Water Recovery Ratio Research Articles

Electro-responsive superabsorbent hydrogel based on carboxymethyl cellulose as a draw agent for forward osmosis desalination

To explore a simple and energy-efficient approach to regenerate draw agent is a key challenge for forward osmosis (FO) desalination. Electro-responsive hydrogels have attracted great attention due to their reversible swelling-shrinking behaviors under an electric stimulus. However, the developed electro-sensitive hydrogels based on 2-acrylamido-2-methyl-l-propanesulfonic acid (AMPS) so far exhibit low reusability due to their unstable electro-sensitive properties and poor degradability with potential environmental impact. This study explored the use of an electro-responsive superabsorbent hydrogel as a draw agent by grafting acrylic acid (AA) and acrylamide (AM) onto sodium carboxymethyl cellulose (CMC). The grafted hydrogel’s morphology and structure were investigated by FTIR and SEM. The swelling behaviors and deswelling properties in an electrode contact system were examined. The swelling kinetics of the hydrogel could be well described by the Schott's pseudo-second-order model with a theoretical swelling ratio of 452.5 g/g. The grafted hydrogel exhibited stable electro-sensitive characteristics with a decrease of 7.3 % in the equilibrium swelling ratio after undergoing three cycles of deswelling and swelling. During the FO test, the dry hydrogel particles produced a water flux of 1.55 L·m−2·h−1 within the first hour, surpassing the performance of other carboxylic acid-based hydrogels used as draw agents. Significantly, it exhibited encouraging water recovery capabilities in the five recycling FO processes, retaining around 84 % of its initial water recovery ratio after 40 min of exposure to a voltage of 15 V. This indicated that the grafted hydrogel could be considered as an effective and sustainable draw agent for FO desalination.

Waste heat-driven water generator with optimized multi-cycle strategy for high water yield

Water scarcity and energy crisis have recently become two severe global problems. Low-grade waste heat, a substantial byproduct of energy consumption, promises to provide safe water by driving sorption-based atmospheric water harvesting (SAWH) device. Herein, a low-grade waste heat-driven atmospheric water generator (LWG) is constructed with rapid kinetics at the system level. Solely in 3 h, the device obtains 1.766 g g−1 of water productivity and up to 98 % of water recovery ratio driven by 120 °C of waste heat. Further, an optimized multi-cycle operation strategy is proposed to guide LWG's daily water harvesting, enabling it to predictably obtain over 15 kg m−2 day−1 water productivity by maximizing systemic sorption and desorption-condensation rates. The strategy not only is widely suitable for all SAWH devices, but also provides a universal optimization guideline for sorption-based dehumidification, thermal storage, and electric thermal management.

Performance Evaluation of a Solar Humidification – Dehumidification Desalination Unit

This paper is to investigate the use of solarenergy in desalination by humidification and dehumid-ification process (HD). Here, a proposal for the desalinationunit has been come out with cylindrical shape containing the evaporator in the middle and surrounded by the condenser.The hot feed water coming from the solar thermal system issprayed at the top of the evaporator where the air flowsfrom the bottom. In the evaporator the air is humidified until it gets out saturated, then introduced to the condenser,where it is dehumidified to obtain the fresh water andcirculated back to the evaporator. Practically there aremany parameters influence on the performance of thisdesalination unit, which are environmental, design and operational. In the current study these parameters are takenin consideration to formulate mathematical models whichgovern the performance of the main components of this unit,which are the evaporator, the condenser and the solarthermal system. The deduced mathematical models have been interpreted in many programs in visual basic languageas a computer software. This software contains many pageswhich help in introducing and analyzing the most influentialparameters. In this case many operational parameters havebeen studied such as feed water temperature, mass flow rate and salinity, in addition to cooling water mass flow rate andinlet temperature, as well as quantity of solar irradiancewith others. At these inputs many outputs have beenobtained which are related to the performance of thedesalination unit such as fresh water productivity, energy consumption, humidifier volume, recovery ratio and gainoutput ratio.

