共查询到19条相似文献,搜索用时 46 毫秒
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在氧化锌法脱除烟气SO2工艺中,脱硫产物亚硫酸锌的氧化是实现锌、硫资源回收的关键环节。在pH为4~5,25℃等条件下,考察了锌、铁、镉离子对亚硫酸锌氧化过程的影响。结果发现,铁离子对亚硫酸锌氧化过程有较强的催化作用,锌离子有一定的催化作用,而低浓度的镉离子几乎不影响氧化过程。进一步的研究表明,锌、铁离子的独自催化氧化速率对各自的浓度均为0.5级响应,但在混合状态下,锌离子对铁离子的催化过程有抑制作用。 相似文献
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CuO/γ-Al2O3的制备及其湿式催化氧化性能研究 总被引:1,自引:1,他引:0
针对常温常压的废水双氧水催化氧化,采用浸渍法制备CuO/γ-Al2O3催化剂,利用比表面积、XRD手段表征了制备工艺对催化剂的影响,以模拟苯酚废水为研究对象考察催化剂的催化性能。研究表明,焙烧温度和活性组分含量等显著影响催化剂的性能,催化剂对双氧水催化氧化苯酚溶液具有较高的催化活性。 相似文献
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活性炭纤维上4-氯酚及焦化废水尾水的O3催化氧化降解实验研究 总被引:2,自引:2,他引:0
选择YT-1000型活性炭纤维(ACF)作为催化剂,考察ACF与O3协同作用催化降解水溶液中4-氯酚的最佳反应条件,并将该条件应用于焦化废水生物处理尾水中难降解有机污染物的催化氧化。ACF表面具有丰富的微孔结构,对4-氯酚有良好的吸附作用,在动力学上提高了其与O3反应的起始浓度,并且在ACF表面含氧、含氮等基团的催化作用下发生氧化反应,1 L浓度为100 mg/L的4-氯酚水样中投加2 g ACF反应6 min时,吸附作用对TOC的去除率为43.4%,而ACF协同O3作用时的TOC去除率提高到72.5%,协同增效作用为67.1%;在选定的反应条件下,ACF协同O3降解焦化废水生物处理尾水,60 min时的TOC与色度的去除率分别达到56.8%和96.3%。上述研究过程证明了吸附作用与催化作用的协同能有效降解生物过程不能降解的焦化废水中惰性有机污染物。 相似文献
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亚临界水技术处理厨余垃圾的比较研究 总被引:2,自引:0,他引:2
在亚临界实验条件下,以淀粉、纤维素类物质为模型化合物,H2O2为氧化剂,研究了厨余垃圾(大米、白菜)在亚临界水中部分氧化获取小分子有机酸的过程中处理时间、处理温度、加氧量对有机酸(甲酸、乙酸)生成的影响。以碳转化率为评价指标,确定反应最佳条件。实验结果表明:淀粉和纤维素分别在处理时间1~1.5 min,加氧量70%~100%,温度280℃;处理时间1~2 min,加氧量70%~100%,温度280~300℃条件下,生成有机酸浓度最大,达到最佳工艺条件。 相似文献
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采用共沉淀法,以Al2O3为载体制备Mn/γ-Al2O3和Mn-Ce/γ-Al2O3催化剂,并分别在N2气氛和O2气氛下焙烧。采用固定床连续流动反应器,研究所制备催化剂在室温条件下催化臭氧氧化甲苯的性能。通过XRD、XPS和FTIR等手段对催化剂的结构和组成进行表征。结果表明,Mn/γ-Al2O3催化剂具有良好的催化臭氧氧化甲苯和催化臭氧自身分解的性能,共沉淀法制备催化剂的最佳Mn负载量为20%。O2气氛焙烧和Ce的加入,可以有效提高催化剂的活性和寿命。原因是O2气氛焙烧和Ce的加入可以提高Mn的氧化价态。催化剂失活的主要原因是有机副产物在催化剂表面吸附堆积,失活催化剂在550℃、空气气氛下焙烧可恢复催化性能。 相似文献
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热镀锌厂酸洗废水及锌灰中锌回收 总被引:1,自引:1,他引:0
分别采用蒸酸法、氨络合法和硫化沉淀法分离回收热镀锌厂酸洗废水及锌灰中锌铁。分别考察了酸洗废水中盐酸的逸出特性和氨浸法回收蒸馏渣中锌的效果;利用酸洗废水的酸度浸取锌灰中的锌并用氨络合法分离酸浸出液中锌铁;利用硫化物不同溶度积选择性沉淀酸浸出液中的锌,考察了Na2S加入量、曝气时间、反应溶液pH和反应时间的影响。研究结果表明硫酸的加入能提高盐酸的蒸发率但效果不明显,氨络合法难于有效分离锌铁,但硫化物沉淀法可较好地分离锌铁,铁回收率可达97.12%,锌沉淀率达到99.99%,所得沉淀物中ZnS纯度为68.51%。 相似文献
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利用高炉瓦斯泥中的锌制备活性氧化锌的研究 总被引:1,自引:0,他引:1
利用高炉炼铁瓦斯泥中的锌,采用火法富集和湿法浸取制取活性氧化锌。考察了温度、时间对火法富集产品中氧化锌含量和原料瓦斯泥中锌挥发率的影响,确定了富集工艺的最佳条件为:在氮气氛围下,温度从常温以10℃/min升温至1 000℃并且在1 000℃下保持1 h,得到的富集产品中氧化锌含量82.24%;瓦斯泥中锌挥发率97%。同时考察了温度、氨水用量、碳酸氢铵用量和液固比等因素对氧化锌浸取率的影响。确定的最佳工艺条件为:浸取温度40℃,氨水用量为理论量的2倍,碳酸氢铵用量为理论量的2倍,液固比4∶1,浸取时间2 h,氧化锌浸取率达99.9%。湿法制得的活性前驱体碱式碳酸锌,经煅烧得到纯度为98.4%的活性氧化锌产品,氧化锌的总回收率达95.3%。 相似文献
