Concentration In Liquid Phase Research Articles

In situ investigations on the amorphous to crystalline phase transformation of precursors for methanol synthesis catalysts

Two in situ methods are presented to study phase transformations in the synthesis of Cu/Zn hydroxycarbonates as catalyst precursors for industrial methanol production. In contrast to the well-established application of in situ FTIR probes in the detection of liquid phase concentrations, we evaluated spectra arising from the structural changes in the solid phase during the transformation of amorphous georgeite to nanocrystalline zincian malachite. Further, a novel microreaction system is employed to gain statistical insight on the scattering of the reaction time as a function of various process parameters. The obtained transformation kinetics during aging are described by a model based on the theory of solvent-mediated phase transformations showing excellent agreement with experimental results. The quantitative impact of temperature, concentration and zinc content on dissolution, nucleation and growth of the respective phases is discussed.

Role of hydrogen (H2) mass transfer in microbiological H2-threshold studies.

Gas-to-liquid mass transfer of hydrogen (H2) was investigated in a gas-liquid reactor with a continuous gas phase, a batch liquid phase, and liquid mixing regimes relevant to assessing kinetics of microbial H2 consumption. H2 transfer was quantified in real-time with a H2 microsensor for no mixing, moderate mixing [100 rotations per minute (rpm)], and rapid mixing (200rpm). The experimental results were simulated by mathematical models to find best-fit values of volumetric mass transfer coefficients-kLa-for H2, which were 1.6/day for no mixing, 7/day for 100rpm, and 30/day for 200rpm. Microbiological H2-consumption experiments were conducted with Methanobacterium bryantii M.o.H. to assess effects of H2 mass transfer on microbiological H2-threshold studies. The results illustrate that slow mixing reduced the gas-to-liquid H2 transfer rate, which fell behind the rate of microbiological H2 consumption in the liquid phase. As a result, the liquid-phase H2 concentration remained much lower than the liquid-phase H2 concentration that would be in equilibrium with the gas-phase H2 concentration. Direct measurements of the liquid-phase H2 concentration by an in situ probe demonstrated the problems associated with slow H2 transfer in past H2 threshold studies. The findings indicate that some of the previously reported H2-thresholds most likely were over-estimates due to slow gas-to-liquid H2 transfer. Essential requirements to conduct microbiological H2 threshold experiments are to have vigorous mixing, large gas-to-liquid volume, large interfacial area, and low initial biomass concentration.

Implementation of electrolyte CPA EoS to model solubility of CO2 and CO2 + H2S mixtures in aqueous MDEA solutions

Abstract The electrolyte version of SRK plus association equation of state (eSRK-CPA EoS) was employed to correlate CO2 solubility in MDEA aqueous solutions. The applied model comprises the classic form of CPA EoS including SRK EoS plus Wertheim association term in addition to MSA theory and Born terms so that the two last terms are responsible for the long-range interactions. A reaction-containing bubble pressure computation technique comprising two nested loops was utilized to model the systems. The internal loop, calculates the liquid phase concentrations via reaction, mass and charge balance equation solving, whereas, the vapor phase concentrations will be obtained in the external one. 470 experimental data were used to correlate binary subsystems and the H2O + MDEA + CO2 ternary system. Since, there not exist any binary VLE data for MDEA + CO2 subsystem, two fitting scenarios were applied. At the first scenario, the binary interaction parameter was assumed equal to zero, while, in second approach the parameter was obtained through ternary system correlation. Both scenarios show very good accuracy in that the Absolute Average Deviation percentages (AAD) obtained were 19.12% and 18.85%, respectively. Also, to show the efficiency of the used model, a comparison between our results and those of the best-known models was made. Finally, having model parameters for H2S solubility from our previous work [A. Afsharpour, Petroleum Science and Technology 35 (3) (2017) 292-298], simultaneous solubility of CO2 + H2S mixtures in MDEA solutions was predicted using the eSRK-CPA EoS with no new optimizable parameters. As the results show, the applied model has a good performance for correlation and prediction of acid gas solubility in a wide range of pressures, temperatures, acid gas loadings, and MDEA concentrations.