Antifouling Polyvinylidene Fluoride Membrane through Dopamine Self‐Polymerization Enhanced Surface Segregation toward Oil‐In‐Water Emulsions Separation

AbstractSurface segregation method, as an in situ method for simultaneous modification of membrane external surfaces and inner pore surfaces, has been more commonly employed to fabricate antifouling membranes. In this study, dopamine (DA) with self‐polymerization and bio‐adhesion ability is chosen as a surface segregation agent to fabricate antifouling polyvinylidene fluoride (PVDF) membrane for oil‐in‐water emulsions separation through synergistically regulating phase inversion, self‐polymerization of DA, and surface segregation of poly‐dopamine (PDA). During the phase inversion process, DA contacts with an alkaline coagulation bath to trigger self‐polymerization of DA, then the surface segregation of PDA proceeds spontaneously. The addition and self‐polymerization of DA can regulate the phase inversion process to acquire membranes with high porosity, as a result, the water permeance is increased from 134 to 538 L m−2 h−1 bar−1 with the oil rejection higher than 99.8%. Because the hydrophilic PDA layer on membrane and pore surfaces leads to a robust hydration layer, the membrane exhibits super‐oleophobicity underwater and excellent antifouling properties with water recovery ratio of more than 99.4%. This study may open a new route to preparing antifouling membranes by using small molecules as surface segregation agents.

Capacitive deionization electrode fabrication using activated carbon derived from agriculture by-products toward industry application: A review

Capacitive deionization (CDI), membrane capacitive deionization (MCDI), and flow capacitive deionization (FCDI) are emerging technologies applied to remove ions from brackish water or saline wastewater based on electrode double layer (EDL) mechanisms. The electrode itself can be seen as the most important factor that determines the deionization efficiency of the CDI system. Electrode fabrication using activated carbon derived from agriculture byproducts is a useful solution to decrease cost, restrict environmental pollution, and enable agriculture waste recovery. In this review, the primary parameter's impact on activated carbon (AC) and the electrode fabrication process from the agriculture byproducts is detailed in a discussion to find the most optimal conditions. With excellent characteristics for the activated carbon such as a surface area of up to 2500 m2/g, it can be used to fabricate electrodes that have a high adsorption capacity of approximately 25 mg/g, able to be advanced to 40 mg/g with a modified AC. It can achieve a cycle performance of 95–97 %. The deionization efficiency of the CDI, MCDI, and FCDI systems can be up to 90 % with an input salt concentration from 2000 to 3000 mg/L where the water recovery ratio achieved is 50–90 %, alongside a salt rejection rate of about 7–75 %. AC can be modified to increase its special properties such as surface area, conductivity, and ion selectivity using different methods. The drawbacks and challenges of the CDI technology are also mentioned along with useful solutions such as electrode coating techniques using an anilox roller and a spray, for use in industry applications.

An Evaluation of Microfiltration and Ultrafiltration Pretreatment on the Performance of Reverse Osmosis for Recycling Poultry Slaughterhouse Wastewater

To implement sustainable water resource management, the industries that produce a huge amount of wastewater are aiming to recycle wastewater. Reverse osmosis (RO) is an advanced membrane process that can produce potable water from wastewater. However, the presence of diverse pollutants in the wastewater necessitates effective pretreatment to ensure successful RO implementation. This study evaluated the efficiency of microfiltration (MF) and ultrafiltration (UF) as two pretreatment methods prior to RO, i.e., MF-RO and UF-RO, for recycling poultry slaughterhouse wastewater (PSWW). The direct treatment of PSWW with RO (direct RO) was also considered for comparison. In this study, membrane technology serves as a post treatment for PSWW, which was conventionally treated at Sanderson Farm. The results demonstrated that all of the processes, including MF-RO, UF-RO, and direct RO treatment of PSWW, rejected 100% of total phosphorus (TP), over 91.2% of chemical oxygen demand (COD), and 87% of total solids (TSs). Total nitrogen (TN) levels were reduced to 5 mg/L for MF-RO, 4 mg/L for UF-RO, and 9 mg/L for direct RO. In addition, the pretreatment of PSWW with MF and UF increased RO flux from 46.8 L/m2 h to 51 L/m2 h, an increase of approximately 9%. The product water obtained after MF-RO, UF-RO, and direct RO meets the required potable water quality standards for recycling PSWW in the poultry industry. A cost analysis demonstrated that MF-RO was the most economical option among membrane processes, primarily due to MF operating at a lower pressure and having a high water recovery ratio. In contrast, the cost of using RO without MF and UF pretreatments was approximately 2.6 times higher because of cleaning and maintenance expenses related to fouling. This study concluded that MF-RO is a preferable option for recycling PSWW. This pretreatment method would significantly contribute to environmental sustainability by reusing well-treated PSWW for industrial poultry purposes while maintaining cost efficiency.

