Enhanced Water Flux Research Articles

Non-equilibrium molecular dynamics simulations of water transport through plate- and hourglass-shaped CNTs in the presence of pressure difference and electric field

In the present work, the water transport dynamics and properties within CNT membranes are studied under the effect of pressure and electric field, using non-equilibrium molecular dynamics (NEMD) simulations. To reduce the pressure loss at the entrance and exit regions, the pore mouth shape has been changed to an hourglass shape for CNT membranes of (6,6), (8,8) and (12,12), inspired by aquaporins, which are capable of high water permeation. It is shown that as the pressure difference increases, the water flux enhancement due to change of pore mouth from plate to hourglass increases rapidly. Furthermore, it is found that the hourglass-shaped geometry has the highest impact on the reduction of entrance resistance within the pores with a smaller diameter. By applying an axial electric field at the entrance of the hourglass-shaped CNT membrane, the enhancement in water flux could be further improved. Interestingly, our results show that applying an electric field at the membrane entrance can cause two opposing effects on the water molecules transport: reduction of water molecules steric crowding at the entrance and increasing the average hydrogen bond numbers of the water molecules entering the tube. It seems that the former effect is dominant for low-intensity electric fields.

Optimal synthesis, characterization and antifouling performance of Pluronic F127/bentonite-based super-hydrophilic polyvinyl chloride ultrafiltration membrane for enhanced oilfield produced water treatment

Pluronic F127 (PF127-) and PF127/bentonite-blended PVC ultrafiltration membranes are prepared in salt coagulation baths involving NaCl, KCl, NH4Cl, MgCl2 and CaCl2. Saturated KCl-coagulation bath delivers super-hydrophilic membrane with improved surface-porosity (10.64 %), pore density (49.26 μm−2), roughness (51.12 nm) and hydrophilicity (contact angle <10°), which endows remarkable enhancement of pure water flux at 100 kPa (i.e., 1610.0 Lm−2 h-1) and antifouling performance (flux recovery ratio: 75.8 %). Membrane performance is further improved by maximizing permeate flux and oil rejection simultaneously for actual oilfield produced water treatment using PVC-, PF127- and bentonite-loading, feed pH and feed temperature as decision variables and Pareto-optimal solution is obtained.

Effect of oxygenic groups on desalination performance improvement of graphene oxide-based membrane in membrane distillation

Graphene oxide (GO) based membranes show an advantage in desalination because of their unique water channels. Although influence of oxygenic groups of GO on water transport has become a focus of research, this is yet to be fully understood. In this work, the relative content of different oxygenic groups of GO was tuned by varying oxidation temperature (50, 60 and 70 °C). GO nanosheets were deposited on the permeate side of PVDF membrane in direct contact membrane distillation to enhance the desalination performance. The continuous GO layer enhanced flux by decreasing the vapor pressure at the permeate side. Salt rejection was improved from 99.2% of PVDF membrane to 99.9% of all the composite membranes. The deterioration of permeate quality caused by membrane wetting was avoided because the tiny solute in permeate was rejected by GO layer. Moreover, raising oxidation temperature resulted in GO that contains more epoxy groups, but less hydroxyl groups. GO oxidized at 70 °C provided the highest flux (17.80 kg m−2 h−1) with enhancement proportion of 18.9% because it contains less hydroxyl groups but more epoxy groups. Therefore, the transformation of hydroxyl groups into epoxy groups of GO would be an effective approach for water flux enhancement of GO based membranes.

Thin-film composite polyamide membrane modified by embedding functionalized boron nitride nanosheets for reverse osmosis

Modifying polyamide membranes with nanomaterials has proven effective for enhancing water flux and salt rejection and membrane resistance against fouling and chlorine. In this study, we prepared a novel thin-film nanocomposite reverse osmosis membrane by embedding functionalized boron nitride nanosheets (FBNS) into the polyamide layer via in situ interfacial polymerization process. As a result of the incorporation of FBNS, the expansion of homogeneous leaf-like structure of the polyamide layer, as indicated by the increased surface roughness as well as the thinner and more hydrophilic active layer, enhances the water permeance of membrane by 25% to 4.0 LMH/bar while maintaining a high salt rejection of 96.4%. The FBNS incorporated nanocomposite membranes also demonstrate improved chlorine resistance and performance stability under various stress test conditions when comparing to the pristine membrane. The humic acid fouling test indicates that the modified membrane has a flux recovery of over 96% after one cleaning cycle. This work provides new insights into the effect of boron nitride nanosheets on membrane network structures and separation performance and provides a scalable membrane improvement strategy based on emerging 2D nanosheets.

