Electrokinetic remediation for the removal of organic contaminants in soils

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Screening methodology for coal-derived organic contaminants in water

A screening methodology designed to detect the presence of organic materials that leach into water from coal deposits was developed and evaluated. Analytical objectives included the ability to detect 16 polynuclear aromatic hydrocarbons (PAHs) at the lowest practical levels, capability for fingerprint analysis of other compounds, and ease of use under remote field conditions. The approach developed involved drawing 1?L water samples through a styrene divinylbenzene-based solid-phase extraction cartridge by suction, elution of the cartridge with tetrahydrofuran/hexane, evaporative concentration of the eluent, and reconstitution in acetonitrile, followed by analysis using high-pressure liquid chromatography with ultraviolet absorption and fluorescence detectors. The method was found to be easy to use under field conditions, providing generally acceptable recoveries and, in most cases, lower detection limits than current regulatory methods. The ability to detect PAHs and other organic compounds in simulated coal leachate solutions was demonstrated.     

Copper-cerium oxide catalysts prepared by the Pechini method for CO removal from hydrogen-containing mixtures

A series of copper-cerium oxide catalysts was prepared by the Pechini method, and their physicochemical and catalytic properties in CO oxidation in hydrogen-containing gas mixtures were studied. The method chosen for catalyst preparation yields finely dispersed copper and cerium oxides in the catalyst.     

Strategies for the microextraction of polar organic contaminants in water samples

In this paper the most recent developments in the microextraction of polar analytes from aqueous environmental samples are critically reviewed. The particularities of different microextraction approaches, mainly solid-phase microextraction (SPME), stir-bar-sorptive extraction (SBSE), and liquid-phase microextraction (LPME), and their suitability for use in combination with chromatographic or electrically driven separation techniques for determination of polar species are discussed. The compatibility of microextraction techniques, especially SPME, with different derivatisation strategies enabling GC determination of polar analytes and improving their extractability is revised. In addition to the use of derivatisation reactions, the possibility of enhancing the yield of solid-phase microextraction methods for polar analytes by using new coatings and/or larger amounts of sorbent is also considered. Finally, attention is also focussed on describing the versatility of LPME in its different possible formats and its ability to improve selectivity in the extraction of polar analytes with acid-base properties by using separation membranes and buffer solutions, instead of organic solvents, as the acceptor solution.     

物理法COD减排理论极限能耗的热力学分析

首先针对系统的可持续性发展提出了三点本质要求,在此基础上提出了基于减排过程节能机制的热力学框架,并根据热力学第一、第二定律建立了计算物理法脱除有机污染物理论极限能耗的热力学分析方法.此外,以典型有机污染物的脱除为例,分别计算了封闭体系中298.15K和1.01325×105Pa下不同初始浓度、不同种类以及不同COD减排量的有机污染物脱除的理论极限能耗.本文的计算结果表明,废水中有机污染物的减排需要很高的能耗,脱除相同量有机污染物所需的理论极限能耗随着初始浓度的减小而显著增加,且不同种类污染物处理的难易程度和能耗高低相差很大,这充分说明减排与节能有着密不可分的联系,充分考虑污染物的种类、物理化学性质、毒性和浓度将有助于减排政策的科学制定.     

Using thermal analysis combined with IR fourier-transform spectroscopy for study and selection of catalysts for removal of organic impurities from water

Russian Journal of General Chemistry - The suitability of the methods of simultaneous thermal analysis combined with Fourier-transform IR spectroscopy for express investigation and selection of...     

Hybrid peroxi-coagulation/ozonation process for highly efficient removal of organic contaminants

Aromatic compounds such as phenols presented widely in coal chemical industry wastewater(CCW) render the treatment facing great challenge due to their biorefractory characteristics and potential risks to the environment and human health. Ozone-based advanced oxidation processes show promising for these pollutants removal, but the mineralization via ozonation alone is unsatisfactory and not cost-effective.Herein, a hybrid peroxi-coagulation/ozonation process(denoted as PCO) was developed using sa...     

Solid-phase extraction for multiresidue analysis of organic contaminants in water

To overcome the limitations of the detection systems associated with gas or liquid chromatography, a sample pretreatment is required with the objective to provide a sample fraction enriched with all the target analytes and as free as possible from other matrix components. There is now no doubt that solid-phase extraction (SPE) has now become the method of choice for carrying out simultaneously the extraction and concentration of many compounds in aqueous samples. Many recent applications of SPE to multiresidue analysis are reviewed with an emphasis on the importance of the choice of the sorbent and of the sample volume. SPE is particularly well adapted to multiresidue analysis including compounds from a wide range of polarity or characterized by various physico-chemical properties. However, SPE is not completely free from practical problems inherent to the nature of the compounds or to the coupling to the chromatographic systems. Many examples are reported to illustrate these problems which can in most cases be circumvented. New developments in SPE are also reviewed.     

