Preparation Of Multi-functional Biomass Aerogels And Their Photothermal Properties

With the acceleration of human civilization,the consumption of natural resources rises sharply.The expansion of industrialization,urbanization and agriculture is also gradually changing the earth's climate and environment.The resulting energy shortage and water resource pollution are serious threats to the earth's ecology and human survival.It becomes a global consensus to seek renewable energy and environmentally friendly development.Solar driven water evaporation technology has great potential to solve the problems of energy consumption and water shortage.At present,a two-layer interfacial system composed of a photothermal conversion layer and a thermal insulation layer is generally adopted as a water treatment platform.However,in the long-term application of seawater desalination,the surface salinity of the photothermal conversion layer increases,and the performance of the system decreases due to salting out.Therefore,it is of great significance to study a solar driven water evaporation system with high performance and stability.In this paper,carbon-based chitosan aerogel was innovatively prepared by solid-liquid direct freeze-drying method and applied to solar driven water evaporation system.The carbonized pomelo peel in nitrogen atmosphere was used as a high efficient photothermal conversion material.The preparation process of aerogel was systematically optimized,and the resulting aerogel has the characteristics of high light absorption?97%?,super hydrophilicity,low thermal conductivity,high porosity?96%?and low density.Under the light intensity of 1 k W m^-2 illumination,the aerogel has high efficient solar steam generation?SSG?performance with an evaporation rate of 2.07 kg m^-2 h^-1 by controlling the height of evaporator.The composite aerogels of various photothermal conversion materials with chitosan were prepared by means of solid-liquid and liquid-liquid freeze drying.Compared with the traditional interface evaporator,the performance of the integrated evaporator using photothermal aerogel has been improved significantly,which is of guiding significance to design and prepare high-performance and low-cost SSG system.The material and process of carbon-based chitosan aerogel were optimized to achieve a high efficiency of SSG in seawater desalination with salinity ranging from 0 to 20 wt%.For seawater with a salinity of 3.5 wt%,it has a long-term stable and efficient SSG rate(1.70 kg m^-2 h^-1),and the water quality after treatment has reached the drinking water standards.In addition,carbon-based chitosan aerogels can also be used for integrated power generation to obtain clean water and electricity.