A continuous photo-Fenton-like process using persulfate salts for the degradation of acetaminophen under solar irradiation at circumneutral pH

Abstract

The demand for sustainable and feasible water treatment technologies (WTT) increases with the growing realization of the magnitude of the damage that our indiscriminate wastewater disposal strategy has caused the Environment. Considering the increasing costs of energy, the development of solar-driven processes is key to ensuring the economic feasibility of WTT for industries of all sizes. In this direction, this paper reports the development of a photo-Fenton-like system based on the persulfate ion and the use of solar irradiation as its coactivator for use in continuous processes. Using acetaminophen as model contaminant (C0 = 5 ppm), we showed that under optimal conditions and circumneutral pH (pH ∼5.6), a removal of 94% was achievable with a residence time of 3.3 min. Economically, this translates into a collector area per order of 11.4 m2/(m3 order), in line with the best numbers found in the literature. We showed that this was achieved due to the improved concentration of sulfate radicals, SO4•−, formed in the system, when compared to the same process carried out in a small-scale batch reactor. Our results, obtained under controlled conditions using a solar simulator, were validated under natural sunlight, confirming the feasibility of our proposed intensification strategy.

Keywords

• Photo-Fenton
• Advanced oxidation processes
• Persulfate
• Solar-driven