共查询到20条相似文献,搜索用时 78 毫秒
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为研究硝基苯在水体中的光化学行为,建立基于液相色谱的硝基苯浓度的测定方法。分别以低压紫外汞灯、氙灯和自然阳光为光源,研究水中硝基苯的光降解规律,探讨光强、pH值、江水中可溶性物质等因素对硝基苯光解速率的影响。结果表明,硝基苯光降解反应符合一级反应动力学规律,反应速率常数k与初始入射光强I0成正比,k=0.0014I0;紫外光辐射强度在水中呈指数衰减。2、3月份太阳辐射强度下,江水表层中(30-40mm厚)硝基苯光降解的半衰期约为2d。酸性条件下,硝基苯光降解反应速率有所提高,碱性条件下基本无变化.江水中的腐殖质和某些杂质对硝基苯的光降解有促进作用。研究为污染水体的自然修复提供理论依据。 相似文献
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本文在总结国内外近40年研究文献的基础上,对不同形态Fe(Ⅲ)盐水解产物的形态分布,光化学特性及其对水体中有机物光降解作用进行了综述,还结合作者在Fe(Ⅲ)_OH络合物体系对水溶性染料光降解的研究,探讨了应用这一体系进行水处理应用的可行性和发展前景。 相似文献
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The batch ozonation of some fractions of aqueous humic substances (humic, fulvic and hydrophilic acids) extracted from natural waters is studied. The reaction leads to oxidation byproducts such as low molecular aldehydes and ketoacids. Formation conditions and origin of some of them (glyoxylic, pyruvic and ketomalonic acids) regarding the extracted fraction of natural organic matter is established. 相似文献
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In this paper the influences of preozonation on the effectiveness of NOM adsorption and biodegradation processes are studied. Three different types of water have been used in this study: A natural water from the Úzquiza Reservoir (Burgos, Spain), synthetics waters prepared using natural humic substances (fulvic and humic acids extracted from the Úzquiza Reservoir) and a synthetic water prepared using a commercially supplied humic acid. The effect of preozonation on NOM adsorption by activated carbon is evaluated: adsorption of humic acids (hydrophobic, high molecular weight compounds) is improved following preozonation; however, for the fulvic acids (hydrophilic, low molecular weight compounds), no net appreciable effect of preozonation on adsorption was observed. Preozonation increases the biodegradability of NOM: biodegradable dissolved organic carbon (BDOC), which was determined using two different bioassays (Billen-Servais method and Joret-Lévi method), increases with increasing ozone dosage. A characterization of humic substances based on their adsorption and biodegradability properties is also reported, showing the effect of ozone. 相似文献
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Takayuki Morioka Motoyama Nobuyuki Hoshikawa Hiroshi Akihiko Murakami Mitsumasa Okada Takeo Moniwa 《臭氧:科学与工程》1993,15(1):1-18
The kinetics of geosmin and 2–MIB decomposition by ozonation in the presence of dissolved inorganic and organic substances were studied. As a first approximation, the decomposition rate of geosmin and 2–MIB were analyzed as a first–order reaction with respect to their concentration. The first–order rate constants decreased significantly with increase in the concentration of carbonate ion, free chlorine, alcohols and volatile fatty acids. Small amounts of humic acids or fulvic acids, however, enhanced the rate of decomposition. It was also demonstrated that the decomposition rates in natural waters were influenced mainly by the concentrations of carbonate and humic substances. 相似文献
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Humic acids (HA) representing the major fraction of the naturally occurring humic substances (HS) are composed of highly functionalized carbon rich polydisperse organic fractions. Clay minerals which are responsible for the transport of inorganic and organic contaminants constitute the main component of the dispersed inorganic material in natural waters. The understanding of interactions between humic substances and clay minerals is an important task for the achievement of an effective water treatment performance. The aim of this research was to investigate the influence of montmorillonite as a representative clay mineral on the TiO2 photocatalytic removal of humic acids as the model compound of natural organic matter. The interactions prevailing between humic acid, montmorillonite and TiO2 surface were assessed prior to the application of photocatalysis in order to address the adsorptive and photolytic behavior of humic acids. The changes attained in humic acid were described by UV–vis spectroscopic i.e. color forming moieties (Color436) and UV absorbing centers (UV365 and UV254), and dissolved organic carbon (DOC) contents. Application of the pseudo first order kinetic model revealed both an enhancement and retardation with respect to the applied montmorillonite dose. The overall effect of montmorillonite on the photocatalytic degradation of humic acid was also evaluated in terms of molecular size distribution profiles (0.45 μm filtered fraction, 100 kDa fraction, 30 kDa fraction and 3 kDa fraction) described by the specified and DOC normalized specific UV–vis parameters. 相似文献
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Ceyda Senem Uyguner Serif Altan Suphandag Aslihan Kerc Miray Bekbolet 《Desalination》2007,210(1-3):183-193
