Materials Science Forum Vols. 743-744

Abstract: Spherical alumina catalysts have been widely used in fluidized bed and slurry-bed or catalyst carrier due to their excellent pore structure, large surface area, good physical strength and resistance to acids and stability. Magnetic microspheres of γ-Fe₂O₃ @ Al₂O₃ with core-shell structure were obtained by γ-Fe₂O₃ magnetic core coating with aluminum sol. After aging, drying and calcinations process, microspheres with certain hardness and magnetic properties can be obtained. During the preparation of core-shell structure microspheres, effect of both the content of aluminum sol, hexamethylenetetramine(HMT), magnetic core γ-Fe₂O₃ and process parameters of shaping time, aging temperature, calcination temperature on the properties of the spherical carrier was investigated. The optimum properties of microsphere carrier for hardness of 36.32 N/mm, specific surface area of 89.016 m²/g, pore volume of 0.874 cm³/g and average pore diameter 18.51 nm were synthesized, respectively.

Abstract: In the study, porous amorphous silica minerals including Porous Silicon (PS), Diatomite Filter Aid (DFA) and Opal (Op) were chosen as carriers or supports to prepare TiO₂/PS, TiO₂/DFA and TiO₂/Op composites by chemical co-precipitation method. The compound materials were characterized by SEM, TEM, and the photo-catalytic property of the prepared composites was investigated by degradation of Rhodamine B (RhB). Characterization showed that nanoTiO₂ was coated on the surface of porous amorphous silica minerals. The crystal form of TiO₂ was mainly anatase, and the size of which was nanoscale. Through comparative analysis, the photo-catalytic efficiency of TiO₂/PS composite was the best, followed by TiO₂/ DFA, and then TiO₂/Op.

Abstract: A kind of bentonite composite with high salt resistance capacity was prepared using physical modification including physical mineral separation and doping porous non-metallic minerals. The results showed that through physical mineral separation, the content of montmorillonite and the salt resistance capacity increased substantially. The bentonite compsite sample doped by 5.0% diatomite showed better salt resistance capacity than the other compsite samples. The salt resistance mechanism was discussed through the double layer theory and physical and chemical properties of doped minerals.

Abstract: Bentonite mainly consists of montmorillonite, but is always associated with other impure minerals. In order to increase the montmorillonite content in raw bentonite from Xinjiang, this paper adopts wet-purification process which integrates the scrubbing process with streamlined centrifugalization. The optimum experiment condition is solid - liquid ratio (wv) 130, macerating time 20h, scrubbing time 10min, centrifugation time 13min, centrifugation velocity 1260r/min, ZHL dosage 0.4% and ZHC dosage 0.4%. According to the amount of methylene blue absorption raising from 64.5mmol/100g to 110mmol/100g and X-ray diffraction analysis, the montmorillonite content raises from 48% to 82%.

Abstract: Kaolin was modified by propionamide in the present study. XRD analysis with X-ray diffractometer of Rigaku Corporation, infrared analysis with a Nicolet MagnaIR750 Fourier transform infrared (FTIR) spectroscope and the analysis of the TG and DTA curve with Composite Thermal Ana-lyzer were carried out. A Plant Growth Chamber was used to study the water-retaining property of modified kaolin. The results demonstrated that the microstructure of modified kaolin was flaky. Using the modified kaolin in arid regions the sub-surface moisture of soil can be maintained effectively, and the seedling survival rate increases obviously.

Abstract: Through the method of the static tests, the removal rate of aqueous carbon tetrachloride onto a new TCAS-loaded resin was researched. This TCAS-loaded resin was made of a novel supramolecular acceptor compound named thiacalix [arenetetrasulfonate (TCAS) and anion exchange resin, and the adsorption mechanism was discussed preliminarily. The results of adsorption indicated that the pH value was an important factor for the removal of carbon tetrachloride and it would be better for the adsorption if the pH value was greater than 6. The operating temperature should be controlled in 5 to 15°C for the adsorption of carbon tetrachloride onto TCAS-loaded resin while the removal rate decreased with the temperature increasing and the best time for reaction was 40min. The removal rate of carbon tetrachloride in aqueous solution was better when 25mL aqueous solution of carbon tetrachloride (1.0mg/L) was adsorbed by 0.5g TCAS-loaded resin. The carbon tetrachloride can be resolving and TCAS-loaded resin can be reused.

