Papers by Author: Hong Xing Dong

Abstract: Pipe reactor simulation of biological growth was investigated based on computational fluid dynamics (CFD) and reaction dynamics in single-phase laminar incompressible flow with the open-source software, OpenFOAM. OpenFOAM supplied a kind of open structure, which made it convenient to add a suitable physical model with CFD equations according to the problem. In order to compute mass transfer and biological growth as a reaction with fluid flow, the component conservation equation was listed with Navier-Stokes equations. With the equations, a pipe reactor was simulated by our solver which was developed based on OpenFOAM. By the simulation, the pressure, velocity and component mass fraction can be obtained at different time and position, which is important to analyze equipments in chemical engineering. Although some details need to be considered such as the definition of reaction term, the boundary conditions, etc., reactor simulation with OpenFOAM has showed very large potential.

Abstract: Ultrasonic cavitation is at the origin of kinetics and yield improvement of ultrasound-assisted chemical processes. Character of ultrasonic field plays a potential role in choosing the best conditions for ultrasound-assisted chemical processes. In this paper, acoustic field distribution was measured with a thermoelectric probe in a 500mL flask filled with distilled water. A 40kHz ultrasonic horn was used and the temperature signal was measured at different locations, including axial and radial directions along the horn. The immersion depth of ultrasonic horn was investigated with ultrasonic power at 250W and 300W. We concluded that at the same power, when the immersion depth was 3cm, the intensity reached maximum.

Abstract: This work reported that ultrasound changed the solid-liquid leaching equilibrium of glycyrrhizic acid (GA) from glycyrrhiza uralensis in water. Several critical variables were considered, including temperature, ultrasonic power and frequency. The equilibrium concentration of GA increased by increasing the temperature, while the optimal ultrasonic frequency was affected by the temperature and the ultrasonic power affected the concentration lightly when the power was more than 100W. To investigate the cause that ultrasound changed the solid-liquid leaching equilibrium, a scanning electron microscope was used to observe the solid structure before ultrasound treatment and after that. It was found that ultrasound was able to change the structure of glycyrrhiza uralensis. So a new equilibrium was built and the equilibrium concentration of GA was influenced because the solid structure was transformed by ultrasound.

Abstract: In this work computational mass transfer was investigated based on computational fluid dynamics (CFD) in single-phase flow with the open-source software, OpenFOAM. OpenFOAM supplied a kind of open structure, which made it convenient that a suitable physical model was added with CFD equations according to the problem. In order to compute mass transfer with fluid flow, the component conservation equation was listed with Navier-Stokes equations. With the equations, a pipe flow with mass transfer was simulated on the assumption that the fluid density is constant by our solver which was developed based on OpenFOAM. By the simulation, the pressure, velocity and component mass fraction can be easily obtained at different time and position, which is very important for the analysis of equipments in chemical engineering. Although some details need to be considered such as the change of density with composition, the boundary conditions and the affect of complex shape, computational mass transfer with OpenFOAM has showed very large potential to be applied in industry.

Abstract: Polymers imprinted with (S)-(-)-1,1’-bi (2-naphthol) and (R)-(+)-1,1’-bi (2-naphthol) have been prepared by non-covalent imprinting. A combinational procedure was used to optimize the functional monomer and crosslinker. A copolymer of 2-vinylpyridine and divinylbenzene resulted in the best chiral recognition. The ratio of template to functional monomer and solvent in the pre-polymerization mixture were also optimized. The imprinted polymers were used as stationary phases in high-performance liquid chromatography (HPLC). The molecularly imprinted polymers (MIPs) were more selective when prepared using a less polar solvent. Effective separations of the enantiomers of racemic (±)-1, 1’-Bi (2-naphthol) were achieved by use of acetonitrile as mobile phase; no cross-selectivity was observed. Interactions between functional monomers and template were investigated by 1H NMR spectroscopy. The results suggest that hydrogen-bonding between the functional monomer and the template and π-π stacking interaction between the cross-linker and the template may contribute to chiral recognition.

Abstract: Silica gel was modified with polymerizable double bonds on the surface. Then the molecular imprinting polymer imprinted with D-Phenylalanin was grafted on the surface of modified silica gel. The molecularly imprinted polymer (MIP) based on the surface of silica gel was characterized by IR and scanning electron microscopy (SEM). The adsorption property of D-Phenylalanin by MIP was mearsured. The MIP with the combined functional monomers exhibited better adsorption properties and selectivity compared with the corresponding non-imprinted polymers or MIP with the single functional monomer. The material could be used in separation research field, such as packing material of high performance liquid chromatography, solid-phase extraction and so on.