Humic substances mainly humic acids constitute the major fraction of natural organic matter in water supplies. Humics express diverse actions primarily related to the formation of potentially harmful disinfection by products (DBPs). Therefore, the removal of DBP precursors through numerous treatment techniques gains high importance. Besides the conventional treatment processes, the applications of advanced oxidation techniques are considered as effective tools for the elimination of humic acids (HAs) from natural waters. In the present study, both the adsorption and coagulation characteristics of humic acid samples are evaluated subsequent to pretreatment by photocatalytic oxidation and ozonation. The changes in preoxidized humic acid solutions are assessed in relation to the alterations induced in the UV-vis and fluorescence spectroscopic properties. The removal efficiency of color in terms of Color436 and aromaticity with respect to UV254 are presented relevant to each treatment step. Major key parameters such as the selection of coagulant types (alum and ferric chloride), coagulant aids (ionic and non-ionic polyelectrolyte) and optimum coagulant dose were comparatively discussed. The adsorption characteristics of powdered activated carbon (PAC) and granular activated carbon (GAC) were investigated. 相似文献
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Abstract An hydrazone derivative, 1,2-cyclohexanedione bis-benzoyl-hydrazone (1,2-CHBBH), has been used as a selective reagent for an advanced environmental application consisting of separating the different species of nickel in natural waters by solvent extraction. The effects of pH and reagent concentration on the extraction process were studied, as well as the influence of both organic (humic acids) and inorganic ligands (Cl?). Under natural conditions, organic and inorganic nickel species presented different extraction behaviors, and the variations in extraction yields could be correlated with the concentrations of organic complexes in the samples, allowing the separation of labile and non-labile nickel species in both fresh and marine waters. 相似文献
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In this article the influence of preozonation on the effectiveness of NOM removal via coagulation processes will be studied (focusing on the influence of the calcium hardness) as well as changes in MW (molecular weight) distribution of humic substances caused by ozonation. Additionally, THMFP removal in both ozonation and preozonation-coagulation processes is assessed. Three different types of water have been used in this study: a natural water from the Úzquiza Reservoir (Burgos, Spain), a synthetic water prepared using natural fulvic acids extracted from the Úzquiza Reservoir and a synthetic water prepared using a commercially supplied humic acid. Molecular weights of humic substances were determined using high-performance size exclusion chromatography (HPSEC); average molecular weights calculated for the unozonated humic substances are 4500 Da for the commercial humic acids and 1000 Da for the natural fulvic acids extracted from the Úzquiza Reservoir. Preozonation shifted the molecular weight distribution of humic substances (both humic and fulvic acids) towards lower average molecular weight values. For the natural water from the Úzquiza Reservoir (with low levels of calcium hardness and hydrophobic fraction (humic substances) being the main fraction of NOM), preozonation has a negative effect on the effectiveness of the coagulation process for NOM removal: the percentages of TOC removal via coagulation decrease with increasing ozone dosage; the maximum TOC removal (33%) is achieved for the unozonated water. Also for this water, ozonation reduced 5–25% of THMFP with ozone doses varying from 0.25 to 2.5 mg O3/L. A preferential THMFP removal, that is to say, higher reduction in THMFP (43%) relative to TOC (28%) is achieved by the coagulation-flocculation process; this also occurs when preozonation is used, independently of ozone dosage. 相似文献
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比较了Enga西。海湾海水(大西洋)和丘布特河水(阿根廷的巴塔哥尼亚)中腐殖质的结构。这些腐殖质被分离、纯化后,通过元素分析法,核磁共振法(C13和1H谱),红外光谱法,紫外吸收法和荧光法等对其结构特性进行了分析鉴定,并以氮含量、氧含量、H/C比、C/N比、红外波段中氮和羧基官能团含量、核磁共振吸收谱线中官能团的斜率系... 相似文献
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The saving and recycling of chemical substances, which may be hazardous to human health and ecosystems, constitute a desirable goal worldwide. It is important to use a natural polymer that has a highly specific function and an environmental friendliness. In this study, humic acid was added to a natural polymer, a pectin membrane, and a hydrophobic poly(1‐trimethylsilyl‐1‐propyne) (PMSP) membrane to enhance the affinity for phenol or aniline. Also, the separation performance, based on the membrane materials and methods of addition, was investigated. The effect of the adsorption of phenol and aniline by humic acid was investigated. A high rate of aniline adsorption was observed. The interaction of the humic acids and the aniline was mainly observed by polar bonding. For the PMSP membrane with humic acid added to the surface, the humic acid exists in a colloidal state. During pervaporation, the permeation of water was prevented by the adsorbed solute. Because the permeability of aniline increased and the permeability of water significantly decreased, the PMSP membrane with humic acid added to the surface had a high permeate aniline concentration, and the permselectivity was improved. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 461–468, 2004 相似文献