Flat Sheet Membrane Contactor Research Articles

Hybrid enzymatic CO2 capture process in intensified flat sheet membrane contactors with immobilized carbonic anhydrase

A hybrid enzymatic CO2 absorption process in an intensified flat sheet membrane contactor with immobilized human carbonic anhydrase II (hCA II) enzyme was proposed. In addition to be immobilized on the membrane surface, extra carbonic anhydrase enzyme was immobilized on the surface of magnetic nanoparticles (MNPs) dispersed in the liquid phase to reduce the mass transfer limitations and enhance the absorption process. This hybrid enzymatic process is beneficial to attain high CO2 absorption rates, even if a component of the enzymatic system, either the biocatalytic membrane or biocatalytic MNPs, does not operate appropriately. The improvement CO2 hydration in the presence of biocatalytic MNPs was more significant at lower CA loadings on membrane surface. Reusability of the biocatalytic membranes and biocatalytic MNPs was demonstrated by 10 absorption cycles and the intensified membrane contactor displayed stable operation for several hours. A multiscale mathematical model (under gas-filled or partially liquid-filled membrane pores conditions) was proposed to explore the behaviour of the intensified membrane contactor. Model simulations showed that the resistance to mass transfer in membrane wetted zones is overcame by the CO2 enzymatic absorption in these zones (catalyzed by enzyme immobilized in membrane pores) and possible by the absorption of CO2 in the presence of biocatalytic MNPs.

Enzyme-immobilized flat-sheet membrane contactor for green carbon capture

• Enzyme-mediated CO 2 capture in a flat-sheet gas–liquid membrane contactor. • Biocatalytic membranes with immobilized carbonic anhydrase on amine functionalized PP. • Multiscale modeling considering enzyme attached on membrane surface and inside pores. • Mass transfer in wetted pores mitigated by enzymatic CO 2 hydration inside the pores. Membrane contactors (MC) represent an attracting system for CO 2 capture due to the enhanced mass transfer and gas–liquid interfaces, modularity, and compactness. A novel gas–liquid MC with biocatalytic flat sheet membrane was developed. The biocatalytic membrane was prepared via co-deposition of polydopamine (PDA)/ polyethyleneimine (PEI) and covalent bonding of carbonic anhydrase (CA) on polypropylene (PP) flat sheet membrane, using different deposition and enzyme immobilization conditions. The highest CA activity was achieved for 7 h deposition time, PDA/PEI ratio = 2/2, 1.0 (v/v)% glutaraldehyde, 0.8 mg/ml CA solution, 32 h immobilization time, and pH 6.0 in the immobilization process. The biocatalytic membrane showed good storage stability after 40-day. The MC performance was investigated under various conditions, including buffer type/concentration, liquid flow rate, temperature, and counter-current/co-current operating conditions. A CO 2 absorption flux of 0.29 × 10 -3 mol/m 2 s was obtained when the biocatalytic membrane was integrated into a flat sheet MC and 100 mM Tris in water was used in the absorption process. The absorption rate stability of the biocatalytic MC was also examined for several hours to verify the potential of the new flat sheet bioreactor in industrial applications. A multiscale model (with gas-filled or partially liquid-filled membrane porous structure and enzyme attached on the surface of the membrane and inside the pores) was developed to investigate the behaviour of the MC. Overall, the employment of biocatalytic membrane in flat sheet MC is a novel, green, and environmentally friendly approach allowing CO 2 capture with water (in presence of buffer) as absorbent.

Chromium (VI) removal by Aliquat-336 in a novel multiframe flat sheet membrane contactor

Recently designed, a multiframe flat sheet membrane contactors (MF-FSMC), consisting in ten parallel frames alternating aqueous and organic phase, was successfully used for chromium (VI) removal from aqueous solution. As a result, five chambers contain aqueous phase and the others contain the organic phase. Aliquat-336 was used as a carrier using polypropylene flat sheet membrane for Chromium (VI) removal. The results show that the extraction was more efficient by increasing the inlet chromium concentration and the number of frames but was not affected by the increasing of the thickness of frames (volume of chambers).To determine the interaction between different parameters, a full factorial design of experiment was used. The results show that the concentration of Aliquat-336 was the most important parameter, decreasing the efficiency of the system when increasing its concentration. Moreover, the temperature and the membrane contact aera have a positive effect on the extraction efficiency. However, no interaction effects were found in the chosen interval. The optimal values of different parameters are 10 % for Aliquat-336 concentration, 59 cm2 for the membrane contact area and 40 °C for the temperature.

Polymer Blends for Improved CO2 Capture Membranes.

