Investigation of CO2 and CH4 capture from syngas in adsorption process and breakthrough modeling by modified Lattice-Boltzmann mesoscale method.

A modified Lattice Boltzmann method (LBM) was developed to model and analyze the transient flow and multi-component adsorption in a dispersive packed bed column of activated carbon as a new kind of meso-scale modeling. The model using D2Q9 (two dimensions and 9 speed) lattice solves the two-dimensional space, convection-dispersion adsorption model for the CO2-CH4 mixture in rich H2 at transient condition. The sink/source term model was considered as the adsorption/desorption kinetic rate based on Extended Langmuir theory for multicomponent mixture. The mole balances in the solid phase were considered as the lumped kinetic model of adsorption-desorption reaction. The results of the developed model was presented as the flow velocity and molar fractions of the components in axial and radial directions of the bed as well as breakthrough curves of CO2 and CH4 from their mixture in H2 gas stream under pressures of 3 and 5 bar and inlet linear velocities of 0.01, 0.04, 0.08 and 0.1m/min. The breakthrough curves were validated with the experimental data and the average absolute relative deviations (AARD) were calculated for both components. In addition, the results of LBM were compared with finite difference method in which AARDs were dtermined as 3% and 8% for CO2,4% and 7% for CH4 , by LBM and FDM, respectively.

New comprehensive mathematical model for HPMC-MCC based matrices to design oral controlled release systems.

A comprehensive model with all effective phenomena in drug release such as diffusion, swelling and erosion was considered. In this work, a mathematical model was developed to describe drug release from controlled release HPMC matrices as a favorable system in pharmaceutical industries. As a novel study, the impact of the MCC presence as a filler in tablet preparation process was considered in the mathematical model. In addition, we found that the volume expansion of these polymeric matrices did not follow the ideal mixing rule and we derived an equation for estimating the volume of hydrated matrix. Furthermore, some equations were derived to estimate the parameters of model (Kerosion, Deq) as well as the change in matrix volume based on the amount of polymer and filler in formulation. This investigation gave deeper insight into underlying drug release mechanisms. According to the results, Kerosion increases linearly and Deq increases exponentially with the increase in the amount of MCC in formulation. Application of this comprehensive mathematical model enables us to predict the behavior of HPMC-MCC based matrices. Furthermore, this model is able to represent the formulation for the desired drug release profile which is useful to design new controlled release matrix as well as improving the system geometry and dimensions of tablets. The presented model was validated by two independent tests: (a) predicting the behavior of matrix with certain MCC/HPMC ratio upon exposure to the release medium; (b) designing formulation of Bupropion hydrochloride extended release tablet.