The Experts below are selected from a list of 2457 Experts worldwide ranked by ideXlab platform
Tai-shung Chung - One of the best experts on this subject based on the ideXlab platform.
-
the forward osmosis pressure retarded osmosis fo pro hybrid system a new process to mitigate membrane fouling for sustainable Osmotic Power generation
Journal of Membrane Science, 2018Co-Authors: Zhen Lei Cheng, Tai-shung ChungAbstract:Abstract Pressure retarded osmosis (PRO) is an emerging technology to harvest the renewable salinity-gradient energy. However, its performance can be significantly limited by severe membrane fouling if a real waste effluent is used as the feed solution. To tackle this, we have experimentally demonstrated that forward osmosis (FO) can be used as a pretreatment means to extract water from the wastewater stream to the inter-loop solution. Subsequently, the diluted inter-loop solution could serve as a clean feed to the PRO unit at negligible fouling tendency. As a result, the newly developed FO-PRO hybrid system is capable of sustaining Osmotic Power generation with the advantages of FO such as (1) low fouling propensity, (2) easy membrane cleaning, and (3) minimal external energy required. Model simulations of full-scale analyses reveal that, by choosing the salinity of the inter-loop solution to PRO as 0.1 M, it is possible to reach a Power density greater than 5 W/m2 set by Statkraft as the commercially viable benchmark. Meanwhile, the concentrated brine draw solution of PRO can be diluted back to the seawater level for easy disposal or reuse. Under this condition, FO possesses a comparable water flux with conventional pretreatment methods using pressure driven membrane processes. A simple design strategy is also provided in detail for the integration of FO and PRO units.
-
advanced anti fouling membranes for Osmotic Power generation from wastewater via pressure retarded osmosis pro
Environmental Science & Technology, 2018Co-Authors: Gang Han, Jiang Tao Liu, Tai-shung ChungAbstract:A facile and versatile approach was demonstrated for the fabrication of low-fouling pressure retarded osmosis (PRO) membranes for Osmotic Power generation from highly polluted wastewater. A water-soluble zwitterionic random copolymer with superior hydrophilicity and unique chemistry was molecularly designed and synthesized via a single-step free-radical polymerization between 2-methacryloyloxyethyl phosphorylcholine (MPC) and 2-aminoethyl methacrylate hydrochloride (AEMA). The P[MPC-co-AEMA] copolymer was then chemically grafted onto the surface of PES/Torlon hollow fibers via amino groups coupling of poly(AEMA) with the polyimide structures of Torlon, leaving the zwitterions of poly(MPC) in the feed solution. Because of the outstanding hydrophilicity, unique cationic and anionic groups, and electrical neutrality of the zwitterionic brush, the newly developed membrane showed great resistances to both inorganic scaling and organic fouling in PRO operations. When using a real wastewater brine comprising mul...
-
Novel thin film composite hollow fiber membranes incorporated with carbon quantum dots for Osmotic Power generation
Journal of Membrane Science, 2018Co-Authors: Wenxiao Gai, Die Ling Zhao, Tai-shung ChungAbstract:Abstract By means of carbon quantum dots incorporation, we have developed novel thin film composite (TFC) membranes for Osmotic Power generation. The newly developed TFC membrane exhibits a peak Power density as high as 34.20 W/m2 at 23 bar using 1.0 M NaCl and deionized water as the feed pair. To our best knowledge, this is the highest ever Power density reported in the literature. The carbon quantum dots (CQDs) are a new class of carbon nanomaterials with advantages of excellent hydrophilicity, low toxicity, environmental friendliness, easy synthesis and low cost. The CQDs are incorporated into the polyamide selective layers via the conventional interfacial polymerization reaction. The effects of incorporating different CQDs and their loadings on membrane morphology, properties and PRO performance have been examined. It is found that the addition of Na+–functionalized CQDs not only increases the existence of hydrophilic oxygen-containing groups and surface area of the polyamide layer, but also changes the morphology with a looser and thinner polyamide network. The TFC membrane comprising 1 wt% Na–CQD-9 has the optimal performance. Compared with the control, the water flux and Power density at 23 bar increase from 44.52 to 53.54 LMH and 28.44 to 34.20 W/m2 respectively, while the reverse salt flux remains unchanged.
