Calibration for measured crystal size distribution

The crystal size distribution (CSD) measured by laser diffraction technique is obtained by assuming spherical crystals. If crystals are non-spheres, calibration is responsible for the true crystal size, particle number concentration and population density. In this paper, CSD calibration equations have been deduced. It was shown that when shape factors are size-independent, the weight percent of particles is not affected by crystal shape and calibration is just a horizontal shift of measured CSD. Calibration was taken for plate-like crystals of cefazolin sodium and rod-like crystals of l-threonine. The effect of CSD calibration on crystal growth kinetics has been investigated in l-threonine-water evaporation crystallization system.     

用除尘灰分离炭粉制备活性炭及其改性研究

以除尘灰分离炭粉为原料，确定了制备颗粒活性炭的最佳工艺，并对制备的颗粒活性炭进行不同的改性处理和对不同有机蒸气的吸附实验。利用X—光电子能谱仪分析了改性处理后的表面化学性质。吸附实验证明，活性炭的比表面积、表面化学性质和有机物的性质对吸附过程产生影响。     

Integrated UV-based photo microreactor-distillation technology toward process intensification of continuous ultra-high-purity electronic-grade silicon tetrachloride manufacture

Ultra-high-purity silicon tetrachloride (SiCl₄) is demanded as an electronic-grade chemical to meet the stringent requirements of the rapidly developing semiconductor industry. The high requirement for ultra-high-purity SiCl₄ has created the need for a high-efficient process for reducing energy consumption as well as satisfying product quality. In this paper, a mass of production technology of ultra-high-purity SiCl₄ was successfully developed through chlorination reaction in the ultraviolet (UV)-based photo microreactor coupled with the distillation process. The influences of key operational parameters, including temperature, pressure, UV wavelength and light intensity on the product quality, especially for hydrogen-containing impurities, were quantified by the infrared transmittance of Fourier transform infrared spectroscopy (FT-IR) at 2185 cm^-1 and 2160 cm^-1 indicating that characteristic vibrational modes of Si—H bonds, as well as the operating conditions of distillation were also investigated as key factors for metal impurities removing. The advanced intensification of SiCl₄ manufactured by the integration of photo microreactor and distillation achieves the products with superior specifications higher than the standard commercial products.     

Integrated UV-based photo microreactor-distillation technology toward process intensification of continuous ultra-high-purity electronic-grade silicon tetrachloride manufacture

Ultra-high-purity silicon tetrachloride (SiCl₄) is demanded as an electronic-grade chemical to meet the stringent requirements of the rapidly developing semiconductor industry. The high requirement for ultra-high-purity SiCl₄ has created the need for a high-efficient process for reducing energy consumption as well as satisfying product quality. In this paper, a mass of production technology of ultra-high-purity SiCl₄ was successfully developed through chlorination reaction in the ultraviolet (UV)-based photo microreactor coupled with the distillation process. The influences of key operational parameters, including temperature, pressure, UV wavelength and light intensity on the product quality, especially for hydrogen-containing impurities, were quantified by the infrared transmittance of Fourier transform infrared spectroscopy (FT-IR) at 2185 cm⁻¹ and 2160 cm⁻¹ indicating that characteristic vibrational modes of SiH bonds, as well as the operating conditions of distillation were also investigated as key factors for metal impurities removing. The advanced intensification of SiCl₄ manufactured by the integration of photo microreactor and distillation achieves the products with superior specifications higher than the standard commercial products.     

Artificial neural network approaches on composition-property relationships of jet fuels based on GC-MS

The relationships of composition-properties of 80 jet fuels concerning chemical compositions and several specification properties including density, flashpoint, freezing point, aniline point and net heat of combustion were studied. The chemical compositions of the jet fuels were determined by GC-MS, and grouped into eight classes of hydrocarbon compounds, including n-paraffins, isoparaffins, monocyclopraffins, dicyclopraffins, alkylbenzens, naphthalenes, tetralins, hydroaromatics. Several quantitative composition-property relationships were developed with three artificial neural network (ANN) approaches, including single-layer feedforward neural network (SLFNN), multiple layer feedforward neural network (MLFNN) and general regressed neural network (GRNN). It was found that SLFNNs are adequate to predict density, freezing point and net heat of combustion, while MLFNNs produce better results as far as the flash point and aniline point prediction are concerned. Comparisons with the multiple linear regression (MLR) correlations reported and the standard ASTM methods showed that ANN approaches of composition-property relationships are significant improvement on MLR correlations, and are comparable to the standard ASTM methods.     

