Papers by Author: Jun Qiu

Abstract: In order to research the colloidal and thixotropic performance of the inorganic gel prepared by high purity montmorillonite, this study uses the moderate grade bentonite ores from Weifang (China) as raw material. Two-stage hydrocyclone classification was applied to obtain the high purity montmorillonite with its content of 94.8 per cent. In contrast to other methods of montmorillonite purification, two-stage purification by hydroclone has the advantages of larger throughput and easily achieving auto-control in industry, and products with different montmorillonite content can be obtained by this method. And then the inorganic gel was prepared by the prepared high purity montmorillonite , its colloidal and thixotropic performances were further studies. Research results show that the inorganic gel belongs to plastic body liquidity, the viscosity decreases with the increase of the shear rate, the static and dynamic shearing stress values are 33.98 Pa and 91.89 Pa respectively, and the thixotropic value is 95.2 dyne·s/cm², which indicates that it has preferable colloidal and thixotropic performance. Montmorillonite inorganic gel prepared by bentonite with high montmorillonite content and low- layer charge has better gel performance. The application result of inorganic gel in dentifrice and medicine shows that it has excellent effect.

Abstract: In order to study the phase of Fe and Ti in a beach placer , different methods such as the X-ray diffraction analysis, chemical analysis, scanning electron microscopic , electron probe microanalysis are used to study the characteristics of the beach placer . The research results show the major metallic mineral in the beach placer is titanic magnetite, EDS and energy spectrum map features of which indicate that the vast majority of titanic magnetite contain a certain amount of Ti , the two elements of Fe and Ti take on closely symbiosis and distribute more evenly in titanic magnetite. The Ti exists in the Magnetite lattice in form of isomorphism. The theoretical highest grade of Fe and Ti in the separated Magnetic concentrate are 66.02per cent and 4.86 per cent respectively. In addition, the beach placer contains a small quantity of Ilmenite which is hysterogenic and exists in the form of fine solid solution separation structure in the titanic magnetite

Abstract: Al3+/clay ratio is one of the important factors influencing microstructure of Al-pillared montmorillonite. Microstructure variation laws of Al-pillared montmorillonite prepared under the condition of different Al3+/clay ratio are systematically studied by XRD, FTIR, specific surface area and pore size analysis. The results show that the interlayer spacing and BET specific surface area of Al-pillared montmorillonite are remarkably affected by the Al3+/clay ratio. The interlayer spacing d(001) value and BET specific surface area of Al-pillared montmorillonite increase firstly and then decrease with the increases of the Al3+/clay ratio, and they reach to maximum when the Al3+/clay ratio is 10mmol/g. Besides, the BJH porous volume distribution of Al-pillared montmorillonite is the most probable distribution, and the most probable pore size is about 2 nm, which is attributed to mesopore. The porous structure of hydroxy-Al pillared montmorillonite is characterized as parallel plate slit or “house-of-cards” wedge-shaped pore which is formed by novel meso-microporous delaminated structure and fragments. With the increase of the Al3+/clay ratio, BJH total porous volume and mesoporous volume of hydroxy-Al pillared montmorillonite decreases, while the proportion of microporous volume in the total porous volume increases. The proportion of microporous specific surface area of all the hydroxy-Al pillared montmorillonite samples is about 62% and is much larger than that of Na-M and those of mesopore and macropore, indicating the main action of intercalation of hydroxy-Al pillaring solution into montmorillonite interlayer is to increase the micropore amount.

Abstract: Using Octadecyltrimethylammonium (OTA) cations with long carbon chain to intercalate into Na-montmorillonite samples, the change of adsorption amount and adsorption state of OTA with the retention time was investigated. The sdudy on the reaction kinetics for the alkylammonium adsorption in the montmorillonite interlayers showed that the isothermal adsorption behavior fit in with a second order reaction kinetics equation. Reaction rate constants had great differences with application force of adsorption process. OTA in the montmorillonite interlayers through re-arrangement constantly at different time, adsorption state of OTA are analysised by XRD and FTIR. The interlayer spacing and diffraction peak relative intensity of montmorillonite/OTMA complexes shows a dynamic change, the alkyl chain conformations can change from “liquid-like” to “solid-like” with the reaction time. The arrangement of alkylammonium cations are more orderly.

