光助Fenton氧化法降解水中六氯苯的研究

采用光助Fenton氧化法处理六氯苯模拟废水,考察了反应时间、Fe3 与H2O2摩尔比、Fenton试剂用量、初始pH、六氯苯初始浓度、光强对六氯苯降解效果的影响,并初步探讨了六氯苯的降解动力学规律.结果表明.光助Fenton法降解六氯苯的最佳工艺条件为:紫外灯功率为300 W、Fe3 投加量为1.0 mmol/L、H2O2投加量为5.0 mmol/L、反应时间为60 min、初始pH为3,在此条件下,浓度为500μg/L的HCB的去除率可达91.3%.UV辐射与Fenton氧化对HCB的降解具有协同效应.光助Fenton法对HCB的降解符合一级反应动力学方程,表观速率常数为0.04 min-1,与Fenton法相比,提高了近9倍.     

Fenton试剂氧化降解聚丙烯酰胺污水及其反应动力学研究

采用Fenton试剂氧化处理聚丙烯酰胺(HPAM)污水取得了良好的效果.通过正交试验得到了Fenton试剂各影响因素的影响权重,并通过单因素实验确定了最佳实验条件.研究了Fenton试剂中各影响因素的作用机制,在最佳实验条件下,HPAM的降解率能达到近89%.针对Fenton试剂氧化处理HPAM的反应特性,深入研究了反应动力学模型,确定反应为一级反应.     

Fenton试剂催化氧化嘧啶废水的特性

研究了Fenton催化氧化法对废水中嘧啶的去除效能,优化了处理体系中的反应条件,分析了各影响因子的作用机理;并用一元线性回归方程对不同温度下,嘧啶相对残余浓度对反应时间的相关性进行了定量分析。结果表明:温度为25℃,pH为3.5,Fe²⁺的投加量64 mmol/L,H₂O₂投加量为300 mmol/L时,反应2 h,Fenton试剂对嘧啶和COD的去除率分别达90%和50%以上;同时发现Fenton试剂对嘧啶的氧化降解具有相对优先性,且符合一级反应动力学模式,并计算表观反应速率常数和活化能。     

Fenton试剂法预处理发酵甘油生产提取废水

采用Fenton试剂预处理高浓度难降解发酵法甘油生产提取废水。研究了pH、Fe2 + 、H2 O2 、反应时间和H2 O2 投加次数对废水COD去除效果的影响。结果表明 ,通过Fenton试剂氧化可使废水中的COD值从 135 0 0mg/L降至 4 0 30mg/L ,COD去除率达到 70 1%。废水的BOD5/COD值从 0 2 0 2提高至 0 5 6 8,可生化性得到较大提高 ,为后续处理创造了条件。研究成果为发酵法甘油生产提取废水的预处理提供了一种非常有效的方法。     

MnO2催化Fenton试剂降解苯酚废水

实验对MnO2催化Fenton试剂氧化高浓度苯酚废水的动力学特性和去除效果进行了研究。结果表明,MnO2可以提高Fenton试剂体系对苯酚的降解率以及COD的去除率;Fenton试剂以及MnO2催化Fenton试剂氧化苯酚废水体系中苯酚的降解都符合拟一级动力学模型。在MnO2催化Fenton试剂氧化体系中,苯酚的降解速率常数有明显提高,反应活化能也有所降低,说明MnO2的加入可以使反应容易进行。废水降解前后紫外可见吸收光谱和红外谱图表明,Fenton试剂法将苯酚可能降解为羧酸、烯烃等有机物中间体。     

电生成Fenton试剂光催化降解孔雀石绿的研究

为了提高染料废水的处理效果,采用电生成Fenton试剂光催化氧化系统对孔雀石绿模拟印染废水进行了降解研究,通过与无光照时的对比实验发现:光照能明显加快电生成Fenton试剂对孔雀石绿印染废水的降解脱色速率,20 min内脱色率达到98%以上,40 min内COD去除率达到80%以上,同时通过红外光谱、紫外-可见光谱等手段研究了光照与电生成Fenton试剂的协同作用,初步探讨了电生成Fenton试剂光催化降解孔雀石绿印染废水的反应机理,很好地实现了光催化与电化学氧化降解技术的联合应用。     

