Deposition of metal-dielectric hybrid composite on the polymer based membrane is important for the electrochemical, photochemical and photothermal reactions on the membrane surface. The hydrophilic ...reactants such as catalysts and photothermal materials are not easy to be deposited directly on the hydrophobic membrane surface, so in most cases, binder material has been adapted to stably combine them. In this study, commercial PTFE membrane and Ti/MgF2 photothermal layers were combined without any binder. Ar plasma pretreatment was applied to a membrane surface before depositing optimized Ti/MgF2 stacks to fabricate a mechanically robust photothermal membrane. The successful fabrication of Ar plasma pretreated Ti/MgF2 photothermal membrane was demonstrated by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), atomic force microscope (AFM) characterization. Through Ar plasma pretreatment, an increase in Ti/MgF2 photothermal membrane heating temperature of 40.5 % was achieved under 1 sun condition compared with unpretreated membrane. This membrane showed improved performance and reduced energy loss in solar desalination. Utilizing these membranes in a membrane distillation system, water flux increased by up to 26.9 %, performance ratio (PR) increased by 18.9 % and thermal efficiency improved by 21.9 %. After 24-h stress test, the Ar plasma pretreated Ti/MgF2 photothermal membranes demonstrated durability and maintained thermal efficiency.
Display omitted
•Ar-Plasma pretreatment enhanced conformal deposition and adhesion of Ti/MgF2 on PTFE membrane.•Ar-Plasma pretreatment increased exothermicity on photothermal PTFE membrane by 40.5 %.•The fabricated membrane enhanced solar membrane distillation (MD) performance.•The pretreated photothermal membrane showed excellent robustness after stress test.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Display omitted
Membrane-based photothermal crystallization - a pioneering technology for mining valuable minerals from seawater and brines - exploits self-heating nanostructured interfaces to boost ...water evaporation, so achieving a controlled supersaturation environment that promotes the nucleation and growth of salts.
This work explores, for the first time, the use of two-dimensional graphene thin films (2D-G) and three dimensional vertically orientated graphene sheet arrays (3D-G) as potential photothermal membranes applied to the dehydration of sodium chloride, potassium chloride and magnesium sulfate hypersaline solutions, followed by salt crystallization. A systematic study sheds light on the role of vertical alignment of graphene sheets on the interfacial, light absorption and photothermal characteristics of the membrane, impacting on the water evaporation rate and on the crystal size distribution of the investigated salts.
Overall, 3D-G facilitates the crystallization of the salts because of superior light-to-heat conversion leading to a 3-fold improvement of the evaporation rate with respect to 2D-G. The exploitation of sunlight graphene-based interfaces is demonstrated as a potential sustainable solution to aqueous wastes valorization via recovery in solid phase of dissolved salts using renewable solar energy.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
One of the most promising desalination techniques is photothermal membrane distillation (PhMD). The research focus of PhMD technology is material renewal and structural design. Herein, the CuMOF-PVDF ...photothermal membranes were designed for PhMD. Firstly, a combination of chemical plating and oxidation was used to generate Cu(OH)2 nanowires (NWs) onto the PVDF membrane. Then, the ligands were chemically bonded with Cu(OH)2 NWs to grow the photothermal layer formed by the CuMOF hierarchical structure (CMHS). Under sunlight irradiation, the light was trapped in the CMHS, amplifying absorption and conversion of light. The CuMOF-PVDF membrane with the match-like CMHS absorbed 88.6 % of the light, resulting in a surface temperature of 74.3 °C after 600s. Moreover, by reducing the evaporation enthalpy of water, the performance of the CuMOF photothermal layer was comprehensively improved, realizing a water evaporation rate of 1.55 kg‧m−2‧h−1 and a high photothermal conversion rate of 71.4 %. During the PVMD process, the feed solution in the CuMOF photothermal layer was fully heated and supplied to the vaporization area, weakening the temperature polarization. Consequently, the flux of the CuMOF-PVDF membrane was 3.07 kg‧m−2‧h−1 and a 99.9 % rejection rate, corresponding to an energy efficiency of 85.2 %. The CuMOF-PVDF membrane is an efficient tool for PhMD, helping to advance desalination technologies.