Tuning thin-film composite reverse osmosis membranes using deep eutectic solvents and ionic liquids toward enhanced water permeation

Deep eutectic solvents (DES) have invoked an enormous interest as inexpensive, greener and biorenewable solvents and additives with promising applications. In the present study, we investigated a choline chloride-urea based DES and a series of commercial ionic liquids (ILs) as additives including 1-hexyl-3-methyl-imidazolium chloride, 3-methyl-1-octyl-imidazolium tetra fluoroborate, N-butyl pyridinium and betaine monohydrate to modify the polyamide (PA) layer of reverse osmosis (RO) membranes. The ILs were selected from various categories to find better of them in RO modification. Accordingly, the DES and ILs with different concentrations were added to the MPD aqueous solution. The results of SEM and AFM analyses showed a smoother surface for the DES and ILs-modified membranes. The membrane modified with 1 wt% of DES achieved the pure water flux of 56.7 L/m2h and the observed salt rejection of 96.4%, exhibiting a 27% and 3% increase in water flux and salt rejection, respectively, as compared with the unmodified membrane. Among the used ILs, the membranes modified with N-butyl pyridinium and betaine monohydrate showed the best desalination performance, with the pure water flux of 78.9 L/m2h and 51.7 L/m2h and the NaCl rejection of 97.3% and 94.4%, respectively. Also, choline hydroxide IL was used for the surface modification of the SO3H-g-C3N4 nanosheets to examine efficiency of ILs on membranes, when located on nanosheet surface. The results of the desalination experiments showed that the incorporation of the modified nanosheets at low concentrations was effective in enhancing the membrane performance. Although increasing the concentrations of nanosheets in the PA layer of the membranes resulted in the enhanced water flux, the salt rejection was decreased.

Simulation and multi-objective optimization of heat and mass transfer in direct contact membrane distillation by response surface methodology integrated modeling

Membrane distillation (MD) traditionally utilizes low-grade thermal energy to drive vapor transport through hydrophobic membrane pores for water treatment. The concurrent enhancement of water flux, thermal efficiency and water productivity to achieve the global optimization of MD is still a challenge. In this work, a new simulation and optimization approach is proposed by integrating theoretical heat and mass transfer models with response surface methodology to investigate the complicate interaction effects of various influencing factors on heat and mass transfer parameters, including overall mass transfer coefficient, feed/permeate side heat transfer coefficients, membrane surface temperature and temperature polarization coefficient, in direct contact membrane distillation (DCMD). The operating and module configuration variables show important interaction effects on enhancing the heat and mass transfer in the membrane module. The significantly elevated heat transfer coefficient on account of the combined high feed temperature, short module length and high feed velocity leads to a great improvement of water flux and thermal efficiency. The ultimate global optimum conditions for the high water productivity were determined where the high levels of heat transfer coefficient (5905W/(m2·K)), temperature polarization coefficient (0.66), water flux (63.0kg/(m2·h)) and thermal efficiency (0.83) all synchronously approach to their own pinnacles. The results indicate that it is an effective way to take advantages of the interaction effects of operating conditions with module configuration parameters to achieve the overall enhancement of MD performance.

Water and nutrient recovery by a novel moving sponge – Anaerobic osmotic membrane bioreactor – Membrane distillation (AnOMBR-MD) closed-loop system

For the first time, a novel sponge-based moving bed-anaerobic osmosis membrane bioreactor/membrane distillation (AnOMBR/MD) system using mixed Na3PO4/EDTA–2Na as the draw solution was employed to treat wastewater for enhanced water flux and reduced membrane fouling. Results indicated that the moving sponge-AnOMBR/MD system obtained a stable water flux of 4.01 L/m2 h and less membrane fouling for a period lasting 45 days. Continuous moving sponge around the FO module is the main mechanism for minimizing membrane fouling during the 45-day AnOMBR operation. The proposed system’s nutrient removal was almost 100%, thus showing the superiority of simultaneous FO and MD membranes. Nutrient recovery from the MF permeate was best when solution pH was controlled to 9.5, whereby 17.4% (wt/wt) of phosphorus was contained in precipitated components. Moreover, diluted draw solute following AnOMBR was effectively regenerated using the MD process with water flux above 2.48 L/m2 h and salt rejection > 99.99%.