Volumetric mass transfer coefficient for carbon monoxide in a dual impeller stirred tank reactor considering a perfluorocarbon–water mixture as liquid phase

Overall volumetric mass transfer coefficient (kLa) of carbon monoxide in a perfluorocarbon–distilled water mixture was evaluated in a dual impeller stirred tank bioreactor (Rushton-type and Smith-type). Two agitation speeds (300 and 500 rpm), three specific gas flow rates (2.0, 2.5 and 2.7 vvm), two working volumes (0.75 and 1 L) were tested, as well as four different liquid phase compositions: pure distilled water; distilled water and perfluorodecalin (PFC); distilled water and Tween® 80; and distilled water, PFC and Tween® 80. CO concentration in liquid phase was determined using a myoglobin bioassay technique and kLa and saturated CO concentration were determined using Maximum Likelihood Estimation (MLE) with a hybrid optimization strategy. A maximum kLa of 603.48 h−1 was obtained at 500 rpm, 2.7 vvm and distilled water, PFC and Tween® 80 as liquid phase. Tween® 80 was responsible for increasing mass transfer when mixing these three components comparing to a liquid phase composed of PFC and distilled water (7 time increase at 2.7 vvm and 500 rpm), and pure distilled water (2.9 time increase at 2.0 vvm and 1.6 times at 2.5 vvm). Moreover, MLE proved to be a valuable tool to critically analyse experimental uncertainty in parameter estimation.

Electrochemical model of lithium ion battery with simplified liquid phase diffusion equation

The pseudo-two-dimensional (P2D) model is the most widely used electrochemical model for lithium-ion batteries. Because of the complexity and the difficulty in using the complete P2D model, many simplified P2D models, such as the single particle model (SP model) and the parabolic profile approximation model (PP model), have been proposed. However, the using of the SP model can cause a large amount of precision to lose in its simplified process, while the PP model has a high complexity. In this paper, we propose a liquid phase simplification P2D (LSP2D) model. The using of the LSP2D model has a small precision loss and a relatively low complexity. The LSP2D model is based on the electrochemical average kinetics of the lithium ion battery. We first simplify the terminal voltage into an equation containing only the solid phase concentration <i>c</i><sub>s</sub> and the liquid phase concentration <i>c</i><sub>e</sub>. Then we use the partial differential equation to represent the solid phase concentration <i>c</i><sub>s</sub> and the liquid phase concentration <i>c</i><sub>e</sub>, and then obtain a final model. The simulation environment is based on COMSOL, and the simulation results show that when the discharge rate is 1C, the estimation accuracy and speed from the LSP2D model are similar to those from the SP model. But when the discharge rate is 3C, the estimation time from the LSP2D model is reduced by 99.73% compared with that from the P2D model, and the estimation accuracy is greatly improved compared with the estimation accuracy from the SP model.

Magnesium absorption as influenced by the rumen passage kinetics in lactating dairy cows fed modified levels of fibre and protein

The potassium sensitive magnesium absorption through the rumen wall may be influenced by additional dietary properties, such as diet type, forage type or forage to concentrate ratio. These properties are likely associated to rumen passage kinetics modified by dietary fibre content. The study aimed to assess the effects of rumen passage kinetics on apparent Mg absorption and retention in lactating dairy cows fed modified levels of fibre. Six lactating Red-Holstein and Holstein cows, including four fitted with ruminal cannulas were randomly assigned to a 3 × 3 cross-over design. The experimental diets consisted of early harvested low NDF (341 g NDF/kg DM) and late harvested high NDF (572 g NDF/kg DM) grass silage (80% DM) and of concentrates (20% of DM). As the low-fibre diet was excessive in protein, a third high-fibre diet was formulated to be balanced in digestible protein with the low-fibre diet to avoid any eventual confounding effects of NDF and protein excess. All diets were formulated to contain iso-Ca, -P, -Mg, -K and -Na. Passage kinetics of solid and liquid phase of rumen digesta were evaluated using ruminal marker disappearance profiles. Cows fed the low-fibre diet had compared to the other diets, an up to 40% lower solid and 26% lower liquid phase volume of rumen digesta and a 10% numerically higher fractional rumen liquid passage rate. Rumen pH lost 0.6 units and Mg concentration in the rumen liquid phase tripled when cows were fed the low-fibre diet. Faecal Mg excretion was up to 14% higher in cows fed the low-fibre diet and Mg absorbability was 12% compared to up to 19% in other diets. Urinary Mg excretion in cows fed the low-fibre diet was half of the ones in the other treatments, but Mg retention was not affected. Dietary protein excess neither affected rumen passage kinetics nor Mg absorption and retention. Absorption of Mg was correlated with rumen liquid volume which both decreased with decreasing daily NDF intake (NDFi, 11.8 ± 2.4 l/kg NDFi). Consequently, daily Mg absorption decreased by 1.32 ± 0.28 g/kg decreasing NDFi. To conclude, in addition to the known antagonistic effect of dietary K, the present data indicate that Mg absorption was dependent from NDFi which modified rumen liquid volume, but was independent of dietary protein excess likely associated to low NDF herbages.