Binding of several heavy metal ions by polyaspartyl polymers and their application to some Chinese herbal medicines

Water‐insoluble polyaspartyl polymers were synthesized by using water as medium instead of organic medium. Taking Ca²⁺ as a reference, the binding of several heavy‐metal ions, including Pb²⁺, Cd²⁺, Hg²⁺, Cr³⁺, Cu²⁺, and Mn²⁺, by polyaspartyl polymers was studied. The experimental results revealed that polyaspartate is an excellent binding agent for the investigated heavy‐metal ions. These cation ions were bound to polyaspartate polymer by the same mechanism as Pb²⁺, which can be explained by ion exchange model. Since polyaspartate has a protein‐resembling structure that is sensitive to trace heavy metal, it was used to remove some trace heavy‐metal elements in Chinese herbal medicines. It was found that polyaspartate material was an effective agent for the removal of Pb²⁺, Cd²⁺, and Hg²⁺ ions from glycyrrhizin, angelica, and gynostemma pentaphyllum. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

采用不同锰源合成尖晶石LiMn2O4正极材料

The spinel LiMn2O4 cathode material was synthesized with the solid-state reaction method. Four manganese compounds including electrolytic manganese dioxide (EMD), MnCO3, Mn3O4 and nano-EMD were used as Mn sources while LiOH·H2O was used as the uniform Li source. The crystal structure characteristics of these samples produced were investigated by means of XRD, SEM, particle size distribution analysis and specific surface area testing. Their electrochemical properties were also studied by comparing their specific capacity, charge and discharge efficiency and cycle performance.     

利用膨胀床吸附技术单步纯化分子伴侣—GroEL

Expanded bed adsorption (EBA) is an integrative downstream processing technique for the purification of biological substances directly from unclarified feedstock. In this study, molecular chaperone GroEL, an important protein folding helper both in vivo and in vitro, was purified by the single-step EBA technique from the unclarified homogenate of recombinant E. coli cells. Compared with packed bed adsorption, the EBA technique provided a single-step approach to yield an electrophoretic purity of GroEL. After the homogenate loading and column washing in the expanded bed mode, the GroEL protein was recovered by stepwise salt-gradient elution in packed-bed or expanded-bed modes, respectively. The expanded-bed elution mode was found as efficient as the packed-bed mode in the purification of GroEL from cell disruptate.     

Modeling of batch phenol biodegradation in internal loop airlift bioreactor with gas recirculation by Candida tropicalis

A mathematical model for simulating the dynamic behaviors of batch phenol biodegradation processes in internal loop airlift bioreactor (ILAB) with gas recirculation using free cells of the yeast Candida tropicalis was established by coupling the fluid dynamic model and the mass balance model. Based on the coupling arithmetic, the program for evaluating batch phenol biodegradation processes was achieved. The predicted results of linear liquid velocities, gas holdups, linear gas velocities, cell and phenol concentration profiles in the riser and the downcomer of the ILAB with gas recirculation agreed very well with the corresponding experimental data, and the applicability and reliability of this proposed model were validated.     

同时发生初次和二次成核且为聚结控制的沉淀过程多定态及稳定性分析

The possibility of multiplicity in an isothermal continuous mixed suspension-mixed product removal crystallizer is explored using the bifurcation theory.A process involving agglomeration controlled precipitation is considered in which secondary nucleation occurs simultaneously with primary nucleation.The determinant equations for the existence of multiple steady states are developed and the multiplicity boundaries dependent on the physical and kinetic properties and operational parameters of the process are obtained by resolving these determinant equations.The number of steady states in the precipitator for various multiplicity regions is determined and the linear stability of these steady states is analyzed by using the Routh criterion.