Hollow Fiber Contactor Research Articles

Hollow Fiber Contactors with Improved Hydrophobicity for Acid Gas Removal: Progress and Recent Advances

The gas–liquid membrane contactor technology, which integrates the absorption process with membranes, is a developing membrane technology that is especially pertinent to acid gas absorption. When it comes to removing acid gases from natural gas or after combustion, membrane technology has demonstrated potential as a substitute for conventional absorption columns. The membrane contactor offers exceptional operating flexibility and a high mass transfer area. In addition to summarizing the key elements of membrane materials, absorbents, and membrane contactor design, this paper presents the working principle and wetting mechanism of hollow membrane contactors and focuses the most recent advancements in membrane contactor research in gas separation from gas mixtures. The state-of-the-art overview of highly hydrophobic microporous membranes is presented after a discussion of the main challenges to the preparation of superhydrophobic membranes.

Hollow fibre supported liquid membranes for nuclear fuel cycle applications: A review

This article gives a comprehensive review on hollow fibre supported liquid membrane based methods for the separation of actinides, lanthanides and fission elements in nuclear fuel cycle applications. The nuclear fuel cycle operations result in large volumes wastes containing long-lived actinides and fission elements which need to be remediated before their release into the environment. The routinely used methods for such wastes treatments are precipitation, solvent extraction and ion-exchange. However, these traditional methods lead to solid waste generation, use of large volumes of toxic/inflammable chemicals and suffer with slow processing issues. In the past few decades, attempts have been made to explore the supported liquid membrane based separation methods using hollow fibre contactors with highly encouraging results. This article gives a comprehensive account of studies on hollow fibre supported liquid membrane aimed at separations relevant to the back-end of nuclear fuel cycle.

Extraction of La(III) by a nonionic microemulsion containing D2EHPA in hollow fiber contactor

This study aimed to prepare a W/O nonionic microemulsion system(MEs) consisting of OP-4[polyoxyethylene(4) nonylphenol], OP-7[polyoxyethylene(7) nonylphenol], 1-hexanol, D2EHPA, kerosene and HCl solution and applied to the extraction of La(III) from chloride aqueous solution within the polysulfone hollow fiber contactor (HFC),laboratory-scale experiments were carried out to investigate the recovery of La(III) using as-prepared microemulsion from the simulation wastewater containing La(III),Al(III) and Fe(III). The right weight ratio(Rs) of OP-4 to OP-7 was firstly confirmed through determination of the solubilization capacity of HCl solution(W0,HCl) in microemulsion, the effect of several factors such as the HCl concentration, temperature and effective extraction time on the extraction efficiency of La(III) was discussed. Results showed that the acceptable Rs was 4:6 to prepare the W/O MEs. The extraction yield of La(III) increased with the increasing of HCl concentration, temperature and effective extraction time and reaches to 97.3% while using five-stage modules. The recovery yield of La(III) from simulation La-bearing wastewater was 90.6%.

Computational modelling of non-dispersive solvent extraction of uranium in hollow fiber contactor operated in recycle mode

Extraction of uranium and acidity by using TBP (tri-n-butyl phosphate)-n-dodecane through hollow fiber contactor operated in the Non-Dispersive Solvent Extraction (NDSX) configuration with recycle mode is simulated by using a two-dimensional axisymmetric multi-component Computational Fluid Dynamics (CFD) model. This multi-component model solves continuity and momentum transport equations for the feed and shell sides and solute transport equation for the feed side, shell side as well as for the membrane phase. Complex boundary conditions of flux continuity and concentration jump are implemented in the model. Recycle mode of operation is simulated by solving the differential equations representing transient mass balance for feed and solvent reservoirs bottles simultaneously with the governing equations of the CFD model. Validation of the model has been done by comparing predicted and experimentally measured percentage extraction of uranium and nitric acid for different parametric conditions. The validated model has been used to have detailed insights into the spatial and temporal variation of concentration and flux profiles inside the contactor. The CFD model of hollow fiber contactor, which is widely accepted as a separation process intensification tool, will be useful for optimization of the design, operation and scale-up.