-
Sulfonated hyperbranched polyglycerol grafted membranes with antifouling properties for sustainable Osmotic Power generation using municipal wastewater
Journal of Membrane Science, 2018Co-Authors: Yu Zhang, Tao Cai, Zhen Lei Cheng, Tai-shung ChungAbstract:Abstract In recent years, pressure retarded osmosis (PRO) has drawn considerable attention due to its feasibility of harvesting clean and sustainable Osmotic Power through a membrane process. When municipal wastewater is fed into this process, fouling in the porous substrate of the PRO membrane is the major concern since it can hinder the membrane performance tremendously and lower the Power generation. In this work, sulfonated hyperbranched polyglycerol (SHPG) polymers with a dendritic architecture have been molecularly designed and then grafted onto the surface of polydopamine (PDA) coated poly(ethersulfone) (PES) hollow fiber membranes. Comparing to the pristine PES membranes, the SHPG modified PRO membranes show significantly improved resistance to protein adhesion and bacterial attachment due to the high wettability of their ionic polymer brushes. In PRO tests under different hydraulic pressures, the SHPG-grafted membranes show a lower flux reduction and a higher flux recovery rate of 94% vs. 87% in comparison with the pristine PES membranes. Therefore, the Osmotic Power generation can be significantly sustained by modifying the PRO membranes with SHPG polymers. This work may provide a versatile approach and useful insights for the design of membranes with antifouling properties in the molecular level.
-
Advanced Anti-Fouling Membranes for Osmotic Power Generation from Wastewater via Pressure Retarded Osmosis (PRO)
2018Co-Authors: Gang Han, Jiang Tao Liu, Tai-shung ChungAbstract:A facile and versatile approach was demonstrated for the fabrication of low-fouling pressure retarded osmosis (PRO) membranes for Osmotic Power generation from highly polluted wastewater. A water-soluble zwitterionic random copolymer with superior hydrophilicity and unique chemistry was molecularly designed and synthesized via a single-step free-radical polymerization between 2-methacryloyloxyethyl phosphorylcholine (MPC) and 2-aminoethyl methacrylate hydrochloride (AEMA). The P[MPC-co-AEMA] copolymer was then chemically grafted onto the surface of PES/Torlon hollow fibers via amino groups coupling of poly(AEMA) with the polyimide structures of Torlon, leaving the zwitterions of poly(MPC) in the feed solution. Because of the outstanding hydrophilicity, unique cationic and anionic groups, and electrical neutrality of the zwitterionic brush, the newly developed membrane showed great resistances to both inorganic scaling and organic fouling in PRO operations. When using a real wastewater brine comprising multifoulants as the feed, the P[MPC-co-AEMA] modified membrane exhibits a much lower flux decline of 37% at ΔP = 0 bar after 24-h tests and a smaller Power density decrease of 28% at ΔP = 15 bar within 12-h tests, compared to 61% and 42% respectively for the unmodified one. In addition to the low fouling tendency, the modified membrane shows outstanding performance stability and fouling reversibility, where the flux is almost fully recovered by physical backwash of water at 15 bar for 0.5 h. This study provides valuable insights and strategies for the design and fabrication of effective antifouling materials and membranes for PRO Osmotic Power generation
Sui Zhang - One of the best experts on this subject based on the ideXlab platform.
-
Hyperbranched poly(ionic liquid) functionalized poly(ether sulfone) membranes as healable antifouling coatings for Osmotic Power generation
Journal of Materials Chemistry, 2019Co-Authors: Yu Zhang, Sui Zhang, Xue LiAbstract:Membrane fouling and membrane deterioration are two major concerns since they greatly worsen membrane performance in pressure retarded osmosis (PRO) and shorten the membrane lifetime. Herein, inspired by biological systems where microdamage induces an autonomous repair process, intrinsically healable poly(ionic liquid) (PIL) coating layers with sufficiently high mobility from short-distance electrostatic interactions have been fabricated by sequential immobilization of sulfonated hyperbranched polyglycerol (hbSPG) and quaternized polyethylenimine (QPEI) on polydopamine (PDA) pretreated poly(ether sulfone) (PES) membranes. XPS, SEM, and AFM results confirmed the successful incorporation of a PIL polymer pair onto the PES supports. Zeta potential analysis validated the charge alteration by electrostatic conjugation of the QPEI polymer onto the hbSPG modified surface. The antifouling and self-healing characteristics of the resultant PES-g-hbSPG-QPEI hollow fiber membranes were demonstrated by the excellent anti-protein adsorption behaviors and improved antibacterial performances on both non-aged and aged samples that were soaked in real municipal wastewater (WWRe) for two months. In PRO tests, the pristine PES membranes were contaminated seriously under high pressure operation, leading to a significant flux drop of 60%. In comparison, a flux reduction of 30% and a recovery rate of 98% after backflushing and hydraulic pressure impulsion on the non-aged membrane and a flux reduction of 40% on the aged membranes were observed. The intrinsically healable and antifouling PIL coating layers exhibit great potential of the developed strategy for the fabrication of high-performance PRO membranes toward Osmotic Power generation.