Preparation and Properties of Pseudo-boehmite Obtained from High-Alumina Fly Ash by a Sintering–CO2 Decomposition Process

A sintering–CO2 decomposition process for preparation of pseudo-boehmite is proposed for clean valorization of high-alumina fly ash. The effects of different synthesis conditions on the crystal structure and textual properties of the pseudo-boehmite were studied systematically. The results showed that the main product was NaAlCO3(OH)2 when the decomposition terminal pH was below 9.5, and the optimal terminal pH for the pseudo-boehmite (PB) product was 10.5. The optimal aging time was 4 h, and the peptization ratio of PB reached 97.5% when the aging temperature was 90°C. Under decomposition conditions of 30 g/L initial alumina concentration in liquid phase and temperature of 40°C, followed by 4 h of aging treatment, the specific surface area of PB was 425 m2/g. The pore volume of PB product reached 0.6920 cm3/g at decomposition conditions of 40 g/L and 30°C.

Insight into the effect of glycerol on stability of globular proteins in high protein model system

A model system was established to investigate the effect of glycerol on stability of globular proteins. To study whether protective effect of glycerol is dependent on the nature of protein, four kinds of globular protein were used including α-lactalbumin, β-lactoglobulin, native lactoferrin and lysozyme. Differential scanning calorimetry (DSC) was used to study the thermal stability of the proteins with glycerol aqueous (0–80% v/v). The results showed that the stability of β-lactoglobulin and lysozyme (hydrophobicity-dominated proteins) increased with glycerol concentration. However, that of α-lactalbumin and lactoferrin (metalloproteins), regardless of the ion-binding state, initially increased and then decreased. Different protective effects were observed beyond 50% (v/v) glycerol concentrations in liquid phase. The secondary structure and tryptophan exposure remained unchanged. In conclusion, the protection of glycerol on protein stability was highly dependent on the nature of proteins.

Pd-Pt bimetallic Nb-doped TiO2 for H2 photo-production: Gas and liquid phase processes

The performance of binary PtPd co-catalysts supported on Nb-TiO2 was tested in the gas and liquid phase photo-reforming of methanol. Co-catalyst formulations having Pt:Pd ratios from 2:1 to 1:4 were tested and the activity measured through the calculation of the quantum efficiency. Characterization of the initial and post-reaction materials showed that optimum activity is achieved in both processes by samples containing binary co-catalysts where Pd suffers an oxidation process and a PtPd alloying metallic phase is formed under reaction conditions. The analysis of catalytic output through an experimental design considering tree factors (methanol:water ratio, irradiance level, and catalyst volumetric concentration at liquid phase or surface concentration at gas phase) shows that the liquid phase process presents a rather high quantum efficiency value compared with the gas phase but the latter process displays higher atom efficiency as well as renders products with lower toxicity.

Mechanism, ab initio calculations and microkinetics of straight-chain alcohol, ether, ester, aldehyde and carboxylic acid hydrodeoxygenation over Ni-Mo catalyst

Hydrotreatment of bio-based model compounds was investigated in a three-phase slurry reactor over pre-sulphided NiMo/γ-Al2O3 bifunctional catalyst. Experimental results were supported by comprehensive in silico studies. Mathematical microkinetic model was developed for mass transfer phenomena, adsorption, desorption and surface kinetics description, while quantum chemical calculations were performed for the proposed reaction mechanism validation. Every moiety followed the same chemical reduction sequence as its predecessor down the oxidation ladder, except of aldehyde. Experiments using hexanal as a model compound resulted in its extraordinary high concentrations in liquid phase and on the catalyst surface, which led to mutual aldol condensation. However, this reaction was not observed when aldehyde was formed as an intermediate from hexanoic acid or methyl hexanoate, due to its low concentration and high hydrogen availability which promoted further hydrogenation into hexanol. C12/C6 (aldol condensation/hydrogenation) product ratio increased with higher temperature, reflecting higher activation energy (EA) for hexanal condensation compared to negligible hydrogenation energy barrier, confirmed by density functional theory (DFT) calculations. Primary alcohols are more resistant to HDO compared to secondary counterpart (studied in previous work) over NiMo/γ-Al2O3, specifically; the activation energy of 1-hexanol deoxygenation to olefin was 43% higher compared to secondary hexanols according to microkinetic model, and 45% higher according to quantum mechanics calculations. Primary alcohols are also extensively dehydrated into ethers, which was never the case for secondary alcohols at tested reaction conditions, while aldehydes are much easier to hydrogenate than ketones, which cannot undergo CC coupling reactions.