Acrylation of pre-irradiated polypropylene and its application for removal of organic pollutants

Reactive extrusion of pre-irradiated polypropylene (PP) at different doses of gamma radiation was studied in the presence of different concentrations of acrylic acid monomer (AAc). Preliminary investigations study the feasibility or removal of organic pollutants. The optical properties and surface morphology of the grafted polypropylene were observed by FT–IR, UV/vis and scanning electron microscopy (SEM). The affinity of this membrane to the basic dye was found to be increased with increase in the dose of gamma irradiation and the ratio of acrylic acid monomer (AAc).     

有序多孔过渡金属氧化物及其负载贵金属催化剂对挥发性有机物氧化的催化性能

大部分的挥发性有机物(VOCs)污染环境,危害人身健康.目前,我国虽然已开展了治理 VOCs污染的工作,但还缺乏有效的、拥有自主知识产权的 VOCs治理技术,因此研发新型高效 VOCs处理技术迫在眉睫.催化氧化法是公认的最有效消除 VOCs的途径之一,而高性能催化剂的研发是实现该过程的关键.近年来,人们围绕消除 VOCs的高效且价廉的催化剂的研发开展了卓有成效的工作,许多过渡金属氧化物、混合或复合金属氧化物及其负载贵金属催化剂均被认为是有效的催化氧化材料.与体相材料相比,多孔材料具有发达的孔道结构和高的比表面积,一方面有利于反应物的扩散、吸附和脱附,因而具有更高的催化活性和选择性;另一方面有利于活性组分(如贵金属等)在多孔材料表面的高分散,抑制活性组分的烧结,因而具有更好的催化稳定性.本文简述了近年来多孔金属氧化物在环境污染物消除领域的研究进展,阐述了以有序介孔或大孔过渡金属氧化物、钙钛矿型氧化物和负载贵金属催化剂的制备及其对典型 VOCs(如苯系物、醇类、醛类及酮类等)氧化的催化性能,重点介绍了四类催化材料,包括有序介孔过渡金属氧化物或复合氧化物(Co3O4, MnO2, Fe2O3, Cr2O3和 LaFeO3等)催化剂,有序介孔金属氧化物负载贵金属(Au/Co3O4, Au/MnO2和 Pd/Co3O4等)催化剂,三维有序大孔过渡金属氧化物或复合氧化物(Fe2O3, LaMnO3, La0.6Sr0.4MnO3和 La2CuO4等)催化剂,以及三维有序大孔金属氧化物负载贵金属(Au/Co3O4, Au/LaCoO3, Au/La0.6Sr0.4MnO3和 AuPd/Co3O4等)催化剂的制备及其物化性质与对苯、甲苯、二甲苯、乙醇、丙酮、甲醛、甲烷或氯甲烷等 VOCs氧化的催化性能之间的相关性.借助二氧化硅或聚甲基丙烯酸甲酯微球等硬模板,采用纳米浇铸法可制备出二维或三维的有序单一或多级孔道结构的金属氧化物.研究表明,多孔金属氧化物的催化性能远优于其体相甚至纳米催化剂的.有序多孔材料的优异催化性能与其拥有大的比表面积、高的吸附氧物种浓度、优良的低温还原性、独特的孔道结构、活性组分的高分散以及贵金属与氧化物载体之间的强相互作用等有关.探明影响催化剂活性的因素有利于从原子水平上认识催化过程,为新型高效催化剂的设计与制备奠定基础.本文还指出了此类研究中存在的一些问题,例如利用硬模板法制备多孔材料的缺点是目标催化剂的收率低,硬模板浪费严重,大规模制备多孔催化剂势必增加制备成本,这些问题有待于妥善解决.与此同时,还展望了 VOCs消除技术的未来发展趋势,采用多种技术联用的方法有望最大程度地提高 VOCs的消除效率.     

Strategies for monitoring the emerging polar organic contaminants in water with emphasis on integrative passive sampling

Although polar organic contaminants (POCs) such as pharmaceuticals are considered as some of today's most emerging contaminants few of them are regulated or included in on-going monitoring programs. However, the growing concern among the public and researchers together with the new legislature within the European Union, the registration, evaluation and authorisation of chemicals (REACH) system will increase the future need of simple, low cost strategies for monitoring and risk assessment of POCs in aquatic environments. In this article, we overview the advantages and shortcomings of traditional and novel sampling techniques available for monitoring the emerging POCs in water. The benefits and drawbacks of using active and biological sampling were discussed and the principles of organic passive samplers (PS) presented. A detailed overview of type of polar organic PS available, and their classes of target compounds and field of applications were given, and the considerations involved in using them such as environmental effects and quality control were discussed. The usefulness of biological sampling of POCs in water was found to be limited. Polar organic PS was considered to be the only available, but nevertheless, an efficient alternative to active water sampling due to its simplicity, low cost, no need of power supply or maintenance, and the ability of collecting time-integrative samples with one sample collection. However, the polar organic PS need to be further developed before they can be used as standard in water quality monitoring programs.     