Computational fluid dynamics modeling of uranium(VI) transport through hollow fiber supported liquid membrane

ABSTRACT Uranium(VI) ions transport through hollow fibre supported liquid membrane (HFSLM) using TBP (tri-n-butyl phosphate) in n-dodecane as the extractant and 0.01 M HNO3 as strippant is modelled by using Computational Fluid Dynamics (CFD) model for once-through the mode of operation. The model solves the momentum transport equation for the feed on the lumen side and the stripping phase on the shell side. The species transport equation is solved for the feed on the lumen side, the liquid membrane phase within the pores of the lumen and the stripping phase on the shell side. The boundary conditions of flux continuity and concentration jump at the feed-liquid membrane and the liquid membrane–strip interfaces are implemented. The results obtained from the CFD model at different parametric conditions are compared with the experimental data and found a good agreement between them. Validated CFD model is used to have in-depth insights into mass transfer phenomena at different hydrodynamic and chemical conditions. The effect of geometry on mass transfer is also evaluated. Overall this study will give valuable input to the supported liquid membrane (SLM) processes using hollow fibre contactor in the optimization of process design, operation and scale-up.

Scale-Up of Membrane-Based Zinc Recovery from Spent Pickling Acids of Hot-Dip Galvanizing.

Zinc recovery from spent pickling acids (SPAs) can play an important role in achieving a circular economy in the galvanizing industry. This work evaluates the scale-up of membrane-based solvent extraction technology aimed at the selective separation of zinc from industrial SPAs as a purification step prior to zinc electrowinning (EW). The experiments were carried out at a pilot scale treating SPAs batches of 57 to 91 L in a non-dispersive solvent extraction (NDSX) configuration that simultaneously performed the extraction and backextraction steps. The pilot plant was equipped with four hollow fiber contactors and 80 m2 of total membrane area, which was approximately 30 times higher than previous bench-scale studies. Tributylphosphate diluted in Shellsol D70 and tap water were used as organic and stripping agents, respectively. Starting with SPAs with high Zn (71.7 ± 4.3 g·L−1) and Fe (82.9 ± 5.0 g·L−1) content, the NDSX process achieved a stripping phase with 55.7 g Zn·L−1 and only 3.2 g Fe·L−1. Other minor metals were not transferred, providing the purified zinc stripping with better quality for the next EW step. A series of five consecutive pilot-scale experiments showed the reproducibility of results, which is an indicator of the stability of the organic extractant and its adequate regeneration in the NDSX operation. Zinc mass transfer fluxes were successfully correlated to zinc concentration in the feed SPA phase, together with data extracted from previous laboratory-scale experiments, allowing us to obtain the design parameter that will enable the leap to the industrial scale. Therefore, the results herein presented demonstrate the NDSX technology in an industrially relevant environment equivalent to TRL 6, which is an essential progress to increase zinc metal resources in the galvanizing sector.

Numerical Simulation of Uranium Extraction from Nitric Acid Medium Using Hollow-Fiber Contactor

ABSTRACTA two-dimensional axisymmetric computational fluid dynamics (CFD) model is presented to simulate uranium extraction from nitric acid medium using tri-n-butyl phosphate in n-dodecane in a hollow-fiber membrane contactor operated in non-dispersive solvent extraction mode. CFD model solves continuity and momentum-transport equations for the feed and shell sides and species transport equations for the feed side, shell side, as well as the membrane. Complex boundary conditions of flux continuity and concentration jump are implemented in the CFD model. The estimates of percentage of uranium extraction obtained from CFD simulations for different parametric conditions are compared with the experimental results, and a good agreement is observed. The validated CFD model is used to gain detailed insights into the hydrodynamics and mass transfer.Abbreviations CFD: Computational fluid dynamics; NDSX: Non-dispersive solvent extraction; TBP: Tri n-butyl phosphate

