Hydrophobic Hollow Fiber Membrane Contactor Research Articles

Mechanisms for Direct Separation of Oil from Water with Hydrophobic Hollow Fiber Membrane Contactors

Oil–water separation in membranes traditionally involves the transfer of water through the membrane. Instead, this study presents the novel approach of permeating insoluble oil through a hydrophobi...

Mass transfer modelling of hollow fiber membrane contactor for apple juice concentration using osmotic membrane distillation

The present research study is based on theoretical and experimental investigation of hydrophobic porous hollow fiber membrane contactor (HFMC) module. The mass transfer diffusional model was developed for osmotic membrane distillation (OMD) and applied in apple juice concentration. The mathematical model was developed, taking into consideration the resistance-in-series concept for the mass transfer of water vapor molecules across the hydrophobic HFMC. The model was adapted to include the pore geometry, dimensionless numbers and concentration variation due to viscosity. The water vapor transport model was then simulated in MATLAB® and successfully validated with the experimental data. The model was applied to study the effects of driving forces for mass transfer and membrane porosity. Process parameters like juice concentration, stripping solution concentration, and Reynolds number were also studied to evaluate their effect on the overall mass transfer co-efficient and water vapor flux. The OMD experiments for the concentration of clarified apple juice were carried out in a laboratory-scale HFMC mini-module composed of two independent circuits, for stripping solution (CaCl2) and apple juice, respectively, in a total recycled mode. For the concentration of clarified apple juice, the evaporation flux ranged from 0.122 to 0.472 kgm−2h−1 resulting in a juice concentration of 30°Brix. The increase in pore diameter from 0.1 to 0.6 µm resulted in an increase in the mass transfer coefficient from 1.57 × 10−10 to 7.23 × 10−10 ms−1. Similarly, water vapor flux was increased from 0.02 to 0.50 kgm−2h−1, when the activity coefficient was changed from 0.1 to 0.5. Moreover, the results indicated that if the experimental parameters are carefully controlled, the simulation results can be used to predict the OMD process efficiency.

Ammonia recovery from human urine as liquid fertilizers in hollow fiber membrane contactor: Effects of permeate chemistry

The production of the existing nitrogen fertilizer is costly and less environmental-friendly. Various green technologies are currently emerging toward providing alternative options. In this study, a liquid/liquid hydrophobic hollow-fiber membrane contactor was employed at ambient temperature and natural urine pH ~ 9.7 to recover ammonium fertilizers from human urine. Results showed that permeate side chemistry was one of the major factors affecting the ammonia mass transfer. The study on the ammonia capturing performance of diluted sulfuric acid, phosphoric acid, nitric acid, and DI water confirmed that acid type, acid concentration, and permeate side operating pH were the most important parameters affecting the ammonia capturing tendency. Sulfuric acid was slightly better in capturing more ammonia than other acid types. The study also identified increasing acid concentration didn’t necessarily increase ammonia mining tendency because there was always one optimum concentration value at which maximum ammonia extraction was possible. The best permeate side operating pH to extract ammonia for fertilizer purposes was selected based on the dissociation equilibrium of different types of acids. Accordingly, the analysis showed that the membrane process has to be operated at pH > 3 for sulfuric acid, between 3.5 to 11.5 for phosphoric acid, and above 0.5 for nitric acid so as to produce their respective high-quality liquid ammonium sulfate, ammonium monophosphate/diphosphate, and ammonium nitrate fertilizer. Therefore, permeate side acid concentration, pH, and acid type has to always be critically optimized before starting the ammonia mining experiment.

NOx Removal from Air through Super Hydrophobic Hollow Fiber Membrane Contactors

NOx Removal from Air through Super Hydrophobic Hollow Fiber Membrane Contactors

N2O absorption through super hydrophobic hollow fiber membrane contactor

Dinitrogen monoxide (N2O) is mainly produced in Horticulture and farming activities, industrial processes and combustion of fossil fuels. N2O is one of the harmful emissions and its global warming potential is 310 times greater than CO2 on a molecular basis. This research aims to absorb N2O from its mixture with air through super hydrophobic hollow membrane contactor using a mixture of 0.5M HNO3 and 0.5 wt % H2O2 solutions as absorbent. In the experiment, the feed gas flowed through the shell side of the contactor, while absorbent solution flowed through the lumen fibers. Experimental results show that the amount of N2O absorbed and N2O absorption efficiency increased with the absorbent flow rate and the number of fibers in the contactor resulting from the increase in the turbulence and surface area for gas–liquid contact, respectively. The overall mass transfer coefficient and the flux increased with the absorbent flow rate due to the decrease of the mass transfer resistance in the liquid phase. However, the overall mass transfer coefficient and the flux decreased with the number of fibers in the contactor due to the decrease of the absorbent flow rate in a single fiber. The amount of N2O absorbed and the flux increased but the N2O absorption efficiency decreased with increasing the feed gas cross flow rate. © 2018 American Institute of Chemical Engineers Environ Prog, 38: 362–366, 2019

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.

Effects of Absorbent Flow Rate on Co2 Absorption through a Super Hydrophobic Hollow Fiber Membrane Contactor

Effects of Absorbent Flow Rate on Co2 Absorption through a Super Hydrophobic Hollow Fiber Membrane Contactor

Effects of operational conditions on the removal of phenols from wastewater by a hollow-fiber membrane contactor

Abstract The removal of phenols from wastewater has been investigated under various operational conditions using hydrophobic hollow fiber membrane contactors. Experimental overall mass transfer coefficients were obtained in both handmade and Liqui-Cel modules. Model predictions based on a resistance in series model with solvent-filled membrane pores matched well with experimental values for tributyl phosphate/Shellsol extraction systems. However, the predictions were in poor agreement with experimental data obtained when 50% pentanol/xylene was used to treat industrial wastewater in the handmade module. Further analysis showed that the operational pressure on the aqueous side and the breakthrough pressure for the two solvents probably influenced the position of the interface within the membrane pores. This change in wetting patterns resulted in significant differences in mass transfer and solute recovery which can be accounted for by adjusting the position of the interface within the membrane fiber.

Modified modeling of the effect of pH and viscosity on the mass transfer in hydrophobic hollow fiber membrane contactors

This paper studied the effect of pH and the viscosity of feed solution on the mass transfer in two different specifications of hydrophobic hollow fiber membrane contactors. Experimental results showed that the pH of the feed had a significant effect on the rate of mass transfer, the flux and the removal efficiency of easily ionized volatile compounds (VCs), such as ammonia. In unbuffered feed solutions, both the resistance of membrane and the resistance of feed side were affected by the pH of feed and both of them had contributions to the overall mass transfer. A model, 1 K = 1 K f + 1 K m 1 α N H 3 2 , was proposed to predict the effect of pH and gave good agreement with the experimental data for the two contactors. The relationship between viscosities and the mass transfer coefficient could be described by K 1 K 2 = η 2 η 1 0.33 . Based on our experiments, the change of the viscosities in the concentration range of ammonia from 50 to 10,000 mg l −1 caused about 3–4% variation of the mass transfer coefficients. Moreover, it may be more suitable to use the equilibrium concentrations of volatile species instead of the total concentrations of VCs to estimate mass transfer coefficients, removal efficiency and flux. Experimental results also revealed that the choice of the pH of feed might be one of the most crucial factors for removing easily ionized VCs, such as ammonia, from water and wastewater.