The objective of this study was to investigate the potential process of the removal of carbon dioxide (CO2) from flue gases by using developed membrane gas absorption system. The experiments were performed in membrane gas absorption system consisted 0.45 μm pore size microporous polyvinylidenefluoride (PVDF) flat sheet membrane. Diethanolamine (DEA) solution was employed as the liquid absorbent. The operating parameters such as the gas and liquid flow rate were setup at 100 cm3/min and 25 cm3/min and liquid absorbent was at room temperature. The effect of DEA concentration was studied with variation in range 1 M to 5 M. In addition, the experiments were carried out with 20%, 40% and 100% gas ratio CO2 to N2. The results show that hydrophobic polymeric membranes such as PVDF can be efficiently used for gas absorption with optimized concentration of DEA.

A comprehensive mathematical model and experimental study of single particle growth for styrene polymerization over a silica-supported metallocene catalyst were investigated. The model was developed based on the modification of the well-known multigrain model (MGM) by introducing mesoparticle scale limitations. Thereafter, the model was employed to predict the effects of bulk phase temperature and catalyst properties (initial catalyst active site concentration and initial catalyst particle size) on the polymerization rate, degree of polymerization (DP), and the polydispersity index (PDI) of syndiotactic polystyrene (SPS). The simulation results showed a significant radial distribution of styrene concentration across polymer particle growth at different polymerization conditions. It was found that increasing the initial catalyst concentration and bulk phase temperature resulted in polymerization rate enhancement. In context, the polymerization rate decreased as the initial catalyst particle size increased from 20 to 50 μm. The results revealed that a uniform increase in DP of the polymer was obtained by increasing the initial catalyst concentration and the reaction temperature, while resulting in a decrease of the PDI value. Meanwhile, the DP and PDI values varied inversely under the influence of initial catalyst particle size within a period of time similar to the one needed in the catalyst decay. The simulated results in the study agree well with experimental data of SPS.

A detailed mathematical model for syndiospecific styrene polymerization based on combining features of the multigrain model (MGM) and the polymeric multigrain model (PMGM). This model has been established to predict the radial monomer concentration within the growing macro particles and the rate of polymerization. The latter, the parameters, have an effect on the molecular weight distribution (MWD). In this model, the effect of intraparticle diffusion resistance and the radius of catalyst particles on the rate of polymerization and MWD were studied. The model simulation showed the presence of a large distribution of monomer concentration across the radius of particles. It was further noticed that the diffusion resistance was most intense at the beginning of the polymerization process. For MWD, the model simulation showed that the existence of diffusion resistance led to have an increase in the molecular weight within a period of time similar to the one needed in the catalyst decay. Moreover, the validation of the model with experimental data given a good agreement results and show that the model is able to predict a correct monomer profile, polymerization rate, particle growth factor and MWD, an algorithm, which embeds physicochemical effects, has been developed to model the industrial reactors.

In this study, polyvinylidenefluoride (PVDF) flat sheet membranes were fabricated by immersing into various concentrations of ethanol in water (M-1:0%, M-2:25%, M-3:50% and M-4:75% respectively) as the coagulation bath via a non-solvent induced phase-inversion (NIPS) method. It was observed that the presence of ethanol affected the properties of the membranes. Low concentration of ethanol improved the hydrophobicity of the membranes. It also caused the formation of smaller pore size with more uniform, narrower pore distribution. Hydrophobicity of the fabricated membranes increased when the concentration of ethanol was raised. The absorption of carbon dioxide, CO2 in 2-amino-2-methyl-1-propanol (AMP), 1 M was also studied in a Membrane Gas Absorption (MGA) system where membranes M-2 and M-4 had better mass transfer and higher CO2 fluxes. CO2 removal efficiency, eta generally decreased with time for all membranes and had the highest value for M-2. The increasing trend of CO2 removal efficiency for all membranes was as follows: M-1 < M-3 < M-4 < M-2 which indicates membrane with higher porosity has higher absorption rate. Stability of membranes was tested for 150 min of operation. Membrane wettability was observed to be dependent on hydrophobicity of each membrane. Smaller pore size with higher hydrophobicity eliminates penetration of liquid into the pores. (C) 2011 Elsevier B.V. All rights reserved.

