Numerical evaluation of sweeping gas membrane distillation for desalination of water towards water sustainability and environmental protection

Sweeping gas membrane distillation (SGMD) is considered a membrane distillation configuration. It uses an air stream to collect the water vapour. A 2D mathematical model is prepared in the current study to predict the effect of various operating parameters on the SGMD performance. Also, the temperature distribution in the SGMD was obtained. The effect of air inlet temperature, salt concentration, feed and air flowrate on air and salted solution outlet temperature and vapour flux through the membrane is investigated. There was good agreement between experimental data and modelling outputs. It was found that increase in air inlet temperature from 40 to 72 °C was increased the outlet temperature of air stream and cold solution from 37 to 63 °C and 38 to 65 °C respectively. Furthermore, increase in air inlet temperature led to the enhancement of vapour flux in the membrane distillation. Also, the salt concentration and feed flow rate did not have meaningful influence on the outlet temperatures, however, the flux was increased by increasing feed flowrate.

Computational fluid dynamics simulation study of hypersaline water desalination via membrane distillation: Effect of membrane characteristics and operational parameters

In this study, a comprehensive model was developed using Computational Fluid Dynamics (CFD), and the behaviour of a direct contact membrane distillation (DCMD) system was investigated at hypersaline feedwater conditions. The effects of various operating parameters including feed and permeate velocities, temperatures and salinities, as well as different membrane characteristics like thickness, porosity, and thermal conductivity were studied. The developed simulation model was also validated using experimental data. The results showed that the membrane conductivity and thickness had a significant impact on the DCMD performance, and the optimum operational condition was necessary to be determined. The results showed that increasing the feedwater salinity from 50 to 200 g/l decreased the membrane flux by up to 33%, while a four times decrease in thermal conductivity of the membrane could lead to an increase in the membrane flux from 11.2 to 32.4 l/m²·h (LMH). In addition, the optimal membrane thickness was found to increase with salinity, reaching >120 μm for treatment of 22 wt% NaCl feedwater solution. However, the flux declined from >32 LMH to <13 LMH upon the increase in feedwater salinity (up to 22 wt% NaCl solution). It is also shown that a thinner membrane performed better for desalination of low salinity feedwater, while the thicker one produces higher separation performance and thermal efficiency for hypersaline brine desalination.

Applications of Polymeric Membranes with Carbon Nanotubes: A Review

Nanomaterials have been commonly employed to enhance the performance of polymeric membrane materials that are used in several industrial applications. Carbon nanotubes (CNTs) have gained notable attention over the years for use in membrane technology due to their anti-biofouling properties, salt rejection capability, exceptional electrical conductivity, and mechanical properties. This paper aims to discuss some of the recent applications of CNTs in membrane technology and their effect on a larger scale. The paper reviews successful case studies of incorporation of CNTs in membranes and their impact on water purification, desalination, gas separations, and energy storage, in an effort to provide a better understanding of their capabilities. Regarding the future trends of this technology, this review emphasizes improving the large-scale production processes and addressing environmental and health-related hazards of CNTs during production and usage.

Vertically Aligned Carbon Nanotube Membranes: Water Purification and Beyond

Vertically aligned carbon nanotube (VACNT) membranes have attracted significant attention for water purification owing to their ultra-high water permeability and antibacterial properties. In this paper, we critically review the recent progresses in the synthesis of VACNT arrays and fabrication of VACNT membrane methods, with particular emphasis on improving water permeability and anti-biofouling properties. Furthermore, potential applications of VACNT membranes other than water purification (e.g., conductive membranes, electrodes in proton exchange membrane fuel cells, and solar electricity–water generators) have been introduced. Finally, future outlooks are provided to overcome the limitations of commercialization and desalination currently faced by VACNT membranes. This review will be useful to researchers in the broader scientific community as it discusses current and new trends regarding the development of VACNT membranes as well as their potential applications.

Modification of polyethersulfone membrane using MWCNT-NH2 nanoparticles and its application in the separation of azeotropic solutions by means of pervaporation

In this study, functionalized multi-walled carbon nanotubes (MWCNT-NH₂) were synthesized as an additive for the preparation of mixed matrix membranes (MMMs) and then were investigated by FTIR and FE-SEM techniques. Polyether sulfone (PES) polymeric membrane modified with functionalized MWCNT-NH₂ carbon nanotubes was prepared by phase inversion method. The effect of MWCNT-NH₂ on the morphology and property of the PES membrane was evaluated using scanning electron microscopy. The flux, enrichment factor and swelling properties of modified membranes were also used to investigate the membranes performance. The results showed that the flux and enrichment factor in modified PES membrane containing 5 wt.% of functionalized MWCNT-NH₂ carbon nanotubes were obtained 1.2 L.m^-2h^-1 and 3.3, respectively. The influence of methanol concentration on the flux and enrichment factor was investigated. The results corroborated that the flux didn’t change significantly, while the enrichment factor was decreased.

Numerical simulation of reactive extraction of benzoic acid from wastewater via membrane contactors

Membrane-based non-dispersive solvent extraction is used in many chemical processes due to its significant benefits such as straightforward scale-up and low energy consumption. A mechanistic model was developed to predict recovery of benzoic acid (BA) from wastewater using membrane contactors. Model equations were derived for benzoic acid transport in the membrane module, and solved using FEM. The model findings were compared with experimental results, and an average deviation of 4% was observed between experimental and simulation results. Simulations showed that change in organic phase flowrate and initial concentration of BA does not have considerable effect on the removal efficiency of benzoic acid. In addition, increasing feed flowrate leads to the enhancement of convective mass transfer flux in the tube side of membrane contactor which decreases removal efficiency of benzoic acid.

Synthesis and characterization of polyurethane/poly(vinylpyridine) composite membranes for desulfurization of gasoline

Polyurethane/poly(vinylpyridine) (PU/PVP) composite membranes for desulfurizing gasoline were prepared.