Novel and stable carbon black/polyvinyl acetal aerogels efficiently harvesting solar energy for seawater desalination

Abstract

A novel interfacial solar steam generators (ISSG) was prepared by a porous carbon black/polyvinyl acetal aerogel (CPA) with high light-absorbing hydrophilic properties, to achieve efficient solar-driven water evaporation and seawater desalination. The polyvinyl acetal was produced by the aldol condensation reaction of polyvinyl alcohol(PVA) and glutaraldehyde(GA). It was freeze-dried to create a hydrophilic porous structure that constructs an efficient hydrophilic channel. Carbon black (CB) exhibits high light absorption capabilities. Incident light undergoes multiple scattering within its porous network structure, effectively reducing reflected light energy loss and enabling efficient thermal conversion of sunlight. Benefited from its highly light-absorbing porous hydrophilic structure, CPA-40-3 evaporation rate achieves an impressive 3.23 kg·m−2·h−1 and an evaporation efficiency of 94 % under 1 sun irradiation, without obvious decay even during long-term use. Furthermore, CPA-40-3 demonstrates remarkable salt tolerance, the evaporation rate remains at 2.55 kg·m−2·h−1 although in simulated Dead Sea salt water under 1 sun irradiation. Compared to traditional ISSG, the CPA has advantages such as superior mechanical properties, prevention of surface salt precipitation, faster water supply, and a larger light absorption area. This design had tremendous promise for efficient solar desalination due to its extraordinarily high evaporation performance in high-salinity brine.