Preparation Of Antibacterial And Anti-oil Adhesion MXene Aerogels And Its Solar Water Evaporation To Purify Oily, Bacterial Sewage And Self-generated Electricity

The rapid development of human society has led to an increasing shortage of clean water and energy resources,and there is an urgent need to develop a technology for obtaining fresh water resources with low energy consumption.In recent years,solar-driven water purification technology has been widely studied due to its green,low-energy sustainable features.However,the solar absorbers that have been reported so far are largely multi-functional and mainly focus on improving the water evaporation performance and solar-vapor conversion efficiency.However,many practical problems need to be faced in the application,such as oily wastewater purification,in which the problem of oil recovery has rarely been studied,which can cause loss of oil resources or secondary pollution;for desalination,metals,oil and bacteria tend to coexist and accumulate on the surface of solar absorbers;in addition,without relying on additional device assistance,the electrical energy generated by water evaporation is not fully utilized,resulting in solar energy loss.To solve the above problems,we constructed a multifunctional solar absorber integrating oil-water separation,antibacterial and power generation for the first time.The main research work of this paper is listed as follows:(1)Preparation of MXene based aerogel with vertically aligned pore channels and study on the water evaporation performance: Using polyvinyl alcohol(PVA)and chitosan(CS)as raw materials and MXene(Ti₃C₂)as a functional material for photothermal conversion,they were assembled into MXene based aerogel with vertically aligned microporous channels using a simple ice template method.And the successful preparation of MXene based aerogel was demonstrated by SEM,EDS,FT-IR,XRD and XPS characterization.MXene based aerogels with different pore sizes were prepared by regulating the concentration of MXene solution.Among them,the average pore size of PCM-4 aerogel was 41.9 ?m,with high saturated water content(26.8 g·g^-1),fast water transport rate(57.80 g·min^-1),strong light absorption(84.21%)and photothermal conversion performance(41.2?).The water evaporation test result showed that PCM-4 aerogel had a high water evaporation rate(1.44kg·m-2·h^-1)and solar-steam conversion efficiency(90.6%).The endurance test result showed that after 10 h of continuous water evaporation,PCM-4 aerogel still maintained a evaporation rate of 1.41 kg·m-2·h^-1 of water evaporation rate.(2)Preparation of modified aerogel and study on oil-water separation performance and mechanism driven by solar energy: PCM-4 aerogel was selected for reasonable surface modification to prepare modified aerogel(M@PCM-4)which is anti-oil adhesion.,antibacterial and self-generating.And SEM and XPS tests were used to show the successful preparation of M@PCM-4 aerogel.The solar-driven oil-water separation results showed that M@PCM-4 aerogel had good separation performance for various nano-oil in water emulsions.Especially,the separation efficiency and oil recovery of n-hexadecane in wate emulsion(oil:water=10:90;v:v)were as high as 99.33% and 99.45%.Through surface wettability,infrared thermal image,underwater oil adhesion test and corresponding mechanism diagram,it was revealed that super-hydrophilicity,photo-thermal conversion and low underwater oil adhesion were the internal mechanisms of oil-water separation and oil recovery driven by solar energy.(3)Research on desalination performance of M@PCM-4 aerogel for seawater containing oil and bacteria: The results of shock method showed that M@PCM-4 aerogel had excellent antibacterial performance,and the antibacterial performance of E.coli and S.auerus were as high as 99.96% and 99.93% respectively;the results of desalination of complex seawater showed that M@PCM-4 aerogel can efficiently desalinate complex seawater.The desalinated water did not contain bacteria,in which the concentration of metal ions decreased to less than3 mg·L^-1,which met the drinking water standard defined by the World Health Organization(WHO).(4)Study on power generation performance and mechanism of water evaporation:Dynamically adjusted simulated sunlight,the results of the current and voltage test of M@PCM-4 aerogel showed that M@PCM-4 aerogel had controllable response to illumination,and the current and voltage under illumination can reach 15.45?A and 0.22 V respectively.The output power of M@PCM-4 aerogel reached 0.59 ?W(power density 0.96 m W·m^-2)under load 0.1 M? resistance.The results of infrared thermal image,SEM and Zeta potential indicated that temperature gradient and charged microchannel surface were the internal mechanism of power generation.The practical application results showed that the electricity generated by M@PCM-4 aerogel water evaporation can be stored or used to detect different water quality and rainfall.