Humidification potential optimization of various membranes for proton exchange membrane fuel cell: Experiments and deep learning assisted metaheuristics

This study addresses the durability and performance challenges in Proton Exchange Membrane Fuel Cell (PEMFC) technology, primarily focusing on optimal humidity management. Acknowledging that, beyond technical aspects, the broader commercialization of PEMFCs is critically influenced by factors such as the cost and availability of hydrogen, this research aims to provide a comprehensive solution to enhance PEMFC applicability. Utilizing Nafion (NR-212), reverse osmosis (RO), and pervaporation (PV) membranes, the study optimizes five key performance metrics: pressure drop (∆P), dew point approach temperature (DPAT), water recovery ratio (WRR), Water Flux (J), and coefficient of performance (COP). These optimizations are conducted considering variables like temperature, humidity, flowrate, and membrane material. A deep neural network (DNN) model, incorporating Bayesian surrogacy with Gaussian process, gradient boost regression trees, and random forest, is developed using experimental data. With a correlation coefficient of 0.986, the model demonstrates high accuracy in predicting performance metrics, subsequently guiding genetic algorithms for effective PEMFC humidity control. The results show significant improvements in all metrics, with optimal values achieved for NR-212, RO, and PV membranes. This study thus presents a novel, practical deep learning approach, considering both technological advancements and external economic factors, for enhancing PEMFC operations.

A Feasibility Study on the Implementation of a Solar Powered Water Desalination Plant

Water desalination plants powered by solar energy represent a viable solution for addressing a part of the water needs in areas without a reliable water supply. In this case extending the electric grid and water delivery to remote communities remain challenging for some countries. Using Namibia as a case study, this work carried out a feasibility study on the extent of which, solar energy could be used to power the entire desalination process thereby aiding groundwater usable for human consumption. This process includes but not limited to desalination of underground wells and boreholes as solution to the water shortage problem in remote places. In this study, a solar-powered desalination technique that could enhance the process of clean water provision to villagers is proposed. It further compares and analyzed various desalination technologies to determine the best fit based on the dryness of areas. Ohawuwanga Village in Namibia was used for evaluation purpose with a sampling instrument-questionnaire which determine the village's daily water consumption and corresponding power required. Modelling, simulation and analysis of the system was carried out using MATLAB Simulink in terms of energy consumption. Other parameters considered in this research are cost, water recovery ratio, salt removal factor, durability and market analysis. The research revealed that electrodialysis is the best technology for desalination in terms of efficient power consumption amidst other factors compared.

In situ bridges of nano-titanium dioxide constructed in MXene self-cleaning loose nanofiltration membranes for dye wastewater treatment

It has been a longstanding problem to combat the oxidation process of MXene membranes. Here, we propose a strategy to construct nano bridge defect repair loose nanofiltration membrane with the help of MXene oxidation. The oxidation kinetics of Ti3C2Tx was investigated in both model and experimental aspects. The acid solution leads to aggregation and smaller d-spacing. However, the oxidation of MXene was accelerated in alkaline solution via reaction with hydroxyl anions resulting in a hydrophilic MXene membrane surface. The water permeability of the pH = 12-Ti3C2Tx membrane increased to a maximum value of 26.5 L·m−2·h−1·bar−1 together with a high rejection (98 %) of Janus green B (JGB). Titanium dioxide, which was in situ formed by oxidation of MXene, gives the membrane self-cleaning properties under UV light. The water recovery ratio was as high as 96.6 %. To further study the mechanism of in situ oxidation of MXene to form nano-titanium dioxide, the oxidation stages were analyzed which revealed that the in-situ oxidation process involved three different oxidations stages. This research offers a new perspective on MXene membrane design, paving the way for a new method of in situ nano bridge defect repair loose MXene nanofiltration membrane.

