more toxic and demonstrating a more complex degradation pathway. The strain PN1001 degraded more contaminants when both were present because of the pi and sigma electron cloud coordination functions of aniline and pentyl amine, respectively, presumed to reduce the toxic effect of aniline. Once inoculated with the strain, oil refinery sludge degraded 93% and 88% of the pentyl amine and aniline, compared to the strain alone which degraded 72% and 82%, likely because of the sludge's buffering effect against the toxic environment.     

Assessing the potential of yield improvements, through process scrap reduction, for energy and CO2 abatement in the steel and aluminium sectors

Targets to cut 2050 CO₂ emissions in the steel and aluminium sectors by 50%, whilst demand is expected to double, cannot be met by energy efficiency measures alone, so options that reduce total demand for liquid metal production must also be considered. Such reductions could occur through reduced demand for final goods (for instance by life extension), reduced demand for material use in each product (for instance by lightweight design) or reduced demand for material to make existing products. The last option, improving the yield of manufacturing processes from liquid metal to final product, is attractive in being invisible to the final customer, but has had little attention to date. Accordingly this paper aims to provide an estimate of the potential to make existing products with less liquid metal production.Yield ratios have been measured for five case study products, through a series of detailed factory visits, along each supply chain. The results of these studies, presented on graphs of cumulative energy against yield, demonstrate how the embodied energy in final products may be up to 15 times greater than the energy required to make liquid metal, due to yield losses. A top-down evaluation of the global flows of steel and aluminium showed that 26% of liquid steel and 41% of liquid aluminium produced does not make it into final products, but is diverted as process scrap and recycled. Reducing scrap substitutes production by recycling and could reduce total energy use by 17% and 6% and total CO₂ emissions by 16% and 7% for the steel and aluminium industries respectively, using forming and fabrication energy values from the case studies. The abatement potential of process scrap elimination is similar in magnitude to worldwide implementation of best available standards of energy efficiency and demonstrates how decreasing the recycled content may sometimes result in emission reductions.Evidence from the case studies suggests that whilst most companies are aware of their own yield ratios, few, if any, are fully aware of cumulative losses along their whole supply chain. Addressing yield losses requires this awareness to motivate collaborative approaches to improvement.     

Urbanization's impact on timber harvesting in the south central United States

The impact of urbanization on timber harvesting in the south central United States was investigated. Geo-referenced Census and Forest Inventory Analysis (FIA) data were combined using a geographic information system (GIS) in order to examine the effects of various demographic and biophysical forest inventory characteristics on timber harvesting. These effects were estimated for intermediate and final harvests using a multinomial logit model. The probability for both types of harvests decreased with increasing population density, decreasing forest size, and decreasing distance to urban areas; however, the reduction in intermediate harvests was greater for each variable. Harvesting rates decreased by as much as 19% as population densities increased or distance to urban areas decreased. The results indicated that active forest management is curtailed far beyond the urban boundary. In order to model the impact of urbanization adequately, timber supply projections must also account for its impact on harvesting frequencies in surrounding areas.