Fenton试剂氧化预处理橡胶促进剂NS生产废水的研究

采用Fenton试剂氧化处理橡胶促进剂NS生产废水,研究H2O2、Fe2＋投加量及pH值对COD去除率的影响。通过实验,确定了Fenton试剂处理该废水的最佳操作条件：pH值为3,Fe2＋加入量为0.3 g/L,而H2O2为15 mL/L。     

Fenton试剂生成·OH的动力学研究

通过试验研究确定了Fenton试剂中羟基自由基·OH生成的动力学规律 ,系统考察了Fenton体系中三个主要因素 :H2 O2 浓度、FeSO4 浓度、pH值对羟基自由基·OH生成规律的影响情况 ,结果表明 ,这三个因素对羟基自由基的生成均有较大的影响 ,在实际生产过程中需加以严格控制 ,以保证最佳的处理效果     

异相Fenton试剂催化氧化-混凝沉淀深度处理焦化废水

针对焦化废水二级生化处理出水COD、色度和浊度无法达标的问题,实验研究了异相Fenton试剂催化氧化法和混凝沉淀法以及二者联合深度处理焦化废水的效果,分别探讨了H2O2、FeOOH投加量、初始pH,混凝剂投加量及种类对COD去除的影响,确定了最佳运行条件,采用GC-MS分析了联合工艺对废水中有机物的去除规律。异相Fenton试剂催化氧化静态实验研究表明,当H2O2(10%)投加量为2 mL/300 mL,FeOOH投加量为3 g/L,初始pH为4~6之间,处理效果最佳;混凝沉淀实验中最佳的混凝剂为聚丙烯酰胺阳离子,最佳投加量为8 mg/L。异相Fenton试剂催化氧化-混凝沉淀联合工艺深度处理焦化废水,出水COD基本在90 mg/L左右,浊度为0.8NTU左右,色度为40度以下,满足国家污水综合排放二级标准(GB8978-1996)。GC-MS分析显示,联合工艺能有效减少废水中有机物的种类和浓度,并将废水中长链大分子化合物和杂环化合物分解为短链的小分子化合物,构成联合工艺出水COD的主要是小分子有机物,尤其是卤代烷烃含量较高。     

Fenton试剂处理电厂离子交换树脂再生废水

采用 Fenton试剂对电厂离子交换树脂再生废水进行催化氧化处理 ,实验结果表明 ,当溶液 p H=2 .0、H2 O2 ( 30 % )投加量为 6 0 m L/L、F e SO4· 7H2 O投加量为 4.5 g/L、H2 O2 投加次数为 4、反应时间为 1.5 h时 ,废水的处理效果最佳     

Dioxin- and POP-contaminated sites—contemporary and future relevance and challenges