Modeling and experimental analysis for syndiospecific polymerization of styrene over silica-supported metallocene catalyst was carried out. A detail model was developed by coupling the single particle growth model (PGM) with particle population balance equation. The model was employed to predict the effects of intraparticle mass transfer limitations and the initial catalyst particle size on the rate of polymerization and the particle size distribution (PSD) of syndiotactic polystyrene (sPS). The single PGM, based on a modified polymeric multigrain model, was first utilized to calculate the single particle growth rate and polymerization rate under intraparticle mass transfer limitations and different initial catalyst particle sizes. Then, the model was solved simultaneously with particle population balance equation to estimate the PSD of sPS under the same limitations. The single PGM results showed a significant radial distribution of styrene concentration across polymer growth. It was further noticed that the diffusion resistance was most intense at the beginning of the polymerization reaction and the effects of polymerization rate were stronger. Moreover, it appeared that increasing the initial catalyst particle size led to lower rate of polymerization. The PSD simulation results revealed that the mass transfer limitation, as well as the initial catalyst particle size made a strong impact on the PSD of sPS. In addition, the simulation results obtained from this model showed good agreement results with experimental data of sPS.

Lamellar hydrotalcite (HT) was synthesized in the laboratory following combustion method. Tapai fueled HT was found to exhibit more orderly packed microstructure and was more crystalline in nature than its urea fueled counterpart, particularly at higher combustion temperature. The pore structure of tapai fueled HT resembled that of bottle neck with possibility of tapered with open-end that might also be present. The crystal size of tapai fueled HT was larger than urea fueled HT but greater size reduction was experienced by the former material, suggesting that more energy might have been supplied to the sample to disintegrate the particles, since tapai has higher and cleaner carbohydrate source than urea.

Experiments were carried out in order to evaluate the particle removal efficiency from a wafer surface by means of a buffing disk in a process for flow rates of chemical media ranging from 3.33×10−6m3/s to 6.67×10−6m3/s, buffing disc pressures of 6.894kPa to 20.684kPa and three relative speeds were used in the experiments. A mathematical model which considered the toppling of a particle as a result of forces due to friction, hydrodynamic drag, adhesion and capillary phenomena was developed in order to correlate the particle removal efficiency with the flow rate, buffing disc pressure and relative rotational speed. Results of simulations of the model showed a good agreement with the experimental data with satisfactory correlation coefficients.

A comprehensive mathematical model for styrene stereoregular polymerization was carried out. This model was generated by coupling the single particle growth model (SPGM) with kinetics model, to predict the effect of intraparticle mass transfer resistance and initial catalyst size on the polymerization kinetics. SPGM was derived based on a modified multigrain model (MMGM) to calculate the spatial-time evolution of styrene concentration under intraparticle mass transfer limitations. Then, the SPGM was solved simultaneously with kinetics model to estimate the polymerization rate and molecular weight distribution (MWD) under the above mentioned limitations. The results show that a significant radial distribution of styrene concentration across polymer growing. Moreover, the diffusion resistance was most intense at the early step of the polymerization and the effects of the polymerization rate are more strongly. Additionally, it is appear that increasing the initial catalyst size leads to a decrease in the rate of polymerization. For MWD, the model simulation show that the diffusion resistance led to have an increase in the molecular weight within a period of time similar to the one needed in the catalyst decay. The validation of the model with experimental data given a agreement results and shows that the model is able to predict monomer profile, polymerization rate, and MWD of syndiotactic polystyrene.