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The pore water zinc concentration and the calcium chloride extracted zinc fraction are higher in the soils spiked with a zinc salt (ZnCl2) compared to soils spiked with zinc oxide or zinc powder. Based on total zinc concentrations in the soil, the acute toxicity of zinc salt to the compost worm Eisenia fetida, the potworm Enchytraeus albidus and the springtail Folsomia candida was lower compared to zinc oxide and zinc powder. However, when expressed on the basis of pore water concentrations or calcium chloride extracted fractions, acute toxicity was higher for zinc salt, which indicated that dermal uptake via the pore water is not the only route of uptake. Chronic toxicity of zinc salt, zinc oxide and zinc powder was similar when based on total concentrations in the soil which again indicates that the pore water route of uptake is not the only route of exposure but that oral uptake is also important. 相似文献
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从热镀锌厂的酸洗废水和锌灰中回收硫化锌,采用X射线能谱仪(EDS),X射线衍射仪(XRD),傅里叶红外光谱仪(FTIR)和场发射透射电镜(FETEM)表征样品ZnS性质,电感耦合等离子发射体(ICP-OES)分析上清液性质,并研究该反应动力学过程。EDS和ICP分析表明,样品ZnS纯度达到85.45%,其上清液含有高浓度铁,含量为2 g/L,可用于制备复合亚铁絮凝剂,而其他重金属离子浓度均低于电镀废水排放标准。XRD分析表明,样品ZnS是立方晶型,调节pH和采用滴加方式能有效改善样品ZnS的晶型。采用Scherrer公式计算晶体粒径,结果表明,晶粒大小在3~6 nm之间。FTIR分析表明,样品ZnS呈现良好的红外透明性,且温度、pH和滴加方式对样品的红外透光性基本没有影响。FETEM结合XRD图表明,该纳米晶呈片状,近似为球形,呈多层叠加,分散性不明显,有团聚现象。动力学实验表明,逆一级动力学方程适合描述硫化沉淀的反应动力学过程,活化能为39.04 kJ/mol,沉淀过程受化学反应和扩散联合控制。 相似文献
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Zinc adsorption equilibria were measured in soils differing in pH but with similar textures and total zinc concentrations, using adsorption isotherm and isotopic exchange techniques. The results suggested that the equilibrium between solution and exchangeable zinc was strongly pH dependent and the active zinc species in adsorption was single charged (e.g. Zn(OH)(+)). The size of the exchangeable zinc pool was not strongly pH dependent. Similar results were obtained when zinc was added to the soils, either as Zn(NO(3))(2) or in sewage sludge. 相似文献
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Speciation of zinc in contaminated soils 总被引:1,自引:0,他引:1
Stephan CH Courchesne F Hendershot WH McGrath SP Chaudri AM Sappin-Didier V Sauvé S 《Environmental pollution (Barking, Essex : 1987)》2008,155(2):208-216
The chemical speciation of zinc in soil solutions is critical to the understanding of its bioavailability and potential toxic effects. We studied the speciation of Zn in soil solution extracts from 66 contaminated soils representative of a wide range of field conditions in both North America and Europe. Within this dataset, we evaluated the links among the dissolved concentrations of zinc and the speciation of Zn(2+), soil solution pH, total soil Zn, dissolved