Preparation Of Zeolite-Based Aerogels And Solar Interfacial Evaporation Performance Study

With a growing population and the rapid development of irrigated agriculture,animal husbandry,energy production and manufacturing,the shortage of freshwater resources has become one of the most serious energy crises today.Seawater accounts for 96.5%of the Earth’s total water reserves,so there is a need to find an efficient,low-cost,and sustainable desalination technology to solve the problem of freshwater shortage.In recent years,solar interfacial evaporation technology has been considered a viable solution to the shortage of freshwater resources due to the advantages of clean energy,high efficiency,and low heat loss.Zeolite has excellent thermal insulation and adsorption properties and has not been reported in previous studies.Therefore,in this paper,a series of novel zeolite-based aerogels were prepared as solar evaporators using zeolite as the matrix material,and their photothermal evaporation performances in seawater/oily wastewater/organic pollutants were systematically investigated.Zeolite-based aerogels stand out due to their lightweight,porous nature and low thermal conductivity,exhibit excellent light absorption,thermal management and water transport capabilities,and offer an excellent realization for solar absorbers.The main research contents and conclusions are as follows:（1）A solar evaporator with high salt resistance and efficient heavy metal wastewater treatment capacity was designed using modified zeolite,cellulose acetate,and carbon nanotubes as the main raw materials,named MZPC@CNTs.The application of MZPC@CNTs evaporator in water evaporation,seawater desalination,heavy metal wastewater,and organic pollutant water purification was systematically studied.By orderly adjusting the pore structure,the evaporation rate of the prepared MZPC@CNTs aerogel under one solar radiation is 1.72 kg m^-2 h^-1,and the conversion efficiency is 95.33%.In addition,MZPC@CNTs aerogels also exhibit excellent ion removal performance and salt tolerance in the purification of heavy metal polluted wastewater and high salt solution.This solar evaporator has the advantages of simple preparation,low cost,stable desalination performance,and has great potential for application in alleviating the global shortage of freshwater resources.（2）The ZC@CB evaporator was prepared by using zeolite,carboxymethyl cellulose,and carbon black as raw materials,which can be used for long-term seawater desalination and wastewater purification.Due to the superhydrophilicity and rapid water delivery capacity of aerogels,the salt deposition phenomenon was avoided.The ZC@CB evaporator had a high evaporation rate in pure water and high salt solution,which were 3.50 and 3.18kg m^-2 h^-1,respectively.To further expand the application range,the bottom of the aerogel was oil-repellent modified to obtain a hydrophilic and oleophobic OR-ZC@CB aerogel.The evaporation rate was not significantly reduced in oily wastewater with different ratios.Since the OR-ZC@CB evaporator has excellent evaporation performance in oily wastewater,it can be used as an ideal functionalized photothermal conversion material in actual seawater or oily wastewater.（3）A three-dimensional all-weather solar evaporator（ZCTP）was designed and constructed using zeolite,chitosan,TiO₂,and PPy as raw materials.Benefiting from the novel structure and functional design,ZCTP aerogels have high broadband light absorption,fast water transport,and excellent mechanical properties.More importantly,with the assistance of carbon fiber heating wire,ZCTP aerogel can make full use of the solar energy collected during the day to achieve long-term operation,thereby improving energy utilization and water purification rate.The results showed that the evaporation rate of ZCTP aerogel was 1.66 kg m^-2 h^-1 under 1 solar radiation,but in the photothermal-electrical cogeneration system,the evaporation rate was as high as 11.70 kg m^-2 h^-1 under1 solar radiation and 5 V voltage,which realizes the all-weather continuous water purification.In addition,due to the excellent salt resistance of the ZCTP aerogel,the high evaporation rate was maintained in 20 wt%high-salt wastewater,indicating that the aerogel has good stability and reusability.