-
Hyperbranched poly(ionic liquid) functionalized poly(ether sulfone) membranes as healable antifouling coatings for Osmotic Power generation
Journal of Materials Chemistry, 2019Co-Authors: Yu Zhang, Sui Zhang, Xue LiAbstract:Membrane fouling and membrane deterioration are two major concerns since they greatly worsen membrane performance in pressure retarded osmosis (PRO) and shorten the membrane lifetime. Herein, inspired by biological systems where microdamage induces an autonomous repair process, intrinsically healable poly(ionic liquid) (PIL) coating layers with sufficiently high mobility from short-distance electrostatic interactions have been fabricated by sequential immobilization of sulfonated hyperbranched polyglycerol (hbSPG) and quaternized polyethylenimine (QPEI) on polydopamine (PDA) pretreated poly(ether sulfone) (PES) membranes. XPS, SEM, and AFM results confirmed the successful incorporation of a PIL polymer pair onto the PES supports. Zeta potential analysis validated the charge alteration by electrostatic conjugation of the QPEI polymer onto the hbSPG modified surface. The antifouling and self-healing characteristics of the resultant PES-g-hbSPG-QPEI hollow fiber membranes were demonstrated by the excellent anti-protein adsorption behaviors and improved antibacterial performances on both non-aged and aged samples that were soaked in real municipal wastewater (WWRe) for two months. In PRO tests, the pristine PES membranes were contaminated seriously under high pressure operation, leading to a significant flux drop of 60%. In comparison, a flux reduction of 30% and a recovery rate of 98% after backflushing and hydraulic pressure impulsion on the non-aged membrane and a flux reduction of 40% on the aged membranes were observed. The intrinsically healable and antifouling PIL coating layers exhibit great potential of the developed strategy for the fabrication of high-performance PRO membranes toward Osmotic Power generation.
-
Facile Preparation of Antifouling Hollow Fiber Membranes for Sustainable Osmotic Power Generation
ACS Sustainable Chemistry & Engineering, 2016Co-Authors: Sui Zhang, Yu Zhang, Tai-shung ChungAbstract:Organic fouling in the membrane support is one of the major causes for the flux decline and low efficiency in the pressure retarded osmosis (PRO) process for Osmotic Power generation, especially when the fouling is complicated by inorganic salt ions. A facile method to fabricate antifouling hollow fiber membranes was demonstrated in this study, which employed the readily available poly(vinyl alcohol) (PVA) as the modification agent. The poly(ether sulfone) (PES) support for the thin film composite (TFC) membranes was first coated by polydopamine (PDA) and then coated with PVA with the aid of glutaraldehyde (GA). PDA was found to detach from the support in the first 2 h and gradually stabilized at pH 2, verifying its applicability for PRO processes. In addition, the existence of a PVA layer was confirmed by X-ray photoelectron spectroscopy. It is important to note that by controlling the reaction conditions, the water flux and salt reverse flux in the PRO process were not sacrificed, proving that the modif...
-
Sandwich-structured hollow fiber membranes for Osmotic Power generation
Desalination, 2015Co-Authors: Sui Zhang, Tai-shung ChungAbstract:Abstract In this work, a novel sandwich-structured hollow fiber membrane has been developed via a specially designed spinneret and optimized spinning conditions. With this specially designed spinneret, the outer layer, which is the most crucial part of the sandwich-structured membrane, is maintained the same as the traditional dual-layer membrane. The inner substrate layer is separated into two layers: (1) an ultra-thin middle layer comprising a high molecular weight polyvinylpyrrolidone (PVP) additive to enhance integration with the outer polybenzimidazole (PBI) selective layer, and (2) an inner-layer to provide strong mechanical strength for the membrane. Experimental results show that a high water permeability and good mechanical strength could be achieved without the expensive post treatment process to remove PVP which was necessary for the dual-layer pressure retarded osmosis (PRO) membranes. By optimizing the composition, the membrane shows a maximum Power density of 6.23 W/m2 at a hydraulic pressure of 22.0 bar when 1 M NaCl and 10 mM NaCl are used as the draw and feed solutions, respectively. To our best knowledge, this is the best phase inversion hollow fiber membrane with an outer selective PBI layer for Osmotic Power generation. In addition, this is the first work that shows how to fabricate sandwich-structured hollow fiber membranes for various applications.