BACKGROUND, AIM AND SCOPE: Once they have been generated, polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) and other persistent organic pollutants (POPs) can persist in soils and sediments and in waste repositories for periods extending from decades to centuries. In 1994, the US EPA concluded that contaminated sites and other reservoirs are likely to become the major source of contemporary pollution problems with these substances. With this in mind, this article is the first in a new series in ESPR under the title 'Case Studies on Dioxin and POP Contaminated Sites--Contemporary and Future Relevance and Challenges', which will address this important issue. The series will document various experiences from sites contaminated with PCDD/F and other POPs. This article provides an overview of the content of the articles comprising the series. In addition, it provides a review of the subject in its own right and identifies the key issues arising from dioxin/POP-contaminated sites. Additionally, it highlights the important conclusions that can be drawn from these examples. The key aim of this article and of the series as a whole is to provide a comprehensive overview of the types of PCDD/F contaminated sites that exist as a result of historical activities. It details the various processes whereby these sites became contaminated and attempts to evaluate their contemporary relevance as sources of PCDD/Fs and other POPs. It also details the various strategies used to assess these historical legacies of contamination and the concepts developed, or which are under development, to effect their remediation. MAIN FEATURES: Special sessions on 'Contaminated sites--Cases, remediation, risk and policy' were held at the DIOXIN conferences in 2006 and 2007, and this theme will be continued at DIOXIN 2008 to be held in Birmingham. Selected cases from the approximately 70 contributions made to these sessions, together with some additional invited case studies are outlined together with the key issues they raise. By evaluating these cases and adding details of experiences published in the current literature, an overview will be given of the different features and challenges of dioxin and POP-contaminated sites. RESULTS: This article provides a systematic categorisation of types of PCDD/F and POP-contaminated sites. These are categorised according to the chemical or manufacturing process, which generated the PCDD/Fs or POPs and also includes the use and disposal aspects of the product life cycle in question. The highest historical PCDD/F and dioxin-like polychlorinated biphenyl (PCB) contamination burdens have arisen as a result of the production of chlorine and of chlorinated organic chemicals. In particular, the production of chlorinated pesticides, PCBs and the related contaminated waste streams are identified being responsible for historical releases of toxic equivalents (TEQs) at a scale of many tonnes. Along with such releases, major PCDD/F contaminated sites have been created through the application or improper disposal of contaminated pesticides, PCBs and other organochlorine chemicals, as well through the recycling of wastes and their attempted destruction. In some extreme examples, PCDD/F contaminated sites have also resulted from thermal processes such as waste incinerators, secondary metal industries or from the recycling or deposition of specific waste (e.g. electronic waste or car shredder wastes), which often contain chlorinated or brominated organic chemicals. The examples of PCDD/F and dioxin-like PCB contamination of fish in European rivers or the impact of contaminated sites upon fishing grounds and upon other food resources demonstrate the relevance of these historical problems to current and future human generations. Many of the recent food contamination problems that have emerged in Europe and elsewhere demonstrate how PCDD/F and dioxin like PCBs from historical sources can directly contaminate human and animal feedstuffs and indeed highlight their considerable contemporary relevance in this respect. Accordingly, some key experiences and lessons learnt regarding the production, use, disposal and remediation of POPs from the contaminated sites are summarised. DISCUSSION: An important criterion for evaluating the significance and risks of PCDD/Fs and other POPs at contaminated sites is their present or future potential for mobility. This, in turn, determines to a large degree their propensity for off-site transport and environmental accessibility. The detailed evaluation of contaminated site cases reveals different site-specific factors, which influence the varied pathways through which poor water-soluble POPs can be mobilised. Co-contaminants with greater water solubility are also typically present at such sites. Hence, pumping of groundwater (pump and treat) is often required in addition to attempting to physically secure a site. At an increasing number of contaminated sites, securing measures are failing after relatively short time spans compared to the time horizon, which applies to persistent organic pollutant contamination. Due to the immense costs and challenges associated with remediation of contaminated sites 'monitored natural attenuation' is increasingly gaining purchase as a conceptual remediation approach. However, these concepts may well prove limited in their practical application to contaminated sites containing persistent organic pollutants and other key pollutants like heavy metals. CONCLUSIONS: It is inevitable, therefore, that dioxin/POP-contaminated sites will remain of contemporary and future relevance. They will continue to represent an environmental issue for future generations to address. The securing and/or remediation of dioxin/POP-contaminated sites is very costly, generally in the order of tens or hundreds of millions of dollars. Secured landfills and secured production sites need to be considered as constructions not made for 'eternity' but built for a finite time scale. Accordingly, they will need to be controlled, supervised and potentially repaired/renewed. Furthermore, the leachates and groundwater impacted by these sites will require ongoing monitoring and potential further remediation. These activities result in high maintenance costs, which are accrued for decades or centuries and should, therefore, be compared to the fully sustainable option of complete remediation. The contaminated site case studies highlight that, while extensive policies and established funds for remediation exist in most of the industrialised western countries, even these relatively well-regulated and wealthy countries face significant challenges in the implementation of a remediation strategy. This highlights the fact that ultimately only the prevention of contaminated sites represents a sustainable solution for the future and that the Polluter Pays Principle needs to be applied in a comprehensive way to current problems and those which may emerge in the future. RECOMMENDATIONS AND PERSPECTIVES: With the continuing shift of industrial activities in developing and transition economies, which often have poor regulation (and weak self-regulation of industries), additional global challenges regarding POPs and other contaminated sites may be expected. In this respect, a comprehensive application of the "polluter pays principle" in these countries will also be a key to facilitate the clean-up of contaminated areas and the prevention of future contaminated sites. The threats and challenges of contaminated sites and the high costs of securing/remediating the problems highlight the need for a comprehensive approach based upon integrated pollution prevention and control. If applied to all polluting (and potentially polluting) industrial sectors around the globe, such an approach will prove to be both the cheapest and most sustainable way to underpin the development of industries in developing and transition economies.     

