Hollow Fiber Membrane Contactor Research Articles

Lattice Boltzmann modeling for enhanced membrane separation of geothermal energy utilization

Reducing carbon emissions and utilizing geothermal energy via supercritical carbon dioxide extraction from reservoirs for direct power generation necessitates the removal of mixed vapor. A shell-tube hollow fiber membrane contactor, utilizing differential pressure and absorption fluid, is devised for vapor absorption. This membrane-based separation process encompasses a multicomponent multiphase system of supercritical carbon dioxide and water, water-salt transport, and mass transfer across the porous membrane. To investigate pore-scale mass transfer, a multicomponent multiphase pseudopotential lattice Boltzmann model is established, simulating carbon dioxide-water two-phase flow, coupled with a continuous species transfer model for salt behavior in the absorbent. Flow direction analysis reveals countercurrent flow as superior to cocurrent for vapor absorption. Augmenting the original membrane with equal macropore counts enhances mass transfer, with increasing size amplifying the effect. Macropore arrangements at constant porosity suggest minimizing resistance in the propagation path as crucial for mass transport improvement. A left-small-right-large macropore size gradient distribution outperforms its reverse counterpart, enhancing performance by approximately 20%. This is attributed to larger macropores in high-concentration regions facilitating localized vapor transport.

Modelling of carbon dioxide absorption in hollow fiber membrane contactor for different flow configurations

In the study of gas absorption using hollow fiber membrane contactor (HFMC), quantitative analysis between the parallel flow and crossflow configurations remains unclear, leading to difficulty in understanding the mass transfer behaviour in membrane module. Additionally, the presence of crossflow within the parallel flow influences the absorption performance but has not been considered in recent models. Hence, mathematical models were developed to assess the CO2 separation performance of the parallel flow and crossflow configurations. Subsequently, the developed models were adapted to investigate the impact of the crossflow effect on the HFMC separation performance. The succession of states method was proposed to model the membrane module, which showed good agreement when validated against experimental data (⩽14.9 % error). Comparison between the two configurations were conducted based on varying gas and liquid flow rates, number of fibers and inlet CO2 compositions. The crossflow HFMC demonstrated better performance (up to 50 % difference) in terms of CO2 % removal. Moreover, the consideration of crossflow effect showed significant improvement on simulation results when compared with experimental data (⩽ 1 % error). Hence, this study indicates that crossflow effect does exist within parallel flow and the developed mathematical model serves as the basis towards modelling an actual HFMC for gas absorption.

Concentrating Nitrogen Waste with Electrodialysis for Fertilizer Production.

Recovery of nitrogen from wastewater presents a unique opportunity to valorize waste and contribute to a more circular nitrogen economy. However, dilute solution separations are challenging for most state-of-the-art separations technologies. This often results in technologies having low concentration factors that result in low-value products (e.g., < 1 wt % N). Here, we demonstrate how a cascading electrodialysis system combined with a hollow fiber membrane contactor (ED+HFMC) system can achieve efficient recovery of ammonia from simulated centralized animal feeding operation (CAFO) wastewater. The integrated system achieved an overall concentration factor of ∼200× (∼40× in ED and ∼5× in HFMC). This resulted in a ∼10 wt % NH4 +-N fertilizer product. The specific energy consumption (SEC) for the three stages of the ED was 1.89-6.14 kWh/kg NH4 +-N, which is lower than that of the Haber-Bosch process (8.9-19.3 kWh/kg N). Operating costs were <$0.90/kg NH4 +-N for each of the electrodialysis stages and NH3 stripping. This integrated ED+HFMC system holds promise for the recovery of ammonia from dilute feedstreams as the ED+HFMC achieves high concentration factors and has low energy demand.