-
Progress in pressure retarded osmosis (PRO) membranes for Osmotic Power generation
Progress in Polymer Science, 2014Co-Authors: Gang Han, Sui Zhang, Xue Li, Tai-shung ChungAbstract:The rapid increases in global energy consumption and greenhouse gas emissions have stimulated the exploration of renewable energy sources as alternative fuels. Osmotic pressure gradient energy released from the mixing of water streams with different salinities is an unexploited resource of renewable energy. By employing a semipermeable membrane to control the mixing process, the Osmotic pressure gradient energy can be harvested in terms of electrical Power via pressure retarded osmosis (PRO) without causing adverse environmental impacts. The ideal of harvesting Osmotic Power via PRO was proposed in the early seventies; however, the absence of effective membranes with desirable structure and performance hindered further advancement of the PRO technology. During the last few years, a significant progress in PRO technology has been achieved. Novel flat-sheet and hollow fiber polymeric membranes with desired structure, mechanical robustness and permeation characteristics have been developed for PRO applications. Membranes with a target Power density of 5 W/m2to produce commercially viable PRO processes have been achieved. At this point of time, a comprehensive review is imperative in order to summarize what we have accomplished and provide insights for the development of next generation PRO membranes. After a brief introduction of the PRO process and the early PRO development using the existing RO/NF and FO membranes, this review focuses primarily on novel and the state-of-the-art PRO membranes. Furthermore, the requirements for fabricating effective PRO membranes will be discussed and future perspectives will be presented.
Chun Feng Wan - One of the best experts on this subject based on the ideXlab platform.
-
Tuning water content in polymer dopes to boost the performance of outer-selective thin-film composite (TFC) hollow fiber membranes for Osmotic Power generation
Journal of Membrane Science, 2017Co-Authors: Zhen Lei Cheng, Chun Feng Wan, Yingnan Feng, Tai-shung ChungAbstract:Abstract The lack of effective membranes greatly hinders the use of pressure retarded osmosis (PRO) to harvest renewable Osmotic energy. In comparison to the flat sheet and inner-selective hollow fiber configurations, the development of outer-selective hollow fiber membranes is much slower although it may be more attractive for real PRO applications. This study demonstrates that tuning the water content in polymer dopes can be an effective means to simultaneously enhance the mechanical robustness and water transport properties, boosting the PRO performance of outer-selective thin-film composite (TFC) hollow fiber membranes. Fundamental properties of polymer dopes with different water content and their influence on the hollow fiber supports as well as resultant TFC membranes were systematically investigated. With a low water content of 2 wt% in the polymer dope, the newly developed TFC membrane not only has the smallest structural parameter, highest toughness, and largest water permeability among all membranes studied but also displays an impressive peak Power density of 10.05 W/m 2 at 22 bar using 1 M NaCl and DI water as feeds. To our best knowledge, this is the highest Power density of outer-selective TFC PRO hollow fiber membranes reported in the literature. Mathematical models predict that approximately 25% performance increase can be further achieved if the external concentration polarization (ECP) effect is minimized. This study may provide useful insights to design high performance outer-selective TFC hollow fiber membranes for Osmotic Power generation.
-
Zwitterions coated hollow fiber membranes with enhanced antifouling properties for Osmotic Power generation from municipal wastewater.
Water research, 2016Co-Authors: Die Ling Zhao, Chun Feng Wan, Guanglei Qiu, Tai-shung ChungAbstract:Fouling on pressure-retarded osmosis (PRO) membranes leads to severe declines in water flux and Power density because their porous substrates are facing the wastewater feed. Thus, inorganics, organics and microorganisms in the wastewater are prone to depositing on the substrate surface and even in its pores. In order to reduce the fouling propensity, coating the substrate surface of PRO membranes with zwitterionic materials proves to be an effective way. In this work, 2-methacryloyloxyethylphosphorylcholine (MPC), is modified and grafted onto the polydopamine (PDA) coated poly (ether sulfone) (PES) hollow fiber substrate. Both the synthesis and surface coating of MPC are easy and facile to be scaled up. Compared with the pristine PES and PES-PDA substrates, the MPC modified substrate (PES-PDA-MPC) exhibits high resistance to protein adsorption as well as bacteria adhesion. By using a state-of-the-art thin-film composite poly (ether sulfone) (TFC-PES) hollow fiber membrane as the control for Power generation, the Power density of the TFC-PES-PDA-MPC membrane can achieve as high as 7.7 W/m2 while the unmodified one has only 6.0 W/m2 after 3 h's PRO tests. In conclusion, the Osmotic Power generation of PRO membranes can be significantly sustained by modifying the membrane surface with zwitterions.
