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421.
用生产草酸产生的废草酸泥渣,通过采用以加热转化,硝酸溶解提取,重铬酸钠合成为主要步骤的制备新工艺,用草酸泥渣制得了铬酸铅.对用草酸泥渣制备铬酸铅的工艺原理进行了分析.本文着重研究了原料粒度、反应温度、反应时间和硝酸用量等因素对产品产量和铬酸铅含量的影响. 相似文献
422.
一种新型环境矿物材料在废水治理中的应用研究 --磷矿石去除水溶液中铅离子和镉离子的对比研究 总被引:1,自引:0,他引:1
采用天然磷矿石及其改性产品对水溶液中铅离子和镉离子的去除进行了对比研究.天然磷矿石能够有效地去除水溶性铅离子和镉离子,在强酸介质条件下对铅离子的去除效果最好,而对于镉离子,在弱酸或中性的介质中去除效果达到最佳;改性后的磷矿石能够在广泛的pH值范围内对铅离子具有良好的去除作用,显著地提高了对铅离子的去除能力,但是对镉离子的去除没有明显的改善;最后指出,磷矿石对铅离子和镉离子去除差异的根本原因是其对铅离子和镉离子去除机理的不同. 相似文献
423.
含铅废水处理技术及其展望 总被引:2,自引:0,他引:2
详细介绍了含铅废水的 5种主要处理方法 ,包括化学沉淀法、离子交换法、液膜法、生物吸附法及电解法 ,对各种方法的优缺点及发展现状进行了介绍 ,另外 ,还对含铅废水处理的前景进行了展望 ,提出了电解法与离子交换法或与生物吸附法相结合是处理含铅废水的发展方向。 相似文献
424.
PbO2电极的改性及其在难降解有机废水电化学处理中的应用 总被引:2,自引:0,他引:2
电化学方法处理难降解有机废水是一种很有前途的技术,其应用的关键是开发出高效、稳定、低成本的电极材料.PbO2电极在工业领域具有广泛的应用基础,具有较高的析氧电势和电催化活性,被认为在电化学处理难降解有机废水方面有重要的应用前景.本文对PbO2电极制备方法与改性以及在难降解有机废水电化学处理中应用的研究成果和最新进展进行了综述,并对该研究领域今后的发展趋势进行了分析. 相似文献
425.
研究了高岭石吸附水相中铅离子的动力学行为.结果表明:高岭石对水溶液中铅离子的吸附是一个复杂的非均相固液反应,从动力学角度来看,大致可以分为2个阶段:初期阶段反应速度快,动力学过程复杂,有待于深入研究;后期阶段反应速度较慢,并符合一级反应动力学方程.吸附速率常数k与温度T之间的关系符合阿累尼乌斯公式,吸附的活化能为Ea=26.44 J/mol,吸附的频率因子A=603s-1.ln(k/T)与1/T之间的关系符合Eyring公式,其活化焓△H=23.94J/mol,活化熵△S=-200J/K·mol.同时,k与铅离子初始浓度呈负相关性,与高岭石用量、介质pH值呈正相关性. 相似文献
426.