We investigated the possibility of improving the performance of polysulfone (PSf) membranes to be used in carbon dioxide capture devices by blending PSf with a commercial polyethylene imine, Lupasol G20, previously modified with benzoyl chloride (mG20). Additive amount ranged between 2 and 20 wt %. Membranes based on these blends were prepared by phase inversion precipitation and exhibited different morphologies with respect to neat PSf. Surface roughness, water contact angles, and water uptake increased with mG20 content. Mass transfer coefficient was also increased for both N2 and CO2; however, this effect was more evident for carbon dioxide. Carbon dioxide absorption performance of composite membranes was evaluated for potassium hydroxide solution in a flat sheet membrane contactor (FSMC) in cross flow module at different liquid flow rates. We found that, at the lowest flow rate, membranes exhibit a very similar behaviour to neat PSf; nevertheless, significant differences can be found at higher flow rates. In particular, the membranes with 2 and 5 wt % additive behave more efficiently than neat PSf. In contrast, 10 and 20 wt % additive content has an adverse effect on CO2 capture when compared with neat PSf. In the former case, a combination of additive chemical affinity to CO2 and membrane porosity can be claimed; in the latter case, the remarkably higher wettability and water uptake could determine membrane clogging and consequent loss of efficiency in the capture device.

Chromium(VI) Removal by Polyvinyl Chloride (PVC)/Aliquat-336 Polymeric Inclusion Membranes in a Multiframe Flat Sheet Membrane Module

A new multiframe flat sheet membrane contactor module containing several flat membranes was designed and implemented. Each frame contains a chamber (central hole) in which the feed and the receiving phases are put in contact with polyvinyl chloride (PVC)/Aliquat-336 polymeric flat sheet membranes for Cr(VI) removal from aqueous solutions (feed phase). To evaluate the efficiency of the system, the experimental design methodology was used to analyze the effect of temperature (T, °C), PVC/Aliquat-336 ratio, and Cr (VI) concentration in the feed phase and the concentration of sodium chloride (NaOH-NaCl) in the receiving phase. Two representative mathematical models of the two responses (extraction and back-extraction) were respectively obtained. A good correlation between the experimental results and those predicted (RS2 = 97.77 and RR2 = 97.87) was achieved, allowing the optimization of the different factors selected for each response, separately. The proposed system showed a good separation performance, leading to Cr(VI) extractions up to 93% when working at the optimized operating conditions.

Carbon Dioxide Desorption from Amine Solution in a Nonporous Membrane Contactor

Long-term testing of a membrane contactor based on a blend of the nonporous polymers polytrimethylsilylpropyne (PTMSP) and polyvinyltrimethylsilane (PVTMS) has been carried out. The flat-sheet membrane contactor has been tested for CO2 desorption from an aqueous methyldiethanolamine solution at 100°C. It has been found that the mass transfer parameters (CO2 flux and stripping efficiency) of the 95%PTMSP/5%PVTMS membrane stabilize after the 7th day of testing. The CO2 mass transfer coefficient in the membrane contactor has been evaluated, and optimal desorption parameters have been determined.

Modeling and Experimental Study of Carbon Dioxide Absorption in a Flat Sheet Membrane Contactor

comIn the present study, CO2 removal from natural gas stream has been studied using a flat sheet membrane contactor. A three dimensional mathematical model is developed to describe the process. The model considers the transport of a gas mixture containing carbon dioxide and methane through a flat sheet membrane contactor module. The model is based on the non-wetted mode of operation, in which the gas fills the membrane pores in a countercurrent gas-liquid contact. Simulation was performed using computational fluid dynamics (CFD) of the model material and momentum transport equations in the flat sheet membrane for laminar flow conditions. Physical and chemical absorptions were considered in the simulations for the absorption of CO2 in aqueous sodium hydroxide solution. Simulation predictions were in good agreement with the experimental data for different values of gas flow rates. The modeling predictions indicate that the removal of CO2 increased with increasing inlet liquid flow rate and increasing solvent temperature, by contrast, increase in inlet gas flow rate has negative effect.

Performance evaluation and mass transfer study of CO2 absorption in flat sheet membrane contactor using novel porous polysulfone membrane

The performance of gas-liquid membrane contactor for CO2 capture was investigated using a novel polysulfone (PSF) flat membrane prepared via non-solvent phase inversion method. Polyvinyl pyrrolidone (PVP) was used as an additive in the dope solution of PSF membranes. Morphological studies by scanning electron microscopy (SEM) analysis revealed that PSF membrane with PVP has a finger-like structure, but the PSF membrane without PVP has a sponge-like structure. Also, characterization results through atomic force microscopy (AFM) and contact angle measurement demonstrated that the porosity, surface roughness and hydrophobicity of the PSF membrane increased with addition of PVP to the dope solution. Mass transfer resistance analysis, based on CO2 absorption flux, displayed that addition of PVP to the dope solution of PSF membrane decreased membrane mass transfer resistance, and significantly improved CO2 absorption flux up to 2.7 and 1.8 times of absorption fluxes of PSF membrane without PVP and commercial PVDF, respectively.

