具有层级互联孔道的拒盐碳气凝胶太阳能蒸发器用于高盐废水处理

Salt-resistant carbon aerogel with hierarchical interconnected channels for continuous and efficient solar evaporation of hypersaline water

太阳能蒸发是一种可持续的高盐废水处理技术,然而运行中蒸发器表面的盐积累会严重缩短蒸发器的寿命.如何使蒸发器兼具高蒸发效率和良好拒盐性是目前面临的挑战.本研究设计了一种三维碳纳米纤维/氧化石墨烯复合气凝胶(CNF/GOA).氧化石墨烯的引入不仅增强了CNF/GOA的力学性能,同时构建了丰富的分级互连孔道结构,加快了水的传输和盐的扩散,实现了高蒸发速率和良好的拒盐性.此外,通过调控CNF/GOA的浸没深度和孔道结构,抑制了水的热传导损失,降低了水的蒸发焓,在一个太阳照射下实现了3.47 kg m^(-2)h^(−1)的蒸发速率.更重要的是,即使处理高盐水,蒸发器表面也没有产生任何盐结晶.长期实验和户外脱硫废水蒸发实验表明,CNF/GOA具有良好的实际应用前景.

Solar-driven water evaporation is a sustainable solution for hypersaline water treatment,but salt accumulation on the evaporator surface seriously threatens the evaporation system longevity.Despite previous great efforts,critical challenges remain in preventing salt accumulation while maintaining a high evaporation rate.Herein,a salt-resistant three-dimensional carbon nanofiber/graphene oxide composite aerogel(CNF/GOA)with a high evaporation rate was designed.The introduction of GO dramatically enhanced the mechanical property of CNF/GOA and constructed abundant hierarchical interconnected channels for rapid water replenishment and salt diffusion.By suppressing heat conduction loss to bulk water and decreasing water evaporation enthalpy based on regulating the immersion depth and pore structure of CNF/GOA,an evaporation rate of 3.47 kg m^(-2)h^(−1)(3.5 wt%NaCl solution)was achieved under 1 sun irradiation(1 kW m^(-2)).More importantly,hypersaline water evaporation(24.0 wt%NaCl brine and industrial hypersaline wastewater)without salt crystallization was achieved.The results of 24-h continuous testing and 10 cycles of 8-h testing proved that CNF/GOA possessed outstanding long-term stability.The outdoor evaporation experiment of the concentrated desulfurization wastewater exhibited a high evaporation rate(23.26 kg m^(-2)d−1,7:00–17:00),indicating CNF/GOA had great practical application prospect.This work may offer a fascinating avenue towards practical hypersaline wastewater treatment.