Achieving More Efficient and Reliable Operation of Geothermal Turbines by Using a Secondary Flash Steam Superheating System

Problems encountered in operation of saturated steam geothermal turbine units that stem from the specific features of a geothermal heat carrier are considered. A two-phase state, increased content of salts, and corrosiveness of geothermal working medium have a negative influence on the efficiency and reliability of the turbine’s first and last stages. Owing to high concentrations of impurities in the liquid phase, the first stages suffer from intense generation of deposits. The resulting decrease in the power output is due to both fouling of the flow path and significantly growing roughness of the turbine cascade blades. The flow of wet steam in the geothermal turbine flow path is accompanied by droplet impingement erosion of the last-stage blades and corrosion fatigue of the metal of rotor elements. In addition, the losses due to steam wetness in the flow path cause an essential decrease of the geothermal turbine efficiency. The article gives examples of erosioninduced damage inflicted to the last-stage rotor blades, corrosion fatigue of the metal of integrally-machined shroud elements, and deposits in the nozzle vane cascades of geothermal turbine stages. The article also presents the results from numerical investigations of the effect that the initial steam wetness has on the silicic acid concentration in the wet steam flow liquid phase in a 4.0 MW geothermal turbine’s stages. A method for achieving more efficient and reliable operation of the geothermal turbine low-pressure section by applying a secondary flash steam superheating system with the use of a hydrogen steam generator is proposed. The article presents a process arrangement for preparing secondary flash steam supplied to the geothermal turbine low-pressure section in which the flash steam is evaporated and superheated through the use of a hydrogen steam generator. The technical characteristics of the system for preparing secondary flash steam to be used in the intermediate inlet to the turbine were preliminarily assessed (taking the upgrading of the Mutnovsk geothermal power plant as an example), and it has been shown from this assessment that the wetness degree in the low-pressure section can be decreased down to its final value equal to 2.0%.

Cyclone separator for gas-liquid mixture with high flux density

The study is aimed at improvement of efficiency of a gas-liquid separator operating at the pressure of 2.5 MPa and high flux density in the cyclone body. The submitted schematic construction of the separator provides the reduced dynamic head of gas in the zones with increased liquid phase concentration and prevents the entrainment of separated liquid to the outlet receiver. The receiver consisting of a conical converging channel and an externally finned circular pipe is located in the middle of cylindrical cyclone body. A fin-and-tube flow conditioner is mounted upstream of the converging channel inlet. Detailed flow structure in the separator has been obtained from numerical study based on Reynolds-averaged Navier–Stokes equations with anisotropic Reynolds stress turbulence model. Simulation results were involved in estimation of the main performance characteristics of the separator and probability of droplet entrainment and upwards flowing film. Experimental research on a 1:2 separator model allowed estimation of separation efficiency and flow resistance coefficient of the separator.

A Study on DSLM Transporting the Rare Earth Metal La (III) with a Carrier of PC-88A.

This paper studies transmission behavior of La (III) in dispersed supported liquid membrane (DSLM) of dispersed phase constituted by dispersed supported liquid membrane solution and HCl solution with polyvinylidene fluoride membrane (PVDF) as support and kerosene as membrane solvent, with 2-ethyl hexyl phosphonic acid-single-2-ethyl hexyl ester (PC-88A) and two-(2-ethyl hexyl) phosphoric acid (D2EHPA) as mobile carrier. It also investigates the influence of La (III) transmission by the material liquid acidity, initial concentration of La (III), HCI concentration, membrane solution, and HCI solution volume ratio, resolving agent and carrier concentration, as well as concluding that the optimal transmission and separation conditions are dispersed phase of 4.00 mol/L HCl concentration, 30:30 volume ratio of membrane solution, and HCl solution, within 0.160 mol/L controlled carrier concentration and 4.00 pH value of material liquid. Under the optimal conditions, the La (III) initial concentration of material liquid phase is 8.00 × 10–5 mol/L mol/L, 125 min, and 93.9% migration rate. Under the condition of unchanged acidity of resolving phase, HCL, H2SO4, and HNO3 as resolving agent, at 125th min, the migration rates of La (III) are 93.9%, 94.0%, and 87.8%, respectively. HCl solution, H2SO4 solution, and HNO3 solution have a certain effect on the La (III) resolution, of which 4.00 mol/L HCl solution and 2.00 mol/L H2SO4 solution are better. The effect of HNO3 is slightly lower than HCl and H2SO4.

