scholarly journals Interplay of the Factors Affecting Water Flux and Salt Rejection in Membrane Distillation: A State-of-the-Art Critical Review

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2841
Author(s):  
Lin Chen ◽  
Pei Xu ◽  
Huiyao Wang
Keyword(s):  
Water Flux ◽  
Feed Solution ◽  
Membrane Distillation ◽  
Operating Conditions ◽  
Membrane Properties ◽  
Membrane Thickness ◽  
Membrane Pore ◽  
Factors Affecting ◽  
Term Operation ◽  
Salt Rejection

High water flux and elevated rejection of salts and contaminants are two primary goals for membrane distillation (MD). It is imperative to study the factors affecting water flux and solute transport in MD, the fundamental mechanisms, and practical applications to improve system performance. In this review, we analyzed in-depth the effects of membrane characteristics (e.g., membrane pore size and distribution, porosity, tortuosity, membrane thickness, hydrophobicity, and liquid entry pressure), feed solution composition (e.g., salts, non-volatile and volatile organics, surfactants such as non-ionic and ionic types, trace organic compounds, natural organic matter, and viscosity), and operating conditions (e.g., temperature, flow velocity, and membrane degradation during long-term operation). Intrinsic interactions between the feed solution and the membrane due to hydrophobic interaction and/or electro-interaction (electro-repulsion and adsorption on membrane surface) were also discussed. The interplay among the factors was developed to qualitatively predict water flux and salt rejection considering feed solution, membrane properties, and operating conditions. This review provides a structured understanding of the intrinsic mechanisms of the factors affecting mass transport, heat transfer, and salt rejection in MD and the intra-relationship between these factors from a systematic perspective.

scholarly journals Simulation of direct contact membrane distillation regeneration of liquid desiccant solutions used in air-conditioning

2020 ◽  
Vol 58 (6) ◽  
pp. 747
Author(s):  
Hung Cong Duong ◽  
Lan Thi Thu Tran
Keyword(s):  
Direct Contact ◽  
Air Conditioning ◽  
Water Flux ◽  
Experimental Tests ◽  
Membrane Distillation ◽  
Operating Conditions ◽  
Membrane Properties ◽  
Experimental Investigations ◽  
Liquid Desiccant ◽  
Direct Contact Membrane Distillation

Membrane distillation (MD) has great potential for the treatment of hyper saline waters, including liquid desiccant solutions used in air-conditioning systems. Previous experimental investigations have demonstrated the technical feasibility of MD for regeneration of liquid desiccant solutions. In this study, a direct contact membrane distillation (DCMD) process of the LiCl liquid desiccant solution was simulated using MATLAB software. The simulation was first validated using data obtained from experimental tests. Then, it was used to elucidate the water temperatures, LiCl concentration, and water flux profiles along the membrane leaf inside the DCMD membrane module. Finally, with the help of the simulation, the effects of membrane properties and process operating conditions on the DCMD process performance were systematically examined. The results obtained from this simulation enrich the knowledge and hence facilitate the realization of MD for the liquid desiccant solution regeneration application.

scholarly journals Developing a Thin Film Composite Membrane with Hydrophilic Sulfonated Substrate on Nonwoven Backing Fabric Support for Forward Osmosis

Membranes ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 813
Author(s):  
Soleyman Sahebi ◽  
Mohammad Kahrizi ◽  
Nasim Fadaie ◽  
Soheil Hadadpour ◽  
Bahman Ramavandi ◽  
...  
Keyword(s):  
Water Flux ◽  
Forward Osmosis ◽  
Feed Solution ◽  
Membrane Properties ◽  
Solute Flux ◽  
Blend Ratio ◽  
Factors Affecting ◽  
Membrane Performance ◽  
Thin Film Composite ◽  
Sulfonated Polyethersulfone