-
Zwitterionic polymers grafted poly(ether sulfone) hollow fiber membranes and their antifouling behaviors for Osmotic Power generation
Journal of Membrane Science, 2016Co-Authors: Tao Cai, Chun Feng Wan, Tai-shung ChungAbstract:Fouling on pressure retarded osmosis (PRO) membranes must be eliminated to maximize the efficiency of Osmotic Power generation. This is particularly applicable to PRO membranes due to its nature of fouling when wastewater is fed. To improve this, PRO thin-film composite (TFC) membranes for the first time will be redesigned by incorporating well-defined zwitterionic copolymers of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (DMAPS) or 2-methacryloyloxyethyl phosphorylcholine (MPC) onto the poly(ether sulfone) (PES) hollow fiber membranes. The introduction of 2-methacryloyloxyethyl lipoate (MEL) components into the zwitterionic copolymers provided sufficient grafting sites for the facile decoration of polydopamine (PDA) pretreated PES membranes via Michael addition. The PDMAPS and PMPC grafted membranes were shown to be effective in reducing protein adsorption and bacterial adhesion, in comparison to the pristine PES membranes and PDA pretreated membranes. The pristine TFC–PES membranes are fouled greatly in high pressure PRO tests with concentrated wastewater, resulting in a flux reduction of 61%. In contrast, the TFC–PES membranes grafted by zwitterionic PDMAPS and PMPC copolymers exhibit substantial improvement of flux recovery up to 98% after backwashing and hydraulic pressure impulsion. In summary, the Osmotic Power generation may be sustained by grafting the PRO membranes with the properly designed zwitterionic polymers.
-
Evolution of micro-deformation in inner-selective thin film composite hollow fiber membranes and its implications for Osmotic Power generation
Journal of Membrane Science, 2016Co-Authors: Wenxiao Gai, Jun Ying Xiong, Chun Feng Wan, Tai-shung ChungAbstract:Abstract Since thin film composite (TFC) hollow fiber (HF) membranes may experience micro-deformation under high hydraulic pressures in the pressure retarded osmosis (PRO) process due to their polymeric nature and self-supported configuration, this paper aims to elucidate (1) the micro-deformation of polyethersulfone (PES) TFC HF membranes within the pressure range from 0 to 20 bar and (2) its effects on water and salt permeability of the polyamide layer, and structure parameter and tortuosity of the substrate layer for Osmotic Power generation. It is found that pre-stabilization of the TFC HF membranes at a high pressure close to their burst pressures for a certain period of time is a Powerful way to maximize their PRO performance. After stabilization at 20 bar for 30 min, the Power density of the PES TFC HF membranes increase from 15.37 to 22.05 W/m 2 due to the increased membrane surface area, stretched polyamide selective layer (i.e., decreased water transport length and resistance) and decreased membrane structure parameter (i.e., lower tortuosity and internal concentration polarization (ICP)). The intermittent cycle tests have confirmed the sustainability of the enhanced water flux and Power density after stabilization of the TFC HF membranes at 20 bar without compromising their selectivity.
-
hybrid pressure retarded osmosis membrane distillation pro md process for Osmotic Power and clean water generation
Environmental Science: Water Research & Technology, 2015Co-Authors: Gang Han, Tai-shung Chung, Jian Zuo, Chun Feng WanAbstract:A novel pressure retarded osmosis–membrane distillation (PRO–MD) hybrid process has been experimentally conceived for sustainable production of renewable Osmotic Power and clean water from various waters. The proposed PRO–MD system may possess unique advantages of high water recovery rate, huge Osmotic Power generation, well-controlled membrane fouling, and minimal environmental impacts. Experimental results show that the PRO–MD hybrid process is promising such that not only it can harvest Osmotic energy from freshwater but also from wastewater. When employing a 2 M NaCl MD concentrate as the draw solution, ultrahigh Power densities of 31.0 W m−2 and 9.3 W m−2 have been demonstrated by the PRO subsystem using deionized water and real wastewater brine as feeds, respectively. Simultaneously, high-purity potable water with a flux of 32.5–63.1 L (m−2 h−1) can be produced by the MD subsystem at 40–60 °C without any detrimental effects of fouling. The energy consumption in the MD subsystem might be further reduced by applying a heat exchanger in the hybrid system and using low-grade heat or solar energy to heat up the feed solution. The newly developed PRO–MD hybrid process would provide insightful guidelines for the exploration of alternative green technologies for renewable Osmotic Power and clean water production.
Ho Kyong Shon - One of the best experts on this subject based on the ideXlab platform.
