Preparation Of Salt-Resistant Interfacial Evaporation Materials And Their Evaporation Performance

Water scarcity is a major challenge for countries around the world,especially in less developed regions.Although various desalination technologies have been developed,the shortcomings of expensive equipment,large size and high energy consumption severely limit the availability of clean water for people living in remote areas.As a sustainable and clean energy source,solar energy is widely used in many areas of research.After continuous research on photothermal materials,micro-and nano-structures,thermal insulation measures and water transfer performance by researchers,the performance of interface solar-driven evaporation（ISE）technology has been greatly improved,but there are still problems such as the inability of evaporators to perform long-term stable desalination and low fresh water collection rate.Based on this,this thesis prepares solar evaporators with high salt resistance and high evaporation performance by using melamine sponge and polyester fabric as carriers combined with silica nanoparticles/nanowires of photothermal materials with high water transport performance.The following work was mainly carried out:（1）Melamine sponge@silicone nanoparticles/polypyrrole/gold nanoparticles interfacial solar evaporation material with extremely excellent salt resistance was prepared by modifying melamine sponge with organosilicon nanoparticles and then combining it with a composite photothermal material.The evaporation material has excellent evaporation performance,and the surface temperature is maintained above50°C throughout the evaporation process.Under one solar irradiation,it exhibited an evaporation rate as high as 1.646 kg m^-2h^-1for 3.5 wt%Na Cl solution,and no salt deposition appeared on the surface of this evaporator when the concentration of Na Cl solution was lower than 20 wt%;the average evaporation rate remained very stable in the continuous evaporation experiment for 10 hours.In addition,the water collection can be stable for a long time in 3.5 wt%,10 wt%and 20 wt%Na Cl solutions,and the water collection is sufficient to meet the fresh water demand of adults.（2）Polyester fabric@silicone nanofibers/polypyrrole/gold nanoparticles interfacial solar evaporation material was prepared by growing a large number of silicon nanofibers on the surface of polyester fabric after loading two photothermal materials.The ultra-fast water transport and special thermal insulation conferred the evaporator with ultra-high evaporation performance,with evaporation rates as high as2.43 kg m^-2h^-1for a 3.5 wt%Na Cl solution in the open system under one sunlight irradiation,and even in 20 wt%Na Cl solution the evaporation rate still reached 2.1 kg m^-2h^-1.The closed system experiments under natural outdoor sunlight A total of 11.28kg m^-2of fresh water were collected by the customized water collection device in 8hours of continuous operation,and all ionic indicators met the drinking water standards.This thesis presents a new idea to solve the problems of salt deposition and freshwater collection devices in long-term water treatment by solar-driven interfacial evaporation technology with good performance of evaporation materials,which has great prospects for application in clean energy utilization,desalination and wastewater treatment.