Sorption and desorption of Cu and Cd by macroalgae and microalgae

The sorption and desorption of Cu and Cd by two species of brown macroalgae and five species of microalgae were studied. The two brown macroalgae, Laminaria japonica and Sargassum kjellmanianum, were found to have high capacities at pHs between 4.0 and 5.0 while for microalgae, optimum pH lay at 6.7. The presence of other cations in solution was found to reduce the sorption of the target cation, suggesting a competition for sorption sites on organisms. Sorption isotherms obeyed the Freundlich equation, suggesting involvement of a multiplicity of mechanisms and sorption sites. For the microalgae tested, Spirulina platensis had the highest capacity for Cd, followed by Nannochloropsis oculata, Phaeodactylum tricornutum, Platymonas cordifolia and Chaetoceros minutissimus. The reversibility of metal sorption by macroalgae was examined and the results show that both HCl and EDTA solutions were very effective in desorbing sorbed metal ions from macroalgae, with up to 99.5% of metals being recovered. The regenerated biomass showed undiminished sorption performance for the two metals studied, suggesting the potential of such material for use in water and wastewater treatment.     

Persistence and dissipation kinetics of trifloxystrobin and tebuconazole in onion and soil

The persistence and dissipation kinetics of trifloxystrobin and tebuconazole on onion were studied after application of their combination formulation at a standard and double dose of 75 + 150 and 150 + 300 g a.i. ha^?1. The fungicides were extracted with acetone, cleaned-up using activated charcoal (trifloxystrobin) and neutral alumina (tebuconazole). Analysis was carried out by gas chromatograph (GC) and confirmed by gas chromatograph mass spectrometry (GC-MS). The recovery was above 80% and limit of quantification (LOQ) 0.05 mg kg^?1 for both fungicides. Initial residue deposits of trifloxystrobin were 0.68 and 1.01 mg kg^?1 and tebuconazole 0.673 and 1.95 mg kg^?1 from standard and double dose treatments, respectively. Dissipation of the fungicides followed first-order kinetics and the half life of degradation was 6–6.6 days. Matured onion bulb (and field soil) harvested after 30 days was free from fungicide residues. These findings suggest recommended safe pre-harvest interval (PHI) of 14 and 25 days for spring onion consumption after treatment of Nativo 75 WG at the standard and double doses, respectively. Matured onion bulbs at harvest were free from fungicide residues.     

Kinetic and structural relationships of transition monomeric and oligomeric carboxyl- and choline-esterases

The kinetic and structural relationships of eight electrophoretically pure mammalian serum and liver serine carboxylesterases (CE) and cholinesterases (ChE) have been studied. Eight CE's and ChE's, which were fully resolved but only partially purified, provided additional information. Five of the electrophoretically pure esterases were monomeric, and of these, four belonged to a new and widely distributed class. These four monomeric esterases hydrolyzed choline esters, but at widely differing rates. Thus two were termed monomeric butyrylcholinesterases, mBuChE I and II, and two were monomeric CE's (mCE). The rabbit liver mCE was not a subunit of the oligomeric CE (oCE), although the oCE also hydrolyzed choline esters at a very low rate. The complex kinetics of the mCE's, mBuChE's, oCE's, and of the oligomeric BuChE's of horse and human serum could be interpreted according to a single reaction scheme involving an allosteric site and the equation derived from it. Thus activation and inhibition at high substrate concentrations, together with sigmoidal activity versus substrate concentration plots, all of which characterize the reactions of these esterases, could be interpreted by a single scheme and equation. Structural and kinetic comparisons showed a progressive transition of properties from the oCE's through the mCE's to the oBuChE's. One of the purified mCE's was from horse serum, and it exhibited physical and kinetic properties unlike those of the liver mCE's or oCE's.     

