Topic
Vermiculite
About: Vermiculite is a research topic. Over the lifetime, 2320 publications have been published within this topic receiving 37142 citations.
Papers published on a yearly basis
Papers
More filters
TL;DR: In this paper, the authors compared the performance of different fitting models with different combinations of Gaussian components for the Fe sites and found that the models with chi(2) near 1.0+/-0.1237 and with the least number of free parameters were adopted as working models.
Abstract: Biotite, muscovite and vermiculite were treated in HCl and H2SO4 solutions at pH ranging between 7 and 1. The solid residue was studied using Mossbauer spectroscopy at room temperature. The spectra of the untreated samples, D0Bio, D0Mus and DOVer were fitted assuming quadrupole splitting distribution, QSD. Different fitting models with different combinations of Gaussian components for the Fe sites were tested and the models with chi(2) near 1.0+/-0.1237 and with the least number of free parameters were adopted as working models. The models were then used to fit the experimental products of each group. If a model fails to describe a spectrum of a sample in the group then this is taken to signal a significant crystal chemical change induced by weathering. All three minerals are oxidized during weathering and the correlation between oxidation ratio and pH is modeled using a Weibull function. The rate of oxidation in biotite is higher than that in muscovite and vermiculite, The average CS and QS of the Fe sites in a group remain more or less constant during the experiment. However, the position of the peak QS of Fe-[6](2+) in biotite is shifted to low energies with decreasing pH, a measure of the decreasing covalence character of the Fe/Mg-O bonds. In muscovite the major feature observed is the enhancement of the bi-modal distribution of the QSD of Fe-[6](2+) with decreasing pH. (Less)
20 citations
20 citations
Patent•
17 Jan 1989TL;DR: In this article, chemically prepared mica and vermiculite materials are described along with the method for preparing them, and they have dimethylacetamide-lithium chelation complexes at interlayer cationic sites.
Abstract: Chemically prepared mica and vermiculite materials are described along with the method for preparing them. The mica and vermiculite has dimethylacetamide-lithium chelation complexes at interlayer cationic sites. These materials can be made into suspensions and flocculated.
20 citations
TL;DR: In this paper, the authors used a typical vermiculite to obtain organic complexes of two kinds, one due to a cation exchange reaction and the other due to the interlamellar adsorption of complete molecules.
Abstract: MONTMORILLONITE is known to be capable of forming organic complexes of two kinds, one due to a cation-exchange reaction1 and the other to the interlamellar adsorption of complete molecules2,3. Halloysite has also been reported as giving complexes of the latter type2, and recently also vermiculite4,5. Using a typical vermiculite, complexes of both types have been obtained in this laboratory, and are being studied by means of X-ray diffraction.
20 citations
TL;DR: In this paper, the average basicity (OH/Al = B) of the Al adsorbed by smectite and vermiculite was always above the average Basicity of the added Al.
Abstract: Smectite (from South Dakota, Wyoming, and Mississippi) and Vermiculite (Transvaal) were treated with solutions of Al(OH)B(3-B+), with B varying from 0 to 2.5. The average basicity (OH/Al = B) of the Al adsorbed differed very much from the basicity of the Al added. The average basicity of the Al adsorbed by smectite was always above the average basicity of the Al added. In contrast to smectite, Vermiculite adsorbed smaller hydroxy-Al complexes. One reason for the different selective behavior was the difference in expansion between smectite (about 18 A) and vermiculite (about 14 A). Because of the adsorption of the relatively more basic OH-Al by smectite, smectite adsorbed considerably more Al than vermiculite. The total amount of aluminum in the interlayer generally could not be calculated by the difference between Al added and that remaining in solution after the reaction because of possible protonation of the clay mineral and adsorption of structural Al and other cations, which is more pronounced for vermiculite. The results in the present study demonstrated that neither the quantitative nor the qualitative composition of an Al(OH)B-treated exchanger can be deduced from B of the Al salts added. These points are frequently overlooked when cation exchangers are pretreated with Al of variable basicity and are used for further investigations, such as studies of CEC, surface area, interlayer spacing, anion reactions, the formation of gibbsite, etc. Before these kinds of investigations are conducted employing the pretreated OH-Al-exchangers, their composition should be known precisely.
20 citations