Degassing behavior of noble gases from groundwater during groundwater sampling

Noble gases dissolved in groundwater have been used to evaluate characteristics such as origin, residence time and recharge temperature. Although obtaining samples without degassing is highly desired, in certain cases, degassing during sampling is unavoidable. This study investigated the degassing behavior of noble gases during sampling and evaluated the correction methods that can be applied. Groundwater samples were obtained from an underground laboratory and a deep borehole. The amount of exsolved gas was estimated by comparing pressurized and non-pressurized samples. Henry's model, which assumes equilibrium between gas and water, and a diffusion model were applied to the results. In addition, the compositions of gases extracted into an evacuated vessel or hollow fiber contactor were also compared with those of pressurized groundwater samples. The results indicated that significant degassing occurred in unpressurized samples, but equilibrium was achieved between gas and water when the total dissolved gas pressure (TDGP) was relatively small (up to 4.2 atm). Therefore, the d’Ne value, defined as the difference between the Ne concentration of air-saturated water and a sample normalized by the Ne concentration of air-saturated water, could be used in Henry's model to correct exsolution. However, inclusion of the effects of excess air and contamination is problematic. However, when TDGP was high (32 atm in this study), the degassing behavior completely changed and could not be predicted by Henry's model. During extraction of noble gases using an evacuated vessel and hollow fiber contactor, degassing was observed to take place following the diffusion model. As a result, fractionation between Ne vs. Kr and Xe was significant. Thus, although we could extract dissolved Ne with a high recovery ratio (over 0.85), the ratios of Kr/Ne and Xe/Ne were found to be significantly smaller than those in groundwater. The gases extracted by an evacuated vessel or hollow fiber contactor appeared to be applicable only for evaluating He/Ne.

Highly efficient separation of Am3+ and Eu3+ using an aqueous soluble sulfonated BTP derivative by hollow-fiber supported liquid membrane containing TODGA

ABSTRACTSeparation of Am3+ and Eu3+ was attempted using phenyl sulphonic acid functionalized bis-triazinyl pyridine (SO3-Ph-BTP) employing supported liquid membrane-based technique with varying concentrations of N,N,N’,N’-tetraoctyl diglycolamide as the liquid membrane. Supported liquid membrane-based separation of Am3+ and Eu3+ was attempted for the first time using a hollow-fiber contactor. A single-fiber-based hollow-fiber microextraction could selectively concentrate Am3+ with a volume reduction factor of >1000. On the other hand, Eu3+ was selectively transported from a mixture of Am3+ and Eu3+ from 100 ml feed solution containing SO3-Ph-BTP in 30 min with a DF >100.

Fluid flow and mass transfer in an industrial-scale hollow fiber membrane contactor scaled up with small elements

Current gas/liquid membrane contactors are classified into tubular hollow fiber contactors and tube-shell cross flow hollow fiber contactors. They are usually built with a closed and integrated structure, which reduces the maintainability of the contactor and makes the scaling-up of the contactor inconvenient. In this paper, a novel gas/liquid hollow fiber membrane contactor is proposed. It is consisted of many changeable and standard small contactors (elements), in which the fibers are randomly packed. These randomly packed small elements are then serially and orderly arranged to form the scaled up contactor for industrial applications. A two-dimensional predictive model is proposed to study the performance of the contactor, which is validated by air humidification experiments. The effects of inter-elements and intra-element flow maldistributions are investigated. Correlations are proposed to estimate the performance of the contactor from the parameters of the elements. It is found that for the contactors built with elements of high packing densities (0.5), the inter-elements effect is dominant for flow maldistribution, but for contactors built with elements of low packing densities (0.35), the collaborative effect of inter-elements and intra-element is dominant. It could maximally decrease the average air side Sherwood numbers by about 83%, with a pressure drop reduction of about 50%. The scaled up contactor has a comparable performance to the small elements when the elements are optimized, which shows the good scalability of this novel contactor.

