In-situ preparation of hierarchical Beta zeolite by steam- assisted crystallization method using meso-macroporous silica

In this paper, a series of meso-macroporous silica (MMS) were prepared by phase separation, then mic-meso-macroporous Beta zeolite was prepared by steam-assisted crystallization (SAC) method using the meso-macroporous silica as substrate. The factors such as the amount of water, crystallization time, aluminum source, amount of template agent during the SAC method were investigated. Various characterization methods such as BET, XRD, SEM were used to investigate the physical and chemical properties of the prepared materials. The results showed that the meso-macroporous silica could be transformed into Beta zeolite through the SAC method while the macroporous structure was still maintained.

Effect of adding dodecanol as modifier to N,N,N′,N′-tetra-n-hexyl-3,6-dithiaoctane-1,8-diamide silica-based adsorbent on the adsorption behaviors of platinum-group metals and other metals from simulated high-level liquid waste

To adsorb and separate platinum-group metals efficiently from simulated high-level liquid waste, two adsorbents, N,N,N′,N′-tetra-n-hexyl-3,6-dithiaoctane-1,8-diamide (THDTODA)/SiO2-P and (THDTODA + dodecanol)/SiO2-P, were prepared by impregnation of THDTODA with or without dodecanol into macroporous silica/styrene–divinylbenzene copolymer composite particles SiO2-P. The effect of the addition of dodecanol to THDTODA fixed silica-based adsorbents on the separation of platinum-group metals and other metals was evaluated by batch adsorption and chromatographic separation experiments. THDTODA/SiO2-P adsorbed Ru(III) and Rh(III) more than (THDTODA + dodecanol)/SiO2-P did in concentrated HNO3 solution. From the calculated thermodynamic parameters, dodecanol was considered to have little effect on the temperature dependence of the adsorptions of Ru(III), Zr(IV), Mo(VI), and Re(VII) onto the THDTODA adsorbents. Furthermore, in the results of column chromatography experiments, the effects of dodecanol addition on the separation properties were observed for Ru(III), Zr(IV), and Mo(VI), but little effect was observed for Pd(II) and Re(VII).

The Potential of Macroporous Silica—Nanocrystalline Cellulose Combination for Formulating Dry Emulsion Systems with Improved Flow Properties: A DoE Study

The objective of this study was to explore the possible use of a new combination of two excipients, i.e., nanocrystalline cellulose (NCC) and macroporous silica (MS), as matrix materials for the compounding of dry emulsion systems and the effects these two excipients have on the characteristics of dry emulsion powders produced by the spray drying process. A previously developed liquid O/W nanoemulsion, comprised of simvastatin, 1-oleoyl-rac-glycerol, Miglyol 812 and Tween 20, was employed. In order to comprehend the effects that these two matrix formers have on the spray drying process and on dry emulsion powder characteristics, alone and in combination, a DoE (Design of Experiment) approach was used. The physicochemical properties of dry emulsion samples were characterised by atomic force microscopy, scanning electron microscopy, mercury intrusion porosimetry, energy-dispersive X-ray spectroscopy and laser diffraction analysis. Additionally, total release and dissolution experiments were performed to assess drug release from multiple formulations. It was found that the macroporous silica matrix drastically improved flow properties of dry emulsion powders; however, it partially trapped the oil—drug mixture inside the pores and hindered complete release. NCC showed its potential to reduce oil entrapment in MS, but because of its rod-shaped particles deposited on the MS surface, powder flowability was deteriorated.

Controllability of pore size on macroporous sol-gel silica films embedding rhodamine 6G

A facile method is reported to synthesize macroporous silica films embedding rhodamine 6G. The films were obtained by sol-gel and spin-coating processes. Results pointed out a dependence of pore formation on the addition of rhodamine 6G in the film composition. The probable formation process of the pores was attributed to the aggregation of charged species from rhodamine 6G. Although the pores were randomly distributed on the film surface, the pore size was tuned at certain extent by controlling the evaporation and condensation rates at early stages of spin coating. Results indicated that the evaporation rate determined the pore size distribution of the films.

An Efficient Solid-Phase Extraction-Based Liquid Chromatography Method to Simultaneously Determine Diastereomers α-Tocopherol, Other Tocols, and Retinol Isomers in Infant Formula

The separation and simultaneous quantitation of diastereomers of DL-α-tocopherol, eight tocol forms, and retinols (trans and cis) have been conducted by reversed-phase liquid chromatography followed by solid-phase extraction. A chiral silica stationary phase modified with polysaccharide derivative on the monodisperse macroporous silica gel (Unichiral OD-5H column, 150 mm × 4.6 mm, 5 μm, NanoMicro Technology Co., Ltd.) was employed for eluting each target compound. Instead of conventional solvent extract, a green and eco-friendly solid-phase extraction column, packing with nonpolar polystyrene divinylbenzene, was optimized in terms of capacity and solvent used in steps. Validation of the method was examined and confirmed to be satisfactory, with excellent linearity regression (r > 0.9999), acceptable accuracy (74.66%∼112.92%), and precision (0.20%∼10.52%) results. Limit of detection ranged from 0.05 mg·kg−1 (retinols) to 0.4 mg·kg−1 (tocols). The method was checked by infant formula reference material SRM 1849a as well, which illustrated good agreement of mass fraction with certified value and enriched the important isomer data.

Phase Behaviour of Methane Hydrates in Confined Media

In a study designed to investigate the melting behaviour of natural gas hydrates which are usually formed in porous mineral sediments rather than in bulk, hydrate phase equilibria for binary methane and water mixtures were studied using high-pressure differential scanning calorimetry in mesoporous and macroporous silica particles having controlled pore sizes ranging from 8.5 nm to 195.7 nm. A dynamic oscillating temperature method was used to form methane hydrates reproducibly and then determine their decomposition behaviour—melting points and enthalpies of melting. Significant decreases in dissociation temperature were observed as the pore size decreased (over 6 K for 8.5 nm pores). This behaviour is consistent with the Gibbs–Thomson equation, which was used to determine hydrate–water interfacial energies. The melting data up to 50 MPa indicated a strong, essentially logarithmic, dependence on pressure, which here has been ascribed to the pressure dependence of the interfacial energy in the confined media. An empirical modification of the Gibbs–Thomson equation is proposed to include this effect.

Study on the graft modification mechanism of macroporous silica gel surface based on silane coupling agent vinyl triethoxysilane

Study on the mechanism of the alkylation reaction on the surface of porous silica gel.