Theoretical, numerical and experimental research on an innovative ocean thermal energy conversion coupled VMD desalination system

This paper proposes an OTEC-VMD desalination system that fully exploits tropical ocean thermal energy to alleviate freshwater shortages on remote islands, with no need of coupling with other heat sources. Based on an in-depth analysis of the mass and heat transfer theory of the OTEC-VMD desalination, a CFD model is established by embedding a UDF program in commercial software and an experimental prototype with a water production capacity of 1 kg/h is designed and manufactured. The CFD simulation and experimental test results show good agreement, with relative errors around 5 %. The proposed system can stably produce water, demonstrating the feasibility of OTEC-VMD seawater desalination experimentally for the first time. At a warm seawater temperature of 30 °C, the water production reaches 1.07 kg/h, achieving the design target. The system's water recovery ratio and specific electrical energy consumption are 0.254 % and 2.62 kWh/m3, respectively, and the TDS is lower than 5 mg/L. Compared to low-pressure flashing, the equipment achieves an average volume reduction rate of 94.71 %, making it more suitable for installation and transportation in remote marine locations, with great potential in replacing the low-pressure flashing device in the open-cycle of OTEC power plant to promote the large-scale application of OTEC technology.

A novel solar-powered thermal desalination unit coupled with a reverse osmosis plant to increase overall water recovery

The global water crisis could be alleviated by converting saline water to potable water through desalination technologies. Reverse osmosis is the dominant technology in the market. However, its brine disposal is challenging. This paper proposes and investigates a novel hybridization between a solar-driven reverse osmosis plant and a solar-driven thermal desalination unit to enhance the water recovery ratio (freshwater produced/feed saline water). The thermal desalination unit combines an adsorption cycle, ejectors, and a humidification-dehumidification cycle. The brine from the reverse osmosis unit is used as a feed for the thermal desalination unit to produce higher amounts of freshwater. The extra-high saline water discharged from the proposed system can be used for salt extraction in a solar pond as a byproduct. Theoretical and economic models are developed to evaluate the performance and cost of the proposed system. It is found that the recovery ratio of standalone reverse osmosis and the proposed hybrid desalination plant is 40.8% and 70.5%, respectively, having a feed salinity and brine salinity limit of 32,500 ppm and 110,000 ppm. The recovery ratio of the hybrid system could reach 84%, with brine disposal of 220 ppm (which is valid for salt crystallization processes). The reduction in freshwater cost by using the hybrid plant is 23% to 27% compared to the standalone reverse osmosis plant for 40,000 to 50,000 ppm feed salinity and 10 m3 plant capacity. The suggested system can produce freshwater of 83 and 47 m3 per ton of silica gel per day at the gained output ratio of 2.71 and 2.6 in June and December, respectively.

Dual regulation of graphene oxide membrane by crosslinker and hydrophilic promoter for dye separation

Graphene oxide (GO)-based membranes have shown considerable promise in the field of water treatment. However, the structural swelling of GO membranes in water has hindered their further development. A single regulatory approach seems difficult to simultaneously improve permeability, selectivity, and stability. In this study, we present a dual regulation strategy for GO membranes employing the 1,4-Diaminobutane crosslinker to prevent swelling and maintain an interlayer spacing of 1.34 nm, resulting in effective dye rejection, and employing the hydrophilic EMT-type zeolite promoter to improve the membrane's water permeability. The obtained NH2-GO/10EMT composite membrane exhibited enhanced pure water flux (from 9.0 to 20.8 L/m2 h bar) and anionic dye rejection (from 87.2% to 97.6%) with promising structure stability (at least 20 h), while greatly improving the membrane's fouling resistance (the water recovery ratio increased from 46.5% to 86.2%). Our findings provide a straightforward and efficient approach to the development of high-performance GO membranes for selective water separation.

