共查询到20条相似文献,搜索用时 62 毫秒
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一、前言钡盐是无机盐类产品中用途较广、产量较大的一种,但无论是氯化钡、碳酸钡,还是硫酸钡的生产,都不可避免地要产生大量泥渣——钡泥,由于钡泥中多含有少量水溶性钡或酸溶性钡,如不进行处理,既浪费了钡资源,同时也严重污染环境。 相似文献
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用钡盐法处理含铬废水,考察了废水初始pH、重铬酸钾的浓度、反应温度及计量比(氯化钡与六价铬物质的量比)对六价铬回收效果的影响。采用原子吸收分光光度法测量溶液中六价铬浓度。结果表明,废水初始pH为8~9时,六价铬的回收率达95%以上;重铬酸钾的浓度对六价铬的回收率几乎没有影响,但处理后废水中六价铬的浓度随其浓度的增加而上升;10℃以上时,反应温度对六价铬的回收率没有很大影响,当温度降至10℃时,六价铬的回收率随反应温度的下降而急剧下降;计量比为1.1∶1时,六价铬的回收率为99.22%,处理后废水中六价铬的浓度为0.276 7 mg/L,达到了国家关于含铬污水排放时的标准。 相似文献
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通过改进的两次盐酸浸取法将毒重石尾矿钡渣中的钡转化为氯化钡实现二次回收,考察了包括液固比、盐酸浓度、浸取时间、浸取温度等因素对除杂提钡效果的影响。实验结果表明,第一步盐酸洗渣能将铁、钙、锶等杂质酸化为相应的氯盐,并将其大部分转入液相,所得含钡滤渣进行第二步盐酸浸取,得氯化钡溶液。实验优化工
艺条件:第一步盐酸洗渣,液固质量比为1∶2,盐酸浓度为1 mol/L;第二步盐酸浸取,液固质量比为7∶1,盐酸浓度为
2 mol/L,浸取时间为2 h,浸取温度为70 ℃,钡的回收率可达95%;第三步氯化钡粗品精制,用草酸进一步沉淀钙、锶,调节滤液pH为3,滤液蒸发浓缩结晶,晶体经无水乙醇洗涤后烘干,所得氯化钡产品纯度可达99.9%。 相似文献
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用氯化钾和硝酸在常温下进行反应,经过冷却和结晶可以得到纯净的硝酸钾。此工艺具有成本低,投资少等优点。主要存在的问题是反应以后生成的废酸的处理。该项研究是用其从钡渣中提取BaSO_4。这样一来既解决了前者的难题,又处理了钡渣并得到了一种新的产品,具有较好的经济效益和社会效益。 相似文献
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A commercial submicrometer BaTiO3 powder was analyzed using X-ray photoelectron spectroscopy. The analysis revealed the powder surfaces to be covered with a layer of physisorbed H2 O and chemisorbed –OH ions. A BaCO3 residual not detected with XPS was shown to be present in the powder using X-ray diffraction, suggesting that the carbonate takes the form of discrete particles rather than of a continuous surface layer. A relaxed surface phase detected in previous XPS analyses of bulk BaTiO3 was also shown to be present. Depth profiling revealed the powder surfaces to be Ti-rich, confirming the presence of a phase, or phases, to stoichiometrically balance the barium carbonate. 相似文献
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Hiromi Nakano Kazuyori Urabe Hiroyuki Ikawa 《Journal of the American Ceramic Society》2003,86(4):741-43
A BaCO3 phase is found on the surfaces of hydrothermally synthesized BaTiO3 particles; it occurs as aggregates or small protuberances. A small proportion of the phase decomposes to BaO crystallites when heated by a convergent electron beam in a transmission electron microscope. The BaO and BaCO3 crystallites disappear when they are irradiated successively by the convergent electron beam. The BaO crystallites and the BaCO3 phase sublimate and/or react with BaTiO3 crystals whose surface layers are deficient in Ba2+ ions. 相似文献
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简述了硝酸钡的应用前景及国内外生产技术现状,论述了以硫化钡和硝酸铵为原料复分解法制硝酸钡的工艺流程及反应机理。试验结果表明,新工艺可获得符合国家标准GB-1613-79一级品硝酸钡产品,产品收率在98%以上,有较好的经济效益。 相似文献
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Ungyu Paik Sangkyu Lee Vincent A. Hackley 《Journal of the American Ceramic Society》2003,86(10):1662-1668
Hysteresis in the electrokinetic behavior of colloidal hydrothermal BaTiO3 occurs during sequential acid and base titrations. Ba dissolution during acid titration results in an oxide-rich surface. When the acid-treated BaTiO3 is titrated back to pH 10, dissolved Ba is specifically adsorbed and/or precipitated onto the particle surface. The combined effects of dissolution and subsequent adsorption–precipitation results in titration hysteresis. Most of the labile Ba can be removed by multiple acid treatments, which result in a TiO2 -like surface layer composition. Barium dissolution increases with decreasing pH but levels off below pH 4 due to diffusion through the surface oxide layer as predicted previously. A phenomenological model is offered to explain the electrokinetic behavior as a function of pH. It is suggested that inherent BaCO3 contamination is not the primary source of dissolved Ba from hydrothermal BaTiO3 in acidic solution. 相似文献
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The effects of excess free barium ions in aqueous barium titanate slip on the resulting BaTiO3 tape properties were investigated in terms of the slip behavior, green/sintered tape density and morphology, and dielectric properties. The excess free barium ions expressed by means of the Ba/Ti ratio adversely affected most tape properties. Increase in the slip viscosity, green porosity, and agglomeration along with a decrease in mechanical properties and green/sintered density were found with the increase in the Ba/Ti ratio. However, dielectric permittivity was increased with increase in the Ba/Ti ratio. An effort was made to correlate these phenomena with Ba2+ leaching in water for realistic multilayer ceramic capacitor applications. 相似文献
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介绍了巯基乙酸合成的新方法,对传统的水解法进行了改进。采用氢氧化钠和氯化钡两级水解,试验表明,水解温度85℃,钠盐水解时间30min,钡盐水解时间5min,钠钡盐摩尔比为1-1.5:1,转化率85%左右,水解时间大大缩短。 相似文献