-
Melamine-based covalent organic framework-incorporated thin film nanocomposite membrane for enhanced Osmotic Power generation
Desalination, 2019Co-Authors: Ralph Rolly Gonzales, Myoung Jun Park, Yanqin Yang, Ahmed Abdel-wahab, Sherub Phuntsho, Ho Kyong ShonAbstract:Abstract A melamine-based covalent organic framework (COF) nanomaterial, Schiff base network-1 (SNW-1), was incorporated into the polyamide layer of a novel thin film nanocomposite (TFN) pressure retarded osmosis (PRO) membrane. The deposition of SNW-1 was made on an open mesh fabric-reinforced polyamide-imide (PAI) support substrate through interfacial polymerization (IP). SNW-1 loading influence on the water permeability and Osmotic Power density during PRO operation was investigated. The porous and highly hydrophilic SNW-1 nanomaterial facilitated the flow of water molecules across the membranes, while maintaining satisfactory salt rejection ability of the polyamide selective layer. The membranes exhibited significantly enhanced surface hydrophilicity, water permeability, and Power density. The mode of incorporation of SNW-1 during IP was also investigated and it was observed that the secondary amine groups of SNW-1 react with the carbonyl groups of 1,3,5-benzenetricarbonyl trichloride, the acyl halide precursor in polyamide formation; thus, SNW-1 was incorporated through the amine precursor, 1,3-phenylenediamine. Testing with 1.0 M NaCl as the draw solution, the TFN membrane with a loading of 0.02 wt% SNW-1 exhibited the highest water flux of 42.5 Lm−2 h−1 and Power density of 12.1 Wm−2, while withstanding hydraulic pressure over 24 bar. This study suggests that COF-incorporation can be a promising method in PRO membrane fabrication to improve both Osmotic performance and energy harvesting capability for the PRO process.
-
Thin-film composite hollow fiber membranes incorporated with graphene oxide in polyethersulfone support layers for enhanced Osmotic Power density
Desalination, 2019Co-Authors: Myoung Jun Park, Ralph Rolly Gonzales, Ahmed Abdel-wahab, Sherub Phuntsho, Sungil Lim, Dong Suk Han, Samer Adham, Ho Kyong ShonAbstract:Abstract This study focused on the development of pressure retarded osmosis (PRO) thin film composite (TFC) membranes for enhanced Osmotic Power using hollow fiber polyethersulfone (PES) support structure modified by incorporating hydrophilic graphene oxide (GO) nanosheets. The GO loadings in the hollow fiber substrates were varied to improve water flux performances without compromising the mechanical strength. GO embedded (≤0.2 wt%) PES hollow fiber supports revealed noticeable improvements in pure water permeability, improved structural morphologies, as well as the hydrophilicity within the support layer, without deteriorating the mechanical properties. The GO (0.2 wt%)-incorporated TFC-PRO membrane appeared to have an initial PRO flux (without any applied pressure) of 43.74 L m−2 h−1, lower specific reverse salt flux of 0.04 g L−1 and structural parameter (S) of 522 μm, significantly better than the control membrane. The maximum Power density of 14.6 W m−2 was achieved at an operating pressure of 16.5 bar under the condition of DI water and 1 M NaCl as feed and draw solutions, respectively. The results obtained in this study indicate that modification of PRO hollow fiber support layer by incorporating nanoparticles such as GO nanosheet can be a useful tool to improve the PRO performance.
-
dual layered nanocomposite membrane incorporating graphene oxide and halloysite nanotube for high Osmotic Power density and fouling resistance
Journal of Membrane Science, 2018Co-Authors: Myoung Jun Park, Anthony B. Murphy, Anne Maiprochnow, Sherub Phuntsho, Ho Kyong ShonAbstract:Abstract This study introduces a thin-film composite (TFC) membrane with a dual-layered nanocomposite substrate synthesized using a dual-blade casting approach for application in Osmotic Power generation by the pressure-retarded osmosis (PRO) process. The approach incorporates halloysite nanotubes (HNTs) into the bottom polymer substrate layer and graphene oxide (GO) on the top layer substrate, on which a thin polyamide active layer is formed. The fabricated membrane substrate showed highly desirable membrane substrate properties such as a high porosity, opened-bottom surface, suitable top-skin surface morphology for subsequent active layer formation and high mechanical strength, which are essential for high-performance PRO processes. At a GO loading of 0.25 wt% and HNT loading of 4 wt%, the Power density (PD) of the nanocomposite membrane was 16.7 W/m2 and the specific reverse solute flux (SRSF) was 2.4 g/L operated at 21 bar applied pressure using 1 M NaCl as draw solution and deionized water as feed, which is significantly higher than the those for a single-layered or commercial PRO membrane. This membrane performance was observed to be stable in the pressure cycle test and under long-term operation. The membrane substrate with HNTs incorporated exhibited high fouling resistance to sodium alginate and colloidal silica foulants, with the PD decreasing by 17% after 3 h of operation, compared to a membrane substrate without HNTs and commercial PRO membranes, which decreased by 26% and 57%, respectively. A fluorescence microscope study of the membranes subjected to feed water containing Escherichia coli confirmed the good antibacterial properties of the dual-layered TFC membrane. The study provides an attractive alternative approach for developing PRO membranes with high PD and fouling resistance.
