Recently, a scientific research team led by researcher Zhu Yingjie of the Shanghai Institute of Ceramics, Chinese Academy of Sciences, based on the research work of new inorganic refractory paper, using hydroxyapatite ultra-long nanowire refractory paper as a carrier, loaded carbon nanotubes, successfully Developed large-sized new light-to-heat conversion refractory paper. Hydroxyapatite ultra-long nanowire refractory paper has the advantages of low thermal conductivity, excellent thermal insulation performance, high thermal stability, good biocompatibility, and environmental friendliness. It can significantly reduce heat loss and improve the efficiency of solar energy utilization. . The new light-to-heat conversion refractory paper can effectively absorb sunlight and convert it into heat energy under sunlight, and is used to heat water on its surface to generate water vapor. The water vapor is condensed in a condensation device to produce clean water. The new light-to-heat conversion refractory paper has good application prospects in the fields of seawater desalination, sewage containing heavy metal ions, dyes, and bacteria. The relevant research results were published in the international authoritative journal Small (Zhi-Chao Xiong, Ying-Jie Zhu * et al., Small, 14, 1803387 (2018)) (I.F. = 9.598).
Related research background
In recent years, with the global water pollution problem becoming increasingly serious, water shortage and water crisis have become one of the global problems. One of the most promising solutions to the severe freshwater crisis is the development and use of water that is not directly drinkable, such as seawater. Traditional seawater desalination technology requires direct or indirect consumption of non-renewable fossil fuel resources, which will accelerate resource consumption and pollute the environment. Solar energy is a kind of efficient, sustainable and clean energy. Using solar energy to drive seawater desalination has huge potential for development. However, the traditional solar distillation technology has low efficiency and small output. The main reason is that water absorbs sunlight inefficiently, and most of the heat is dispersed in water. In order to improve the evaporation efficiency of water in the process of solar distillation, on the one hand, it is necessary to use light-to-heat conversion materials to improve the absorption of sunlight and the light-to-heat conversion efficiency; on the other hand, according to the feature that water evaporation only occurs on the surface of water, Floating material, which collects the heat generated by solar energy absorption materials at the air / water interface to reduce heat loss. In recent years, researchers have studied a variety of light-to-heat conversion materials used to produce water vapor and clean water from sunlight. However, many light-to-heat conversion materials have disadvantages such as poor thermal stability and low efficiency.
Related research work
The research team developed a calcium oleate precursor solvothermal method and combined with vacuum suction filtration molding method to prepare large-size hydroxyapatite ultra-long nanowire refractory paper, and then added carbon nanotube dispersion liquid to continue vacuum suction filtration to prepare a new type Light-to-heat conversion refractory paper. This method is expected to be used for the scale-up preparation of large-sized new light-to-heat conversion refractory paper, and has the potential for mass production. At present, the research team has realized the scale-up preparation technology of a 100-liter reactor in the laboratory. The prepared light-to-heat conversion refractory paper has excellent high-temperature resistance, fire resistance, flame retardancy and heat insulation performance, and can be kept intact in the flame of an alcohol lamp and in a high-temperature environment.
The experimental results show that the surface temperature of the new light-to-heat conversion refractory paper rapidly rises to about 80 ° C under the condition of 1 kW / m2 simulated solar light source for 1 minute, while the surface temperature of the refractory paper without carbon nanotubes is only about 35 ℃. The new light-to-heat conversion refractory paper is placed in an aqueous solution and can float on the water surface without sinking. The water evaporation performance of the new light-to-heat conversion refractory paper was further tested. The water evaporation efficiency was 83.2% under 1 kW / m2 simulated solar light source, and the water evaporation efficiency was 92.8% under 10 kW / m2 simulated solar light source. In addition, the new light-to-heat conversion refractory paper can be used repeatedly and for a long time, and the stability of water evaporation performance is good.
During solar-driven water evaporation, pollutants such as heavy metal ions, dyes, and bacteria in the solution can be effectively blocked and retained in the aqueous solution. The generated water vapor condenses to produce clean water. The new light-heat conversion refractory paper is applied to 5 types of solar-driven desalination processes that simulate seawater. The concentration of sodium chloride can be reduced by 3 orders of magnitude, and the removal rate of sodium chloride is as high as 99.95%. The desalinated clean water can meet the World Health Organization. Developed standards for healthy drinking water. The research team conducted desalination research on real seawater taken from the East China Sea. The experimental results show that after a new type of light-to-heat conversion refractory paper solar-driven desalination treatment, several major ions in the seawater such as Na, Mg2, K, Ca2, and B3 The removal rate exceeds 94.32%, and the highest can be close to 100%. The water quality after desalination can reach the drinking water standard set by the World Health Organization. When a new type of light-to-heat conversion refractory paper solar drive is used to process an aqueous solution containing heavy metal ions Ni2, Cu2, Cd2, Ba2, and Mn2, the removal rate of heavy metal ions exceeds 99.99%. After the new photothermal conversion refractory paper solar-driven treatment of wastewater containing dyes and water containing bacteria, the quality of the collected condensed water can meet the national drinking water standard (GB5749-2006).