This paper reviews our work on the fundamental principles of high gravity controlled precipitation (HGCP) technology, and its applications in the production of drug nanoparticles, which was carried out in a rotating packed bed (RPB). Several kinds of drug nanoparticles with narrow particle size distributions (PSDs) were successfully prepared via HGCP, including the 300-nm Cefuroxime Axetil (CFA) particles, 200–400-nm cephradine particles, 500-nm salbutamol sulfate (SS) particles (100 nm in width), and 850-nm beclomethasone dipropionate (BDP) particles, etc. Compared to drugs available in the current market, all the drug nanoparticles produced by HGCP exhibited advantages in both formulation and drug delivery, thus improving the bioavailability of drugs. HGCP is essentially a platform technology for the preparation of poorly water-soluble drug nanoparticles for oral and injection delivery, and of inhalable drugs for pulmonary delivery. Consequently, HGCP offers potential applications in the pharmaceutical industry due to its cost-effectiveness, efficient processing and the ease of scaling-up.
Ting-Ting Hua, Jie-Xin Wanga, Zhi-Gang Shena, Jian-Feng Chena,b, a Key Lab for Nanomaterials, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029, China b Research Center of Ministry of Education for High Gravity Engineering and Technology, Beijing University of Chemical Technology, Beijing 100029, China
A thermodynamic model has been developed to determine the reaction conditions favoring low temperature direct synthesis of barium titanate (BaTiO3). The method utilizes standard-state thermodynamic data for solid and aqueous species and a Debye-Hǔckel coefficients model to represent solution nonideality. The method has been used to generate phase stability diagrams that indicate the ranges of pH and reagent concentrations, for which various species predominate in the system at a given temperature. Also, yield diagrams have been constructed that indicate the concentration, pH and temperature conditions for which different yields of crystalline BaTiO3 can be obtained. The stability and yield diagrams have been used to predict the optimum synthesis conditions (e.g.,reagent concentrations, pH and temperature). Subsequently, these predictions have been experimentally verified.As a result, phase-pure perovskite BaTiO3 has been obtained at temperature ranging from 55 to 85℃ using BaCl2,TiCl4 as a source for Ba and Ti. and NaOH as a orecioitator.
A novel rotating packed bed(RPB)technology was used to prepare butyl rubber for the first time.The effects of the operating parameters,such as rotate speed,polymerization temperature,on the molecular weight and molecular weight distribution of isobutylene-isoprene rubber(IIR)were investigated in the experiment.The results revealed that IIR prepared by the unique high gravity reaction technology with the molecular weight of 2.89×105,molecular weight distribution index of 1.99 and single-pass conversion 30% was obtained at N=1200 r·min-1,Tp=-100℃ in the experimental condition.In addition,the mean residence time of the products was less than 1s while that of the conventional technology was 30—60 min.The production efficiency per unit volume of the equipment was increased by 2—3 orders of magnitude.With increasing N and decreasing Tp,the molecular weight of IIR increased whereas no obvious difference of the distribution index of molecular weight was observed.
