News on alginate recovery by forward osmosis: Reverse solute diffusion is useful

Chemosphere ◽  
2021 ◽  
pp. 131483
Author(s):  
Da-Qi Cao ◽  
Xiu-Zhen Sun ◽  
Wen-Yu Zhang ◽  
Yu-Ting Ji ◽  
Xiao-Xuan Yang ◽  
...  
Keyword(s):  
Forward Osmosis ◽  
Solute Diffusion

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>

Fabrication of PSS/PDADMAC Polyelectrolyte Membrane via Layer-by-Layer (LbL) Technique for Forward Osmosis (FO) Application

2019 ◽  
Vol 797 ◽  
pp. 13-19
Author(s):  
Mok Tze How ◽  
Mazrul Nizam Abu Seman
Keyword(s):  
Deposition Time ◽  
Pure Water ◽  
Water Flux ◽  
Forward Osmosis ◽  
Solute Diffusion ◽  
Layer By Layer ◽  
Styrene Sulfonate ◽  
Membrane Performance ◽  
Coated Layer ◽  
Polyelectrolyte Membrane

In this study, FO membrane was fabricated by Layer-by-Layer (LbL) coating technique using Poly (sodium 4-styrene-sulfonate)(PSS) and Poly (diallyl-dimethylammoniumchloride) (PDADMAC) as the active polyelectrolytes. Different concentrations of polyelectrolytes and deposition time of polyelectrolytes were investigated. The success of the coated layer was confirmed using ATR-FTIR and FESEM images. The membrane performance was determined by water flux and reverse solute diffusion (RSD) using pure water and 1.75M Na2SO4 as feed and draw solution, respectively. It was observed that the highest water flux, 6.76 L/ was recorded at the lowest polyelectrolytes concentration and longer deposition time. Meanwhile, the minimum RSD was achieved by the membrane fabricated at the longest deposition time and highest polyelectrolyte concentration.

scholarly journals Optimization of Operating Conditions in Forward Osmosis for Osmotic Membrane Bioreactor

2009 ◽  
Vol 3 (1) ◽  
pp. 27-32 ◽  
Author(s):  
Jian-Jun Qin ◽  
Maung Htun Oo ◽  
Guihe Tao ◽  
E. R. Cornelissen ◽  
C. J. Ruiken ◽  
...  
Keyword(s):  
Flow Pattern ◽  
Membrane Bioreactor ◽  
Concentration Polarization ◽  
Forward Osmosis ◽  
Operating Conditions ◽  
Solute Diffusion ◽  
External Concentration ◽  
Selective Layer ◽  
Draw Solution ◽  
Osmotic Membrane Bioreactor

Objective of this study was to conduct a baseline study of osmotic membrane bioreactor (OMBR) - optimization of operating conditions in forward osmosis (FO). Experiments were conducted with an FO pilot system. Tap water was used as the feed and NaCl and MgSO4 solutions were used as draw solution. Effects of various operating conditions on flux have been investigated. In addition, pure water permeability of the FO membrane was tested. It was observed that the plant operation could be stablized within 1 h. When the membrane selective layer faced to the feed, a flux of 6.3 lm-2h-1 (LMH) was achieved at 24 atm osmotic pressure and 25 °C and effects of feed velocity and air velocity on flux were not siganificant under the testing conditions due to low external concentration polarization (ECP). However, when the selective layer faced to the draw solution, the flux was enhanced by 64% due to much reduced internal concentration polarization (ICP), the flux sharply increased with an increase in velocity of the draw solution in the laminar flow pattern range due to a countable effect of dilutive external concentration polarization (DECP) and leveled off after the flow pattern became turbulent. NaCl performed much higher efficiency than MgSO4 as an osmotic agent due to a greater solute diffusion coefficient of NaCl.

scholarly journals Dynamical Modeling of Water Flux in Forward Osmosis with Multistage Operation and Sensitivity Analysis of Model Parameters

Water ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 31
Author(s):  
Hoyoung Ryu ◽  
Azeem Mushtaq ◽  
Eunhye Park ◽  
Kyochan Kim ◽  
Yong Keun Chang ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Concentration Polarization ◽  
Water Flux ◽  
Forward Osmosis ◽  
Solute Diffusion ◽  
Model Parameters ◽  
Sensitivity Index ◽  
Water Recovery ◽  
Asymmetric Membrane ◽  
Simulation Results