A new kind of filter paper comprising ultralong hydroxyapatite nanowires and double metal oxide nanosheets for high-performance dye separation

Simultaneous enhancement in water flux and removal efficiency during the filtration process remains a big challenge for separation membranes. The porous structure of the filter paper can provide many channels for water transportation, but the separation performance is generally poor. The purpose of this study is to develop a new kind of filter paper consisting of ultralong hydroxyapatite (HAP) nanowires, cellulose fibers (CFs) and double metal oxide (LDO) nanosheets, and to achieve the simultaneous enhancement of both water flux and removal efficiency for high-performance dye separation. In this work, a novel kind of LDO/HAP/CF nanocomposite filter paper consisting of ultralong HAP nanowires and CFs and LDO nanosheets has been developed for rapid water filtration and highly efficient dye adsorption. Positively charged LDO nanosheets can adsorb on the surface of negatively charged ultralong HAP nanowires and embed in the porous networked structure of the LDO/HAP/CF nanocomposite filter paper, which can provide a porous structure for rapid water transportation and can adjust the pore size of the nanocomposite filter paper. As a result, the pure water flux of the LDO/HAP/CF nanocomposite filter paper can be adjusted. The optimized pure water flux of the LDO/HAP/CF nanocomposite filter paper can reach 783.6 L m−2 h−1 bar−1, which is 1.51 times that of the HAP/CF filter paper without LDO nanosheets (518.6 L m−2 h−1 bar−1). More importantly, the adsorption capacity of LDO nanosheets is high for dye molecules, the rejection percentage of Congo red (CR) by the as-prepared HAP/CF filter paper is only 59.8%, and its water flux is 534.7 L m−2 h−1 bar−1. The optimized rejection percentage and water flux of the LDO/HAP/CF nanocomposite filter paper for CR are significantly enhanced (98.3% and 736.8 L m−2 h−1 bar−1, respectively) compared to those of the HAP/CF filter paper. The size of LDO nanosheets has a significant effect on the water flux and dye rejection percentage of the LDO/HAP/CF nanocomposite filter paper. The as-prepared LDO/HAP/CF nanocomposite filter paper is promising for the applications in highly efficient purification of wastewater containing dye molecules.

Covalent organic framework incorporated outer-selective hollow fiber thin-film nanocomposite membranes for osmotically driven desalination

In this study, new outer-selective hollow fiber (OSHF) thin film nanocomposite (TFN) forward osmosis (FO) membranes incorporated with amine-rich Schiff-based network (SNW-1) nanoparticles (NPs), a type of covalent organic frameworks (COFs), were developed by vacuum-assisted interfacial polymerization (VAIP). The SNW-1 NPs possess hydrophilic nature and porous internal structures, which are desirable for producing highly permeable and efficient FO membranes. SNW-1 NPs were conformally packed across the outer surface of the HF substrate by vacuum pressure applied during the VAIP process leading to defect-free coatings. Furthermore, covalent bonding between secondary amine (NH2−) groups across the SNW-1 network and remanent carboxylic groups present from the monomer used for the interfacial polymerization step supported the adhesion of SNW-1 NPs to the native poly(amide) layer present across the TFN membrane surface. As a result, SNW-1 loading at 0.001 wt% exhibited the best FO performance with enhanced water flux more than 23% of the pristine one (31.5 L m−2 h−1) and relatively low specific reverse solute flux (SRSF, Js/Jw) at 0.18 g L−1 using 1 M NaCl and DI water in series of TFN composite membranes. The optimum loading at 0.001 wt% was much lower than those in other home-made TFN membranes (normally above 0.05 wt%) due to the minimum loss of SNW-1 in the VAIP. Also, the TFN membrane offered excellent FO operation stability tested for 72 h. Such novel approach is promising to optimize FO processes for desalination and water treatment in the future.

Effect of Loading and Functionalization of Carbon Nanotube on the Performance of Blended Polysulfone/Polyethersulfone Membrane during Treatment of Wastewater Containing Phenol and Benzene.