organic matter (DOM), soil organic matter (SOM) and the concentrations of different inorganic anions. The solid-liquid partitioning coefficient (K(d)) for Zn ranged from 17 to 13,100Lkg(-1) soil. The fraction of dissolved Zn bound to DOM varied from 60% to 98% and the soil solution free Zn(2+) varied from 40% to 60% of the labile Zn. Multiple regression equations to predict free Zn(2+), dissolved Zn and the solid-liquid partitioning of Zn are given for potential use in environmental fate modeling and risk assessment. The multiple regressions also highlight some of the most important soil properties controlling the solubility and chemical speciation of zinc in contaminated soils. 相似文献
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Jadwiga Wyszkowska Edyta Boros-Lajszner Agata Borowik Małgorzata Baćmaga Jan Kucharski Monika Tomkiel 《Journal of environmental science and health. Part. B》2016,51(5):261-270
This study was undertaken to evaluate zinc's influence on the resistance of organotrophic bacteria, actinomyces, fungi, dehydrogenases, catalase and urease. The experiment was conducted in a greenhouse of the University of Warmia and Mazury (UWM) in Olsztyn, Poland. Plastic pots were filled with 3 kg of sandy loam with pHKCl – 7.0 each. The experimental variables were: zinc applied to soil at six doses: 100, 300, 600, 1,200, 2,400 and 4,800 mg of Zn2+ kg?1 in the form of ZnCl2 (zinc chloride), and species of plant: oat (Avena sativa L.) cv. Chwat and white mustard (Sinapis alba) cv. Rota. Soil without the addition of zinc served as the control. During the growing season, soil samples were subjected to microbiological analyses on experimental days 25 and 50 to determine the abundance of organotrophic bacteria, actinomyces and fungi, and the activity of dehydrogenases, catalase and urease, which provided a basis for determining the soil resistance index (RS). The physicochemical properties of soil were determined after harvest. The results of this study indicate that excessive concentrations of zinc have an adverse impact on microbial growth and the activity of soil enzymes. The resistance of organotrophic bacteria, actinomyces, fungi, dehydrogenases, catalase and urease decreased with an increase in the degree of soil contamination with zinc. Dehydrogenases were most sensitive and urease was least sensitive to soil contamination with zinc. Zinc also exerted an adverse influence on the physicochemical properties of soil and plant development. The growth of oat and white mustard plants was almost completely inhibited in response to the highest zinc doses of 2,400 and 4,800 mg Zn2+ kg?1. 相似文献