To mathematically predict the behavior of a forward osmosis (FO) process for water recovery, a model was constructed using an asymmetric membrane and glucose as a draw solution, allowing an examination of both phenomenological and process aspects. It was found that the proposed model adequately described the significant physicochemical phenomena that occur in the FO system, including forward water flux, internal concentration polarization (ICP), external concentration polarization (ECP), and reverse solute diffusion (RSD). Model parameters, namely the physiochemical properties of the FO membrane and glucose solutions, were estimated on the basis of experimental and existing data. Through batch FO operations with the estimated parameters, the model was verified. In addition, the influences of ECP and ICP on the water flux of the FO system were investigated at different solute concentrations. Water flux simulation results, which exhibited good agreement with the experimental data, confirmed that ICP, ECP, and RSD had a real impact on water flux and thus must be taken into account in the FO process. With the Latin-hypercube—one-factor-at-a-time (LH–OAT) method, the sensitivity index of diffusivity was at its highest, with a value of more than 40%, which means that diffusivity is the most influential parameter for water flux of the FO system, in particular when dealing with a high-salinity solution. Based on the developed model and sensitivity analysis, the simulation results provide insight into how mass transport affects the performance of an FO system.

Synthetic polymer materials for forward osmosis (FO) membranes and FO applications: a review

2019 ◽  
Vol 35 (2) ◽  
pp. 191-209 ◽  
Author(s):  
Wenxuan Xu ◽  
Qingchun Ge
Keyword(s):  
Membrane Fouling ◽  
Forward Osmosis ◽  
Polymer Materials ◽  
Solute Diffusion ◽  
Chemical Modifications ◽  
Chemically Modified ◽  
Modified Polymer ◽  
Membrane Fabrication ◽  
Novel Approach ◽  
Commercial Polymers

Abstract Forward osmosis (FO) has played an important role in alleviating the problems caused by freshwater shortage and water contamination in recent years. However, issues of low water permeability, reverse solute diffusion, concentration polarization and membrane fouling are still widely present in FO processes. These challenges are the current research focus in exploring novel FO membranes. Fabricating FO membranes from chemically modified commercial polymers is a relatively novel approach and has proven effective in obtaining appropriate FO membranes. This paper focuses on the progress of FO membranes made specially from chemically modified polymer materials. First of all, a brief overview of commercial polymers commonly used for FO membrane fabrication is provided. Secondly, the chemical modification strategies and synthesis routes of novel polymer materials as well as the resultant FO membrane performance are presented. The strengths and weaknesses of chemical modifications on polymer materials are assessed. Then, typical FO applications facilitated by the FO membranes made from modified polymer materials are exemplified. Finally, challenges and future directions in exploring novel polymers through chemical modifications for FO membrane fabrication are highlighted. This review may provide new insights into the future advancement of both novel membrane materials and FO membranes.

Observation by HVEM of the martensite transformation and the superconducting transition in Nb3Sn

1988 ◽  
Vol 46 ◽  
pp. 788-789
Author(s):  
M. A. Kirk ◽  
M. C. Baker ◽  
B. J. Kestel ◽  
H. W. Weber
Keyword(s):  
Thin Films ◽  
Low Temperature ◽  
Superconducting State ◽  
Martensite Transformation ◽  
Sputter Deposition ◽  
Diffusion Reaction ◽  
Solute Diffusion ◽  
Superconducting Transition ◽  
Twin Boundaries ◽  
Martensite Structure

It is well known that a number of compound superconductors with the A15 structure undergo a martensite transformation when cooled to the superconducting state. Nb3Sn is one of those compounds that transforms, at least partially, from a cubic to tetragonal structure near 43 K. To our knowledge this transformation in Nb3Sn has not been studied by TEM. In fact, the only low temperature TEM study of an A15 material, V3Si, was performed by Goringe and Valdre over 20 years ago. They found the martensite structure in some foil areas at temperatures between 11 and 29 K, accompanied by faults that consisted of coherent twin boundaries on {110} planes. In pursuing our studies of irradiation defects in superconductors, we are the first to observe by TEM a similar martensite structure in Nb3Sn.Samples of Nb3Sn suitable for TEM studies have been produced by both a liquid solute diffusion reaction and by sputter deposition of thin films.

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