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《吉林大学学报(地球科学版)》2015,(Z1)
蛭石是一种在工业、农业等众多领域广泛应用的非金属矿。蛭石在受热时,层间水分子受热汽化产生压力使结构迅速撑开,体积瞬间急剧膨胀,体积膨胀达到几倍甚至十几倍,从而获得膨胀蛭石。膨胀蛭石导热率降低、密度减小、体积增大,具有隔音、保温、防震、耐火的性质,可广泛应用于农业、电力、建筑、冶金、轻工、化工、冷藏、机械、船舶制造、运输包装及海洋捕捞等领域。热膨胀是目前制备膨胀蛭石最常用的方法,对蛭石热膨胀机理普遍认可的解释是:在急剧加热蛭石时,四周边缘部位先受热,边缘水首先散逸出去,四周边缘质点间距和晶层间距缩小而形成"封闭"状态,蛭石结构中间被加热后的水蒸气无法及时散逸出去而形成强大的层间蒸汽压力,撑开蛭石晶层,蛭石体积膨胀。由于微波和水分子之间存在着强烈的相互作用,因此微波作用可加热含水物质,且加热速度快。近年来采用微波加热方法来制备膨胀蛭石受到学者的关注,具有良好的应用前景,但研究相对薄弱。对新疆尉犁蛭石进行了微波膨胀实验,并与热膨胀进行对比。研究了影响蛭石微波膨胀的因素,对比讨论了两种方法的膨胀机理。研究结果表明:蛭石在微波条件下有较好的膨胀效果,微波频率和蛭石粒径是影响蛭石微波膨胀效果的关键因素。粒径大的蛭石膨胀效果优于小粒径蛭石。蛭石膨胀倍随着微波功率的增加和加热时间的延长而增大,且当加热时间为60 s时达到最大值;在不同微波功率下加热60 s时,蛭石和金属阳离子饱和蛭石的膨胀倍均随着功率的增加而增大,但金属阳离子饱和蛭石的膨胀倍均低于蛭石原样。蛭石层间离子对层间水的束缚力差异是导致不同金属阳离子饱和蛭石膨胀倍不同的主要因素。Na+对层间水的束缚力较弱,Na+饱和蛭石在低功率微波条件下膨胀倍明显增大,而Mg型和Ca型蛭石的层间离子分别结合有两层水分子且对水的束缚力很强,在高功率下才能有大的膨胀倍。 相似文献
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HDTMA改性蛭石的结构特征研究 总被引：20，自引：0，他引：20
用十六烷基三甲基溴化铵 (HDTMA·Br)对蛭石矿物进行改性 ,制成有机蛭石。应用X射线衍射分析、差热分析等对有机蛭石结构进行研究。结果显示 ,HDTMA能较容易地进入蛭石矿物的层间域 ,以倾斜立式在层间排列 ,倾角约为 5 7°。蛭石与HDTMA之间的反应 ,在HDTMA加入量较少时以离子交换为主 ;在HDTMA加入量较多时 ,分子吸附也变得重要。当HDTMA加入量小于蛭石的阳离子交换容量时 ,HDTMA将尽量以紧密排列方式进入部分蛭石层间 ,进入蛭石层间的HDTMA具有较好的稳定性 ,不易解吸。 相似文献
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采用十六烷基三甲基溴化铵(HDTMAB)对蛭石精矿进行了有机改性,利用X射线衍射法(XRD)、红外光谱(IR)、差示扫描量热法(DSC)和热失重分析(TG)对蛭石精矿和有机改性蛭石进行了表征。实验结果表明,当反应液中蛭石与水的质量比为1∶10、反应温度在60~70℃时,HDTMAB的阳离子HDTMA进入绝大部分蛭石晶粒的晶层,将蛭石的晶层间距撑大,蛭石的(001)晶面间距d001从1.45986 nm增大到3.70134 nm。HDTMA进入了单晶颗粒之间,将蛭石颗粒分散成单晶颗粒。 相似文献
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研究了工业膨胀蛭石对模拟养殖废水中磷酸盐的吸附性能,考察了pH值、吸附时间、固液比对吸附效果的影响,并通过原子吸收光谱法测定了蛭石在对磷酸盐吸附过程中主要金属元素的浸出含量,探究膨胀蛭石吸附水中磷的吸附平衡,对吸附机理进行了探讨。结果表明,工业膨胀蛭石对磷酸盐的吸附量可达2.76 mg/g,pH值在3~9的范围内有较高的吸附量;K、Ca、Mg这3种元素的浸出含量随着溶液中磷酸盐浓度升高而增加,Fe、Al元素则相应减少;工业膨胀蛭石对磷的吸附机理主要是先通过离子交换作用交换出层间阳离子,然后与H2PO-4、HPO2-4反应形成沉淀被吸附;吸附等温曲线均符合Freundlich公式与Langmuir公式,相关系数分别为0.978 1和0.985 1。 相似文献
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新疆尉犁蛭石矿工业蛭石化学法膨胀的实验研究 总被引：1，自引：0，他引：1
在对采自新疆尉犁蛭石矿的工业蛭石样品进行化学成分和XRD分析研究基础上,选用工业级双氧水作为化学膨胀处理剂进行化学膨胀处理试验研究,结果表明:工业蛭石的化学膨胀特点和影响工业蛭石膨胀效果的主要因素是其晶层层间域中的过氧化氢分子在分解过程中所产生的氧气压力。对蛭石样品用不同浓度的双氧水作用相同的时间或用相同浓度的双氧水作用不同时间后发现:用浓度为25%的双氧水处理工业蛭石样品可以达到大于4倍的体积膨胀,膨胀后的工业蛭石样品的结构特征无明显变化,并能保持工业蛭石膨胀产物的韧性。 相似文献
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膨胀蛭石的性质及其应用前景 总被引：2，自引：0，他引：2
蛭石是一种复杂的铁、镁含水硅铝酸盐类矿物,呈薄片状结构,由两层层状的硅氧骨架,通过氢氧镁石层或氢氧铝石层结合而形成双层硅氧四面体,"双层"之间有水分子层.高温加热时"双层"间的水分变为蒸汽产生压力,使"双层"分离、膨胀[1].蛭石在150℃以下时,水蒸气由层间自由排出,但由于其压力不足,蛭石难以膨胀.温度高于150℃,特别是在850～1000 ℃时,因硅酸盐层间基距减小,水蒸气排出受限,层间水蒸气压力增高,从而导致蛭石剧烈膨胀. 相似文献
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利用天然矿物蛭石的阳离子交换特点，通过离子交换法将Cu^2 植入到蛭石中，制得铜含量高达5.5%（相当于蛭石阳离子交换容量的80%）、具良好抗菌性能的铜型蛭石。经XRD、TEM、AAS分析，结合晶胞参数及晶体化学式的计算，铜型蛭石的XRD特征值更接近于标准的Mg^-蛭石，这与Cu^2 与Mg^2 半径相近，电价相等的特点相符合，Cu^2 部分以水合物的形式存在于蛭石层间，部分进入八面体中以六次配位的形式存在。铜型蛭石的a0和b0值无明显变化而c0值略有减小，这对于Cu^2 的稳定是有利的，上述各特点有利于铜型蛭石抗菌剂的稳定性和持久性。 相似文献
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蛭石的有机改性研究进展 总被引：1，自引：0，他引：1
本文综述了国内近十年关于粘土矿物和蛭石表面性质及表面改性的资料,分析了粘土矿物和蛭石表面改性的原理、方法和影响因素,研究了烷基季铵盐阳离子在粘土矿物和蛭石层间的排布模式,总结了有机粘土和有机蛭石吸附有机物的吸附理论和机理,为有机粘土和有机蛭石在废水处理和聚合物填充增强改性中的应用提供理论依据。 相似文献
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有机插层蛭石对有机污染物苯酚和氯苯的吸附特性研究 总被引：21，自引：0，他引：21
