Design And Application Of Composite System Of Photothermal Transformation Of Carbon Point In Balsa Wood

In the face of increasing water pollution,shortage of fresh water resources,and energy scarcity,solar-driven water evaporation is considered to be one of the most sustainable technologies to solve the above problems,which has attracted widespread attention.At present,although reports on the photothermal evaporation of water are endless,there are more or less problems with high cost,manufacturing process,and low evaporation efficiency.Therefore,it is still necessary to design more advanced solar energy absorption conversion system to produce efficient steam.In this paper,two kinds of photothermal conversion devices are designed using natural Balsa as raw materials,and an exploratory study is made on their photothermal properties and applications:First,we develop a novel system for water evaporation through assembly of carbon dots within microchannels of processed wood.Not only is a dual-layer structure including of heat barrier and water transport channel formed,but also the modulation of carbon dot energy structures in favor of photothermal conversion is realized synchronously.This system exhibits higher water evaporation rate and energy efficiency for solar to steam generation than other black photothermal sheets?e.g.carbon,nanotube,graphene,graphene oxide?.On the one hand,the constructed size-dependent vaporization enthalpy theory shows that the micropores are beneficial to reduce vaporization enthalpy of water.On the other hand,the presented direct evidences for the roles of oxidation functional groups in solar thermal evaporation demonstrate that hydroxyl groups can improve solar-to-heat efficiency.Therefore,tailoring pore sizes and surface functional groups could be an efficient method for solar-to-vapor systems.Second,solar energy as an inexhaustible energy,if we only use it to evaporate water,the utilization rate seems to be far from enough.Moreover,as a renewable resource,the lignin extracted from it has a significant application in heavy metal ion adsorption.Herein,we provide a novel avenue for boosting adsorption activities towards specific metal ions in wastewater.Solar-driven interfacial water evaporation produces the localized temperature field and concentration gradient of metal ions inside small pores,endowing with a new sorption mechanism.By using chemically-treated carbonized wood as all-in-one solar absorption and metal ion adsorption system,we achieved higher water evaporation rate and heavy metal ion removal efficiency than carbonization-only wood reported previously.In particular,this system exhibited a strong dependence of specific metal ion adsorption capacity on solar intensity.Pb²⁺adsorption capacity was enhanced by over 225%with the solar intensity increased to 3.0 kW·m^-2.Besides,the chemical-treated&carbonized wood showed excellent cyclic stability and can be directly utilized for wastewater treatment,recovery and reuse.