Preparation and properties of substrate PVA-GO composite membrane for solar photothermal conversion

Solar thermal desalination(STD)is a promising and sustainable technology for extracting clean water resources.Whereas recent studies to improve STD performance primarily focus on interfacial solar evaporation,a non-traditional bottom heating method was designed in this study.Herein,we prepared the polyvinyl alcohol/graphene oxide(PVA-GO)composite membrane and adhered to the bottom of a beaker using crystallized PVA.The GO was loaded on a non-woven fabric and different concentrations of PVA were compared for their effect on the evaporation efficiency.The results showed that the addition of PVA increased the evaporation rate.The surface characteristic of GO membrane without PVA was a fibrous filamentous structure as observed by SEM,whereby the fibers were clearly visible.When the PVA concentration reached 6%,the non-woven fiber was completely wrapped by PVA.Under the action of a fixed light intensity,the photothermal conversion rates of GO,2%PVA-GO,4%PVA-GO and 6%PVA-GO membrane device could reach 39.93%,42.61%,45.10%and 47.00%,respectively,and the evaporation rates were 0.83,0.88,0.94 and 0.98 kg$m-2$h-1,respectively.In addition,the PVA-GO composite membrane showed an excellent stability,which has significance for industrial application.

Transpiration-prompted Photocatalytic Degradation of Dye Pollutant with AuNPs/PANI Based Cryogels

Incautious discharge of organic dyes such as methyl orange(MO)has produced serious pollution to the environment,calling for the efficient techniques to remove them with retaining the green world.The photo-catalytic degradation of organic dyes is promising among the developed techniques.Thus,a strategy based on transpiration-prompted photocatalytic degradation of dye pollutant under sunlight is put forward.Aniline(ANI)is graft-polymerized onto poly(acrylamide-co-N-4-aminophenylacrylamide)(PAAm)cryogel embedded with gold nanoparticles(AuNPs,diameter:4-10 nm).The obtained cryogels integrated with AuNPs and PANI inside PAAm matrix(AuNP@PAAm-g-PANI)have been structurally explored based on the chemical composition and the phase/porous morphology.SEM and TEM observation shows that PANI and AuNPs are uniformly distributed in PAAm matrix.Since the macro-porosity of cryogel,hydrophilicity of PAAm and photo-thermal activity of PANI,PAAm-g-PANI cryogels without AuNPs can have a photo-thermal evaporation rate of water at 1.63 kg·m^(-2)·h^(-1).As a comparison,Au NP@PAAm-g-PANI cryogels with AuNPs exhibit higher one at 2.20 kg·m^(-2)·h^(-1),suggesting the promotion of AuNPs to photo-thermal evaporation.Meanwhile,PANI appreciatively assists AuNPs to display higher catalytic ability for the oxidative degradation of MO.Therefore,the removal of MO from water is obviously prompted by the water transpiration under sunlight with AuNP@PAAm-g-PANI cryogels,whose rate constant can reach to 0.320 h^(-1),being three folds of that for the sole absorption of MO.This transpiration-prompted photocatalytic degradation provides a fascinating route to eliminate organic pollutants and obtain pure water from wastewater simultaneously with sustainable sunlight energy.