Regeneration of CO2 from CO2-rich absorbents using hollow fiber membrane contactors in liquid–liquid extraction mode

This study explores the use of hollow fiber membrane contactors (HFMCs) to efficiently regenerate CO2 from CO2-rich absorbents and convert it into calcium carbonate (CaCO3) via a novel liquid–liquid extraction process. CO2 is absorbed into a potassium carbonate (K2CO3) solution and then desorbed directly into a calcium chloride (CaCl2) solution through a porous polypropylene (PP) hollow fiber membrane. This single-step process significantly reduces the energy costs associated with traditional CO2 chemical capture methods, such as reboilers and gas compression. Key operational parameters, including stripping liquid chemistry (Ca2+ concentration and pH), feed liquid temperature, and HFMC stages, were optimized. CO2 regeneration peaked at pH 11.0 with a Ca2+ concentration of 108.00 mmol/L, achieving a 37 % efficiency at 80 ℃ in a single-stage HFMC. A three-stage HFMC in parallel mode increased CO2 regeneration efficiency to 49 %, though with a lower Ca2+ carbonation efficiency of 2.92 %. The open-loop configuration, which facilitates continuous CO2 absorption from flue gas, demonstrated practical application potential, regenerating approximately 30 % CO2 at a feed flow rate of 0.3 cm/s.

Optimization of hollow fiber membrane contactor system for CO2 mineralization using seawater brine: Comparative analysis of performance and transport mechanisms

Carbon mineralization is a promising approach for carbon capture, utilization, and storage (CCUS) but still faces technical and economic challenges. This study reports on CO2 mineralization using various hollow fiber membrane contactors (HFMCs) to optimize the system and understand the mass transport mechanism. We conducted a quantitative comparative assessment through theoretical and experimental approaches to evaluate the performance of three HFMC types with different morphological and chemical characteristics at various gas and liquid velocities. Results showed that the in-house developed highly porous hollow fiber (HF) membrane exhibited superior CO2 capture efficiency compared to commercial membranes. In contrast to other HFMCs showing a sharp decline in CO2 flux due to internal fouling caused by pore wetting and external fouling, the highly porous HF membrane with surface modification maintained stable performance during continuous operation due to its superhydrophobicity and surface roughness. The HF membrane also achieved the highest overall mass transfer coefficients, closely matching the theoretical non-wetted mode due to negligible partial wetting. We expect that this study will provide insights into optimizing HFMCs for enhanced carbon mineralization efficiency.

Development of a multicomponent counter‐current flow model to evaluate the impact of oxygen and water vapor on CO2 removal performance in a hollow fiber membrane contactor

Development of a multicomponent counter‐current flow model to evaluate the impact of oxygen and water vapor on CO₂ removal performance in a hollow fiber membrane contactor

Performance enhancement of hollow fiber membrane contactors for CO2 absorption using MEA-based functionalized nanofluids

Performance enhancement of hollow fiber membrane contactors for CO2 absorption using MEA-based functionalized nanofluids

Circular hybrid membrane process treating high-salinity ammonium-rich pharmaceutical wastewater

Ammonia-rich saline wastewater is a common byproduct of the pharmaceutical industry. Hollow fiber membrane contactors (HFMCs) show potential for NH3 recovery, enabling valuable product recycling. Our previous work indicated that excessive NaOH usage and increased salinity of the treated effluent are major setbacks when employing HFMCs for NH3 recovery from pharma wastewater. Therefore, finding alternative approaches to reduce chemical use and salinity is vital. This study demonstrates the integration of bipolar membrane electrodialysis (BMED) with HFMC for NH3 recovery, chemical recycling, and salinity reduction. This novel, highly circular concept was tested using real pharmaceutical wastewater. We varied the volume ratios between compartments to assess the BMED flexibility in attaining different treatment goals. BMED achieved over 90% salinity reduction and produced concentrated base and acid in all volume ratios tested, saving 70% of the NaOH required for pH increase before the HFMC step. The HFMC achieved over 98% NH3 recovery in two sets of five consecutive cycles, using either a BMED-generated base or NaOH. A preliminary economic analysis revealed a 47% reduction and 86% increase in expenses on chemicals and energy, respectively, compared to HFMC without BMED. Nevertheless, since the largest operating expense was the purchase of chemicals, integrating the BMED step reduced the overall operating expenses of the treatment by 33% (from $3.76 to $2.54 per kg N). The treated effluent’s quality allows discharge to conventional wastewater treatment plants, resulting in economic and environmental benefits. This work highlights the importance of innovative separation processes in advancing toward cleaner drug manufacturing.

