共查询到19条相似文献,搜索用时 140 毫秒
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本研究选用了甲酸、乙酸、乳酸、草酸、苹果酸、马来酸、酒石酸、柠檬酸和琥珀酸对土壤中的难溶性铬进行活化。同时,用这9种低分子量有机酸对三氧化二铬(Cr_2O_3)和铬酸铅(PbCrO_4)进行活化模拟实验。结果表明,这9种低分子量有机酸对难溶性铬都具有一定的活化作用,其中草酸对难溶性铬的活化效果最佳,然而混合有机酸对难溶性铬的活化能力高于各种单一有机酸。相比之下,5 mmol/L的有机酸活化效果优于1 mmol/L的有机酸。各有机酸对土壤中难溶性铬活化能力较弱,活化率较低,可能是因为污染土壤中铬存在形态较为复杂。低分子量有机酸是植物根系分泌物的重要组成部分。研究有机酸对重金属铬的活化效应,对于植物土壤修复技术的发展具有重要意义。 相似文献
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C-S-H凝胶作为硅酸盐水泥最主要的水化产物,是影响水泥混凝土行业工程质量的重要因素.本文围绕29Si固体核磁共振技术(29Si NMR)在硅酸盐水泥水化产物应用展开,从水化硅酸钙晶型、C-S-H聚合机理、钙硅比、机械力活化作用、矿物掺合料对C-S-H影响等几方面阐述29Si NMR在硅酸盐水泥水化产物C-S-H凝胶中的应用,提出了利用29Si NMR分析硅酸盐水泥水化产物存在的问题,并展望了29Si NMR在水泥水化领域的发展趋势. 相似文献
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管学茂刘松辉张海波豆珍珍邱满冯春花 《硅酸盐学报》2018,(2):263-267
低钙硅酸盐矿物在一定湿度下能够与二氧化碳发生反应,反应产物能够迅速凝结、硬化形成致密的硬化体。为了更好地研究和利用低钙硅酸盐矿物的碳化硬化性能,综述了低钙硅酸盐矿物的碳化反应过程、碳化硬化机理等方面的研究进展。低钙硅酸盐矿物碳化形成的碳酸钙晶体和高度聚合的非晶态二氧化硅凝胶是硬化体强度增长的主要来源,并且低钙硅酸盐矿物组成、结构及其与胶凝性能的关系,碳化反应及硬化机理,碳化硬化体的结构和耐久性等方面需要进一步系统研究。 相似文献
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采用化学结合水、SEM、XRD对掺有活化煤矸石的硬化水泥浆体的性能和微观结构进行了研究.研究发现,煅烧后的煤矸石具有火山灰活性,掺有煤矸石的水泥浆体的结合水量低于不掺煤矸石的硅酸盐水泥,但后期增长较快;掺有煤矸石的水泥浆体结构较疏松,孔隙较多;煤矸石掺量的增加促进了水泥熟料矿物的水化,而且掺量越大,越有利于熟料矿物的水化. 相似文献
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硅酸盐矿物制白炭黑的研究进展 总被引:3,自引:0,他引:3
综述了中国硅酸盐矿物制白炭黑的研究进展.白炭黑常用的制备方法包括气相法、沉淀法和硅酸盐矿物分解法.气相法对设备要求较高,技术控制复杂;沉淀法能耗高,对环境要求较高;硅酸盐矿物分解法是一种以硅酸盐矿为原料制备白炭黑的有效方法.该方法在技术上是可行的,经济效益也是好的,为中国硅酸盐矿的深加工和综合利用提供了一条新途径.最后提出,改进硅酸盐矿制备白炭黑技术是今后的一个重要研究方向. 相似文献
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黏土矿物(clay minerals)是组成黏土岩和土壤的主要矿物,它是一种含镁、铝为主的水合硅酸盐矿物.研究发现黏土矿物液晶与有机液晶材料相比,具有光、电、磁性能强,热稳定性好,价格低廉等优点.简要介绍了黏土矿物液晶材料的形成机理,概述了片层状黏土液晶材料、纤维型黏土液晶材料、类黏土矿物液晶材料的制备方法和研究现状,同时介绍了不同条件(浓度、离子强度、外电场作用、分散介质、重力作用)对黏土及类黏土分散体系相变的影响,并对黏土矿物液晶材料的应用发展前景进行了概述. 相似文献
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Anton Zubrik Slavomír Hredzák Michal Lovás Klaus Dieter Becker Vladimír Šepelák 《Fuel》2010,89(8):2126-2132
A low-rank Slovak sub-bituminous coal from the Handlová deposit was physically treated by washing in a water-only cyclone with the goal to find the separation effect for inorganic (mainly Fe-bearing minerals) and organic substances (humic acids, diterpanes). A high-quality coal product with the ash content in the dry matter of 9.02% and carbon content of Cd = 68.12% at a mass yield of 29.51% was obtained using the water-only cyclone processing. At first, the physically treated coal samples were detailed characterized by XRD, 57Fe Mössbauer spectroscopy, FT-IR and HR-TEM. In addition to non-crystalline organic coal components, inorganic compounds belonging to silicate minerals (kaolinite, muscovite and quartz) as well as to Fe-bearing sulphide minerals (pyrite) were identified in the sub-bituminous coal by XRD. 57Fe Mössbauer spectroscopy detected the presence of iron carbonate (siderite), iron-containing clay mineral and two sulphur-containing minerals (pyrite, jarosite) in the untreated coal. On the other hand, only one Fe-bearing mineral, (pyrite) was found in the washed coal. Effect of the physical separation is also demonstrated in FT-IR spectra, where the peak at 1040 cm−1 representing the silicate component in the untreated sample is not detectable in the washed coal sample. Presence of extractive organic substances, i.e. humic acids and tetracyclic diterpane (16α(H)-phyllocladane), in the hydrocyclone products is also evidenced. It was confirmed that the isolated diterpenoic compound is attendant in the washed product with the lowest ash content and it is assimilated with the organic part of coal. Surprisingly, humic acids were found in the highest concentration in the slurry that has the highest content of ash (63.14%). 相似文献