Effect of Feed Gas Flow Rate on CO2 Absorption through Super Hydrophobic Hollow Fiber membrane Contactor

Carbon dioxide is pollutant in natural gas that could reduce the heating value of the natural gas and cause problem in transportation due to corrosive to the pipeline. This study aims to evaluate the effects of feed gas flow rate on CO2 absorption through super hydrophobic hollow fiber contactor. Polyethyleneglycol-300 (PEG-300) solution was used as absorbent in this study, whilst the feed gas used in the experiment was a mixture of 30% CO2 and 70% CH4. There are three super hydrophobic hollow fiber contactors sized 6 cm and 25 cm in diameter and length used in this study, which consists of 1000, 3000 and 5000 fibers, respectively. The super hydrophobic fiber membrane used is polypropylene-based with outer and inner diameter of about 525 and 235 μm, respectively. In the experiments, the feed gas was sent through the shell side of the membrane contactor, whilst the absorbent solution was pumped through the lumen fibers. The experimental results showed that the mass transfer coefficient, flux, absorption efficiency for CO2-N2 system and CO2 loading increased with the feed gas flow rate, but the absorption efficiency for CO2-N2 system decreased. The mass transfer coefficient and the flux, at the same feed gas flow rate, decreased with the number of fibers in the membrane contactor, but the CO2 absorption efficiency and the CO2 loading increased.

Modeling of Ethylene Absorption from an Ethylene–Ethane Mixture by Silver Nitrate Aqueous Solution in a Hollow-Fiber Membrane Contactor

Convection–diffusion mass transfer in a gas–liquid membrane contactor based on porous polysulfone hollow fiber membranes with a mesoporous (dpore ~ 2 nm) structure of the separation layer has been studied. The characteristics of the membrane contactor have been investigated in the recovery of ethylene from its mixture with ethane using an aqueous silver nitrate solution as the absorption liquid. A procedure based on the method of lines is proposed for calculating a mass transfer in hollow fiber contactor with a longitudinal laminar flow in an array of parallel fibers. An ethylene flux, depending on the process conditions, has been found by solving numerically a set of convection–diffusion equations with allowance for both the chemical reaction in the liquid stream and transmembrane transport.

Recovery of radio-cesium from actual high level liquid waste using solvents containing calix[4]arene-crown-6 ligands

This paper gives two methods, viz. a solvent extraction method and a hollow fiber contactor based liquid membrane method, for the separation of radio-cesium from actual high level liquid waste (HLLW) solutions using calix[4]arene-crown-6 based solvent systems. While the solvent extraction method involved calix[4]arene-bis-benzo-crwon-6 (CBC) in PTMS (phenyltrifluoromethyl sulphone), the hollow fiber supported liquid membrane method used a polysulphone fiber containing contactor and bis-octyl-benzo-calix[4]arene-mono-crown-6 (CMC) in 40% iso-decanol+60% n-dodecane. Both methods reported selective radio-cesium separation with almost no contamination from the associated fission product radionuclides. The radiolytic stability of the hollow fiber contactor was checked by keeping the contactor module in contact with the diluted HLLW for 50days. The second run carried out after 50days resulted in excellent reproducibility suggesting efficacy of this method for radioactive waste remediation.

Development of a mechanistic model for prediction of CO2 capture from gas mixtures by amine solutions in porous membranes.

A mechanistic model was developed in order to predict capture and removal of CO2 from air using membrane technology. The considered membrane was a hollow-fiber contactor module in which gas mixture containing CO2 was assumed as feed while 2-amino-2-metyl-1-propanol (AMP) was used as an absorbent. The mechanistic model was developed according to transport phenomena taking into account mass transfer and chemical reaction between CO2 and amine in the contactor module. The main aim of modeling was to track the composition and flux of CO2 and AMP in the membrane module for process optimization. For modeling of the process, the governing equations were computed using finite element approach in which the whole model domain was discretized into small cells. To confirm the simulation findings, model outcomes were compared with experimental data and good consistency was revealed. The results showed that increasing temperature of AMP solution increases CO2 removal in the hollow-fiber membrane contactor.

RED WINE EXTRACT OBTAINED BY MEMBRANE-BASED SUPERCRITICAL FLUID EXTRACTION: PRELIMINARY CHARACTERIZATION OF CHEMICAL PROPERTIES.

