Solar-driven desalination has been considered as a promising technology for producing clean water through an abundant and pollution-free energy source.It is a critical challenge to reasonably design the porous morphol...Solar-driven desalination has been considered as a promising technology for producing clean water through an abundant and pollution-free energy source.It is a critical challenge to reasonably design the porous morphology and the thermal management of photothermal membranes for enabling efficient energy conversion and water production.In this work,a Janus poly(vinylidene fluoride)membrane was fabricated in combination of penetrative pore structure,asymmetric surface wettability with proper thermal management for high-efficiency solar desalination.Highly open and directly penetrative pores achieved by the two-dimensional solvent freezing strategy are considered to provide direct pathways for water and vapor transportation.The unique feature of hydrophobic upper layer/hydrophilic lower layer enables the photothermal membranes to self-float on the water surface and rapidly pump water from the bulk to the surface.The resulting Janus membrane exhibits a satisfactory light absorbance as high as 97%and a photothermal conversion efficiency of 62.8%under one-sun irradiation in a direct contact mode.The solar-to-vapor efficiency rises up to 90.2%with the assistance of a thermal insulator adopted beneath.Both the Janus membrane and the composite setup are able to work efficiently with a high stability in seawater desalination,and the concentration of ion in condensed water is reduced to below 1 ppm.Therefore,Janus membranes with directly penetrative pores and photothermal surfaces shine a light on the development of high-performance solar evaporators for the practical application in solar seawater desalination.展开更多
Polysulfone （PSF） membranes have gained great attention in the fields of ultrafiltration, microfiltration, and thin film composite membranes for nanofiltration or reverse osmosis. For the first time, it is proposed ...Polysulfone （PSF） membranes have gained great attention in the fields of ultrafiltration, microfiltration, and thin film composite membranes for nanofiltration or reverse osmosis. For the first time, it is proposed to fabricate PSF membranes via thermally induced phase separation （TIPS） process using diphenyl sulfone （DPSO2） and polyethylene glycol （PEG） as mixed diluent. DPSO2 is chosen as a crystallizable diluent, while PEG is considered in terms of molecular weight （Mw） and dosage. We systematically investigate the interactions between PSF, DPSO2 and PEG based on the simulation calculations and solubility parameter theory. It is inferred that DPSO2 has an excellent compatibility with PSF, and the addition of PEG results in the ternary system thermodynamically less stable and then facilitates its liquid-liquid （L-L） phase separation. SEM images indicate that cellular-like pores are obvious throughout the membrane when the PEG content in the mixed diluent is 25 wt%-35 wt%. We can facilely manipulate the pore size, water flux and mechanical properties of PSF membranes with the dosage of PEG-200, the Mw of PEG or the cooling rate. The successful application of TIPS can provide a new approach for structure manipulation and performance enhancement of PSF membranes.展开更多
基金This work was supported by the National Natural Science Foundation of China(Grant no.51673166 and no.51803180).
文摘Solar-driven desalination has been considered as a promising technology for producing clean water through an abundant and pollution-free energy source.It is a critical challenge to reasonably design the porous morphology and the thermal management of photothermal membranes for enabling efficient energy conversion and water production.In this work,a Janus poly(vinylidene fluoride)membrane was fabricated in combination of penetrative pore structure,asymmetric surface wettability with proper thermal management for high-efficiency solar desalination.Highly open and directly penetrative pores achieved by the two-dimensional solvent freezing strategy are considered to provide direct pathways for water and vapor transportation.The unique feature of hydrophobic upper layer/hydrophilic lower layer enables the photothermal membranes to self-float on the water surface and rapidly pump water from the bulk to the surface.The resulting Janus membrane exhibits a satisfactory light absorbance as high as 97%and a photothermal conversion efficiency of 62.8%under one-sun irradiation in a direct contact mode.The solar-to-vapor efficiency rises up to 90.2%with the assistance of a thermal insulator adopted beneath.Both the Janus membrane and the composite setup are able to work efficiently with a high stability in seawater desalination,and the concentration of ion in condensed water is reduced to below 1 ppm.Therefore,Janus membranes with directly penetrative pores and photothermal surfaces shine a light on the development of high-performance solar evaporators for the practical application in solar seawater desalination.
基金supported by the National Natural Science Foundation of China(Nos.21174124 and 21534009)
文摘Polysulfone （PSF） membranes have gained great attention in the fields of ultrafiltration, microfiltration, and thin film composite membranes for nanofiltration or reverse osmosis. For the first time, it is proposed to fabricate PSF membranes via thermally induced phase separation （TIPS） process using diphenyl sulfone （DPSO2） and polyethylene glycol （PEG） as mixed diluent. DPSO2 is chosen as a crystallizable diluent, while PEG is considered in terms of molecular weight （Mw） and dosage. We systematically investigate the interactions between PSF, DPSO2 and PEG based on the simulation calculations and solubility parameter theory. It is inferred that DPSO2 has an excellent compatibility with PSF, and the addition of PEG results in the ternary system thermodynamically less stable and then facilitates its liquid-liquid （L-L） phase separation. SEM images indicate that cellular-like pores are obvious throughout the membrane when the PEG content in the mixed diluent is 25 wt%-35 wt%. We can facilely manipulate the pore size, water flux and mechanical properties of PSF membranes with the dosage of PEG-200, the Mw of PEG or the cooling rate. The successful application of TIPS can provide a new approach for structure manipulation and performance enhancement of PSF membranes.