This study describes the fabrication of sulfonated polyethersulfone (SPES) as a super-hydrophilic substrate for developing a composite forward osmosis (FO) membrane on a nonwoven backing fabric support. SPES was prepared through an indirect sulfonation procedure and then blended with PES at a certain ratio. Applying SPES as the substrate affected membrane properties, such as porosity, total thickness, morphology, and hydrophilicity. The PES-based FO membrane with a finger-like structure had lower performance in comparison with the SPES based FO membrane having a sponge-like structure. The finger-like morphology changed to a sponge-like morphology with the increase in the SPES concentration. The FO membrane based on a more hydrophilic substrate via sulfonation had a sponge morphology and showed better water flux results. Water flux of 26.1 L m−2 h−1 and specific reverse solute flux of 0.66 g L−1 were attained at a SPES blend ratio of 50 wt.% when 3 M NaCl was used as the draw solution and DI water as feed solution under the FO mode. This work offers significant insights into understanding the factors affecting FO membrane performance, such as porosity and functionality.

scholarly journals EVALUATION OF BACTERIAL CELLULOSE-SODIUM ALGINATE FORWARD OSMOSIS MEMBRANE FOR WATER RECOVERY

2018 ◽  
Vol 80 (3-2) ◽  
Author(s):  
Ngan T. B. Dang ◽  
Liza B. Patacsil ◽  
Aileen H. Orbecido ◽  
Ramon Christian P. Eusebio ◽  
Arnel B. Beltran
Keyword(s):  
Contact Angle ◽  
Bacterial Cellulose ◽  
Sodium Alginate ◽  
Water Flux ◽  
Forward Osmosis ◽  
Composite Membranes ◽  
Membrane Thickness ◽  
Water Recovery ◽  
Sem Images ◽  
Salt Rejection

Water resources are very important to sustain life. However, these resources have been subjected to stress due to population growth, economic and industrial growth, pollution and climate change. With these, the recovery of water from sources such as wastewater, dirty water, floodwater and seawater is a sustainable alternative. The potential of recovering water from these sources could be done by utilizing forward osmosis, a membrane process that exploits the natural osmotic pressure gradient between solutions which requires low energy operation. This study evaluated the potential of forward osmosis (FO) composite membranes fabricated from bacterial cellulose (BC) and modified with sodium alginate. The membranes were evaluated for water flux and salt rejection. The effect of alginate concentrations and impregnation temperatures were evaluated using 0.6 M sodium chloride solution as feed and 2 M glucose solution as the draw solution. The membranes were characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and Contact Angle Meter (CAM). The use of sodium alginate in BC membrane showed a thicker membrane (38.3 μm to 67.6 μm), denser structure (shown in the SEM images), and more hydrophilic (contact angle ranges from 28.39° to 32.97°) compared to the pristine BC membrane (thickness = 12.8 μm and contact angle = 66.13°). Furthermore, the alginate modification lowered the water flux of the BC membrane from 9.283 L/m2-h (LMH) to value ranging from 2.314 to 4.797 LMH but the improvement in salt rejection was prominent (up to 98.57%).

scholarly journals Fabrication and Performance Evaluation of Integrated Solar-Driven Membrane Distillation System with Serpentine-shape of Flat Plate Solar Collector for Seawater Desalination

2019 ◽  
Vol 23 (3) ◽  
Author(s):  
M. A. H. M. Hanoin ◽  
N. S. Mohammed ◽  
M. A. I. Z. Arris ◽  
A. I. A. Bakar ◽  
N. M. Mokhtar ◽  
...  
Keyword(s):  
Performance Evaluation ◽  
Flat Plate ◽  
Solar Collector ◽  
Pure Water ◽  
Feed Solution ◽  
Membrane Distillation ◽  
The Self ◽  
Permeate Flux ◽  
Salt Rejection ◽  
Flat Plate Solar Collector

