多孔Ni/CNT/Ni_(3)S_(2)复合薄膜体系的设计及其光热海水淡化性能

Design of Porous Ni/CNT/Ni_(3)S_(2) Composite Film System for Solar Desalination

目的针对目前水资源短缺的问题,设计Ni/CNT/Ni_(3)S_(2)复合薄膜,并测试其光热海水淡化性能。方法在多孔Ni网上,采用化学气相沉积(CVD)和水热合成相结合的方法制备Ni/CNT/Ni_(3)S_(2)复合薄膜,并构建太阳能蒸发器。利用SEM、TEM对样品的微观形貌进行表征,通过XRD、XPS分析样品的物相组成和表面元素,利用紫外可见近红外光谱分析蒸发器的光吸收能力,通过电感耦合等离子体光发射光谱仪检测海水淡化前后的离子浓度变化。结果在制备的蒸发器中,Ni/CNT/Ni_(3)S_(2)-12蒸发器表现出优异的性能,在整个太阳光谱能吸收90.1%的太阳光。在1个太阳的光照强度下,蒸发速率高达2.57 kg/(m^(2)·h),在不同质量分数的盐溶液中也有很好的蒸发效果。此外,淡化后的海水、污水中的离子浓度达到世界卫生组织对安全饮用水规定的标准。结论多孔Ni基底具有大孔结构,既能漂浮于水面上实现界面加热,又能提供水的运输通道与蒸汽逸出通道,有很好的耐腐蚀性和机械强度。CNT和Ni_(3)S_(2)具有优异的光热转换能力,并且隔热层限制了热量向水体的传递,提高了蒸发器的蒸发速率。制备的Ni/CNT/Ni_(3)S_(2)-12太阳能蒸发器在海水淡化方面有很大的应用潜力。

The shortage of fresh water resources has become one of the most serious global challenges faced by human beings in the 21st century.The interface solar desalination technology has received extensive attention due to its advantages of energy saving and environmental protection.By virtue of photothermal materials,interface solar desalination absorbs solar energy and converts it into thermal energy,which is heated at the air-water interface and condensed by steam to produce clean drinking water from polluted water.Well research progress has been made in carbon materials such as carbon nanotube,but the high thermal conductivity of CNT will cause a large heat loss.Through designing the combination of CNT and other materials,better water evaporation performance can be achieved.CNT was grown by chemical vapor deposition(CVD).The quartz boat with porous Ni mesh was placed in a tube furnace,heated to 860℃under N2 atmosphere,and the mixed solution of acetonitrile and ferrocene was injected for 40 min to obtain Ni/CNT.1.45 g Ni(NO3)26H2O and 0.16 g thiourea were dissolved in 30 mL deionized water to obtain a homogeneous solution.The Ni/CNT and the uniform solution were placed in a 50 mL Teflon lined stainless steel autoclave,and maintained at 120℃in an oven for 8,10,12,and 16 h,respectively.After drying,Ni/CNT/Ni_(3)S_(2) was obtained.The surface morphologies and structure of samples were characterized by scanning electron microscope(SEM)and transmission electron microscope(TEM).The phase composition and surface elements of samples were recorded by X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS).UV-Vis-NIR spectroscopy was used to analyze the light absorption capacity of solar evaporator and electronic balance was used to record the evaporation of seawater.The change of ion concentration before and after seawater desalination was measured by inductively coupled plasma optical emission spectrometer(ICP-OES).Ni/CNT/Ni_(3)S_(2) composite film was successfully prepared by CVD and hydrothermal synthesis on porous Ni mesh,and solar evaporator was constructed.CNTs were bent and wound on the porous Ni mesh,and Ni_(3)S_(2) was uniformly coated on the CNTs.The best hydrothermal time for Ni_(3)S_(2) preparation was 12 h.Porous Ni substrate has macroporous structure,which can not only float on the water surface to achieve interfacial heating,but also provide water transport channel and steam escape channel,with good corrosion resistance and mechanical strength.CNT and Ni_(3)S_(2) have excellent photothermal conversion capacity.The Ni/CNT/Ni_(3)S_(2)-12 solar evaporator can absorb 90.1%sunlight in the whole solar spectrum.Under the illumination intensity of one sunlight,the evaporation rate of Ni/CNT/Ni_(3)S_(2)-12 solar evaporator is as high as 2.57 kg·m–2·h–1.The Ni/CNT/Ni_(3)S_(2)-12 solar evaporator can still maintain a high evaporation rate during the 48 h cycle,showing good cycle stability and it also has a good evaporation effect in different mass fractions of salt solutions.The concentration of ions in desalinated seawater and sewage reaches the World Health Organization's(WHO)standard for safe drinking water,indicating that the Ni/CNT/Ni_(3)S_(2)-12 solar evaporator has great potential in practical application of desalination.