In this study, a carbon nanotube (CNT)-infused blended polymer membrane was prepared and evaluated for phenol and benzene removal from petroleum industry wastewater. A 25:75 (by weight %) blended polysulfone/polyethersulfone (PSF/PES) membrane infused with CNTs was prepared and tested. The effect of functionalization of the CNTs on the quality and performance of the membrane was also investigated. The membranes were loaded with CNTs at different loadings: 0.5 wt. %, 1 wt. %, 1.5 wt. % pure CNTs (pCNTs) and 1 wt. % functionalized CNTs (fCNTs), to gain an insight into the effect of the amount of CNT on the quality and performance of the membranes. Physicochemical properties of the as-prepared membranes were obtained using scanning electron microscopy (SEM) for morphology, Raman spectroscopy for purity of the CNTs, Fourier transform infrared (FTIR) for surface chemistry, thermogravimetric analysis (TGA) for thermal stability, atomic force microscopy (AFM) for surface nature and nano-tensile analysis for the mechanical strength of the membranes. The performance of the membrane was tested with synthetic wastewater containing 20 ppm of phenol and 20 ppm of benzene using a dead-end filtration cell at a pressure ranging from 100 to 300 kPa. The results show that embedding CNTs in the blended polymer (PSF/PES) increased both the porosity and water absorption capacity of the membranes, thereby resulting in enhanced water flux up to 309 L/m2h for 1.5 wt. % pCNTs and 326 L/m2h for 1 wt. % functionalized CNT-loaded membrane. Infusing the polysulfone/polyethersulfone (PSF/PES) membrane with CNTs enhanced the thermal stability and mechanical strength. Results from AFM indicate enhanced hydrophilicity of the membranes, translating in the enhancement of anti-fouling properties of the membranes. However, the % rejection of membranes with CNTs decreased with an increase in pCNTs concentration and pressure, while it increased the membrane with fCNTs. The % rejection of benzene in the pCNTs membrane decreased with 13.5% and 7.55% in fCNT membrane while phenol decreased with 55.6% in pCNT membrane and 42.9% in the FCNT membrane. This can be attributed to poor CNT dispersion resulting in increased pore sizes observed when CNT concentration increases. Optimization of membrane synthesis might be required to enhance the separation performance of the membranes.

Nanocomposite membranes embedded with dopamine-melanin nanospheres for enhanced interfacial compatibility and nanofiltration performance

Nanomaterials incorporation in polymer membranes has been widely recognized as an effective strategy to improve membrane performance in filtration such as desalination. However, the poor compatibility between nanomaterials and polymer matrix restricts the enhancement of rejection because of unavoidable defects. In this work, we present a nanocomposite membrane by incorporating a kind of well-compatible polymeric nanomaterial, dopamine-melanin nanospheres with functional groups in cellulose triacetate (CTA) to improve the separation performance. The abundant amine and hydroxyl groups of dopamine-melanin nanospheres, not only contribute to the increase of membrane hydrophilicity for enhancing water flux, but also improve the interfacial compatibility between dopamine-melanin nanospheres and CTA matrix for maintaining excellent rejection. More significantly, the negative charges of dopamine-melanin nanospheres intensify the zeta potentials of membrane, which enhances the salt rejection by Donnan effect. The optimal NC-0.4 membrane yielded water flux of 22 L m−2 h−1 and high rejections to salts, MgSO4 (97.6%) > Na2SO4 (96.5%) > MgCl2 (91.8%) > NaCl (76.1%), owing to the synergistic effect of size exclusion and electrostatic repulsion. Moreover, the NC-0.4 membrane obtained excellent rejections to monovalent and bivalent ions. Therefore, blending well-compatible polymeric nanomaterials with polymer matrix could be an effective strategy to develop high-performance membrane for desalination.

Membrane fouling mitigation for enhanced water flux and high separation of humic acid and copper ion using hydrophilic polyurethane modified cellulose acetate ultrafiltration membranes

The presence of both copper ion (Cu (II)) from industry and humic acid (HA) in natural waters may generate Cu (II)–HA complex, which is a non-biodegradable and toxic organic pollutant in the water. Removal of such toxic substance is of great importance and environmental significance. Although membrane technology provides a solution for the removal via the filtration, fouling still presents a major challenge for the effective separation. In this study, polyurethanes endcapped with β-cyclodextrin and lactic acid were synthesized and used as additives to be blended with cellulose acetate membranes, which possessed enhanced hydrophilicity, permeability and antifouling property for the removal of Cu (II) and HA. As an example, the polyurethane endcapped with lactic acid (LPU-CA) membrane exhibited high pure water flux (PWF) of 648 L m−2 h−1, as well as high flux recovery ratios (FRRs) of 97.8% and 92% and low irreversible fouling rate (Fir) of 2.2% and 7.8% for the ultrafiltration (UF) of HA and Cu (II)–HA complex, respectively, showing excellent anti-fouling performance. In addition, the Cu (II) and HA rejection was greatly enhanced by the HA enhanced complexation process. These results indicated that the polyurethanes modified cellulose acetate membrane provided enhanced separation with good antifouling property, which can be potentially used for the cleaning of the toxic metal-organic pollutants in wastewaters.

