Monolith floatable dual-function solar photothermal evaporator: efficient clean water regeneration synergizing with pollutant degradation

Abstract

Meeting the growing demands of attaining clean water regeneration from wastewater and simultaneous pollutant degradation has been highly sought after. In this study, nanometric CuFe₂O₄ and plasmonic Cu were in situ confined into graphitic porous carbon nanofibers (CNF) through electrospinning and controlled graphitization, which were integrated onto a melamine sponge (S-FeCu/CNF) as a monolithic evaporator via a calcium ion-triggered network crosslinking method using sodium alginate (SA). This monolithic evaporator serves a dual purpose: harnessing solar-driven photothermal energy for water regeneration and facilitating synchronous contaminant mineralization through advanced oxidation processes (AOPs). The metal-modified FeCu/CNF graphitic porous carbon exhibited an enhanced light absorption property (≥95%) and was further securely anchored on the sponge by a calcium ion-triggered SA crosslinking technique, thereby efficiently restraining salt deposition. The FeCu/CNF evaporator demonstrated a solar-vapor conversion efficiency of 105.85% with an evaporation rate of 1.61 kg m⁻² h⁻¹ under one sun irradiation. The evaporation rate of the monolithic S-FeCu/CNF evaporator is close to 1.76 kg m⁻² h⁻¹, and an evaporation rate of 1.54 kg m⁻² h⁻¹ can be achieved even in 20% NaCl solution, with resistance to salt deposition and cycling stability. Synchronously, the monolithic D-S-FeCu/CNF evaporator also acts as a heterogeneous catalyst to activate peroxymonosulfate (PMS) and trigger rapid pollutant degradation, which also shows excellent catalytic cycling stability, producing clean water that satisfies the World Health Organization (WHO) standards. This work provides a potentially valuable solution for addressing desalination and wastewater treatment.