Abstract: Nanometer photo catalytic-membrane reactor integrated photo catalytic technology with membrane separation technology was applied to remove virus existing in water. Bacteriophage f2 was used as surrogates for human enteric viruses. Two kinds of nanomaterials (TiO₂ and ZnO) were selected as the catalyst. Three kinds of membranes interception performance for virus, adsorption efficiency of nanomaterial for virus, inactivated effect for virus with photo catalysis, and the comprehensive effect to f2 of photo catalytic-membrane reactor were studied under the transmembrane pressure of 20Kpa, with nanomaterial concentration of 100mg/L, light dose of 20mJ/cm2. It showed that the interception effect of flat membrane with casting was the best. the adsorption efficiency of the two kinds of nanomaterials was different, 1.478 lg and 0.201 lg for TiO₂ and ZnO, respectively. The removal effect of the photo catalytic oxidation system to f2 was similar, both in 2-3 log. The removal efficiency of the photo catalytic-membrane reactor system has no obvious difference, both in 3-4 log, and it is improved significantly compared to the effect of individual photo catalysis and membrane separation. Further research indicates that: the elimination function of coupling system to f2 includes UV-inactivated, adsorption of nanomaterials, the inactivation of nanomaterials, the effect of oxide moiety which formed after nanomaterials absorbing ultraviolet light and membrane retention.

Abstract: The effects on CH₄ and N₂ separation performance of coconut shell charcoal by high temperature roasting were studied. Results indicate that the surface area increased firstly and then decreased with the increasing of the roasting temperature, and it is found that surface area of roasting 4 hours is higher. Furthermore, the experiment focused on the effect of high temperature roasting on activated carbon adsorption volume and separation coefficient. It is obvious that the adsorption volume increases earlier and then decreases with the increasing roasting temperature, and there are obvious turning points to adsorption volume of CH₄ and N₂. Comparing various roasting time, it is found that adsorption volume in 4h is greater than that in 1h and also in 6h in the whole process. Separation coefficient decreases with increasing roasting temperature. When the temperature is higher than 800 , separation coefficient decreased rapidly. Considering the adsorption volume and separation coefficient, roasting 4 hours at 600 is selected for industrialized production.

Abstract: Glass-ceramic in the CaO-MgO-Al₂O₃-SiO₂ quaternary system was prepared using Baiyunebo tailing and fly ash as main raw materials by the method of melting. The processes of producing glass-ceramic included mixture, melting, molding, annealing, heat treatment, etc. The processing schedule for glass melting temperature, nucleation and crystallization temperature were chosen as 1450°C, 720°C and 850°C. The influences of glass components ratio on the structure were investigated by X-ray diffraction (XRD). It can be found that the main crystalline phase of augite, anorthite, magnesioferrite or magnetite mainly depended on glass components ratio. The results of mechanical measurements indicated that the bending strengths, density and chemical durability of glass-ceramics were concerned with the main crystal phase. The glass ceramics with augite phase had higher performance compared with others.

Abstract: The effects of the dried macroalga, Gracilaria tenuistipitata (Rhodophyta), on photosynthesis of a highly stress-resistant microalga, Phaeodactylum tricornutum were studied. P. tricornutum was cultured with dried G. tenuistipitata under controlled laboratory conditions for three days. All oxygenic photosynthetic organisms tested so far exhibit a polyphasic rise of fluorescence transients during the first second of illumination. These phases are labeled as O, J, I, P. The chlorophyll a (Chl a) fluorescence transient O-J-I-P curve coupled with its specific parameters in P. tricornutum was established. The Chl a fluorescence transients were recorded in vivo at high time resolution and analyzed according to the JIP-test which can quantify photosystem II activity. A clear dose-and time-dependent relationships were observed between the dried biomass of G. tenuistipitata and its inhibitory effect on Pyramimonas sp. A decrease in the O-J-I-P curve expressed as Chl a fluorescence intensity along with its specific parameters were observed, which was also time-dependent. The main photosynthetic inhibitory targets of the macroalga on the microalga, according to the JIP-test, can be expressed as a decrease in the number of active reaction centers and the blocking of the electron transport chain. The results of the present study suggest that dried fragments of G. tenuistipitata effectively inhibit photosynthesis in P. tricornutum and could thus be potential candidates for use in the control and mitigation of harmful algal blooms.