Respirometric analysis of the biodegradation of organic contaminants in soil and water

Client-funded bench-scale investigations concerning the likelihood of successfully applying biological remediation to hazardous wastes must be cost-effective, and they usually need only determine if biodegradation is likely to occur on site. To assess the potential for stimulating biodegradation, biochemical oxygen demand (BOD) was used to continuously monitor bacterial respiration during growth on mixed organic wastes from contaminated water and soil. Continuously collected oxygen-consumption data provided information on the overall metabolic activity of the resident bacterial population and permitted direct observation of the cessation of microbial respiratory activity and, thus, the termination of aerobic degradation. The correlation of biological oxygen utilization with biodegradation was confirmed using independent analytical methods. Continuous, long-term BOD analysis was applied to bench-scale studies to assess the biodegradation of mixed organic wastes from contaminated sites and industrial waste effluents. This information was used to make an initial determination regarding the need to further explore bioremediation as a potential remedial-action technology using on-site, pilot-scale testing.     

Recyclability of poly (N-isopropylacrylamide) microgel-based assemblies for organic dye removal from water

Poly (N-isopropylacrylamide)-co-acrylic acid (pNIPAm-co-AAc) microgels and their aggregates have been shown to effectively remove organic dye molecules from aqueous solutions. Here, we investigate the reusability of these microgel-based systems by exposing them to the organic azo dye molecule, 4-(2-hydroxy-1-naphthylazo) benzenesulfonic acid sodium salt (Orange II). Following exposure, the microgels are isolated, and added to methanol to extract the trapped Orange II from the microgels, followed by a subsequent isolation. The isolated microgels were then exposed to Orange II once again, and the uptake efficiency of the recycled microgels determined. We found that the microgels and their aggregates could be reused to remove the organic dye with little loss in extraction efficiency with the number of recycling cycles.     

锰负载钛锆和钛锡复合氧化物催化剂烟气脱汞实验研究

采用共沉淀法制备了TiO_2、TiZr和TiSn载体,浸渍锰制备了10%MnO_2的MnTi、MnTiZr和MnTiSn催化剂。采用BET、XRD、H_2-TPR、FT-IR和XPS等对样品进行表征,并对三种催化剂进行固定床脱汞性能实验。结果表明,在100-300℃,MnTiZr和MnTiSn催化剂脱汞性能均优于MnTi催化剂,这归因于Sn和Zr的引入提升了催化剂比表面积和低温氧化还原性能增加了催化剂表面的酸性位点数量、高价态锰离子和O~*含量;在反应温度为150-300℃,MnTiSn催化剂脱汞效率均高于MnTiZr催化剂这是由于前者具有更好的氧化还原性能,表面具有更多含量的高价态锰离子、O~*含量和酸性位点数量;在Hg~0脱除过程中催化剂表面活性组分如高价态锰离子和O~*均消耗,参与了Hg~)氧化为Hg~(2+)的反应且MnTiSn催化剂表面活性组分的消耗量更多。     

Molecular dynamics simulation study of solvent effects on conformation and dynamics of polyethylene oxide and polypropylene oxide chains in water and in common organic solvents

In this paper, the conformation and dynamics properties of polyethylene oxide (PEO) and polypropylene oxide (PPO) polymer chains at 298 K have been studied in the melt and at infinite dilution condition in water, methanol, chloroform, carbon tetrachloride, and n-heptane using molecular dynamics simulations. The calculated density of PEO melt with chain lengths of n = 2, 3, 4, 5 and, for PPO, n = 7 are in good agreement with the available experimental data. The conformational properties of PEO and PPO show an increasing gauche preference for the O-C-C-O dihedral in the following order water>methanol>chloroform>carbon tetrachloride = n-heptane. On the contrary, the preference for trans conformation has a maximum in carbon tetrachloride and n-heptane followed in the order by chloroform, methanol, and water. The PEO conformational preferences are in qualitative agreement with results of NMR studies. PEO chains formed different types of hydrogen bonds with polar solvent molecules. In particular, the occurrence of bifurcated hydrogen bonding in chloroform was also observed. Radii of gyration of PEO chains of length larger than n = 9 monomers showed a good agreement with light scattering data in water and in methanol. For the shorter chains the observed deviations are probably due to the enhanced hydrophobic effects caused by the terminal methyl groups. For PEO the fitting of end-to-end distance distributions with the semi-flexible chain model at 298 K provided persistence lengths of 0.375 and 0.387 nm in water and methanol, respectively. Finally, the radius of gyration of Pluronic P85 turned out to be 2.25 ± 0.4 nm at 293 K in water in agreement with experimental data.     