Colloidal silica particles, grown on a mesoporous silica layer using macroporous alumina substrate as a support, were used to separate hydrogen from carbon dioxide. The particles transformed into rectangular interlocking silicalite-1 structures with size approximately 8 × 4 × 4 μm, oriented epitaxially with film thickness of ca. 22 μm. The silicalite-1 particles grew in size due to the effect of structure directing agent (SDA), Oswald ripening and hydrothermal synthesis that promoted the growth of the colloidal particles into crystals. Permeation experiment using silicalite-1 showed that CO2 flux decreased and H2 flux increased with increase in temperature. The separability of H2 that was unity at the lower temperature became increased in value as the temperature was raised.

Hydrotalcite (HT) like compounds were successfully synthesized from combustion method using aluminum and magnesium nitrates, and potassium carbonate as solid precursors. Glucose was used as solid fuel to facilitate the reaction into mixed oxide and later HT structure at different combustion temperature. The combusted product initially formed disordered mixed oxides, but later returned to its original, more ordered HT state after being in contact with carbonate solution as analyzed from XRD. SEM analysis showed that the sample's microstructure was more orderly packed, less granular and more refined than its mixed oxide counterpart. The EDX analysis showed that the elemental potassium was the strongest energy binding in the hydrotalcite network followed by Al, Mg, O and C.

Hydrotalcite-like compounds (HT) were synthesized following a combustion-recrystallization-impregnation procedure using aluminum, magnesium nitrates precursors and carbonate solutions. Different types and amount of fuels, different amount of carbonate and different synthesis temperature were used during HT synthesis in order to understand their roles in forming HT structure and CO2 adsorption level. It was discovered that the addition of fuels to facilitate the reaction into mixed oxides and later HT influenced the capacity of CO2 adsorption. Beside type and amount of fuels, the carbonate amount and synthesis temperature also played important roles in forming the HT structure and thus, the CO2 adsorption level. The highest adsorption capacity was observed at 1.21 mmol/g by K-Na HT (K of 18.5% and Na of 1.5%) at operating temperature of 300 degrees C and 0.4 bar of CO2 partial pressure in the presence of N-2 (equivalent to total pressure of 1.34 bar). The HT exhibited Type IV isotherm, a typical mesoporous and slit shape pore material with pore size of 5.4 angstrom and BET surface area of 124 m(2)/g. (C) 2010 Elsevier Inc. All rights reserved.

Calcium phosphate fertilizer pellets coated with mixtures of wax and nano calcium oxide were studied for release rates of phosphate through the coating. The composition of the coating mixture has been of 0%, 20% and 30% nano-CaCO3 by weight in the wax solution. The pellets were exposed to solutions of pH 4, pH 7 and pH 9.2 in a reactor in an experimental set-up. Trends of release rates with pH were investigated. Results show that increasing composition of nano-CaCO3 in wax coating layer and decreasing of pH condition increased the nutrient transfer rate to the surrounding. The combination of different compositions of nano-CaCO3 in wax coating layer showed possibilities to control the nutrient release rate and thus reducing the environmental pollution effect and enhance economic efficiency. Parameters with respect to a model fitting the experimental data were evaluated.

The objective of this study is to investigate the potential process for the removal of carbon dioxide (CO2) from flue gas using fundamental membrane contactor, which is a membrane gas absorption (MGA) system. The experiments consisted of microporous polyvinylidenefluoride (PVDF) flat sheet membrane with 0.1μm (as module I) and 0.45μm (as module II) pore size. 2-Amino-2-methyl-1-propanol (AMP) solution was employed as the liquid absorbent. The effect of AMP concentration was studied with variation in the range 1–5M. In addition, the experiments were carried out with 10%, 20%, 30% and 40% gas ratio of CO2 to N2 and pure CO2 as well. Through contact angle measurement, membranes for module I and module II were obtained with CA values of around 130.25° and 127.77°, respectively. The mass transfer coefficients for module II are lower than those of module I for 1–5M of AMP. Furthermore, the increase in CO2 concentration in the feed gas stream enhanced the CO2 flux as the driving force of the system was increased in sequence from 1M to 5M of AMP. However, after the particular percentage (40%) of CO2 inlet concentration, the CO2 fluxes seem saturated. The combination of AMP as liquid absorbent and PVDF microporous membrane in MGA system has shown the potential to remove the CO2 from flue gas. In addition, the higher AMP concentration gave higher mass transfer coefficient at low liquid flow rates.