Abstract – This study aims to obtain an extract from red wine by using membrane-based supercritical fluid extraction. This technique involves the use of porous membranes as contactors during the dense gas extraction process from liquid matrices. In this work, a Cabernet Sauvignon wine extract was obtained from supercritical fluid extraction using pressurized carbon dioxide as solvent and a hollow fiber contactor as extraction setup. The process was continuously conducted at pressures between 12 and 18 MPa and temperatures ranged from 30 to 50oC. Meanwhile, flow rates of feed wine and supercritical CO 2 varied from 0.1 to 0.5 mL min -1 and from 60 to 80 mL min -1 (NCPT), respectively. From extraction assays, the highest extraction percentage value obtained from the total amount of phenolic compounds was 14% in only one extraction step at 18MPa and 35oC. A summarized chemical characterization of the obtained extract is reported in this work; one of the main compounds in this extract could be a low molecular weight organic acid with aromatic structure and methyl and carboxyl groups. Finally, this preliminary characterization of this extract shows a remarkable ORAC value equal to 101737 ± 5324 µmol Trolox equivalents (TE) per 100 g of extract.

Extraction of zirconium from simulated acidic nitrate waste using liquid membrane in hollow fiber contactor

Extraction of zirconium from simulated acidic nitrate waste using liquid membrane in hollow fiber contactor

Numerical modelling and simulation of membrane-based extraction of copper (II) using hollow fiber contactors

Numerical modelling and simulation of membrane-based extraction of copper (II) using hollow fiber contactors

A process intensified technique of liquid membrane employed in in-house hollow fiber contactor

A process intensified technique of liquid membrane employed in in-house hollow fiber contactor

Testing and performance analysis of a hollow fiber-based core for evaporative cooling and liquid desiccant dehumidification

ABSTRACTIn this study, an innovative heat and mass transfer core is proposed to provide thermal comfort and humidity control using a hollow fiber contactor with multiple bundles of micro-porous hollow fibers. The hollow fiber-based core utilizes 12 bundles aligned vertically, each with 1,000 packed polypropylene hollow fibers. The proposed core was developed and tested under various operating and ambient conditions as a cooling core for a compact evaporative cooling unit and a dehumidification core for a liquid desiccant dehumidification unit. As a cooling core, the fiber-based evaporative cooler provides a maximum cooling capacity of 502 W with a wet bulb effectiveness of 85%. As a dehumidification core and employing potassium formate as a liquid desiccant, the dehumidifier is capable of reducing the air relative humidity by 17% with an overall dehumidification capacity of 733 W and humidity effectiveness of 47%. Being cheap and simple to design with their attractive heat and mass transfer characteristics and the corresponding large surface area-to-volume ratio, hollow fiber membrane contactors provide a promising alternative for cooling and dehumidification applications.

Biocatalytic gas-liquid membrane contactors for CO2 hydration with immobilized carbonic anhydrase

CO2 capture from flue gas, biogas and natural gas is still a key challenge in many environmental and energy applications. The gas-liquid membrane contactor provides a promising alternative to traditional packed towers and bubble columns. We developed a novel biocatalytic gas-liquid membrane contactor for CO2 capture with benign solvent absorbents. Both virgin and superhydrophobic PP hollow fiber membranes were investigated. Biocatalytic TiO2 nanoparticles with covalently immobilized carbonic anhydrase were suspended in the solvent absorbent to promote the CO2 hydration. The immobilized enzyme retained a high degree of the original CO2 hydration efficiency of the free enzyme, and the biocatalytic membrane contactor performance under various industrial-related conditions was investigated, including a wide range of pH and high temperature. Satisfactory reusability of the biocatalytic nanoparticles was exhibited by 10 cycles of repeated use. Finally, the mass transfer study and the Wilson plot indicated the limiting factor of the hollow fiber contactor was the high membrane resistance. In comparison, a flat sheet biocatalytic membrane contactor with lower membrane resistance exhibited much higher CO2 hydration efficiency. It also showed that the enzymatic promotion effect was more evident at low liquid Reynolds number (<50) conditions where many conventional gas-liquid membrane contactors operate,