A process of biosorption of Cu^2+, Zn^2+ and Cd^2+ on Bacillus subtilis was investigated. The experiments show that the process of biosorption is quite fast, The maximum adsorption was reached after 5 min and hardl...A process of biosorption of Cu^2+, Zn^2+ and Cd^2+ on Bacillus subtilis was investigated. The experiments show that the process of biosorption is quite fast, The maximum adsorption was reached after 5 min and hardly changed with time. The experimental data was analyzed using four sorption kinetic models: the pseudo-first-order, the Ritchie second-order, the modified second-order and the Elovich equations, which helped to determine the best-fit equation for the sorption of metal ions onto biomass, The results show that both the Ritchie second-order and modified secondorder equations can fit the experimental data. The Langmuir model is able to accurately describe adsorption of Cu^2+ and Zn^2+ on B. subtilis. The experimental data points of adsorption Cd^2+ and Zn^2+ on B. subtilis are described by Freundlich isotherms model.展开更多
In this paper, we consider and resolve a geometric problem by using μ(z)-homeomorphic theory, which is the generalization of quasiconformal mappings. A sufficient condition is given such that a Ct-two-real-dimensio...In this paper, we consider and resolve a geometric problem by using μ(z)-homeomorphic theory, which is the generalization of quasiconformal mappings. A sufficient condition is given such that a Ct-two-real-dimensional connected orientable manifold with almost positive definite metric can be made into a Riemann surface by the method of isothermal coordinates. The result obtained here is actually a generalization of Chern's work in 1955.展开更多
Chromatograms of tocopherol homologues were obtained by a column of analytical size (inner diameter (ID) 0.46 cm cm×10 cm) packed with silica gel. Adsorption isotherms and film mass-transfer coefficient were esti...Chromatograms of tocopherol homologues were obtained by a column of analytical size (inner diameter (ID) 0.46 cm cm×10 cm) packed with silica gel. Adsorption isotherms and film mass-transfer coefficient were estimated from the chroma-tograms by using a general rate model, which considers axial dispersion, external mass-transfer and intraparticle diffusion. Based on the obtained isotherms and mass-transfer coefficient, the separation process of tocopherol homologues on simulated moving bed (SMB) was simulated using the same model. According to the simulated results, a mixture of α-, γ-, δ-tocopherols and other impurities was separated on an SMB equipment. The SMB equipment was composed of 8 columns of ID 2 cm×10 cm, with 2 columns in each section. The solid phase was silica gel, and the mobile phase was n-hexane/2-propanol (99/1 by volume). γ-and δ-tocopherols of purity greater than 98% were obtained with recovery greater than 98%. The effects of operating conditions (flow rates and switching time) on the performance of SMB were studied by both simulation and experiments. It was found that all the simulation results were quite close to the experimental results. We conclude that process development and optimization of operating conditions of SMB by simulation are feasible.展开更多
基金Supported by National Natural Science Foundation of China (No. 20206024)
文摘A process of biosorption of Cu^2+, Zn^2+ and Cd^2+ on Bacillus subtilis was investigated. The experiments show that the process of biosorption is quite fast, The maximum adsorption was reached after 5 min and hardly changed with time. The experimental data was analyzed using four sorption kinetic models: the pseudo-first-order, the Ritchie second-order, the modified second-order and the Elovich equations, which helped to determine the best-fit equation for the sorption of metal ions onto biomass, The results show that both the Ritchie second-order and modified secondorder equations can fit the experimental data. The Langmuir model is able to accurately describe adsorption of Cu^2+ and Zn^2+ on B. subtilis. The experimental data points of adsorption Cd^2+ and Zn^2+ on B. subtilis are described by Freundlich isotherms model.
基金Project (No. 10101023) supported by the National Natural Science Foundation of China
文摘In this paper, we consider and resolve a geometric problem by using μ(z)-homeomorphic theory, which is the generalization of quasiconformal mappings. A sufficient condition is given such that a Ct-two-real-dimensional connected orientable manifold with almost positive definite metric can be made into a Riemann surface by the method of isothermal coordinates. The result obtained here is actually a generalization of Chern's work in 1955.
基金Project (No. 20040335045) supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China
文摘Chromatograms of tocopherol homologues were obtained by a column of analytical size (inner diameter (ID) 0.46 cm cm×10 cm) packed with silica gel. Adsorption isotherms and film mass-transfer coefficient were estimated from the chroma-tograms by using a general rate model, which considers axial dispersion, external mass-transfer and intraparticle diffusion. Based on the obtained isotherms and mass-transfer coefficient, the separation process of tocopherol homologues on simulated moving bed (SMB) was simulated using the same model. According to the simulated results, a mixture of α-, γ-, δ-tocopherols and other impurities was separated on an SMB equipment. The SMB equipment was composed of 8 columns of ID 2 cm×10 cm, with 2 columns in each section. The solid phase was silica gel, and the mobile phase was n-hexane/2-propanol (99/1 by volume). γ-and δ-tocopherols of purity greater than 98% were obtained with recovery greater than 98%. The effects of operating conditions (flow rates and switching time) on the performance of SMB were studied by both simulation and experiments. It was found that all the simulation results were quite close to the experimental results. We conclude that process development and optimization of operating conditions of SMB by simulation are feasible.