Electrosprayed polyamide nanofiltration membrane with intercalated structure for controllable structure manipulation and enhanced separation performance

Intercalated structure and electrosprayed interfacial polymerization methods have recently been proposed for permeability enhancement of polyamide membranes. In this study, a Span 80 intercalated polyamide nanofiltration membrane was fabricated through electrospray for simultaneously improving the surface structure, interfacial stability and separation performance. The membrane obtained through electrosprayed interfacial polymerization (EIP) showed a water flux of 83.0 L m-2 h-1 at an applied pressure of 5.0 bar. The intercalated Span 80 severed as multifunctional layer for simultaneously lowering surface roughness (RSa value of polyamide, 7 nm), enhancing interfacial stability (better anti-backwashing ability) and separation performance (enhanced water flux and BPA rejection). The current study provides new opportunities for fabricating polyamide nanofiltration membrane with high performance by combination of EIP and reactive interlayer strategy.

The role of osmotic agent in water flux enhancement during osmotic membrane distillation (OMD) for treatment of highly saline brines

Brine concentration is of critical importance in achieving zero liquid discharge in modern industrial processes. The effect of osmotic agent (OA) on the system performance in the treatment of different concentrations of brine using osmotic membrane distillation (OMD) was investigated. Significant improvement in water flux for concentrating the hypersaline brine was achieved compared to conventional membrane distillation processes. By altering the hydrodynamic conditions and using different combinations of feed streams and osmotic agents, a mathematical approach was applied, for the first time, to reveal the contribution of temperature and concentration polarization on flux enhancement in treating highly saline brines. This improvement was found to be caused mainly by the temperature polarization on the OA side of membrane, with less contribution from the decrease in vapor pressure of the bulk of the OA. This work illustrates that OMD is a promising process for efficient concentration of highly saline streams such as those found in the chlor-alkali industry. During the concentration of the spent brine from the electrolyte cell (NaCl concentration from 180 g/L to 310 g/L), OMD was shown to be the more cost and energy efficient compared to conventional MD processes.

Enhanced water flux using uncoated magnetic nanoparticles as a draw solution in forward osmosis desalination

Enhanced water flux using uncoated magnetic nanoparticles as a draw solution in forward osmosis desalination

Fouling decline and retention increase of polyvinyl chloride nanofiltration membranes blended by polypyrrole functionalized multiwalled carbon nanotubes

In this study, preparation, characterization and performance of polyvinyl chloride mixed matrix nanofiltration membrane containing multiwalled carbon nanotubes functionalized by polypyrrole (PPy-MWCNTs) was studied. The novel membranes were prepared by the immersion precipitation phase inversion method. The synthesized PPy-MWCNTs were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy techniques. The performance and properties of the fabricated nanocomposite membranes was studied by FTIR-ATR spectrum, SEM images, pure water flux, water contact angle, porosity, permeation measurements, fouling parameters, bovine serum albumin (BSA) and dye rejection tests. Results showed enhancement in pure water flux from about 59.7 L/m2h for the bare membrane to 75.2 L/m2h in the presence of 0.25 wt% PPy-MWCNTs. In addition, the fabricated membranes demonstrate effective rejection for Reactive Blue 50 dye (95%) and BSA (98%). Flux recovery ratio and the antifouling properties during BSA filtration were improved in the hybrid membranes.