Solar-powered membrane distillation (SPMD) system has gained its popularity in desalination application for past decade credit to the system efficiency in producing pure water and the utilization of renewable energy. However, most of the past SPMD works used commercial solar thermal collector (STC) as the thermal energy supply to the feed solution and the study only focused on the performance of the system in terms of flux and salt rejection. In this work, a self-made flat plate solar collector (FPSC) with the serpentine-shape pipe was designed and fabricated to study the effect of the STC towards the membrane performance. Before testing, a simulation work of the fluid flow inside the serpentine-shape pipe of the FPSC was analyzed using NX 10.0 computer-aided design simulation. After that, the efficiency of the self-made FPSC system was tested directly to sunlight in order to identify the maximum irradiance and the temperature of the feed solution. Due to the fluctuation of solar irradiance, the experimental setup of the SPMD system was tested using a solar simulator, and the performance was compared with the membrane distillation (MD) system without integration with FPSC system. Based on the simulation data, it can be concluded that the heat losses across the pipe are due to the slower fluid velocity and sudden pressure drop, which attributed to centripetal force and pressure differences. Meanwhile, the outdoor evaluation data showed that the temperatures of collector and water inside the feed tank could reach up to 84°C and 64°C, respectively when the maximum irradiance of 938 W/m2 was applied. For the performance evaluation between with and without the self-made FPSC system, it can be seen that only marginal difference can be observed for the permeate flux and salt rejection with an average difference of 6.06% and 1.29%, respectively.

scholarly journals Flux Optimization in Reverse Osmosis via the Solution-Diffusion Model

2019 ◽  
Vol 4 (5) ◽  
pp. 39-44
Author(s):  
Hisham A. Maddah
Keyword(s):  
Osmotic Pressure ◽  
Reverse Osmosis ◽  
Diffusion Model ◽  
Water Flux ◽  
Applied Pressure ◽  
Arabian Gulf ◽  
Water Sources ◽  
Operating Conditions ◽  
Membrane Thickness ◽  
Membrane Type

This paper suggests a new method of predicting flux values at reverse osmosis (RO) desalination plants.  The study is initiated by using the solution-diffusion model that is applied to the groundwater source at Abqaiq plant (500 RO plant) at Saudi Aramco, Dhahran, Saudi Arabia in order to calculate the osmotic pressure of the treated water for Shedgum/Abqaiq groundwater. For modelling purposes, the same technique is used to determine the osmotic pressure drops at the same plant configuration and operating conditions when using seawater sources such that of Arabian Gulf and the Red Sea waters. High rejection brackish water RO (BWRO) element Toray TM720D-400 with 8" is the RO membrane type that is used at Abqaiq plant. The calculated osmotic pressures of the three water sources, assuming that they are all treated at Abqaiq plant, are utilized to determine the appropriate flux values as well as membrane resistances of different BWRO Toray membranes. Values of numerous parameters such as water permeability constant, applied pressure, gas constant, water temperature, water molar volume and membrane thickness, water salinity/TDS are taken into account to develop our calculations through the solution-diffusion model. A comparison between low-pressure, standard and high-pressure BWRO Toray membranes performance have been established to select the ideal membrane type for the treatment of water from various sources at Abqaiq plant. The model results confirm an inverse relationship between the membrane thickness and the water flux rate. Also, a proportional linear relation between the overall water flux and the applied pressure across the membrane is identified. Higher flux rates and lower salinity indicate lower membrane resistance which yields to the higher water production. Modelled data predict that BWRO Toray TM720D-440 with 8" membrane is the optimal BWRO membrane choice for the three water sources at Abqaiq plant.

Performance of Cobalt-Silica Membranes through Pervaporation Process with Different Feed Solution Concentrations

2020 ◽  
Vol 981 ◽  
pp. 342-348 ◽  
Author(s):  
Muthia Elma ◽  
Gesit Satriaji Saputro
Keyword(s):  
Cobalt Oxide ◽  
Saline Water ◽  
Water Flux ◽  
Feed Solution ◽  
Water Desalination ◽  
Silica Xerogels ◽  
Silica Membranes ◽  
Salt Rejection ◽  
Bet Analysis ◽  
Value Of Water