Efficient extraction of hydrogen fluoride using hollow fiber membrane contactors with the aid of active‐learning

AbstractThis study presents a sustainable approach to extracting hydrogen fluoride (HF) from wastewater using hollow fiber membrane contactors. HF, a widely used yet hazardous chemical, requires efficient separation techniques due to its environmental and health concerns. Our research compared two operational modes, vacuum mode and liquid–liquid extraction mode, revealing the latter as more efficient for HF separation. Notably, this study introduces a novel aspect by employing a data‐driven decision‐making method, Bayesian optimization (BO) for process optimization of the liquid–liquid extraction mode, aiming to maximize HF removal efficiency at low experimental costs. Subsequent validation through a 96‐h experimental run confirms the suitability of the optimized conditions for industrial applications. This study not only demonstrates an efficient HF separation process using hollow fiber membrane contactors but also establishes a new standard for complex industrial process optimization.

Novel Landfill-Gas-to-Biomethane Route Using a Gas–Liquid Membrane Contactor for Decarbonation/Desulfurization and Selexol Absorption for Siloxane Removal

A new landfill-gas-to-biomethane process prescribing decarbonation/desulfurization via gas–liquid membrane contactors and siloxane absorption using Selexol are presented in this study. Firstly, an extension for an HYSYS simulator was developed as a steady-state gas–liquid contactor model featuring: (a) a hollow-fiber membrane contactor for countercurrent/parallel contacts; (b) liquid/vapor mass/energy/momentum balances; (c) CO2/H2S/CH4/water fugacity-driven bidirectional transmembrane transfers; (d) temperature changes from transmembrane heat/mass transfers, phase change, and compressibility effects; and (e) external heat transfer. Secondly, contactor batteries using a countercurrent contact and parallel contact were simulated for selective landfill-gas decarbonation/desulfurization with water. Several separation methods were applied in the new process: (a) a water solvent gas–liquid contactor battery for adiabatic landfill-gas decarbonation/desulfurization; (b) water regeneration via high-pressure strippers, reducing the compression power for CO2 exportation; and (c) siloxane absorption with Selexol. The results show that the usual isothermal/isobaric contactor simplification is unrealistic at industrial scales. The process converts water-saturated landfill-gas (CH4 = 55.7%mol, CO2 = 40%mol, H2S = 150 ppm-mol, and Siloxanes = 2.14 ppm-mol) to biomethane with specifications of CH4MIN = 85%mol, CO2MAX = 3%mol, H2SMAX = 10 mg/Nm3, and SiloxanesMAX = 0.03 mg/Nm3. This work demonstrates that the new model can be validated with bench-scale literature data and used in industrial-scale batteries with the same hydrodynamics. Once calibrated, the model becomes economically valuable since it can: (i) predict industrial contactor battery performance under scale-up/scale-down conditions; (ii) detect process faults, membrane leakages, and wetting; and (iii) be used for process troubleshooting.

Improving the activity of CO2 capturing from flue gas by membrane gas – solvent absorption process

This work is focused on increasing the capturing efficiency of carbon dioxide (CO2) through flue gas purification systems. To maximize the CO2 capture process, many process variables such as temperature, flow rates, absorbent concentrations, and nanoparticles were investigated. This study describes the use of a polypropylene hollow fiber membrane contactor to separate CO2 from nitrogen using different solvents, including Potassium carbonate (K2CO3), N-methyl diethanolamine (MDEA), and monoethanolamine (MEA). Also, the presence of silica nanoparticles and piperazine (PZ) enhances the process performance. On the other hand, the amine and mixed amino absorbents MDEA-PZ and MDEA-MEA were prepared and compared based on the absorption capacity. The optimal order of amine absorbent performance when applied to CO2 membrane absorption is MDEA-MEA followed by MDEA-PZ. At a solute concentration of 9%, MDEA-MEA exhibits the highest CO2 removal efficiency, which is 74.12%. However, at a concentration of 11%, MEA, MDEA-PZ, and MDEA have the highest CO2 removal efficiencies of 80.15%, 75.13%, and 63.12%, respectively.