CFD simulation of water transport through porous membrane evaporators

Membrane evaporation (ME) presents interesting working conditions including low operating temperature and also low energy consumption. These advantages make the process attractive for concentration of aqueous solutions containing heat-sensitive components. Performance of ME process carried out in a flat-sheet membrane contactor was studied theoretically in this work. A three-dimensional mathematical model was developed to predict the performance of ME process. The concentration, momentum, and energy equations were solved for description of process. Finite element method was utilized for solution of governing equations and simulation of process. By obtaining the concentration distribution, the flux of water evaporation was determined and compared with the experimental data reported in literature. It was also indicated that the developed three-dimensional model is appropriate for the prediction of the performance of membrane evaporators. The simulation results revealed that enhancement of velocity of liquid phase increases evaporation flux of water.

Modeling and CFD Simulation of Water Desalination Using Nanoporous Membrane Contactors

A two-dimensional comprehensive model was developed to predict the transport of water in the nanoporous membrane contactors. The considered membrane distillation device was a counter-current flat-sheet membrane contactor for production of pure water from saline water. The developed model formulates the fundamental transport equations of heat, mass, and momentum in the membrane contactor. The computational fluid dynamics techniques were applied for numerical simulation of model equations. The simulation results were compared with experimental data obtained from literature and showed great agreement with the measured values. A combination of the Knudsen flow and Poiseuille flow was used in the model for estimation of diffusion inside the membrane pores and increased the accuracy of the model. Simulation results revealed that, in the regions adjacent to the membrane wall, the temperature difference is significant. This could be attributed to the fact that a temperature boundary layer is formed near the membr...

Simulations of solute concentration profile and mass transfer behavior near the membrane surface with finite volume method

Membrane gas absorption technique is one of the most attractive alternatives for CO2 capture. In this paper, a mathematical model for membrane gas absorption process has been developed to describe the solute concentration profile and the mass transfer behavior near the membrane surface, which are important factors for the process. The finite volume method is used to solve the model. The modeling results show that the different solute diffusing distances in the vertical and parallel directions near the membrane surface result in varied concentration profiles. For the membrane with small pore size, the solute concentration profile near the membrane surface can reach uniform distribution instantly, and the membrane porosity has little effect on mass transfer. Contrarily, for the membrane with large pore size, especially at higher absorbent pH value or liquid velocity, the solute concentration distribution is comparatively non-uniform. The mass transfer is significantly affected by membrane porosity. That is the mass transfer coefficients are varied at different membrane porosities. Experiments are conducted to verify the model for CO2 removal using flat sheet membrane contactor with de-ionized water or NaOH solution as absorbents. The comparison between the experimental results and the prediction results shows that the model is validated.

Theoretical studies on separation of CO2 by single and blended aqueous alkanolamine solvents in flat sheet membrane contactor (FSMC)

Abstract Absorption of carbon dioxide by different single and blended alkanolamine solvents were studied theoretically using flat sheet membrane contactor. The solvents considered for this study include aqueous solutions of monoethanolamine (MEA), diethanolamine (DEA), N-methyldiethanolamine (MDEA) and 2-amino-2-methyl-1-propanol (AMP) as well as aqueous blends MEA or DEA with AMP or MDEA. Simulation study shows that the absorption flux for CO2 with aqueous solution of MEA was the highest among the single amines solvents studied. There is an increase in CO2 absorption flux with the increase in the concentration of MEA or DEA in the blends of (MEA + MDEA), (DEA + MDEA) and (MEA + AMP). For the (DEA + AMP) system the flux of CO2 is found to have a marginal effect with different blend compositions. The blends of (MEA + MDEA) and (MEA + AMP) are found comparatively suitable for the absorption of CO2 among all the blends. The performance of flat sheet membrane contactor is found to be better than that of hollow fiber membrane contactor if only the absorption flux of CO2 in the amine is considered.

Mass transfer studies in flat-sheet membrane contactor with ozonation

Ozone mass transport in the flat-sheet membrane contactor with chemical reaction in the liquid phase has been investigated. The ozone mass transfer coefficients without reaction in the liquid phase were indirectly determined by the oxygen transfer measurement with the steady state method. The oxidation of nitrite to nitrate was utilized to study mass transfer with ozonation. The ozone fluxes and the enhancement factors ( E) were predicted by the facilitation of the resistance-in-series model together with the film and surface renewal models. The performance of the designed membrane modules was assessed by the decolorization of NOM solutions and indigo reagent I. The ozone mass transfer coefficients from oxygen transport experiments were considerably higher than those calculated from the available correlations but provided good predictions for ozone fluxes for pure water. The ozonation accelerated mass transfer in membrane contactor by 6–100 times in this study. The experimental results validated the proposed methods for the predictions of the ozone fluxes and the enhancement factors. The average discrepancies between the experimental and calculated results were 6% for the ozone flux predictions and 3% for the enhancement factor predictions. The resistances to the ozone mass transfer with and without chemical reaction were controlled by the liquid film. The ozone consumption for the NOM decolouriration in the membrane contactor was considerably lower than that in a conventional bubble column.