Oriented porous hydrogel with excellent anti-salt and antibacterial properties for high-performance interfacial solar steam generation

Abstract

In recent years, solar interfacial evaporation has drawn substantial attention in wastewater and seawater treatment, but it still requires intensive development in high-performance evaporators, particularly simultaneous with high anti-salt and antibacterial abilities to supply freshwater. In this work, a directionally channeled evaporator with excellent resistance to salt crystallization and microbial was designed and synthesized by using silver nanoparticles (AgNPs) / polydopamine (PDA) hydrogel via a simple freeze-dried method. The novel structure was proposed to enhance convection and accelerate water transport that prevents salt crystallization. PDA and AgNPs were deposited to achieve superb optical absorption, photothermal conversion and anti-biofouling ability. Therefore, the evaporation rate of the AgNPs-PDA hydrogel achieved 1.70 kg m−2 h−1 with a light-to-heat conversion efficiency of 90.3 %. Based on the efficient evaporation ability and especially structure of the AgNPs-PDA hydrogel, the evaporator presented a tolerance to high salt water and the stable evaporation performance of actual seawater evaporation during long-time application. Simultaneously, the addition of AgNPs endowed the AgNPs-PDA hydrogel evaporator with excellent antibacterial ability. Thus, these favorable properties endowed the special AgNPs-PDA hydrogel evaporator a great potential for obtaining efficient evaporation and simultaneously solving the fouling problem, especially to waterborne pathogens and salt crystallization in tanglesome applications.