Evaluation of Different Reverse Osmosis Membranes for Textile Dyeing and Finishing Wastewater Reuse

Different commercial reverse osmosis (RO) membranes from Vontron and DuPont Filmtec were evaluated for textile dyeing and finishing wastewater (TDFW) reuse in China. All six tested RO membranes produced qualified permeate meeting TDFW reuse standards at a water recovery ratio (WRR) of 70% in single batch tests. The rapid decline of apparent specific flux at WRR over 50% was mainly ascribed to feed osmotic pressure increase caused by concentrating effects. Multiple batch tests using Vontron HOR and DuPont Filmtec BW RO membranes with comparable permeability and selectivity demonstrated the reproducibility and showed low fouling development. The occurrence of carbonate scaling on both RO membranes was identified by scanning electron microscopy and energy disperse spectroscopy. No obvious organic fouling was detected on both RO membranes by attenuated total reflectance Fourier transform infrared spectrometry. From the orthogonal tests, with an integrated RO membrane performance index (i.e., 25% rejection ratio of total organic carbon + 25% rejection ratio of conductivity + 50% flux ratio of final to initial) as a target, the optimal parameters were determined as WRR of 60%, cross-flow velocity (CFV) of 1.0 m/s, temperature (T) of 20 °C for both RO membranes, while trans-membrane pressures (TMP) of 2 and 4 MPa were optimal for Vontron HOR RO membrane and DuPont Filmtec BW RO membrane, respectively. Both RO membranes with the optimal parameters produced good permeate quality for TDFW reuse and kept a high flux ratio of final to initial, demonstrating the effectiveness of the orthogonal tests.

On the energy performance of the geothermal dehumidifier of the humidification-dehumidification desalination system

The solar-driven humidification-dehumidification desalination system with a geothermal dehumidifier (SD-HDH-GD) has been given special attention, especially for subsurface irrigation. This contribution scrutinizes the performance of the geothermal dehumidifier of the SD-HDH-GD system. To this aim, a comprehensive three-dimensional transient computational fluid dynamics model of the geothermal dehumidifier and the surrounding soil is developed. An experimental setup is established to verify the developed numerical model. The effect of several operating parameters on the performance of the system is examined. The sensitivity of the water yield, recovery ratio, and gain output ratio to the studied parameters are analyzed. It is demonstrated that the system has different behaviors regarding these measures. Therefore, to gain a comprehensive understanding of the performance of the SD-HDH-GD system, all measures should be considered. According to the obtained results, the maximum amount of condensed water, gain output ratio, and recovery ratio obtained using the performed optimization are 180.05 kg/12 hours, 41.20%, and 0.31, respectively, for the open-air HDH cycle. Moreover, to reach the optimum system performance, the temperature of the inlet air stream to the geothermal dehumidifier should be in the range of 60 to 70 °C, and its relative humidity must be as much as possible.

Hierarchically Structured Nanoparticle-Free Omniphobic Membrane for High-Performance Membrane Distillation.

The functional loss of membranes caused by pore wetting, mineral scaling, or structural instability is a critical challenge in membrane distillation (MD), which primarily hinders its practical applications. Herein, we propose a novel and facile strategy to fabricate omniphobic membranes with exceptionally robust MD performance. Specifically, a substrate with a hierarchical re-entrant architecture was constructed via spray-water-assisted non-solvent-induced phase separation (SWNIPS), followed by a direct fluorinated surface decoration via "thiol-ene" click chemistry. Deionized (DI) water contact angle measurements revealed an ultrahigh surface water contact angle (166.8 ± 1.8°) and an ultralow sliding angle (3.6 ± 1.1°) of the resultant membrane. Destructive abrasion cycle and ultrasonication tests confirmed its structural robustness. Moreover, the membrane possessed excellent wetting resistance, as evidenced by the prevention of membrane pore penetration by all low-surface-tension testing liquids, allowing stable long-term MD operation to treat brine wastewater with a surfactant content of 0.6 mM. In a desalination experiment using shale gas wastewater, the omniphobic membrane exhibited robust MD performance, achieving a high water recovery ratio of ∼60% without apparent changes in water flux and permeate conductivity over the entire membrane process. Overall, our study paves the way for a nanoparticle-free methodology for the scalable fabrication of high-performance MD membranes with surface omniphobicity and structural robustness in hypersaline wastewater treatment.