Bacterial and archaeal diversity in oil fields and reservoirs and their potential role in hydrocarbon recovery and bioprospecting

Environmental Science and Pollution Research - Hydrocarbon is a primary source of energy in the current urbanized society. Considering the increasing demand, worldwide oil productions are declining...     

畜禽养殖业污染与循环经济

解决畜禽养殖业的污染问题要以充分利用资源为根本出发点，通过对污染全过程控制及废物综合利用，达到畜禽粪便的减量化、无害化、资源化，走循环经济的发展道路。     

Sorption and Desorption Behavior of Chloroanilines and Chlorophenols on Montmorillonite and Kaolinite

The bioavailability of pollutants, pesticides and/or their degradation products in soil depends on the strength of their sorption by the different soil components, particularly by the clay minerals. This study reports the sorption-desorption behavior of the environmentally hazardous industrial pollutants and certain pesticides degradation products, 3-chloroaniline, 3,4-dichloroaniline, 2,4,6-trichloroaniline, 4-chlorophenol, 2,4-dichlorophenol and 2,4,6-trichlorophenol on the reference clays kaolinite KGa-1 and Na-montmorillonite SWy-l. In batch studies, 2.0 g of clay were equilibrated with 100.0 mL solutions of each chemical at concentrations ranging from 10.0 to 200.0 mg/L. The uptake of the compounds was deduced from the results of HPLC-UV-Vis analysis. The lipophilic species were best retained by both clay materials. The most lipophilic chemical used in the study, 2,4,6-trichloroaniline, was also the most strongly retained, with sorption of up to 8 mg/g. In desorption experiments, which also relied on HPLC-UV-Vis technique, 2,4,6-trichloroaniline was the least desorbed from montmorillonite. However, on kaolinite all of the compounds under study were irreversibly retained. The experimental data have been modelled according to the Langmuir and Freundlich isotherms. A hypothesis is proposed concerning the sorption mechanism and potential applications of the findings in remediation strategies have been suggested.     

Sorption and desorption behavior of chloroanilines and chlorophenols on montmorillonite and kaolinite

The bioavailability of pollutants, pesticides and/or their degradation products in soil depends on the strength of their sorption by the different soil components, particularly by the clay minerals. This study reports the sorption-desorption behavior of the environmentally hazardous industrial pollutants and certain pesticides degradation products, 3-chloroaniline, 3,4-dichloroaniline, 2,4,6-trichloroaniline, 4-chlorophenol, 2,4-dichlorophenol and 2,4,6-trichlorophenol on the reference clays kaolinite KGa-1 and Na-montmorillonite SWy-l. In batch studies, 2.0 g of clay were equilibrated with 100.0 mL solutions of each chemical at concentrations ranging from 10.0 to 200.0 mg/L. The uptake of the compounds was deduced from the results of HPLC-UV-Vis analysis. The lipophilic species were best retained by both clay materials. The most lipophilic chemical used in the study, 2,4,6-trichloroaniline, was also the most strongly retained, with sorption of up to 8 mg/g. In desorption experiments, which also relied on HPLC-UV-Vis technique, 2,4,6-trichloroaniline was the least desorbed from montmorillonite. However, on kaolinite all of the compounds under study were irreversibly retained. The experimental data have been modelled according to the Langmuir and Freundlich isotherms. A hypothesis is proposed concerning the sorption mechanism and potential applications of the findings in remediation strategies have been suggested.     

Synthesis and characterization of m- and p-methylbenzyl-mercapturic acids derived from m- and p-xylenes

Chemical synthesis and physical properties of two mercapturic acids suggested as urinary metabolites of m- and p-xylenes ace described. These compounds may be used for the identification and quantivative determination by high-performance liquid chromatography of the corresponding mercapturic acids in urine.