Preparation Of Biomass Fiber Photothermal Material And Its Application In The Field Of Interfacial Evaporation

The shortage of fresh water resources is an urgent problem to be solved.Solar energy is the most promising renewable energy on the earth surface.Interfacial solar evaporation technology can make comprehensive use of water resources and solar energy resources by heating water to produce steam.At present,has been used in seawater desalination,disinfection and sterilization,sewage treatment and other fields.The technology,which uses clean solar power as the sole source of energy,could be an important way to replenish freshwater supplies on land.Because of the wide sources of biomass fiber materials,renewable,easy to degrade,easy to be modified by a variety of physical and chemical methods,it is an ideal base material.In this paper,Kapok fiber and silk fibroin protein fiber as base materials were combined with gold nanoparticles and melanin respectively to prepare interfacial solar evaporators.Their photothermal conversion and interfacial evaporation properties before and after modification were also analyzed and discussed.The main research contents and conclusions are as follows:(1)Traditional approaches for optimizing interfacial evaporation rely on the external devices to enable floating on water.However,how to unlock the self-floating ability of absorbers for solar interfacial evaporation have not been taken into account.Here,we propose a self-floating absorber based on kapok fibers,which possess large hollow structure and hydrophobicity to enable this absorber float on water without assistance.It is showed an extended adsorption(74.7%)wavelength ranging from 280 nm to 2500 nm.Both the hollow structure of kapok fibres and the thermal localization effect of Au NPs sustaintially enhance the solar interfere vapor generation effect.Also,the Au NPs/kapok membrane exhibited excellent cycling stability maintaining its solar interfere evaporation rate.These results provide new insights for design of advanced photothermal conversion materials with biomass as supporting material.(2)Based on the excellent photothermal conversion ability of carbon-based materials and the buoyancy performance of kapok fiber,we made Kapok fiber have the photothermal performance of carbon-based materials by high temperature carbonization.Using polyethylenimide(PEI)for hydrophilic modification of Kapok fiber after high temperature carbonization,the finally obtained polyethylenimide-carbonized Kapok fiber polymer(CKF-PEI)has good evaporation effect on deionized water and sodium chloride solution,and has the ability to reuse,we also carried out the morphology,structure and performance analysis.The interfacial solar evaporation ability of the polymer is tested.It is proved that the polymer has a wide application prospect in the field of interfacial evaporation.(3)It is an urgent problem to avoid salt deposition on evaporator surface.Based on the self-assembly performance of silk fibroin fiber solution,we used liquid nitrogen for directional freeze-drying,and prepared silk fibroin scaffold with radial channel as the water transport layer of evaporator,so as to avoid the accumulation of salt in the evaporation process and blocking the water transport channel.Due to the excellent photothermal conversion ability of melanin,Because melanin has good photothermal conversion ability,using it as the light absorption layer of the evaporator,the dual-structure silk fibroin-melanin interface solar evaporator prepared has high evaporation ability in different solutions,and there is no salt accumulation when evaporating 15 wt% sodium chloride solution.Finally,the morphology,structure and performance of the evaporator are analyzed,and its interfacial evaporation ability is tested.It is proved that the evaporator has a wide application prospect in the field of interfacial evaporation.