Experimental analysis of water transfer and thermal–hydraulic performance of membrane humidifiers with three flow field designs

An external membrane humidifier (MH) is widely used to control humidity and temperature in a polymer electrolyte membrane (PEM) fuel cell. The arrangement of flow channels highly affects the performance of the humidifier. Although the modified arrangement of flow channels in MHs affects the enhancement of heat and mass transfer, the pressure drop inside the channels also changes by varying the arrangement of flow channels. Therefore, by defining the performance evaluation criteria (PEC), the simultaneous impacts of heat and mass transfer along with pressure drop can be examined. Larger PEC indicates higher heat and moisture transfer rates with lower pressure drop, i.e. higher performance. In this study, three MHs with finned channels, serpentine channels, and simple parallel ones are fabricated and tested to compare their performance based on dew point approach temperature (DPAT), water recovery ratio (WRR), and PEC. The results demonstrate that the PEC of finned-channel and serpentine-channel MHs is greater than 1 for all flow rates on the WS and DS, indicating the improved performance of both MHs. At low flow rates of WS and DS, the PEC of the serpentine-channel MH is much larger than that of the finned-channel MH. By enhancing the flow rate, the PEC of these two MHs approaches each other. At high flow rates of WS and DS, the pressure drop of the serpentine-channel MH is much larger than that of the finned-channel one. The pressure drops of these two MHs approach each other by decreasing the flow rate. Therefore, it is better to use the serpentine flow arrangement at low flow rates and to utilize the finned-channel configuration at high flow rates.

Performance studies of a membrane-based water and heat exchanger using serpentine flow channels for polymer electrolyte membrane fuel cell application

This study proposes a serpentine flow field to enhance the performance of a membrane-based water and heat exchanger (MWHE) to employ in polymer electrolyte membrane fuel cells. Two MWHEs (serpentine and parallel-flow channels) are numerically simulated and compared in terms of water vapor transmission rate (WVTR), water recovery ratio (WRR), temperature and dew point at the outlet of the dry side, and the dew point approach temperature (DPAT). For all mass flow rates at the dry and wet inlets, the outlet temperature of the dry side and the dew point at the dry side outlet of the MWHE with serpentine channels are higher compared to the one with parallel channels. Using serpentine channels, compared to simple parallel channels, the WRR is enhanced by 8.5 % to 20 % and the DPAT is diminished by 4 % to 13.6 % for a range of mass flow rates on the wet side. At higher wet-side flow rates, the use of serpentine arrangement has a more significant influence on WRR and DPAT. In both MWHEs, an increase in the dry side mass flow rate leads to a reduction in heat and water transfer rates and an increment in the wet side mass flow rate, resulting in a reduction in the DPAT and WRR. Enhancing the operating pressure has a negative impact on the performance of the MWHE. By changing the operating pressure from 100 to 150 kPa, WRR is reduced by 18.1 % and DPAT is enhanced by 10.2 %.

Fabrication of laminated composite filter with nonwoven fabrics for oil/water separation