Retraction Note: Hollow fiber membrane contactor based carbon dioxide absorption − stripping: a review

Retraction Note: Hollow fiber membrane contactor based carbon dioxide absorption − stripping: a review

Experimental study of hollow fiber membrane contactor process using aqueous amino acid salt-based absorbents for efficient CO2 capture

Gas–liquid membrane contactors are a promising alternative to packed columns that suffer from channeling, bubble formation, and flooding problems. In this study, potassium serinate + piperazine (PSZ) and potassium alaninate + piperazine (PAZ), which are amino acid salts with good CO2 absorption performances and high surface tensions, are investigated to determine the effects of the operating parameters on the CO2 removal efficiency, CO2 absorption flux, CO2 loading, and overall mass-transfer coefficient in the membrane contactor process. The experimental results demonstrate that the 2.5 M PSZ and 2.5 M PAZ absorbents outperform 2.5 M monoethanolamine (MEA) under various operating conditions, including the gas flow rate, liquid flow rate, CO2 concentration, and CO2-loaded absorbent. Based on these results, an expression for predicting the CO2 loading from the pH is proposed. The amount of cross-over confirmed that amino acids with high surface tension have better resistance to membrane wetting than 2.5 M MEA. In addition, empirical correlation expressions were established from the results of several operating parameters. The absolute average deviation (AAD) values were 6.50 %, 2.95 %, and 4.71 % for 2.5 M MEA, 2.5 M PSZ, and 2.5 M PAZ, respectively, suggesting good agreement between the theoretical and experimental results.

Membrane role in heat and mass transfer resistance distribution and performance of hollow fiber membrane contactor for SGMD desalination

Hollow fiber membrane contactor (HFMC) is the core device of heat mass exchange between seawater solution and sweeping air in sweeping gas membrane distillation (SGMD) desalination. In order to reveal the distribution of heat and mass transfer resistance on feed solution side, porous membrane side and sweeping air side, a mathematical model considering the simultaneous heat mass transfer and water vapor diffusion mechanism in the membrane pores was established for the cross-flow HFMC. The simulation results of the model were compared with experimental results and literature results. Comparison shows that the deviation of simulation results of the model is less than 13.4 %, which verifies the accuracy and reliability of the simulation results. Influences of the main structural characteristics of porous membrane on the resistance distribution of heat and mass transfer, efficiency and membrane flux were explored. Air side dominates the heat transfer process, while the membrane side accounts for less than 39 % of the total heat transfer resistance for the main range of membrane microstructure parameters investigated. The mass transfer is controlled by the porous membrane except for thin membrane with a thickness of less than 100 μm. Membranes with porosity above 0.8 and as thin as possible can achieve better mass transfer efficiency and freshwater flux. Increasing mean pore diameter has a strong promotion effect on the increase of membrane flux before it reaches 150 nm, and beyond this critical value, the water vapor diffusion mechanism changes from Knudsen collision to molecular collision. Effects of different operating parameters and membrane microstructure parameters on air temperature distribution and humidity distribution were also analyzed.

