A novel method was proposed for the in situ synthesis of magnetite-containing mesoporous silica SBA- 16 via a sol-gel process coupled with precipitation and oxidation. The effect of the added amounts of reactants on the mesostructural and magnetic properties of the magnetic mesoporous silica was investigated. It was determined that the synthesized magnetic mesoporous silica with a total pore volume of 0.64-0.96 cm 3 /g and an average pore diameter of 4.0-14.9 nm had a relatively high saturation magnetization value (1.11-5.77 emu/g) and a large surface area (258-747 m 2 /g). Lysozyme was chosen as a model protein to test the performance of the magnetic mesoporous silica as a protein adsorbent. The high adsorption capacity (up to 212 mg/g) suggested a promising future as bimolecular hosts for the magnetic mesoporous silica.
Computational Fluid Dynamics(CFD) has become an alternative method to experiments for understanding the fluid dynamics of multiphase flow.A two-fluid model,which contains additional terms in both the gas-and solid-phase momentum equations,is used to investigate the fluidization quality in a fluidized bed.A case study for quartz sand with a density of 2,660 kg/m3 and a diameter of 500 μm,whose physical property is similar to a new kind of catalyst for producing clean fuels through the residue fluid catalytic cracking process,is simulated in a two-dimensional fluidized bed with 0.57 m width and 1.00 m height.Transient bubbling and collapsing characteristics are numerically investigated in the platform of CFX 4.4 by integrating user-defined Fortran subroutines.The results show that the fluidization and collapse process is in fair agreement with the classical theory of Geldart B classification,but the collapse time is affected by bubbles at the interface between the dense phase and freeboard.
To get high purity caprolactam is a challenging task in the chemical fiber industry. To date, reports on the prediction of the distribution of caprolactam and its derivative chemicals have been few. In this study, the ex-traction of caprolactam with toluene as the extractant and N-methyl caprolactam with benzene and toluene as the extractants has been carried out. By defining new UNIFAC groups and calibrating related interaction parameters, a UNIFAC method was introduced to predict the equilibrium concentration of caprolactam and methyl caprolactam in toluene or benzene extraction processes. The calculated results fit very well with the experimental data. Using the UNIFAC model, the selectivity of extractants can be predicted.
