Three-Dimensional evaporator for simultaneous VOC removal and clean water production

Abstract

Interfacial solar steam generation (ISSG) is a promising and sustainable technology to product clean water, but most of current evaporators suffer the failure to remove volatile organic compounds (VOCs) from condensate water and prevent the production of concentrated water. Herein, we proposed a three-dimensional bi-functional evaporator integrating ISSG with heterogeneous Fenton technology, simultaneously to remove various organics from both condensate water and feed water. The evaporator (rGO-FeOOH@MF) was prepared by loading reduced graphene oxide (rGO) and hydroxy-ferric oxide (FeOOH) nanoparticles onto melamine foam (MF). The results manifested that rGO-FeOOH@MF exhibited an outstanding evaporation flux of 2.20 kg m-2h-1 under one sun irradiation. More importantly, the removal rate of VOC in condensate water reached 92.56 ± 0.11 % due to synergetic Fenton reaction, which was 4 times (23.1 %) than that of sole ISSG. Meanwhile, the VOC removal rate remained ∼92 % even after 7 times cycle tests, demonstrating the evaporator with a good stability. The rGO-FeOOH@MF was also proved to be able to remove VOCs from high saline wastewater (96.43 %). Besides, for the purification of concentrated water, the evaporator achieved ∼100 % removal rates for non-volatile organic compounds. To sum up, the prepared rGO-FeOOH@MF evaporator opens a new way to simultaneous removal of non-volatile and volatile contaminants in wastewater treatment field.