分别应用溴化十六烷基三甲基溴化铵(HDTMA)和溴化十六烷基吡啶(HDPY)改性插层级石对苯酚和氮苯两种非离于型环境污染物进行吸附性能研究。结果表明，蛭石原矿对苯酚和氮苯的吸附能力很小，经表面活性剂处理后其吸附能力大大增强。有机插层级石对苯酚的吸附具有表面吸附特征，其吸附等沮线为Freundish型；而对氮苯的吸附实际上是氮苯在水相与有机级石中有机相之间的一种分配过程，其吸附等沮线为直线型。苯酚和氮苯的竞争吸附并末减弱有机蛭石对氯苯的吸附能力，反而由于它们同时存在产生协同效应，使有机插层蛭石对氯苯总的吸附能力有所提高。 相似文献
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柱撑蛭石吸附去除废水中重金属离子的实验研究 总被引：2，自引：0，他引：2
分别利用有机柱化剂十二烷基磺酸钠(SDS)和无机柱化剂聚羟基铝(HA)对蛭石进行柱撑制得十二烷基磺酸钠柱撑蛭石(SDS-V erm icu lite)和聚羟基铝柱撑蛭石(HA-V erm icu lite),并通过XRD、红外光谱、ZETA电位等表征手段对柱撑蛭石进行表征,同时针对柱撑蛭石对Cu2 ,Cd2 ,C r3 3种重金属离子的吸附进行研究,结果表明:吸附去除率受反应时间、重金属离子的初始浓度、pH值等因素的影响,经柱撑后的蛭石对重金属离子吸附的吸附性能比蛭石原矿要强。柱撑蛭石吸附3种重金属离子的动力学吸附过程可用E lov icb方程和双常数方程进行较好的拟合。 相似文献
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The increasing popularity of compound-specific hydrogen isotope (D/H) analyses for investigating sedimentary organic matter raises numerous questions about the exchange of carbon-bound hydrogen over geologic timescales. Important questions include the rates of isotopic exchange, methods for diagnosing exchange in ancient samples, and the isotopic consequences of that exchange. This article provides a review of relevant literature data along with new data from several pilot studies to investigate such issues. Published experimental estimates of exchange rates between organic hydrogen and water indicate that at warm temperatures (50-100°C) exchange likely occurs on timescales of 104 to 108 yr. Incubation experiments using organic compounds and D-enriched water, combined with compound-specific D/H analyses, provide a new and highly sensitive method for measuring exchange at low temperatures. Comparison of δD values for isoprenoid and n-alkyl carbon skeletons in sedimentary organic matter provides no evidence for exchange in young (<1 Ma), cool sediments, but strong evidence for exchange in ancient (>350 Ma) rocks. Specific rates of exchange are probably influenced by the nature and abundance of organic matter, pore-water chemistry, the presence of catalytic mineral surfaces, and perhaps even enzymatic activity.Estimates of equilibrium fractionation factors between organic H and water indicate that typical lipids will be depleted in D relative to water by ∼75 to 140‰ at equilibrium (30°C). Thus large differences in δD between organic molecules and water cannot be unambiguously interpreted as evidence against hydrogen exchange. A better approach may be to use changes in stereochemistry as a proxy for hydrogen exchange. For example, estimated rates of H exchange in pristane are similar to predicted rates for stereochemical inversion in steranes and hopanes. The isotopic consequences of this exchange remain in question. Incubations of cholestene with D2O indicate that the number of D atoms incorporated during structural rearrangements can be far less than the number of C-H bonds that are broken. Sample calculations indicate that, for steranes in immature sediments, the D/H ratio imparted by biosynthesis may be largely preserved in spite of significant structural changes. 相似文献
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Local coordination of Zn in hydroxy-interlayered minerals and implications for Zn retention in soils
