Efficient photothermal supports from carbonized agave flower stalk for solar water evaporation

In the present work, porous supports from carbonized agave flower stalk (CAFS) were prepared and tested in solar water evaporation. These supports were characterized by FTIR and UV/Vis spectroscopies, and their morphology and structure were determined by SEM microscopy. The results of these studies showed a wide absorption range in the UV/Vis-NIR (200-1100 nm), consisting of structures with micropores and well oriented microchannels whose morphology resembles micro-packed bed distillation columns. Pure water evaporation efficiency of CAFS was studied as a function of the thickness of the support and its diameter under visible light irradiation at different power density. It was observed that optimal thickness of the support is 4.05 mm with 1.99 kg h⁻¹ m⁻² of evaporation rate and 97.5% of efficiency under 1300 W m⁻² of illumination, therefore, this support was tested in the simulated seawater evaporation (3.5% NaCl) with multiple evaporation cycles under 1300 W m⁻² of light irradiation, achieving 1.91 kg h⁻¹ m⁻² of evaporation rate and 93% of efficiency, which demonstrates that this material is comparable to its synthetic counterparts and opens a possible new line of commercial use of agave sub product.