Optimization of bamboo-based photothermal interfacial solar evaporator for enhancing water purification

Although solar desalination is a promising approach for obtaining freshwater, its practical application encounters challenges in achieving efficient photothermal evaporation. Recent research has focused on novel configurations of solar absorbers with unique structural features that can minimize heat loss. High-efficiency interfacial solar steam generation (SSG) can be achieved by optimizing the design of the absorber to harness incident heat energy on the top interfacial surface and ensuring a continuous water supply through microchannels. Artificially nanostructured absorbers might have high solar absorptivity and thermal stability. However, the manufacturing of absorbers is expensive, and the constituting materials are typically non-biodegradable. The unique structural configuration of natural plant-based solar absorbers provides a major breakthrough in SSG. Bamboo, as a natural biomass, possesses exceptional mechanical strength and excellent water transport through vertically oriented microchannels. This study aimed to enhance the performance of SSG with a carbonized bamboo-based solar absorber (CBSA). To achieve this goal, we optimized the carbonization thickness of the absorber by varying the carbonization time. Furthermore, the height of the CBSA was varied from 5 to 45 mm to determine the optimal height for effective solar evaporation. Accordingly, the highest evaporation rate of 3.09 kg m^-2 h^-1 was achieved for the CBSA height of 10 mm and top-layer carbonization thickness of 5 mm. The cost-effectiveness, simple fabrication, and superior desalination performance of the CBSA demonstrate a strong potential for practical applications.