Study On Solar Interface Water Evaporation System Between MnO₂ And Biomass-Based Composites

Today,the shortage of fresh water resources remains a serious challenge for many countries.In order to solve this problem,efforts are made to develop economical and efficient water desalination systems.Therefore,solar-powered interfacial water desalination technology has started to receive a lot of attention from the engineering and materials science communities.This is a technology that occurs at the gas-liquid contact surface,converts solar energy into thermal energy through photothermal materials,and continuously produces clean water.Currently,photothermal materials with high spectral absorption capabilities have been extensively developed.These include semiconductors,metallic materials,polymers,and carbon-based materials.Among them,biomass-derived carbon materials are used as typical solar photothermal materials due to their economic advantages.However,the lower light absorption conversion efficiency and salt accumulation remain the main factors limiting their development.Based on the consideration of these problems,in this study,the photothermal materials were prepared by the composite of biomass materials and metal oxide MnO₂,and the details and conclusions of the study are as follows.（1）A novel material（H-CS/MnO₂）was prepared by co-hydrothermal method of cotton rod（CS）and MnO₂,and a stable and effective evaporation system was designed.While ensuring superhydrophilicity,the stable loading of MnO₂ also gives H-CS/MnO₂ excellent photothermal conversion performance.The experimental results showed that the evaporation efficiency reached 93.46%and the evaporation rate was2.43 kg m^-2 h^-1 under the light condition of 1 KW m^-2.In order to avoid the pollution of the environment by the random discharge of hydrothermal carbonization solution,this chapter was recycled.During the recycling process,carbon quantum dots（CDs）were found to be continuously enriched and exhibited certain photothermal effects,and the synergistic effect of MnO₂ and CDs further improved the photothermal conversion performance of the material,and the evaporation rate increased to 2.85 kg m^-2 h^-1 under the light condition of 1 KW m^-2.In addition,H-CS/MnO₂ has good salt and corrosion resistance,and the resulting purified.The salt ion removal rate of the resulting water was more than 99.9%.（2）The carbon material（C-CP）was obtained by phosphoric acid-assisted low-temperature carbonization using cheap and readily available corrugated paper（CP）as raw material;the redox reaction of potassium permanganate and manganese sulfate resulted in the successful loading of MnO₂ on the surface of C-CP to produce the photothermal material（C-CP/MnO₂）.The evaporation rate could reach 2.563 Kg m^-2 h^-1 under the light condition of 1 KW m^-2.In order to further increase the evaporation rate,a sunflower bionic light-chasing system was constructed.This resulted in an increase in the amount of radiation received by the C-CP/MnO₂ surface by nearly 80%,and the evaporation rate reached 4.314 kg m^-2 h^-1.Moreover,optical simulations were performed by Zemax to demonstrate the light propagation path and to verify the correctness of the experimental results.In addition,C-CP/MnO₂ is not only suitable for desalination of seawater,but also for purification of high concentration organic wastewater and wastewater containing heavy metal ions.（3）The hydrogen dialuminum phosphate（ADP）compound was prepared by heat treatment and used as a catalyst for low-temperature carbonization of corrugated paper to prepare CP-ADP.at room temperature,MnO₂ particles were generated on the surface of CP-ADP by the redox reaction of potassium permanganate and manganese sulfate,which were bonded by hydrogen bonding to form a stable composite（CP-ADP/MnO₂）.The evaporation rate can reach 2.594 Kg m^-2 h^-1 under the light condition of 1 KW m^-2.In order to further improve the evaporation rate,6V solar cell is used as compensation in this paper,and the evaporation rate can reach 3.971 Kg m^-2 h^-1 by the synergistic effect of photo-thermal and electro-thermal.6.361 Kg m^-2 h^-1 can be achieved by combining with solar collector system.In order to solve the problem of salt deposition caused by rapid evaporation,intermittent ion electromigration was used to effectively settle the salt particles.And based on this principle,a portable solar water evaporation small device was prepared.