Lateral flow systems in nitrocellulose (NC) membranes are widely used for transport media applications related to immunoassays. The most important aspect of membranes is their ability to control the diffusion rate of the medium. This study investigated the effects of membrane pore size on lateral diffusion of protein molecules in a NC membrane. Both experimental work and mathematical modeling were carried out in this study. In modeling, the driving force for transportation of the diffusing molecule was the concentration gradient in lateral diffusion cell under unsteady diffusion. Diffusion experiments for Lysozyme and BSA were carried out by using different pore sizes of NC membranes. Good agreement was observed between the developed model and experimental results with correlation coefficients of more than 0.98. Effects of diffusion length and different diffusing molecules toward the lateral diffusion performance in NC membranes were also discussed extensively. The good fit between the model and experimental results has proven the reliability and flexibility of the lateral diffusion model developed in this study. The understanding of the diffusion phenomenon would be a useful tool for membrane properties design and customization of specific membrane applications in immunoassay.

This paper presents investigation results of saturation conditions needed for purification of jacalin lectin from the extract seeds of Artocarpus heterophyllus by ammonium precipitation and affinity chromatography on Galactose-Affi gel Hz. Three different aspects of parameters encompassing the percentage of saturation of ammonium sulfate precipitation, the presence of ammonium sulfate on Lowry method and the suitable galactose concentration for optimum elution of the protein from Galactose-Affi gel Hz were investigated. With three different sets of fractional saturation of jacalin purification using ammonium sulfate precipitation, the maximum yield of 0.463 g/g was achieved at 0-90% saturation range in the absence of dialysis. Maximum yield of 0.425 g/g was obtained at 30-60% and 0-90% saturation range in the presence of dialysis. The result from this work also indicates that excessive quantity of NH4SO4 interferes with Lowry method for protein determination substantially. The 0-90% saturation range was found to be more potentially appropriate for large scale application than 30-60% saturation, since the former involves only 1 step NH4SO4 addition. From the affinity chromatography, elution of 0.2 M galactose (in 0.15 M NaCl) from Galactose-Affi gel Hz produced the maximum peak profile and jacalin concentration. A reduction or increase in galactose concentration of more than 0.2 M did not increase concentration of purified jacalin purified using this method.

Several studies have indicated that effective diffusion coefficients of slices apparently vary with the thickness of the samples. Even though the effective diffusion coefficients have been observed to be dependent on the square of the slice thickness, a theoretical explanation to this behavior is not available to date. A theoretical model is formulated herein, in order to correlate effective diffusion coefficient of moisture in the slices with the slice thickness. Experiments are carried out for drying of slices of different thicknesses of banana, cassava and pumpkin in order to evaluate the effective diffusion coefficients. The model is found to describe the variation of the effective diffusion coefficient with slice thickness very satisfactorily. A possibility of the estimation of the axial and radial diffusion coefficients of moisture in the slices is also outlined.

This paper introduces a facile technique for the calculation of the thermodynamic properties of a gas across a porous membrane. The calculation assumes that the gas undergoes temperature-driven isobaric condensation, pressure-driven isothermal expansion and temperature-driven isobaric evaporation. The gas is in a disordered and chaotic state in all the three processes as a result of the kinetic energy by the driving forces. A zero entropy value is achievable at a remote distance from the membrane after desorption takes place. The deviation of the entropy from zero for isobaric evaporation is indicative of the irreversibility of the process. In contrast, the convergence of the entropy towards zero for the other two systems is indicative of the near-reversibility of the process.