Abstract: A series of montmorillonite/alkylammonium complexes were prepared by the intercalation reaction between montmorillonite and Octadecyltrimethylammonium chloride (OTA). The effects of OTA dosage and intercalation duration on the structure and gelating properties of the complexes were investigated. And, the correlation between the structure of complexes and their gel viscosities were discussed. Results indicate that the OTA dosage and retention time have remarkable influence on the structure and gelating properties of montmorillonite/alkylammonium complexes, and the gelating properties also relates to the arrangement of the alkylammonium molecules in the interlayers of montmorillonite. Along with the increase of the OTA dosage under the same retentation time, both the d001 value of the montmorillonite/alkylammonium complexes and the adsorption amount of OTA increase to some extent, and the layer structure of the complex tends to show an interstratification structure. However, maximum gel viscosity of the complex was obtained at a moderate OTA dosage of 1.1~1.3CEC. Along with the increase of the retentation time, the adsorption amount of the OTA shows little variations, but the interlayer structure of the complex prepared under longer retention time tends to form a stable monolayer structure from an unstable interstratification structure under shorter retention time, and the gel viscosity of the complex increases gradually to the maximum value.

Abstract: The structure and thermal property of organomontmorillonite (OM) were studied by X-ray diffraction (XRD), differential thermal analysis (DTA), and thermalgravimetric analysis (TGA).Based on the thermal property of OM, a new method for quantitative characterization of the alkyl-ammonium adsorbed in the layers was established, and the influence of adsorption amount on the viscosity of OM gel was examined. Changes in the basal spacing of OMs and Na-montmorillonite (Na-mont) indicated that alky-ammonium ions intercalated into the montmorillonite layers. TGA results showed that OM and Na-mont had different thermal property, Na-mont held more free water in the layers. The intercalated alkyl-ammonium in OMs decomposed at the temperature of 230~480°C. Effective dosage (DOSeffective) has significant influence on the viscosity of OM gel. Under the optimal DOSeffective(1.1~1.3CEC), the alkyl-ammonium cations can fully cover the exchangeable site in the layers, then the “card-house” structure formed. Structure of the alkyl-ammonium cations determines the intercalation efficiency, the longer the carbon chain, the higher the intercalation efficiency. The intercalation efficiency has no evident correlativity with the viscosity; however, structure of the alkyl-ammonium cations determines their arrangement in the layers.

Abstract: Thixotropic gel can be formed in the organic solvents is one of the most important application characteristics of montmorillonite/octadecyl trimethy ammonium chloride complexes. The key factor influencing the formation of gel is the preparation technology, and the posterior disposal process is also an important affecting factor which should be paid more attention to. In the paper, the effects of washing, drying temperature, grind size, activators and the polarity of solvents on the gel viscosity of montmorillonite/octadecyl trimethy ammonium chloride complexes were systematically studied. The research shows that fully washing can elute the octadecyl trimethy ammonium chloride ions or molecula adsorbed on the layer and the edge of montmorillonite crystal, and improve viscosity of gel formed by the complexes. Controlling the drying temperature at the range of 90－100°C and ensuring the complexes with a little interlayer water are favorable for the gel formation of the complexes. When the granularity of the complexes is less than 0.074mm, particles in solvents can fully produce solvation action, solvent swells and strips, and then form the thixotropic organic gel. Using the 95% ethanol as the activator, when its dosage is 5 wt%, its activation effect is better. The stronger the polarity of the dispersing solvent is, the more favorable the formation of the organic gel with higher viscosity is.