This work shows the performance of cobalt-silica membranes through water desalination via pervaporation process. The aim of this work is to find out the performance of the cobalt oxide as a templating agent in the silica cobalt membranes for water desalination via pervaporation process. It also aims to investigate the water flux and salt rejection of silica cobalt membranes using artificial saline water. The concentration of cobalt oxide as a template for fabricating cobalt-silica membranes were 5 – 35 wt%. The feed solution applied during pervaporation process were 0.3 – 5 wt% NaCl with operating temperatures of 25, 40 and 60 °C. The silica xerogels were characterized using Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM) and Brunauer-Emmett-Teller (BET). From the FTIR result, it is known that the higher the concentration of cobalt in the membrane, the more silanol and siloxane groups. Based on BET analysis, Si-Co 35 wt% membrane has largest pore volume (0.129387 cm3g-1). In addition, the highest value of water flux (7.2660 kg.m-2.h-1) and salt rejection (100%) is achieved by Si-Co 5% membrane in 0.3% NaCl feed at 60 °C. The value of water flux decreases and the value of salt rejection increases with increasing feed concentration.

scholarly journals Performance of layer-by-layer (LbL) polyelectrolyte forward osmosis membrane for humic acid removal and reverse solute diffusion

2017 ◽  
Vol 19 ◽  
pp. 75 ◽  
Author(s):  
Suriani Husaini ◽  
Mazrul Nizam Abu Seman
Keyword(s):  
Humic Acid ◽  
Chemical Engineering ◽  
Water Flux ◽  
Forward Osmosis ◽  
Feed Solution ◽  
Solute Diffusion ◽  
Membrane Properties ◽  
Layer By Layer ◽  
Engineering Research ◽  
Draw Solution

<p>Recent study claimed that forward osmosis (FO) process could handle the fouling problem due it driven force based on natural osmotic pressure. However, researchers observed that FO membrane had problem with reverse solute diffusion (RSD) of draw solution. Therefore, FO membrane properties must be improved either physically or chemically in order to overcome this problem. Among all, surface modification approach has been acknowledged as a best technique to alter the membrane properties without significantly change the bulk membrane properties. In this study, polyelectrolyte FO membrane has been produced through Layer by Layer (LbL) deposition method by using Poly (diallyl-dimethylammoniumchloride), PDADMAC and Poly (sodium 4-styrene-sulfonate), PSS as an active monomers. Humic acid (HA) as part of Natural Organic Matter constituents was used as the feed solution and NaCl as a draw solution. The chemical structure and morphology of the FO membrane were characterized by FTIR and FESEM, respectively. From this study, the highest water flux and humic acid rejection were achieved at 2.5M of draw solution with value of 2.56 L/m<sup>²</sup>.h and 99%, respectively. In general, the water flux increases as the concentration of draw solutions were increased. However, it was observed that reverse salt diffusion (RSD) become worse at higher concentration of draw solution.</p><p>Chemical Engineering Research Bulletin 19(2017) 75-79</p>

scholarly journals Improved salt rejection, hydrophilicity and mechanical properties of novel thermoplastic polymer/chitosan nanofibre membranes

2020 ◽  
Vol 15 ◽  
pp. 155892502092317
Author(s):  
Fahad S Al-Mubaddel ◽  
Hamad S AlRomaih ◽  
Mohammad Rezaul Karim ◽  
Monis Luqman ◽  
Maher M Al-Rashed ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Contact Angle ◽  
Polyvinylidene Fluoride ◽  
Phase Inversion ◽  
Water Flux ◽  
Tensile Tests ◽  
Membrane Properties ◽  
Inversion Method ◽  
Thermoplastic Polymer ◽  
Salt Rejection

The present study reports on the preparation of novel nanofibre membranes from the thermoplastic polymer polyvinylidene fluoride coated with chitosan to enhance membrane properties such as hydrophilicity, mechanical properties, water flux and salt rejection. Initially, a supporting layer was produced from polyvinylidene fluoride using phase inversion methods, followed by being coated with chitosan using either electrospinning or immersion methods. Two types of fabricated membranes with different coating methods were characterized and tested for physical and chemical performance using field-emission scanning electron microscopy, tensile tests, permeation tests (water flux and salt rejection) and contact angle measurements. It was found that the support membrane (polyvinylidene fluoride) produced by the phase inversion method that was coated with chitosan using electrospinning showed better performance, with a salt rejection up to 70% for MgSO4, a decreased the contact angle (52°) and improved the elongation at the breaking point (~82%).