Various materials have been prepared and applied for the oil-water mixture separation, but there are some problems such as high cost, complicated formulation process and inferior durability. Nonwoven fabrics are widely used in industrial fields because of their low production cost and high economic benefit. In this study, a sandwich-structure filter was prepared for oil/water separation based on laminated nonwovens. Spunbond-meltblown-spunbond (SMS) nonwoven treated with silica and fluorine resin was selected for the hydrophobic top layer. The spunlaced viscose (VS) impregnated with citrate was used for the hygroscopic core layer while spunbond polypropylene (PP) prepared for the bottom substrate. These three layers were reinforced on an ultrasonic-bonding machine and tested for oil-water separation. Surface morphology and chemical group changes of treated fiber were recorded by scanning electron microscope (SEM), atomic force microscope (AFM), energy dispersive spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR). The effect of surface hydrophobicity and core hydrophilicity on separation efficiency was analyzed. The durability after recycles was evaluated and discussed. The possible separation mechanism was proposed. The results demonstrated that coating and spraying methods achieved uniform distribution of silica and fluorine resin onto the fiber surface. The suitable conditions for the preparation of composite filter were obtained as follows: the surface SMS layer was coated with silica, then sprayed with fluorine resin for a 6.0%weight gain to get a hydrophobic layer. The core layer viscose fiber impregnated with 3.0% citrate to enhance its hygroscopicity. The three layers were laminated and reinforced for the composite filter. Improving the hydrophobicity of top layer and the hydrophilicity of core layer both contributed to the enhance of separation efficiency and stability. The pore size of composite filter was mainly in the range of 9-11μm with a 35% distribution. After 15 times recycles, the water recovery ratio remains over 95% while water contact angle decreased from 150° to 135°. After layers laminated and bonding, the hydrophobic surface trapped oil and water in the mixture, hygroscopicity layer enabled a connection with the water in mixture through SMS layer and formed a capillary water channel. The water transferred to the sublayer by gravity and capillary action to actualize oil-water separation. These results provided new insights for the application of nonwoven fabrics on oil-water separation.

Computational study on the three phase displacement characteristics of foam fluids in porous media

Foam technology has shown great potentials not only on enhancing oil recovery (EOR) but also on the Carbon Capture Storage Utilization (CCUS) applications. In this paper, the foam three phase displacement characteristics in the porous media is investigated based on the mechanistic Stochastic Bubble Population Balance (SBPB) model. With taking the foam generation rate Kg and maximum bubble density nmax as the key influential parameters, the dynamic distributions of the water, oil and gas phase saturations as well as the bubble densities along the foam flow direction are successfully obtained. Firstly, the overall computation frame is validated based on good agreements between the numerical and the reported experimental results on the foam displacement efficiency on water and oil phases. Then, the parameter studies are thoroughly performed concerning the two key factors of Kg and nmax in the SBPB model. Numerical results show the parameter of Kg dominates the foam flow behavoir in the inlet region of the porous media therefore doesn't show significant effect on the final oil and gas phase recovery rates. On the other hand, it is found larger nmax could lead to higher oil and water recovery ratio, which indicates to increase the nmax values of the foam fluid could act as the favorable means in oil recovery enhancement practices.

Engineering a covalently constructed superomniphobic membrane for robust membrane distillation

Wetting, scaling, and functionality loss of the active layer are critical challenges facing membrane distillation (MD) technology that substantially hinder its practical applications. Herein, we propose an effective strategy to fabricate a superomniphobic MD membrane with excellent wetting/scaling resistance and mechanical robustness. Specifically, a hierarchical re-entrant architecture was created by immobilizing spherical silica nanoparticles onto a poly(vinylidene fluoride) membrane surface via covalent bonds, followed by fluorination via thiol–ene click chemistry. An ultrahigh water contact angle (166.5 ± 1.4°) and low sliding angle (5.0 ± 1.1°) confirmed the superhydrophobicity and slippery characteristics of the modified membrane, which were further illustrated by its excellent wetting resistance toward various liquids with low surface tension. The membrane sustained a long-duration MD for the treatment of a highly saline brine, with a surfactant content of approximately 2.0 mM, outperforming all the MD membranes reported in the exiting literature. In addition, the membrane exhibited excellent desalination performance for synthetic multi-component hypersaline wastewater, achieving a high water recovery ratio of approximately 60% without a significant decline in water flux. Overall, this study provides a novel and effective approach to fabricate high-performance MD membranes with robust functionality for operations under harsh environments. • A superomniphobic PVDF membrane was constructed via entire covalent bonding. • The membrane exhibited excellent wetting/scaling resistance for membrane distillation. • The membrane demonstrated a robust desalination performance for hypersaline wastewater treatment.