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Silicate solubilisng bacteria (SSB) are distributed in soil, water, aquatic sediments and in silicate minerals but their population is smaller than the total bacteria indicating their uniqueness. Pond sediment showed a higher SSB with 40×104 g?1 while sugarcane field soil recorded 31×104 g?1 dry weight. SSB population in silicate minerals varied with the highest in phyto-sil followed by muscovite but very low in quartz and illite. The silicate solubilisation potential of the six isolates tested on eight minerals varied with the isolates and mineral. Magnesium trisilicate was more easily solubilised than, quartz, or muscovite. Four of the elite isolates were characterized by 16S r RNA sequencing and were found to be Bacillus flexus, B. mucilaginosus, B. megaterium and Pseudomonas fluorescens. The GC/MS analysis of organic acids produced in the medium containing feldspar and quartz by Bacillus flexus and B. muicilaginosus showed variation with the minerals. The release of silica in solution serves as a nutrient for life forms. 相似文献
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研究利用煤矸石中的硅元素制取硅酸钠,先将煤矸石粉在750 ℃下煅烧2 h,除去有机质并破坏了煤矸石中的高岭石等矿物的晶型结构,再将煅烧过的煤矸石粉在95 ℃、液固比(mL/g)为8∶1、质量分数为40%的硫酸中酸浸5 h,煤矸石煅烧粉中的铁和铝等金属杂质离子的总去除率为86.93%;还研究了碱融活化条件对硅元素溶出率的影响,获得了适宜的碱融活化条件:m(酸浸粉)∶m(碳酸钠)=1∶1.5、碱融温度为800 ℃、碱融时间为2 h。在此条件下,硅元素溶出率大于75%,最终获得了硅酸钠溶液。 相似文献
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传统的水热合成分子筛的工艺在源头上并不环保,因为其所使用的硅、铝试剂是由天然硅铝矿物通过复杂的反应与分离过程制备而来的。以天然矿物直接作为分子筛合成的硅、铝源而不经化学试剂中间体被视为分子筛绿色合成的发展方向之一,其关键在于天然矿物的介尺度活化,即通过物理、化学或物理与化学作用相结合的方式破坏天然硅铝矿物的高聚合度结构,将其解聚为具有不同介尺度结构的分子筛合成原料。为此,本文综述了天然矿物介尺度活化方法的研究进展,从能耗、活化机理和所得活化产物的介尺度结构的角度,对比分析了机械活化、热活化、碱熔活化、亚熔盐活化和拟固相活化的优缺点,总结了以不同介尺度活化产物为原料合成高性能分子筛的研究现状,为以天然硅铝矿物为原料高性能分子筛的合成提供思路。 相似文献
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S Kalaitzidis 《Fuel》2003,82(7):859-861
Two leonardite benches occur in the lignite basins of Achlada (NW Greece) and Zeli (Central Greece). In this study, we present some initial results concerning chemical composition (C, H, N and S), kind of inorganic matter, contents of free-humic acids, and the petrological features. Both samples are classified as lignites and display similar values of carbon contents. The Zeli-sample displays higher hydrogen and lower sulphur contents than the sample from Achlada. Nitrogen in both cases remains below the detection limit. Increased silicate inorganic influx, consisting mainly of clay minerals, affected both benches. The organic matter is low to moderately gelified and intensely fragmented, with attrinite being the predominant maceral. Inertinites are almost absent, whereas liptinites occur with low values. Values of free-humic acids are similar, ranging up to 50 wt%. 相似文献