Highly salt-resistant 3D melamine sponge-polypyrrole composites for efficient solar interfacial evaporation

Solar desalination has received great attention as an environmentally friendly and cost-effective way to desalinate seawater. In this paper, a melamine sponge composite polypyrrole (MSPPy) evaporator was prepared by in-situ polymerization of Pyrrole (Py) on a melamine sponge (MS). PPy has an efficient light absorption ability. The large aperture network structure of MS can realize multiple reflections of light and greatly increase the absorption of light. Their synergistic effect makes the light absorption efficiency of the MSPPy evaporator reach 96.97%. Under one sun, the average evaporation rate of 1.886 kg⋅m −2 ⋅h −1 and energy conversion efficiency of 96.8% were achieved during 10 h. Moreover, the evaporator has an edge-priority crystallization function, which enables it to work for a long time in a high-salt environment. It works continuously for 12 h in simulated seawater with a salinity of 20% without further accumulation of salt crystals on its surface. More important, it can rapidly diffuse accumulated salt into the bulk water at night. This study provides a new idea for the application of solar steam generation technology in high-salt wastewater treatment.