Fatigue Cracking Processes of a Thick-Walled Component of a Chemical Pipeline

2013 ◽  
Vol 586 ◽  
pp. 104-107 ◽  
Author(s):  
Marek Cieśla ◽  
Kazimierz Mutwil
Keyword(s):  
Mechanical Properties ◽  
Degradation Mechanism ◽  
Fatigue Cracking ◽  
Operating Conditions ◽  
Material Structure ◽  
Mechanical Loads ◽  
Factors Affecting ◽  
Term Operation ◽  
Materials Used

At present, there are no generally accepted and widely recognized procedures to determine condition of material of devices subject to complex long-term thermo-mechanical loads. Condition of pipeline material usually changes when subjected to the conditions of long-term operation. Its structure changes and, consequently, so do its mechanical properties, including fatigue characteristics and crack resistance. Therefore, the durability of a component operating under thermal and mechanical loads cannot be discussed separately from its current material properties. This applies in particular to changes that take place in the material micro-structure and to their connection with mechanical properties. This paper covers analyses of stress in the material of a selected pipeline component – pipe tee that is used in chemical plants. Thermo-mechanical interactions determining stress distribution in the component have been taken into account in the calculations. Morphology and location of the cracks indicated that a fatigue-like nature of impacts was the cause of material destruction. Loads of this type occur mainly in conditions of start-up and shut-down. For these reasons, condition of the material in the above-mentioned unstable conditions was subjected to numerical stress analysis. Due to geometric complexity of the pipeline, the distribution of stress in the T-pipe was calculated in two stages: the object was modeled from a global and local perspective. The resulting stress distributions helped to determine factors affecting durability of the tested object. Metallurgy tests were also conducted in order to ascertain factors determining the degradation of material structure and processes of crack formation and development. As a result of research one ascertained that the process of T-pipe cracking under operating conditions was a combined effect of thermo-mechanical and chemical actions determined by the course of intercrystalline corrosion. Synergic interaction of corrosion processes and variable thermal and mechanical loads caused nucleation and propagation of cracks. The crack systems in T-pipe areas subject to the highest stress showed courses characteristic for thermal fatigue of material. The results obtained will identify degradation mechanism of materials used in chemical installations.

scholarly journals Development of A Novel Corrugated Polyvinylidene difluoride Membrane via Improved Imprinting Technique for Membrane Distillation

Polymers ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 865 ◽  
Author(s):  
Normi Izati Mat Nawi ◽  
Muhammad Roil Bilad ◽  
Nurazrina Zolkhiflee ◽  
Nik Abdul Hadi Nordin ◽  
Woei Jye Lau ◽  
...  
Keyword(s):  
Surface Area ◽  
Membrane Surface ◽  
Water Flux ◽  
Cross Flow ◽  
Membrane Distillation ◽  
Effective Surface Area ◽  
Effective Surface ◽  
Widespread Application ◽  
Polyvinylidene Difluoride ◽  
Term Operation

Membrane distillation (MD) is an attractive technology for desalination, mainly because its performance that is almost independent of feed solute concentration as opposed to the reverse osmosis process. However, its widespread application is still limited by the low water flux, low wetting resistance and high scaling vulnerability. This study focuses on addressing those limitations by developing a novel corrugated polyvinylidene difluoride (PVDF) membrane via an improved imprinting technique for MD. Corrugations on the membrane surface are designed to offer an effective surface area and at the same time act as a turbulence promoter to induce hydrodynamic by reducing temperature polarization. Results show that imprinting of spacer could help to induce surface corrugation. Pore defect could be minimized by employing a dual layer membrane. In short term run experiment, the corrugated membrane shows a flux of 23.1 Lm−2h−1 and a salt rejection of >99%, higher than the referenced flat membrane (flux of 18.0 Lm−2h−1 and similar rejection). The flux advantage can be ascribed by the larger effective surface area of the membrane coupled with larger pore size. The flux advantage could be maintained in the long-term operation of 50 h at a value of 8.6 Lm−2h−1. However, the flux performance slightly deteriorates over time mainly due to wetting and scaling. An attempt to overcome this limitation should be a focus of the future study, especially by exploring the role of cross-flow velocity in combination with the corrugated surface in inducing local mixing and enhancing system performance.

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