Development of a mathematical model for investigation of hollow-fiber membrane contactor for membrane distillation desalination

This research investigates the predictive modeling of a dataset containing parameters denoted by r(m), z(m), and T(K) which is temperature. The considered process is a membrane distillation (MD) for separation of compounds based on temperature gradient. A membrane contactor is used for the process, and the computations are performed in the context of computational fluid dynamics (CFD) and machine learning. The dataset, which is generated by CFD modeling and encompasses over 5,000 data points, is analyzed using three distinct regression models: Support Vector Machine (SVM), Deep Neural Network (DNN), and Kernel Ridge Regression (KRR). Hyperparameter tuning is performed employing the Stochastic Fractal Search (SFS) algorithm. Our findings unraveled the nuanced intricacies of each model's performance, gauged through a comprehensive set of metrics. The RMSE, MAPE, and R2 score collectively offer a robust evaluation framework. The Deep Neural Network (DNN) exhibits a compelling RMSE of 7.7001E-01, a remarkably low MAPE of 2.05131E-03, and an impressive R2 score of 0.97054. Meanwhile, the Support Vector Machine (SVM) showcases a notable RMSE of 1.7215E-01, a minimal MAPE of 2.90820E-04, and a remarkably high R2 score of 0.99839. On the other hand, the Kernel Ridge Regression (KRR) model presents an RMSE of 1.3588E + 00, a MAPE of 2.63550E-03, and an R2 score of 0.90042.

Techno-Economic Evaluation on Solar-Assisted Post-Combustion CO2 Capture in Hollow Fiber Membrane Contactors

In this study, a novel system which integrates solar thermal energy with membrane gas absorption technology is proposed to capture CO2 from a 580 MWe pulverized coal power plant. Technical feasibility and economic evaluation are carried out on the proposed system in three cities with different solar resources in China. Research results show that the output capacity and net efficiency of the SOL-HFMC power plant are significantly higher than those of the reference power plant regardless of whether a TES system is applied or not. In addition, the CEI of the SOL-HFMC power plant with the TES system is 4.36 kg CO2/MWh, 4.45 kg CO2/MWh and 4.66 kg CO2/MWh lower than that of the reference power plant. The prices of the membrane, vacuum tube collector and phase change material should be reduced to achieve lower LCOE and COR values. Specifically for the SOL-HFMC power plant with the TES system, the corresponding vacuum tube collector price shall be lower than 25.70 $/m2 for Jinan, 95.20 $/m2 for Xining, and 128.70 $/m2 for Lhasa, respectively. To be more competitive than a solar-assisted ammonia-based post-combustion CO2 capture power plant, the membrane price in Jinan, Xining and Lhasa shall be reduced to 0.012 $/m, 0.015 $/m and 0.016 $/m for the sake of LCOE, and 0.03 $/m, 0.033 $/m and 0.034 $/m for the sake of COR, respectively.

Study on design strategies and on new structure-performance relationships for CO2 capture in gas-liquid hollow fiber membrane contactors

The urgent need for carbon dioxide (CO2) capture technologies motivates this chemical engineering study, which systematically investigates the influence of macroscopic and microscopic structure on the CO2 absorption performance of hydrophobic alumina (Al2O3) hollow fiber membrane (A-HFMs) contactors. Six different A-HFMs prepared using the non-solvent-induced phase separation (NIPS) method with select solvents followed by sintering at 1300°C were then tested for chemical CO2 absorption in an A-HFM contactor using a monoethanolamine (MEA) solution. The hydrophobicity of the coatings applied on the A-HFM surfaces was confirmed by the water contact angle and thermogravimetric (TGA) analysis. Pearson's statistical analysis of a correlation matrix revealed the strength of relationships between nine variables, including outer diameter (mm), inner diameter (mm), percentage of sponge layer (%), pore size (nm), maximum pore size (nm), mechanical strength (MPa), surface porosity (m−1), overall porosity (%), and CO2 absorption flux (mol m−2 s−1). Building upon these findings, this study unveils a novel non-linear function linking three specific microscopic characteristics— pore size, surface porosity, and a geometric sponge layer factor—to CO2 absorption flux, offering valuable insights for optimizing hydrophobic A-HFM design and enhancing CO2 capture efficiency. The A-HFM, characterized by the combination of three factors (higher pore size, increased surface porosity, and a thicker sponge layer), achieved a CO2 absorption flux of 6.36 ×10−3 mol m−2 s−1 at room temperature, showcasing its exceptional performance in capturing CO2. The resulting empirical morphological factor provides a novel approach for enhancing the performance of CO2 absorption through A-HFM design optimization.