A three-color absorption/scattering imaging technique for simultaneous measurements on distributions of temperature and fuel concentration in a spray

A three-color imaging technique was proposed for simultaneous measurements on distributions of fuel/air mixture temperature and fuel vapor/liquid concentrations in evaporating sprays. The idea is based on that the vapor concentration is proportional to the absorption of vapor to UV light, the liquid-phase concentration is related to the light extinction due to scattering of droplet to visible light, and the mixture temperature can be correlated to the absorbance ratio at two absorbing wavelengths or narrow bands. For verifying the imaging system, the molar absorption coefficients of p-xylene at the three narrow bands, which were centered respectively at 265, 289, and 532 nm with FWHM of 10 nm, were measured in a specially designed calibration chamber at different temperatures (423–606 K) and pressure of 3.6 bar. It was found that the ratio of the molar absorption coefficients of p-xylene at the two narrow bands centered at the two UV wavelengths is sensitive to the mixture temperature. On the other hand, the distributions of fuel vapor/liquid concentrations can be obtained by use of absorbance due to ultraviolet absorption of vapor and visible light scattering of droplets. Combining these two methods, a simultaneous measurement on distributions of mixture temperature and fuel vapor/liquid concentrations can be realized. In addition, the temperature field obtained from the ratio of the two absorbing narrow bands can be further used to improve the measurement accuracy of vapor/liquid concentrations, because the absorption coefficients depend on temperature. This diagnostic was applied to an evaporating spray inside a high-temperature and high-pressure constant volume chamber.

Simultaneous Measurement of Vapor and Liquid Phase Concentration Distributions in Fuel Spray

Simultaneous Measurement of Vapor and Liquid Phase Concentration Distributions in Fuel Spray

Micropollutant removal from black water and grey water sludge in a UASB-GAC reactor.

The effect of granular activated carbon (GAC) addition on the removal of diclofenac, ibuprofen, metoprolol, galaxolide and triclosan in a up-flow anaerobic sludge blanket (UASB) reactor was studied. Prior to the reactor studies, batch experiments indicated that addition of activated carbon to UASB sludge can decrease micropollutant concentrations in both liquid phase and sludge. In continuous experiments, two UASB reactors were operated for 260 days at an HRT of 20 days, using a mixture of source separated black water and sludge from aerobic grey water treatment as influent. GAC (5.7 g per liter of reactor volume) was added to one of the reactors on day 138. No significant difference in COD removal and biogas production between reactors with and without GAC addition was observed. In the presence of GAC, fewer micropollutants were washed out with the effluent and a lower accumulation of micropollutants in sludge and particulate organic matter occurred, which is an advantage in micropollutant emission reduction from wastewater. However, the removal of micropollutants by adding GAC to a UASB reactor would require more activated carbon compared to effluent post-treatment. Additional research is needed to estimate the effect of bioregeneration on the lifetime of activated carbon in a UASB-GAC reactor.

Thermodynamic assessment of the chemical stability of (La0.8Sr0.2)0.98CrxFe1 − xO3 ± δ under oxygen transport membrane fabrication and operation conditions

A comprehensive thermodynamic study by applying the CALculation of Phase Diagram (CALPHAD) approach on (La0.8Sr0.2)0.98CrxFe1−xO3±δ (x=0.3, 0.5, 0.7) (LSCrF) has been carried out to investigate the effect of atmosphere, temperature, and B-site dopant concentration on phase stability, solid and liquid phase formation, and microstructural evolution in LSCrF. The simulation results for the chemical stability of LSCrF, exposed to oxygen partial pressure (PO2) from 0.21 to 10−10atm and temperature from 1000 to 1400°C, reveal the formation of solid corundum, spinel, La2SrFe2O7, and the liquid phase. The simulations also show the chemical reactions of solid secondary phases with the liquid and perovskites under both equilibrium cooling and fast cooling conditions. The phase stabilities of the LSCrF samples under oxygen transport membrane (OTM) sintering and operation conditions are predicted. The study provides guidance on the densification enhancement of the LSCrF bulk materials during the sintering process through the control of the liquid phase concentration and the perovskite phase separation. In addition, the concerns of the release of the genotoxic carcinogens, i.e. chromium hexavalent (Cr6+) gas species from LSCrF to the environment under the sintering and operation conditions are addressed for the first time.