-
GreenPRO: A novel fertiliser-driven Osmotic Power generation process for fertigation
Desalination, 2018Co-Authors: Federico Volpin, Ralph Rolly Gonzales, Sherub Phuntsho, Sungil Lim, Nirenkumar Pathak, Ho Kyong ShonAbstract:Abstract This study introduces and describes GreenPRO, a novel concept involving fertiliser-driven Osmotic energy generation via pressure retarded osmosis (PRO). The potential of GreenPRO was proposed for three objectives: (a) Power generation, (b) water pressurisation for fertiliser-based irrigation, and (c) water treatment, as a holistic water-energy-food nexus process. Three pure agricultural fertilisers and two commercial blended fertiliser solutions were used as the draw solution and irrigation water as feed to test this concept for Power generation. Theoretical thermodynamic simulation of the maximum extractable Gibbs energy, was first performed. After which, a series of bench-scale experiments were conducted to obtain realistic extractable energy data. The results showed that concentrated fertilisers potentially have 11 times higher energy than seawater. Even after accounting for the irreversibility losses due to constant pressure operation, the investigated pure fertilisers were found to have between 2.5 and 4.6 Wh/kg of energy. The outcomes from the flux and Power density modelling were then validated with real experimental data. This study has successfully demonstrated that concentrated fertilisers can release a substantial amount of chemical potential energy when diluted for fertigation. This energy could be harnessed by transforming it into electric energy or pressure energy via PRO.
Tao Cai - One of the best experts on this subject based on the ideXlab platform.
-
Button and Buttonhole" Supramolecular Structure Enables the Self-Healing Behaviors of Functionalized Poly(ether sulfone) Membranes for Osmotic Power Generation.
ACS applied materials & interfaces, 2019Co-Authors: Chun Ping Wang, Yu Zhang, Xiang Zheng, Yujie Zhao, Tao CaiAbstract:Osmotic Power generation has emerged as an advanced technology toward water-energy nexus to tackle global water pollution. It provides a sustainable use of salinity gradient from water resources yet encounters major obstacles caused by pressure-retarded osmosis (PRO) membrane fouling. Although membranes with good antifouling properties are widely studied, their antifouling functions are readily lost when scratches or detachments occur through physical damage during operation and chemical degradation by water and corrosive foulants. Consequently, it is important to develop antifouling membranes with autonomous self-healing capabilities. Herein, self-healable functionalized poly(ether sulfone) (PES) antifouling membranes have been fabricated via the sequential conjugation of the zwitterionic random copolymer [poly(1-(1-(1-adamantylcarbonyloxy)methyl)-3-vinylimidazolium bromide-co-1-(3-sulfopropyl)-3-vinylimidazolium-co-vinylamine)] (P(ADVI-co-SBVI-co-VA), abbreviated as PASV copolymer) and linear cyclodextr...
-
Sulfonated hyperbranched polyglycerol grafted membranes with antifouling properties for sustainable Osmotic Power generation using municipal wastewater
Journal of Membrane Science, 2018Co-Authors: Yu Zhang, Tao Cai, Zhen Lei Cheng, Tai-shung ChungAbstract:Abstract In recent years, pressure retarded osmosis (PRO) has drawn considerable attention due to its feasibility of harvesting clean and sustainable Osmotic Power through a membrane process. When municipal wastewater is fed into this process, fouling in the porous substrate of the PRO membrane is the major concern since it can hinder the membrane performance tremendously and lower the Power generation. In this work, sulfonated hyperbranched polyglycerol (SHPG) polymers with a dendritic architecture have been molecularly designed and then grafted onto the surface of polydopamine (PDA) coated poly(ethersulfone) (PES) hollow fiber membranes. Comparing to the pristine PES membranes, the SHPG modified PRO membranes show significantly improved resistance to protein adhesion and bacterial attachment due to the high wettability of their ionic polymer brushes. In PRO tests under different hydraulic pressures, the SHPG-grafted membranes show a lower flux reduction and a higher flux recovery rate of 94% vs. 87% in comparison with the pristine PES membranes. Therefore, the Osmotic Power generation can be significantly sustained by modifying the PRO membranes with SHPG polymers. This work may provide a versatile approach and useful insights for the design of membranes with antifouling properties in the molecular level.