The objective of this study was to determine the local coordination of Zn in hydroxy-interlayered smectite (HIS) as a function of Zn loading and synthesis conditions and to assess the importance of hydroxy-interlayered minerals (HIM) for Zn retention in contaminated soils. Published and newly collected extended X-ray absorption fine structure (EXAFS) spectra of HIS reacted with Zn at molar Zn/hydroxy-Al ratios from 0.013 to 0.087 (corresponding to final Zn contents of 1615-8600 mg/kg Zn) were evaluated by shell fitting. In Zn-HIS, Zn was octahedrally coordinated to oxygen at 2.06-2.08 Å and surrounded by Al atoms at 3.03-3.06 Å in the second-shell. With increasing molar Zn/hydroxy-Al ratio, the coordination number of second-shell Al decreased from 6.6 to 2.1. These results were interpreted as a progressive shift from Zn incorporation in the vacancies of gibbsitic Al-polymers to Zn adsorption to incomplete Al-polymers and finally uptake by cation exchange in the polymer-free interlayer space of HIS with increasing Zn loadings. In a second part, we determined the speciation of Zn in eight contaminated soils (251-1039 mg/kg Zn) with acidic to neutral pH (pH 4.1-6.9) using EXAFS spectroscopy. All soils contained hydroxy-Al interlayered vermiculite (HIV). The analysis of EXAFS spectra by linear combination fitting (LCF) showed that a substantial fraction of total Zn (29-84%) was contained in HIM with high Zn loading. The remaining Zn was adsorbed to organic and inorganic soil components and incorporated into phyllosilicates. In sequential extractions of Zn-HIS spiked into quartz powder and the Zn contaminated soils, Zn was mainly released in the two most resistant fractions, in qualitative agreement with the findings from LCF. Our results suggest that formation of Zn-HIM may strongly retain Zn in pristine and moderately contaminated acidic to neutral soils. Due to their limited sorption capacity, however, HIM do not allow for the accumulation of high levels of Zn in response to continued Zn input into soils. 相似文献
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J. Sjöström 《Environmental Geology》1993,21(4):219-226
The groundwater chemistry of 14 shallow wells and 10 springs in Halland, southwest Sweden, and precipitation have been studied in trilinear diagrams. Ionic strength and saturation index (SI) for selected minerals have been calculated. Five springwaters have similar chemical composition to that of the precipitation, which indicates surficial and rapidly recharged water. The SI of the groundwaters is out of equilibrium (undersaturated) with respect to primary silicates such as mafic minerals, feldspar, K-mica and chlorite, but in equilibrium with solid SiO2 (quartz, cristobalite, or chalcedony). The SI shows oversaturation conditions for kaolinite, hydroxy-Al interlayered vermiculite, Na,K,Mg-beidellite, Mg-montmorillonite, and AB-montmorillonite. Concentrations of soluble Al and Si can be governed by Mg,Fe-beidellite, BF-montmorillonite, or Ca-montmorillonite at four springs, and by halloysite at two wells on the coastal plain. For these groundwaters, clay minerals may act as H+ buffers and thus have an influence on pH and toxic Al, i.e., parameters affecting the drinking water quality and environment. The study shows that the soil catena are intensily weathered at the investigated sites. It is further concluded that neither cation exchange nor primary silicate weathering will keep up with buffering the acidic loads into the soils. A general prediction of groundwater quality is presented. 相似文献