Display omitted
•Photothermal membrane consists of CuMOF photothermal layer and PVDF membrane.•Photothermal layer has hierarchical structure, shaping like a match.•Contribution of hierarchical structure to overall performance of membrane.•CuMOF-PVDF membranes perform well in photothermal vacuum membrane distillation.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
To meet the increasing worldwide need for freshwater, it has become critical to exploit non-potable saline water. Solar membrane distillation (MD) is a promising desalination technique, which does ...not require conventional energy and can reduce the cost of water production. We developed a cost-effective and high-efficiency photothermal membrane that employs TiN nanoparticles as an absorber of sunlight and energy converter. Due to a strong photothermal effect, the solar energy efficiency significantly improved. With optimal membrane and MD operating conditions, we obtained an MD flux of 0.940 kg/m2∙h and a solar efficiency of 64.1% under 1.0 kW/m2 solar irradiation. Compared with a bare poly(vinylidene fluoride) (PVDF) membrane, 65.8% more pure water was produced. Furthermore, the temperature polarization encountered in the conventional MD process was relieved on account of the unique interfacial heating of the photothermal coating, which also contributed to the high solar efficiency. In addition, the membrane was quite stable and the permeate water was of a high, potable quality. The as-prepared photothermal membrane demonstrated a good performance and application prospects for solar MD.
Display omitted
•High performance TiN@PVA-PVDF photothermal membrane was fabricated.•64.1% of solar energy utilization efficiency were obtained.•Membrane distillation flux was elevated to 0.940 kg/m2∙h under 1 kW/m2 irradiation.•Temperature polarization was alleviated as the interfacial heating.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Efficient use of solar energy for desalination is one strategy to solve the world's water scarcity issues. In this work, a dual functional, omniphobic−photothermal nanocomposite membrane was ...developed to achieve wetting resistance and low energy consumption in desalination by direct solar membrane distillation (DSMD). The membrane was prepared by forming a hierarchical structure of 1H,1H,2H,2H-perfluorodecyltriethoxysilane (FAS17) modified carbon black (CB) nanoparticles (NPs) on a polyvinylidene fluoride (PVDF) membrane surface. The fluorinated CB NPs absorbed sun light to provide localized heating for DSMD, which increased membrane flux by 25% upon simulated solar irradiation at one sun unit. The utilization efficiency of solar energy in the DSMD process, 75.4%, is more than one order of magnitude higher than the energy efficiency of the conventional direct contact membrane distillation process. Furthermore, the re-entrant structure formed by the CB NPs together with the hydrophobic FAS17 coating led to low surface energy and hence omniphobicity, increasing the contact angle of the 80 vol% ethanol-in-water from 0 to 94.2°. As a result, the dual functional membrane exhibited much higher resistance to wetting by surfactants. Whereas the pristine PVDF membrane was wetted by 0.2 mM SDS, SDS had no effect on the dual function membrane over the whole SDS concentration range tested (0.1–0.4 mM). The photothermal activity, improved thermal efficiency, and strong wetting resistance make the dual functional omniphobic−photothermal membrane an excellent membrane material for the DSMD process.
Display omitted
•First membrane distillation membrane with omniphobic and photothermal properties.•The membrane achieves wetting-resistance and photothermal heating simultaneously.•Photothermal carbon black provides re-entrant structure for omniphobicity.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•The progress of photothermal membrane distillation (PMD) is reviewed.•PMD mechanisms and membrane requirements are summarized.•Photothermal materials for developing PMD membranes are ...reviewed.•Diverse approaches to prepare PMD membranes are classified and discussed.•PMD membrane performance and their applications are reviewed and discussed.
