High efficiency solar interfacial evaporator for seawater desalination based on high porosity loofah sponge biochar

[Display omitted] •A novel biochar solar interfacial evaporator was developed.•The solar absorption layer and substrate were optimized.•The evaporation rate of loofah-based evaporator reached 1.565 kg m−2 h−1.•The evaporation efficiency of loofah-based evaporator reached 80.66%.•The quality of produced freshwater meets the standard of domestic water. Materials based on biochar have good application prospects in the field of solar interfacial evaporation. However, due to their amorphous structure, most biochar materials often require additional chemical treatment for interfacial evaporation, which is inconsistent with the original intention for low cost and easy fabrication. Here, a solar absorption layer made of loofah sponge biochar prepared by direct compression and carbonization and a substrate with water conveyance and heat insulation effects were combined into a squashed loofah sponge biochar interfacial evaporator (SLSBIE). The SLSBIE achieved an evaporation rate of 1.565 kg m−2 h−1 and an evaporation efficiency of 80.66% under 1 sun (1000 W m−2). The good performance of the SLSBIE is mainly due to the porosity (554.1 m2 g−1), light absorptivity (89.21%), and hydrophilicity (rich in C-O and C=O) of the structure of loofah sponge biochar, as well as the optimization. The heat loss and energy balance of LSBIE were analyzed in detail. The measured concentrations of Na+, Mg+, K+, Ca2+ and total dissolved solids of condensate water met the standards of the World Health Organization for drinking water, which indicated that SLSBIE had good practicability.