Alumina double-layered ultrafiltration membranes with enhanced water flux

In the present work, γ-alumina double-layered ultrafiltration (UF) membranes with novel gradient pore-sized active layers and single-layered UF membranes were produced using an approach of tightening the pore size of alumina microfiltration (MF) membranes. With the processes of sol-gel, dip coating and sintering, the achieved single- and double-layered UF membranes displayed similar performance in particle size retention, and the double-layered membrane expressed better properties than the single-layered UF membrane in terms of water flux, resistance and anti-fouling. Compared to the MF membrane, the prepared UF membranes displayed improved hydrophilicity and enhanced particle size retention behavior, but lower flux, higher resistance and weaker anti-fouling performance. However, the UF membrane with double layers exhibited values of flux and resistance in the same order of magnitude as those of the MF membrane. The produced alumina double-layered membranes with enhanced flux are of great potential in UF of water.

Engineering arrangement of nanoparticles within nanocomposite membranes matrix: a suggested way to enhance water flux

ABSTRACTIn this research, with the aim of engineering arrangement of nanoparticles within membrane pores, ZrO2 nanoparticles was modified by sulfate and carboxylate functional groups. Thereafter, the filtration performance of PSf/ZrO2, PSf/Zr-COOH, and PSf/Zr-SO4 nanocomposites in treating textile wastewater were compared. SEM, EDX and AFM analysis showed that the functional groups manipulate surface and structural properties of the membranes. Therefore, water flux of 13PSf/2.68Zr-SO4 and 13PSf/2.68Zr-COOH were 42% and 32% more than those of 13PSf/2.68ZrO2. Moreover, dye rejection of 13PSf/2.68Zr-SO4,13PSf/2.68Zr-COOH and 13PSf/2.68ZrO2 was about 99% and 97% and 95%, which is 14%, 12% and 10% higher than raw membrane.

Hydrophilic polymeric membrane supported on silver nanoparticle surface decorated polyester textile: Toward enhancement of water flux and dye removal

Abstract A novel mixed matrix nanofiltration membrane was constructed by coating a casting solution containing polyvinylidene fluoride (PVDF), polyethylene glycol (PEG) as hydrophilic agent, zeolitic like framework-67 (ZIF-67), ethylenediamine as cross-linking agent on Ag-nanoparticle-decorated polyester textile (PT) support (PT/Ag-NPs/PVDF-PEG/ZIF-67). PT/Ag-NPs/PVDF-PEG/ZIF-67 morphology, crystalline structure, surface chemical composition and hydrophilicity of PT/Ag-NPs/PVDF-PEG/ZIF-67 were fully characterized by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and water contact angle technique, respectively. PT/Ag-NPs/PVDF-PEG/ZIF-67 was applied in cross module set-up for removal of contaminated water containing rose bengal (RB) dye. The effect of operational parameters such as dye concentration, solution pH and flow rate on performance of PT/Ag-NPs/PVDF-PEG/ZIF-67 were investigated and optimized by central composite design (CCD). Casting solution containing 0.5 wt.% ZIF-67 as optimum value showed the good wettability, high pure water flux (PWF; 35.8 L·m-2⋅h-1), flux recovery ratio (FRR;90%), dye removal efficiency (96.41%). The selectivity factor of 12.72 and 14.42 was found to be for RB in the presence of amido black and methylene blue as interferent dyes, respectively, which showed a good selective recognition ability for RB dye.

O2/N2-responsive microgels as functional draw agents for gas-triggering forward osmosis desalination

High cost for draw agent recovery during dewatering operation remains challenging for industrial forward osmosis (FO) processes. Hydrogels and microgels have been recently reported as promising draw agents for FO desalination. Aiming to develop an energy-efficient gas-triggering FO desalination process, smart gas-responsive copolymer microgels were developed as draw agents in this study. Functional O2/N2 gas-responsive microgels were synthesised using fluorine monomers of trifluoroethyl methacrylate (FM) or pentafluorostyrene (FS), and water-soluble monomers of diethylaminoethyl methacrylate (DEAEMA), dimethylaminoethyl methacrylate (DMAEMA), hydroxyethyl methacrylate (HEMA) and N-isopropylacrylamide (NIPAM). These microgels become reversibly active to draw water after purging O2 and release the adsorbed water upon N2 purging. Water flux, water recovery and recyclability of microgels were systematically examined in a series of FO operations. Enhanced water flux in FO process can be achieved for the microgels with FM. DEAEMA-FM and DMAEMA-FM microgels provide a high water flux up to 29 LMH for a 2000 ppm NaCl feed at room temperature, while the NIPAM-FM microgels show the best water recovery of 56%. Our results reveal that O2/N2 gas-responsive microgels can be used as emerging smart draw agents for gas-triggering FO desalination.