Herpin U Siewers U Markert B Rosolen V Breulmann G Bernoux M 《Environmental science and pollution research international》2004,11(1):57-66
This paper shows the geographic distribution in Germany of iron (Fe), nickel (Ni) and lead (Pb) analyzed in mosses in 1995/96 and compares it with the results of the 1990/91 pilot study within a European moss-monitoring programme. Other elements (As, Cd, Cr, Cu, Ti, V, Zn) are compared on basis of the overall element medians for Germany of the 1990/91 and 1995/96 survey. Samples of Pleurozium schreberi, Scleropodium purum, Hypnum cupressiforme and Hylocomium splendens were taken at a total of 1026 sites. In the 1995/96 monitoring campaign, 95% of the original sites of the 1990/91 study were resampled. The results from 1995/96 display local elevated values and many cases of areas affected by known sources of heavy-metal emissions. The industrialized and urban regions of Germany are shown up clearly by the 1995/96 moss-monitoring results: the Ruhr area, parts of Saarland and Baden-Württemberg, as well as areas in eastern Germany. Relatively low values for many elements were found in large areas of Lower Saxony and Bavaria. A comparison of the results of the 1990/91 and 1995/96 moss-monitoring programmes shows a fall in the concentration of the presented elements (except cadmium, copper and zinc) over the relevant period. Especially in the former GDR, chromium (Cr), iron (Fe), titanium (Ti) and vanadium (V) decreased significantly. This is, firstly, a reflection of the closure of and/or technological improvements to large power plants; secondly it is due to the fact that lignite has given way to other fuels. Vanadium (V) and nickel (Ni), typical constituents of crude oil, also show a decrease in the western part and thus document changes in the type of fuel consumed. The significant fall in lead concentration in 1995/96 as compared to 1990/91 in what used to be East and West Germany probably results from the increasing use of lead-free petrol. A comparison of the median values for 1990/91 and 1995/96 in mosses to the rate of emission of heavy metals in Germany for 1990 and 1995 shows similar trends in the case of elements such as arsenic (As), chromium (Cr), nickel (Ni), and lead (Pb). The comparison of the medians of the elements analyzed for 19 European countries indicates for most of the elements a general tendency to lower values in 1995, except for Lithuania, Netherlands, Portugal, Italy and United Kingdom. 相似文献
427.
针对水中微量铅离子和氯乙酸的脱除,考察了成型膨润土及成型钛柱撑膨润土的吸附性能,得出对铅离子的吸附,成型膨润土、成型钛柱撑膨润土与粉末状活性炭性能相当,而对氯乙酸的吸附前两者要比粉末状活性炭低好多。确定了成型膨润土吸附氯乙酸后可用沸水煮沸30 min的方法再生,成型钛柱撑膨润土吸附氯乙酸后,可用500℃焙烧3 h的方法再生,再生的膨润土循环使用3次后性能降低明显。此外,还测得了成型的膨润土及成型的钛柱撑膨润土吸附铅离子和氯乙酸的等温线,计算出其对铅的最大吸附量分别为24.33 mg/g和15.47 mg/g。 相似文献
428.
429.
ABSTRACTNatural polymer Moringa oleifera seed as coagulant and bentonite clay as adsorbent were used for preparing novel composite coagulant. Results obtained from FTIR, SEM, TEM and P-XRD show that the bentonite clay and M. oleifera seed biopolymers physico-chemically interact with each other during the preparation of clay-polymer composite. The FTIR results show that the major functional groups present in bentonite clay and M. oleifera seed are integrated at nano levels in the novel composite to remove heavy metals from aqueous systems. The coagulo-adsorption using clay-polymer composite may be used for the adsorption of heavy metals ions from the aqueous systems. It becomes possible due to the structural characteristics of the clay crystallites together with the functional attraction of the biopolymer and it results in the formation of clay-polymer metal complexes. The clay-polymer nano-composite of M. oleifera seed and bentonite clay showed considerable cadmium, chromium and lead removal property. 相似文献
430.
Susanna T.Y. Tong 《Environmental geochemistry and health》1998,20(3):123-133
Despite some progress in reducing the average lead level in the USA, the streets of Cincinnati, Ohio, are still contaminated by heavy metals. High levels of heavy metals will have significant unequivocal ecological impacts and pose a potential health hazard. This study evaluates the level of heavy- metal contamination in household dust and examines its relationships with the external environment. Samples of outdoor and indoor dust were collected from middle-income residential homes in the Greater Cincinnati Metropolitan District and the metal content was analysed by inductively coupled plasma atomic emission spectrophotometry. Results showed that the mean levels of lead in outdoor and indoor dusts are 650 g g-1 and 377 g g-1 and the copper levels are 253 g g-1 and 510 g g-1, respectively. The median levels are 156 g g-1 and 139 g g-1 for outdoor and indoor lead dusts and 35 g g-1 and 124 g g-1 for outdoor and indoor copper dusts. The degree of contamination may be ascribable to the age of the dwelling unit and the neighbourhood, the time when the unit was last painted, the presence of pets and the type of space heating. In addition, car exhausts seems to be a possible source of contamination. 相似文献