Critical analysis of adsorption/diffusion modelling as a function of time square root

A very common procedure to evaluate intraparticle diffusion in batch adsorption experiments consists in plotting the adsorbed concentration versus the square root of time. Furthermore, some works present in this plot a sequence of linear sections, attributing a specific phenomenon to each one, such as external mass transfer resistance and intraparticle diffusion into pores of different sizes. In spite of this frequent approach, the mathematical foundations of this relationship are rarely presented. In this work, it is presented a complete description of the physical-chemical and mathematical basis that leads to the relationship between adsorbed quantity and time square root, evincing the necessary hypotheses for this relationship to become meaningful. It was observed that this relationship could only be applied within very restrictive conditions: adsorption in a semi-infinite solid and constant liquid phase concentration. Moreover, this relationship is strictly valid in the absence of external mass transfer resistance, for linear adsorption isotherm and instantaneous equilibrium of fluid and solid concentrations inside the pores. It is clear that these restrictions are scarcely achieved under usual batch adsorption experiments. Besides, multilinear plots used to differentiate among external diffusion and macro, micro and mesoporous diffusion are evidently shown to be very subjective and without any mathematical support.

Predicting Vapor-Phase Concentrations for the Assessment of the Odor Perception of Fragrance Chemicals Diluted in Mineral Oil

In this study, the Henry’s law methodology is applied to predict the release of odorants present in single and multicomponent fragrance mixtures diluted in mineral oil, a simplified matrix used in cosmetic products. To attain this goal, the experimental Henry’s law constant (H) of each odorant in each studied fragrance system (containing one, two, three, or four odorants) was first evaluated by plotting their liquid phase and experimental vapor phase concentrations assessed by headspace gas chromatography. From that point, the H value of each odorant in the multicomponent fragrance system was predicted from its corresponding Hexp in the single fragrance component system. The theoretical vapor-phase concentrations were also calculated using the activity coefficients for vapor–liquid equilibria by applying the thermodynamic UNIFAC model. The odor intensity and character of the studied fragrance systems were assessed through the Stevens’s power law and Strongest Component models (psychophysical models). This study confirmed that the headspace concentrations and odor intensity of each odorant present in a multicomponent fragrance mixture dissolved in mineral oil can be efficiently predicted from its corresponding H determined when present alone in the simplified matrix, for low concentrations. Also, comparing both methodologies, UNIFAC and Henry’s law, it was concluded that Henry’s law is a better predictive model for the vapor–liquid equilibria, showing lower deviations from the experimental data. Therefore, the proposed predictive mathematical model can be attractive for the assessment of sensory quality of multicomponent fragrance systems in early formulation stages.

Transport properties of CO2 and CH4 in hollow fiber membrane contactor for the recovery of biogas from anaerobic membrane bioreactor effluent

A significant amount of methane (CH4) produced from anaerobic digestions of wastewater is dissolved in liquid effluent and discharged. The recovery of dissolved CH4 is therefore essential in ensuring an enhanced energy production of the anaerobic processes, and minimizing environmental impacts of the greenhouse gas. In this work, a membrane contactor is employed as a mass transfer equipment for the CH4 recovery. A mathematical model considering simultaneous desorption of CH4 and carbon dioxide (CO2) is developed using a resistance-in-series model to calculate the overall mass transfer coefficients. The simulations were validated with experimental results obtained using an in-house fabricated hollow fiber membrane as well as a real effluent from Anaerobic Membrane Bioreactor (AnMBR) and synthetic effluent made of water saturated with biogas. Results showed that the CO2 fluxes were higher than those of CH4 fluxes due to its higher concentration in liquid phase. A decrease of liquid phase mass transfer resistance by an increase in liquid velocity significantly enhanced both CH4 and CO2 fluxes. While, an increase in gas velocity slightly affected the CH4 flux but enhanced the CO2 flux considerably. It was also found that the CO2 desorption increased the CH4 recovery rate. The desorbed CO2 helped to increase the mass transfer driving force by reducing the partial pressure of CH4 in the gas side, and enhancing the gas phase mass transfer coefficient to facilitate CH4 desorption. The increase of liquid velocity increased mole fraction of CH4 in the gas outlet but decreased the rate of CH4 recovery. On the other hand, applying vacuum conditions to decrease gas pressure enhanced the rate of CH4 recovery but lower the CH4 mole fraction in the product gas.