-
Cleaning strategies and membrane flux recovery on anti-fouling membranes for pressure retarded osmosis
Journal of Membrane Science, 2017Co-Authors: Tao Cai, Gary L. Amy, Tai-shung ChungAbstract:Abstract Study of cleaning procedures to maintain the anti-fouling properties is urgently needed to sustain high Osmotic Power density of the fouling resistant membranes in the pressure retarded osmosis (PRO) process. Therefore, various cleaning agents were evaluated for a charged hyperbranched polyglycerol grafted thin-film composite (CHPG-TFC) membrane: (i) deionized (DI) water; (ii) a high pH alkaline solution, (iii) a low pH acid solution, and (iv) a chelating solution comprised of ethylenediaminetetraacetate (EDTA). Compared with other cleaning agents, the EDTA cleaning was more effective to restore the original surface of the CHPG-TFC membrane and sustain its Osmotic Power density using a real wastewater effluent as the feed. The Power density was maintained at a stable range of 6.0–6.7 W/m 2 in three repeated PRO tests. In comparison, a non-modified PES-TFC membranes with EDTA cleaning showed a large fluctuation of Power density from 3.6 to 4.8 W/m 2 . Instrumental analyses were conducted to reveal the physicochemical relationship between cleanings and membrane properties. The investigations confirmed the effectiveness of EDTA cleaning to mitigate the sulfate scaling, silica fouling, and calcium deposition. In summary, the EDTA cleaning imparted good recovery to the anti-fouling properties of the CHPG-TFC membrane and maintained its resilience to foulants in Osmotic Power generation by PRO.
-
Zwitterionic polymers grafted poly(ether sulfone) hollow fiber membranes and their antifouling behaviors for Osmotic Power generation
Journal of Membrane Science, 2016Co-Authors: Tao Cai, Chun Feng Wan, Tai-shung ChungAbstract:Fouling on pressure retarded osmosis (PRO) membranes must be eliminated to maximize the efficiency of Osmotic Power generation. This is particularly applicable to PRO membranes due to its nature of fouling when wastewater is fed. To improve this, PRO thin-film composite (TFC) membranes for the first time will be redesigned by incorporating well-defined zwitterionic copolymers of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (DMAPS) or 2-methacryloyloxyethyl phosphorylcholine (MPC) onto the poly(ether sulfone) (PES) hollow fiber membranes. The introduction of 2-methacryloyloxyethyl lipoate (MEL) components into the zwitterionic copolymers provided sufficient grafting sites for the facile decoration of polydopamine (PDA) pretreated PES membranes via Michael addition. The PDMAPS and PMPC grafted membranes were shown to be effective in reducing protein adsorption and bacterial adhesion, in comparison to the pristine PES membranes and PDA pretreated membranes. The pristine TFC–PES membranes are fouled greatly in high pressure PRO tests with concentrated wastewater, resulting in a flux reduction of 61%. In contrast, the TFC–PES membranes grafted by zwitterionic PDMAPS and PMPC copolymers exhibit substantial improvement of flux recovery up to 98% after backwashing and hydraulic pressure impulsion. In summary, the Osmotic Power generation may be sustained by grafting the PRO membranes with the properly designed zwitterionic polymers.
-
Negatively charged hyperbranched polyglycerol grafted membranes for Osmotic Power generation from municipal wastewater.
Water research, 2015Co-Authors: Tao Cai, Chunyan Chen, Tai-shung ChungAbstract:Osmotic Power holds great promise as a clean, sustainable and largely unexploited energy resource. Recent membrane development for pressure-retarded osmosis (PRO) is making the Osmotic Power generation more and more realistic. However, severe performance declines have been observed because the porous layer of PRO membranes is fouled by the feed stream. To overcome it, a negatively charged antifouling PRO hollow fiber membrane has been designed and studied in this work. An antifouling polymer, derived from hyperbranched polyglycerol and functionalized by α-lipoic acid and succinic anhydride, was synthesized and grafted onto the polydopamine (PDA) modified poly(ether sulfone) (PES) hollow fiber membranes. In comparison to unmodified membranes, the charged hyperbranched polyglycerol (CHPG) grafted membrane is much less affected by organic deposition, such as bovine serum albumin (BSA) adsorption, and highly resistant to microbial growths, demonstrated by Escherichia coli adhesion and Staphylococcus aureus attachment. CHPG-g-TFC was also examined in PRO tests using a concentrated wastewater as the feed. Comparing to the plain PES-TFC and non-charged HPG-g-TFC, the newly developed membrane exhibits not only the smallest decline in water flux but also the highest recovery rate. When using 0.81 M NaCl and wastewater as the feed pair in PRO tests at 15 bar, the average Power density remains at 5.6 W/m(2) in comparison to an average value of 3.6 W/m(2) for unmodified membranes after four PRO runs. In summary, Osmotic Power generation may be sustained by properly designing and anchoring the functional polymers to PRO membranes.
