A fabric interpenetrating composite hydrospongels with permeability and evaporation enthalpy regulation for efficient solar-driven interfacial evaporation and water purification

Solar-driven interfacial evaporation (SDIE) could utilize solar energy for efficient water purification, possessing sustainability and environmental benefits obviously. The PVA hydrogel owing to its 3D network structure and hydrophilicity performance, has been instrumental in developing materials for SDIE. However, achieving stable and efficient evaporation performance in hydrogel-based solar evaporators remains challenging. In this research, we have developed a fabric interpenetrating composite hydrospongel with permeability and evaporation enthalpy regulation for evaporation and water purification. The incorporation of hydrophilic filter cotton into the hydrogel network, enhancing the permeability of PVA hydrogel, improving the interaction between PVA and water molecules, thereby increasing the hydration interface area and lower evaporation enthalpy. Experimental results demonstrated that under 1 kW/m⁻² solar radiation, the evaporator achieved an evaporation rate of 2.85 kg m⁻² h⁻¹ with an evaporation efficiency of 88 %. Notably, the solar evaporator demonstrated stable evaporation performance in simulated seawater, achieving an evaporation rate of 2.79 kg m⁻² h⁻¹ and exhibited excellent salt resistance performance, moreover, it provided the superior efficiencies in purifying various contaminated wastewaters. The fabric interpenetrating composite hydrospongels offering a novel approach in solar thermal desalination and zero liquid discharge.