The conventional membrane distillation (MD) process is accompanied by large energy consumption, low thermal efficiency and inevitable requirements of centralized infrastructures, which impede its practical applications, especially in the offshore and remote off-grid areas. Thanks to the rapid development of efficient photothermal materials over the last decade, a new photothermal membrane distillation (PMD) process has emerged to harness abundant solar energy and localize heating on the membrane-feed water interface via photothermal effects. Driven by the temperature difference across the PMD membrane, water vapor can be generated on the membrane-feed surface, transported through membrane pores and condensed at permeate side to obtain freshwater, thus tackling the challenge of obtaining clean water using green energy. The PMD process avoids heating the entire bulk feed water and feed transportation from heat units to membrane modules, which save substantial amounts of energy. The interfacial localized heating intrinsically mitigates the temperature polarization across the membrane. The latent heat from vapor condensation can be effectively recovered via multi-level PMD configurations. As great efforts have been made to exploit PMD process, it is imperative to review the state-of-the-art progress of PMD and shed light on its future trend. Here, we briefly illustrate PMD mechanisms and membrane requirements, photothermal materials feasible for developing PMD membranes along with their light-to-heat mechanisms. This is followed by reviewing diverse approaches to prepare PMD membranes, which are classified into one-step fabrication and multi-step modification methods. Comprehensive discussion about PMD membrane performance in different configurations and their small pilot-scaled applications are provided. The effects of operational parameters and module designs are discussed in Section 6. Finally, the current challenges and future perspectives of PMD process are emphasized with the aim of providing guidance for future works.
Display omitted
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The emerging photothermal membrane distillation (PMD), which combines solar harvesting and heat localization, has the potential to address the water-energy nexus. However, PMD membrane scaling and ...its underlying mechanisms need in-depth examination. Herein, we describe a microsphere structured composite membrane (#PCNT-0.5) with simultaneous superior light-to-heat conversion and superhydrophobic properties, produced by electrospraying a polyvinylidene fluoride (PVDF)/polydimethylsiloxane (PDMS)/multi-walled carbon nanotubes (MWCNTs) hybrid solution on an electrospun PVDF nanofibrous substrate (#PVDF). The carbon-based material and a micro-rough structure endowed the membrane with high light absorptivity, heat recovery and vapor production. Meanwhile, it showed excellent wetting resistance with contact angles beyond 150° and 120° for deionized (DI) water and 40% v/v ethanol aqueous solutions. The robustness of the surface multifunctional coating of #PCNT-0.5 was confirmed by chemical erosions and physical treatments. The localized heating alleviated the temperature polarization, increased the permeation flux of the #PCNT-0.5 by ∼15% and reduced its specific thermal energy consumption. In addition, the modified #PCNT-0.5 exhibited better anti-scaling properties compared to #PVDF. The illumination slowed down the flux decline of #PCNT-0.5 and inhibited salt crystallization. The excellent anti-scaling properties of the illuminated #PCNT-0.5 are attributed to the inhibited bulk and heterogeneous crystallization, permission of slippage and accelerated dissolution-diffusion. This study demonstrates that PMD is a feasible and promising method for hypersaline wastewater desalination.
Display omitted
•The photothermal and superhydrophobic membrane #PCNT-0.5 was developed.•#PCNT-0.5 reduced energy consumption while increasing PMD water production.•Localized heating inhibited bulk crystallization and accelerated dissolution/diffusion.•Superhydrophobicity inhibited surface crystallization and provided slippage.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Display omitted
•MOF-based photothermal membrane is designed with Cu-CAT nanosheet arrayed architecture.•Cu-CAT nanosheet array promotes photothermal conversion and delivers hydration chemistry.•High ...evaporation rate of 2.43 kg m−2h−1 and solar-vapor efficiency of 92% are demonstrated.•MOF-based photothermal membrane enables efficient solar seawater desalination.•MOF-based photothermal membrane enables synergy of photocatalytic-photothermal route.
