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试验研究了镉和铅两种重金属在蒙脱土和高岭土上的吸附,以及外加腐植酸的3种组分(富里酸、棕色胡敏酸和灰色胡敏酸)的影响。镉、铅在粘土上的吸附随着介质PH的升高而增加。在pH值4~8范围内的任意pH点,镉在高岭土上的吸附量因富里酸而降低,因两种胡敏酸而升高;当PH值高于6时,吸附量急剧增加。外加富里酸使得铅在粘土上的吸附在pH〉6时意外出现随着介质pH而降低的趋势。 相似文献
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腐植酸对土壤重金属镉的淋溶效果及吸附解吸机制研究 总被引:5,自引:0,他引:5
为了揭示腐植酸对土壤重金属镉(Cd)的淋溶效果及吸附解吸机制,本研究采用土柱模拟淋溶方法和吸附解吸试验方法,开展不同腐植酸用量对土壤重金属Cd的淋溶试验,以及p H变化对土壤Cd吸附解吸效应。结果表明,不同腐植酸用量导致土壤淋溶液中Cd含量有别,淋溶液中Cd含量并不随土壤腐植酸用量的增加而减少,而是当腐植酸的用量达到一定浓度时,淋溶液中Cd含量减少趋稳。在酸性条件下,各处理腐植酸对Cd的吸附性显著;在碱性条件下,当p H=11时,各处理土壤对Cd的吸附量达到最大且基本稳定。解吸试验显示,随着p H增加,各处理的解吸量不断减小,当p H=11时,各处理土壤对Cd的解吸量最小,处理间差异不显著。 相似文献
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采用吸附-解吸热力学和动力学方法研究了腐植酸各组分对土壤吸持汞的影响,发现该试验条件下,腐植酸能提高土壤对汞吸持能力,但不同组分其作用效果不同,富里酸在提高土壤吸持汞方面作用较短暂且不稳定,胡敏酸在增强土壤吸附固定汞的数量和速率上却好于富里酸。 相似文献
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本文在室温条件下采用批处理的方式,研究了MX-80膨润土对水溶液中U(VI)的吸附行为,考察了接触时间、p H值、离子强度、固体含量、腐植酸(H A)、富里酸(F A)和温度等因素的影响。实验结果表明,M X-80膨润土对U(V I)的吸附能力受p H和离子强度的影响较大。U(V I)从水溶液被吸附到M X-80膨润土上的速度相当快,并且其动力学吸附数据符合准二维速率方程。腐植酸可以显著增强MX-80膨润土对的U(VI)吸附,而富里酸对U(VI)的吸附没有显著影响。从不同温度下计算得到的M X-80膨润土对U(V I)的吸附热力学参数(△H0,△S0和△G0)可以看出, MX-80膨润土对U(VI)的吸附反应是自发的吸热反应。 相似文献
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Hengfeng Miao Wenyi Tao 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2008,83(3):336-344
BACKGROUND: Humic acids (HAs) are heterogeneous macromolecules widely dispersed in natural waters, which display significant resistance to biodegradation. Removal of HA by ozone and its related reaction mechanisms are investigated. RESULTS: Ozonation of HA showed a significant reduction of UV254, Color436 and had the capability of mineralizing the TOC to CO2 and improving the biodegradability. Fourier trandform infrared (FT‐IR) spectra, elemental composition analysis and high performance size exclusion chromatography (HPSEC) revealed that ozonation could not only change the structure characteristics but modify the molecular size distribution of HA. Volatile compounds detected by gas chromatography‐mass spectroscopy (GC‐MS) showed that ozonation brought out 43 different organics, which were identified as mainly: aldehydes, ketones, aromatics, carboxylic acids and alcohols. CONCLUSION: Ozonation of HA could be elucidated by the followed mechanism: ozonation with its direct and indirect pathway hydroxylated the HA in water, and polyhydroxy HA was further oxidized to bond rupture leading to the change of molecular structure and size distribution of HA, trimming out a series of small molecular volatile compounds. The volatile compounds with electron denoting group could be further oxidized to acids and esters, and even totally mineralized to CO2. Copyright © 2007 Society of Chemical Industry 相似文献
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L.C. Cides da Silva L.B.O. dos Santos G. Abate I.C. Cosentino M.C.A. Fantini J.C. Masini J.R. Matos 《Microporous and mesoporous materials》2008,110(2-3):250-259
Ordered mesoporous silica with cubic structure, type FDU-1, was synthesized under strong acid media using B-50-6600 poly(ethylene oxide)–poly(butilene oxide)–poly(ethylene oxide) triblock copolymer (EO39BO47EO39) and tetraethyl orthosilicate (TEOS). Humic acid (HA) was modified to the synthesis process at a concentration of 1.5 mmol per gram of SiO2. Thermogravimetry, small angle X-ray diffraction, nitrogen adsorption and high resolution transmission electron microscopy were used to characterize the samples. The pristine FDU-1 and FDU-1 with incorporated 1.5 mmol of HA were tested for adsorption of Pb2+, Cu2+ and Cd2+ in aqueous solution. Incorporation of humic acid into the FDU-1 silica afforded an adsorbent with strong affinity for Cd2+, Cu2+ and Pb2+ from single ion solutions. Adsorption of Cu2+ was significantly enhanced after incorporation of humic acid, a fact that can be explained by the formation of complexes with carboxylic and phenolic groups at low concentrations of the metal cation. The results demonstrated the potential applicability of FDU-1 with incorporated HA in the removal of low concentrations of heavy metal cations from aqueous solution, such as wastewaters, after usual precipitation of metal hydroxides in alkaline medium and proper pH conditioning in the range between 6 and 7. 相似文献
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人类对腐植酸的研究,已有二百多年的历史了,在二百多年的历史中已积累了大量的丰富知识,使腐植酸类物质在人类的生产和科研活动中的许多领域越来越发挥着不可估量的作用,特别是在工业、农业、医学、涂料、化妆、和环保等行业中的作用将越来越突出。从五十年代以来,国内外对腐植酸研究颇为活跃,已经取得了可喜的成果。然而,就腐植酸的化学实体,生成机理,生物活性功能与结构而论,仍还有许多不明之处,而且,就已获得的大量知识而论,也有混乱或相互矛盾的情况,可以说腐植酸的化学现在处在未成熟的阶段,还没有建立起一个统一的科学体系,改革开放以来,腐植酸事业得到蓬勃的发展,取得了可喜的成绩,尤其是腐植酸应用研究不断拓宽,更令人振奋的是发现腐植酸能有效地预防控制恶性肿瘤的生长和扩散,可以想象腐植酸化学的发展将对人类的农业、工业、环保和医学产生重大的影响,相对于应用研究来讲,基础研究还是相对薄弱。本文想就基础研究薄弱的原因作一分析和讨论,以引起同行们的重视和社会的关注。如有不妥之处请同仁指正批评。 相似文献
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分析当前腐植酸复肥生产中常用的酸催化氧解法和碱溶酸析法(酸法和碱法)的活化条件对风化煤腐植酸活化率的影响,探索了两种方法在复肥生产中最佳的腐植酸活化条件.研究表明,风化煤腐植酸最佳活化条件分别为:酸法采用硝酸、硫酸或二者混酸为活化剂,每克风化煤需纯酸量0.5 ~ 1.5 mL、反应时长15 ~ 30 min、反应温度80℃左右;碱法采用强碱或混碱、氨水为活化剂,每克风化煤需碱折纯量0.10~ 0.23 mL、反应时长30 ~ 60 min、反应温度50~90℃. 相似文献
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