A loofah-derived biological activated carbon enhanced solar interfacial evaporator for efficient and stable seawater desalination and wastewater purification

Abstract

In view of problems such as complex preparation processes and poor stability faced by the existing solar interfacial evaporators, in this work, we have successfully prepared a loofah-derived biological activated carbon evaporator (LBAC) through a simple combined high-temperature carbonization and KOH activation process. The modified LBAC has a hierarchically oriented porous structure and an ultra-high light absorption rate of 96.9%. At a solar intensity of 1 kW m⁻², the LBAC can yield an interfacial evaporation rate of 2.04 kg m⁻² h⁻¹, which is 3.09 times that of the natural evaporation rate of pure water, and the photothermal conversion efficiency reaches 94.5%. Thanks to the micron- and nano-scale small pores generated by KOH activation on the inner wall of the microchannels, the interfacial evaporation rate of the LBAC almost maintains a stable value during continuous operation in 10.5 wt% high-concentration brine for 12 hours, and only a significantly low average degradation rate of 0.10% per hour is observed. The LBAC also has an excellent purification effect on industrial wastewater such as desulfurization wastewater and phosphorus chemical wastewater. This work combines the high value-added conversion of biomass materials with the efficient water treatment mode driven by low-grade solar energy and has broad application prospects in fields such as seawater desalination and zero discharge of industrial wastewater.