Yuzhong Su

Modeling of a continuous crystallization process for solvent dewaxing

Abstract A steady 1-D parallel flow model was established for a continuous solvent dewaxing process; the model equations were numerically solved to obtain the wax supersaturations, amount of crystals, crystal sizes and crystal size distributions in the wax-oil-solvent solution along the flow direction. The effects of the operating conditions, including temperature distributions, multiple dilutions, and the composition of dewaxing solvent, the systems characteristics, including nucleation constant, nucleation order, and wax compound, and the crystallizer dimensions on the formed wax crystals were examined and discussed in detail. The systems nucleation constant was determined by an experimentally obtained recovery of wax; further predictions are in acceptable agreement with the results from a pilot plant.

Insulin and Insulin-Tripalmitin Particles Produced by a Supercritical Assisted Drying Process

A supercritical assisted drying (SAD) process was employed to produce insulin submicroparticles from an ethanol/water solution. The effect of the processing conditions on the morphology, size, and thermodynamic activity of the produced particles was investigated. Insulin particles generated from the process were generally spherical with average sizes between 0.4 and 1.1 µm. FTIR, HPLC, the Lowry method, and DTA–TG were implemented to investigate the thermodynamic activity and solvent residue of the produced particles. Results showed that the ethanol content of the aqueous solution had a more sensitive effect on the thermodynamic activity of the insulin particles than other operating factors; a high content of ethanol tended to denature the insulin particles. A rapid expansion of supercritical solutions (RESS)–SAD combined process was proposed to produce insulin–tripalmitin composite particles. Results indicated that irregular composite particles with insulin content of 33.1%, having a bimodal particle size distribution with two peaks at 3.5 and 11.0 µm, were obtained at 50.0°C and 12.0 MPa. These particles revealed no initial burst with a sustained release of insulin of more than 400 min.

Phosphotungstic Acid Immobilized on Imidazole Poly(ionic liquid) for Isomerization of α-Terpineol to 1,8-Cineole

Phosphotungstic acid (PW) was successfully immobilized on imidazole poly(ionic liquid) (PIL) via ion-exchange for the catalytic isomerization of α-terpineol to 1,8-cineole. TG, XRF, FT-IR, XRD, NH3-TPD and DSA were subsequently used to characterize the PW/PIL catalyst. High catalytic activity and stable performance of the catalyst were achieved. A series of 1-alkyl-3-vinylimizolium bromide monomers (alkyl from ethyl to hexadecyl) were applied for the synthesis of PILs as the supports of PW. Results revealed that the lipophilicity of longer chain alkyl PIL exposed the PW active sites efficiently, which consequently enhanced the α-terpineol conversion and reduced the reaction time.Graphical Abstract

Droplet Behavior and Electrically Driven Extraction of Aromatic Hydrocarbon

Abstract The behavior of droplets under horizontal electric fields for the toluene-water-acetic acid and cyclohexane dimethyl sulfoxide (DMSO) toluene systems was experimentally studied. A mathematical model in terms of force balance on moving droplets in an assumed average state was developed to predict the mean size of droplets under horizontal electric fields. The electrically driven extraction of aromatic hydrocarbon for the cyclohexane-DMSO-toluene system was implemented. It is revealed that near the finite field strength, the theoretical stages per cm of the electrically driven extraction can be enhanced by a factor of three over that of a packed θ ring contactor.