Solar-driven interfacial evaporation technology is a promising sustainable approach to mitigate the global energy crisis and clean water scarcity. The advanced interfacial evaporation materials make a non-negligible contribution to the solar thermal utilization for water purification. In this work, a Cu-catecholate metal–organic framework-based photothermal membrane (Cu-CATM) is developed to generate freshwater from seawater and recover clean water from wastewater. Thanks to the unique photothermal effect and the three-dimensional nanosheet array structure of Cu-catecholate metal–organic framework (Cu-CAT MOF), the Cu-CATM enabled a promising evaporation rate of 2.43 kg m−2h−1 and a high solar-vapor conversion efficiency of 92% under solar irradiance of 1 sun. Further, the Cu-CATM could be applied to solar seawater desalination with durable evaporation rate and no salt accumulation. Also, the Cu-CATM enabled solar utilization for synchronous photothermal desalination and photocatalytic degradation, which highlighted the broader environmental application for water remediation or wastewater treatment via photothermal-photocatalytic route. This work presents a viable and effective route for the development of photothermal membranes toward future sustainable clean water production from non-conventional water resources.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•A simple breath figure method was first employed to fabricate double-layer evaporator.•The PC@PPy has advantages of low cost, simple and scalable manufacture process.•The PC@PPy-EPE shows excellent ...energy conversion efficiency of 93.57% under 1 sun irradiation.•The PC@PPy-EPE displays excellent salt-resistant performance even in 20 wt% NaCl.
Solar interfacial evaporation (SIE) is one of the most prospective solar energy harvesting technologies for solving the scarcity of freshwater resources. Herein, we report a novel photothermal membrane polycarbonate (PC)@polypyrrole (PPy) (PC@PPy) adopting to breath figure method followed by surface chemistry modification, and assemble a double-layer solar interfacial evaporator consisting of PC@PPy photothermal membrane as the upper layer and plant fiber-wrapped expanded polyethylene (EPE) foam as the bottom layer for SIE. Due to the abundant porous structure and strong light absorption of the PC@PPy membrane, excellent insulation of the EPE sponge, the as-prepared PC@PPy-EPE evaporator exhibits a high evaporation of 1.78 kg m-2h−1 and photothermal conversion efficiency of 93.57%, and outstanding evaporation stability and resistance in 16% wt NaCl with an evaporation of 1.58 kg m-2h−1 under 1 sun irradiation. Moreover, the PC@PPy photothermal possess superior flexibility and strong mechanical properties. Coupling with cost-effective, environment-friendly, simple and easily scale-up breath figure preparation method, the PC@PPy-EPE generator has broad application prospects in SIE.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Harvesting solar energy for water desalination is considered as one of the most important technologies to effectively address global water scarcity. Recently, it was found that water droplets on ...azobenzene modified anodized alumina membranes and disperse red 1 modified PTFE (polytetrafluoroethylene) membranes can permeate the membrane to be purified and desalinated under light irradiation. Herein, in order to efficiently collect vaporized and condensed water, we demonstrated the immobilization of graphene-based material n hydrophobic PTFE membrane surface for water desalination via photothermal membrane distillation (PMD). An ultrathin graphene-based film, fabricated by a scalable process, serves as efficient solar absorbers (absorption efficiency of rGO/pDA-rGO > 80%), ultrafast water permeable channels, and high salt resistance network. Compared with bare PTFE membrane, water transmembrane flux on the pDA-rGO material modified PTFE membrane can achieve as much as 78.6% enhancement under normal solar illumination. Due to high salt rejection of graphene-based films, the evaporation rate of graphene-based material modified PTFE membrane was unaffected by 4% NaCl solution, which indicated that concentration polarization effect can obviously be eliminated. These results provided new insights into the design and utilization of graphene-based films for effectively solar desalination via PMD.
Display omitted
•Graphene-based material immobilized PTFE membrane was synthesized for water desalination.•Significant stability on high salt concentration was shown with graphene-based material.•pDA-rGO demonstrated some excellent potential in photothermal membrane distillation.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
