Abstract
Solar evaporation exhibits significant potential for the treatment of high-salt organic wastewater. However, it's also confronted with challenges due to the accumulation of organic pollutants and salts in the concentrated wastewater following evaporation, which compromises the long-term stability of evaporation unit and complicates subsequent treatment processes. To address these challenges, a volumetric solar interfacial evaporation (V-SIE) system by integrating Fe(3)O(4) (-)H(2)O nanofluids and peroxydisulfate (PDS) were proposed in this study. In V-SIE system, Fe(3)O(4) magnetic nanoparticles (NPs) were prepared as solar receivers to form a volume-absorbing solar energy interface and enhance evaporation efficiency. The results show that the evaporation rate was 1.412 kg/(m(2)·h) and the solar efficiency reached 93.75 % as the temperature rose to 57.2 ℃. Additionally, the high thermal conductivity of Fe(3)O(4) facilitated the effective heat transfer to the fluid and provided sufficient thermal energy to activate PDS, thereby removing 99.3 % of Rhodamine B (RhB). Fe(3)O(4) NPs effectively promoted the generation of reactive species including SO(4) (·-), ·OH, O(2) (·-) and (1)O(2) from PDS and the four main stages including N-de-ethylation, chromophore cleavage, ring-opening, and mineralization were proposed as the possible degradation pathway of RhB. This study provides a reference for developing V-SIE system and highlights the positive effect of nanofluids in advanced oxidation processes.