Efficient solar-driven steam generation for clean water production using a low-cost and scalable natural rubber composite sponge†

Abstract

Water scarcity is a global issue which might feasibly be addressed through the use of solar energy to produce uncontaminated steam from contaminated water. This technique would allow greater efficiency in purifying wastewater, or desalinating seawater, to produce an adequate supply of clean water. This work therefore presents a novel design for a solar receiver in the form of a composite sponge made from iron oxide black and natural rubber, prepared via the Dunlop process, which is commonly applied in the rubber sector. This composite sponge can absorb solar energy across a broad spectrum before focusing that energy directly on the interfacial surface. In tests using simulated seawater, and water containing organic dyes and heavy metals, the condensed steam produced met the required standards for potable water. The composite material involved exhibited durability, producing stable results beyond 20 cycles of evaporation and cooling. Furthermore, iron oxide black is cheap, abundant, and available in commercial quantities, while natural rubber latex and its associated technologies are widely established for large-scale usage. Therefore, solar receivers based on an iron oxide black/natural rubber composite sponge have significant potential in various applications which make use of solar steam generation, for instance, desalination for freshwater production, or even for sterilization.