Zwitterionic betaine polymers show excellent ability to suppress nonspecific protein adsorption. In this study, to investigate the detailed mechanisms of their antifouling properties at the atomic level, the solvation structures in the vicinity of carboxybetaine, phosphobetaine, and sulfobetaine moieties are determined in water and n-hexane using radial distribution functions obtained from molecular dynamics simulations. In aqueous solution, water molecules tightly bind to the anionic groups of zwitterionic moieties. In contrast, in pure n-hexane solvent, no significant solvation structures are present near the anionic groups in the zwitterionic moieties, suggesting that n-hexane molecules do not interact with the anionic oxygen atoms. Our results indicate that the anionic groups play a major role in the antifouling properties of zwitterionic moieties.
Cocrystals, which are crystallized intermolecular compounds composed of host and guest (organic) compounds, are receiving attention in order to improve the solubility of insoluble host organic compounds. In this study, the composition profiles of salicylic acid (SA) and nicotinamide (NA) in an aqueous solution were examined when SA/NA cocrystals were dissolved in water, and the dissolving phenomena of SA/NA cocrystals were investigated. SA/NA cocrystals were able to be produced by a rapid cooling method of an SA/NA ethanol (EtOH) solution, a rapid cooling method of melt for SA/NA mixtures, evaporation to dryness of an SA/NA EtOH solution and mechano-chemical processing by a planetary ball mill. A ternary phase diagram for the SA/NA/water (H2O) system was made and it grouped near the NA composition axis and two eutectic points existed. Tablets composed of SA/NA cocrystals were dissolved in water and the changes in the composition ratios of SA to NA in the solution and the surface compositions on their tablets with experiment duration were examined. Changes in the composition ratios of SA to NA in a solution for case of SA/NA cocrystals were compared with those for equimolar mixtures of SA and NA crystals. SA and NA composition profiles in a solution and on tablet surfaces are shown and the dissolving phenomena of SA and NA cocrystals are discussed.
Silicalite-1 membranes were prepared on mullite supports in a fluoride containing solution by a secondary growth method. Influence of seed crystal size was examined by applying seeds of 100–200 nm and 1–2 µm, respectively. Randomly oriented poly-crystalline MFI membranes were obtained with larger seeds. On the contrary, membranes formed by applying smaller seeds became more c–axis oriented with longer synthesis time. While seed size had no significant influence on hydrogen permeance, SF6 permeance was ca. three times smaller when smaller seeds were used. Applying smaller seeds and fluoride containing synthesis solution, MFI membranes having H2/SF6 ideal selectivity over 100 were obtained within 6 h.
This study aims to clarify the influence of moisture on the formation of fine particulate matter during coal combustion. Coal samples (A and B) with different moisture contents were pyrolyzed and combusted in a lab-scale drop tube furnace under N2 and air atmosphere, respectively. A coalescence-fragmentation model was modified to evaluate the release of included minerals during coal combsution. The results indicate that a high content of moisture in the raw coal caused the loss of char yield during coal devolatilization due to the steam-gasification between coal carbonancous matter and moisture. A large amount of cracks were formed on the surface of char particles likely due to the rapid vaporization of pore moisture and fragmentaion of char. Existence of inherent moisture in the coal promoted the formation of PM1.0–2.5, which was probably caused by the release of included minerals from char matrix during devolatilization. The effect of free moisture in raw coal on the PM emission was insignificant. The results from the model calculation suggested that the included minerals of 0.15% in coal A and 0.04% in coal B were released into the surrounding gas, and in turn caused the increase of PM1.0–2.5 emission. An increase in drying temperature and/or prolonging the drying time to reduce the inherent moisture content was suggested to prevent the emission of inhalable particulate matters during low-rank coal combustion.
Due to the over-complexity or severe simplification of the traditional methanol-to-propylene reaction model and the neglect of water in the modelling process, there still are many challenges in the industrial application. In this paper, a new six-lump kinetic model for methanol-to-propylene reaction over the hydrothermal treated HZSM-5 zeolite catalyst was established and the influence of water was taken into account to expand the applicable scope of the model. The evolution of the product mass fraction along with the space-time at different temperatures is discussed to expound the main reaction paths. Agreement between the experimental data and the predicted values is good through the temperature ranges investigated with the average error below 4.31%. Apparent activation energies and pre-exponential factors were initially calculated based on the Arrhenius equation to obtain the rate constants of each lump. The fitted results show that the lumped kinetic model well describes the production distribution at conditions close to industrial practice.
The present study has an object of developing a crystallization process by nozzleless electrostatic atomization. This process could control the fine particle size independent of the nozzle diameter. The behavior of liquid–liquid interfaces formed using different organic solvents was observed. A Taylor cone appeared near the interface, particularly in the case where 1-decanol was used as the solvent, resulting in the generation of numerous droplets from the electrode’s tip. This process was applied to the production of taurine particles; as a result, spherical taurine particles were formed along the droplet interface almost without loss. The crystal structure of taurine particles was characterized by powder X-ray diffraction (PXRD). The intensity and position of peaks in the PXRD pattern of the prepared taurine particles were identical to those in the pattern of the untreated taurine particles, where the crystalline structure of the spherical particles was independent of the droplet shape. The yield of precipitated particles was almost 100% since this method was performed in a liquid-liquid system. The influences of the applied voltage and interfacial tension on the particle size of taurine were examined. The particle size decreased with increasing applied voltage or decreasing interfacial tension between the taurine aqueous solution and organic solvent. The developed electrostatic atomization process without a nozzle is a promising method for creating particles whose physical properties are independent of the nozzle diameter. Furthermore, this method has a possibility of being able to control the particle morphology independent of the nozzle. This method would continuously produce the particles in the absence of nozzle clogging.
Al–Cu composite metal oxides were supported on MCM-41 to simultaneous adsorption/oxidation of NO and SO2 from Coal-fired flue gas in this work. The material was prepared by hydrothermal synthesis method and the synthetic conditions such as aluminum content, the second metal selection, the second metal content and calcination temperature were investigated. The experiment results showed that the adsorption/oxidation effect achieved the best when the ratio was Si: 02 Al: 0.02 Cu at 90°C. The synthesized materials were characterized by N2 adsorption–desorption measurements, transmission electron microscope (TEM) and energy dispersive spectrometer (EDS). Compared with other adsorbents, Al–Cu–MCM-41 had larger specific surface area and total pore volume by N2 adsorption–desorption measurements. Meanwhile, the additions of aluminum and copper did not change mesoporous structure of MCM-41 and the active components could be dispersed uniformly within the framework of Al–Cu–MCM-41 by TEM. In addition, the results of EDS explained that the presence of active components was convinced and sulfur element was detected on inactivated Al–Cu–MCM-41adsorbent. The analysis results illustrated that the presence of aluminum and copper could enhance the adsorption/oxidation capacity of NO and SO2. Therefore, it could infer that chemical adsorption probably had a better removal effect than physical adsorption.