Thermodynamic analysis of the theoretical energy consumption in the removal of organic contaminants by physical methods

The essential requirements for evaluating the sustainable development of a system and the thermodynamic framework of the energy conservation mechanism in the waste-removal process are proposed.A thermodynamic method of analysis based on the first and second laws of thermodynamics is suggested as a means to analyze the theoretical energy consumption for the removal of organic contaminants by physical methods.Moreover,the theoretical energy consumption for the removal by physical methods of different kinds of...     

A fiber optic evanescent field absorption sensor for monitoring organic contaminants in water

Summary A fiber optic chemical sensor for determination of organic compounds in aqueous solution has been developed. Based on the evanescent field principle, a quartz glass fiber with a polysiloxane cladding is used as in-situ measuring probe. A compact sensor built from a 6-m coiled fiber has been connected to a commercially available fast scanning dispersive NIR spectrometer. The siloxane cladding fulfils two functions: on the one hand, it acts as protecting layer of the fragile silica fiber core, and on the other hand, it is selective with respect to non-polar organic compounds due to its organophilic properties. Hence, interactions of the evanescent field at the core/cladding interface with organic species penetrating into the cladding can be measured without interferences from broad water OH absorption bands. Aqueous solutions of chlorinated hydrocarbon solvents (CHS) have been used to test the sensor response. NIR evanescent field absorbance spectra of methylene chloride, chloroform and trichloroethylene diffused into the fiber cladding are shown in the 900–2100 nm spectral range. Different amounts of CHCl₃ dissolved in water have been determined in order to evaluate the quantitative sensor response. A linear absorbance/concentration relationship has been found for solutions between 80–6800 mg l^–1. Kinetic experiments performed with CHCl₃ solutions resulted in sensor response times of 5–10 min. The sensor seems to be promising for the remote monitoring of organic contaminants, e.g. CHS, in drainage waters of contaminated areas.     

A study on the removal of organic substances from low-turbidity and low-alkalinity water with metal-polysilicate coagulants

The coagulants of poly-aluminum-chloride (PAC), poly-aluminum-silicate-chloride (PASiC) and poly-aluminum-ferric-silicate-chloride (PAFSiC) were prepared in this study to evaluate their coagulation efficiencies and mechanisms in synthetic low-turbidity and low-alkalinity water containing organic matter. The experimental results show that PASiC and PAFSiC could remove the kaolin turbidity of the synthetic water with or without salicylic acid present. On the other hand, when the synthetic water contained both kaolin and humic acid in low turbidity and alkalinity, PAC would remove the turbidity but charge reversal of the colloidal particles would occur easily. Also, effective coagulation was limited to a very narrow dosage range. Conversely, the dosage range for the effective coagulation of both PASiC and PAFSiC was wider, although a higher dosage was required to remove the turbidity of wastewater. Therefore, the effective removal of turbidity was not only related to the kind of coagulant, but also to the types of organic matter. The coagulants PASiC and PAFSiC, particularly, proved themselves to be superior to the PAC in the treatment of low-turbidity water.     

Adsorptive removal of arsenic from water by an iron-zirconium binary oxide adsorbent

Arsenate and arsenite may exist simultaneously in groundwater and have led to a greater risk to human health. In this study, an iron-zirconium (Fe-Zr) binary oxide adsorbent for both arsenate and arsenite removal was prepared by a coprecipitation method. The adsorbent was amorphous with a specific surface area of 339 m(2)/g. It was effective for both As(V) and As(III) removal; the maximum adsorption capacities were 46.1 and 120.0 mg/g at pH 7.0, respectively, much higher than for many reported adsorbents. Both As(V) and As(III) adsorption occurred rapidly and achieved equilibrium within 25 h, which were well fitted by the pseudo-second-order equation. Competitive anions hindered the sorption according to the sequence PO(4)(3-)>SiO(3)(2-)>CO(3)(2-)>SO(4)(2-). The ionic strength effect experiment, measurement of zeta potential, and FTIR study indicate that As(V) forms inner-sphere surface complexes, while As(III) forms both inner- and outer-sphere surface complexes at the water/Fe-Zr binary oxide interface. The high uptake capability and good stability of the Fe-Zr binary oxide make it a potentially attractive adsorbent for the removal of both As(V) and As(III) from water.