3D-CFD Modeling of Hollow-Fiber Membrane Contactor for CO2 Absorption Using MEA Solution.

Membrane technology is considered an innovative and promising approach due to its flexibility and low energy consumption. In this work, a comprehensive 3D-CFD model of the Hollow-Fiber Membrane Contactor (HFMC) system for CO2 capture into aqueous MEA solution, considering a counter-current fluid flow, was developed and validated with experimental data. Two different flow arrangements were considered for the gas mixture and liquid solution inside the HFMC module. The simulation results showed that the CO2 absorption efficiency was considerably higher when the gas mixture was channeled through the membranes and the liquid phase flowed externally between the membranes, across a wide range of gas and liquid flow rates. Sensitivity studies were performed in order to determine the optimal CO2 capture process parameters under different operating conditions (flow rates/flow velocities and concentrations) and HFMC geometrical characteristics (e.g., porosity, diameter, and thickness of membranes). It was found that increasing the membrane radius, while maintaining a constant thickness, positively influenced the efficiency of CO2 absorption due to the higher mass transfer area and residence time. Conversely, higher membrane thickness resulted in higher mass transfer resistance. The optimal membrane thickness was also investigated for various inner fiber diameters, resulting in a thickness of 0.2 mm as optimal for a fiber inner radius of 0.225 mm. Additionally, a significant improvement in CO2 capture efficiency was observed when increasing membrane porosity to values below 0.2, at which point the increase dampened considerably. The best HFMC configuration involved a combination of low porosity, moderate thickness, and large fiber inner diameter, with gas flow occurring within the fiber membranes.

Direct CO2 mineralization using seawater reverse osmosis brine facilitated by hollow fiber membrane contactor

The urgent demand for sustainable water management has given rise to widespread seawater desalination, leading to significant brine waste and a substantial carbon footprint resulting from extensive energy consumption. To address this challenge, we propose the utilization of hollow fiber membrane contactors (HFMCs) for direct CO2 mineralization. By mimicking lotus leaf surfaces, HFMs are successfully modified to possess superhydrophobic and antifouling properties, resulting in enhanced operational stability, as evidenced by a marginal 3.5 % flux decline after 10 days. Moreover, HFMCs incorporating these modified membranes achieve remarkable CO2 removal (up to 94 %) and selective mineral carbonation of Ca2+ and Mg2+ through staged pH swing. A techno-economic analysis highlights the superiority of our system compared to traditional amine scrubbing, with a 35 % reduction in CO2 capture costs and the generation of valuable products. This innovative application of HFMCs presents a promising solution for CO2 management, transforming seawater reverse osmosis brine into a valuable resource.

A Comprehensive Parametric Study on CO2 Removal from Natural Gas by Hollow Fiber Membrane Contactor: A Computational Fluid Dynamics Approach

AbstractThis study examined essential factors in the use of hollow fiber membranes that affect CO2 removal efficiency. In the simulation, a finite element model for a membrane with ten fibers was used. Each fiber is 175 mm long with inner radius of 0.75 mm and outer radius of 1.5 mm. Liquid and gas flow rates were set at 100–800 mL min−1, and adsorbent concentration was adjusted in the range of 200–1500 mol m−3 for monoethanolamine, piperazine (PZ), and ethylenediamine absorbents. Increasing the liquid flow rate, gas flow rate, and absorbent concentration leads to an increase, decrease, and increase in efficiency, respectively. Thus, using PZ as absorbent with a concentration of 1080 mol m−3 liquid and gas flow rates of 400 and 180 mL min−1, respectively, showed a CO2 removal efficiency of &gt; 95 % for a membrane effective length of 0.3 m.