Sulfate Radicals-Based Technology as a Promising Strategy for Wastewater

Abstract

This study was focused on the generation of sulfate radicals and their applicability as powerful oxidants for degrading complex organic compounds with the final objective of operating in flow systems. To this end, the removal of two compounds from the pharmaceutical industry was assessed, lissamine green and prednisolone. Initially, sulfate radicals were generated by the activation of persulfate with iron as homogenous catalyst, and the key parameters involved in the process, as catalyst concentration and oxidant dosage, were evaluated. Furthermore, with the aim of preventing the secondary contamination due to metal leaching and to be operate in a continuous mode, a heterogeneous catalyst was developed. For it, the iron was fixed on a cationic resin as Amberlite IR120 Na+ form. It was demonstrated that the removal of both pollutants increases with greater catalyst dosages, achieving a decay of 85% within 25 min with 30 g·L−1 of catalyst. Moreover, the reuse capability of the catalyst was tested, illustrating that it is rough enough for its reuse. Conversely, in order to develop a continuous treatment in flow system, a fixed bed reactor was constructed and its feasibility was proven. Different experiments with residence times from 10 min to 60 min were performed, obtaining a removal level of ≈95% and 90% for prednisolone and lissamine green, respectively, at residence time of 60 min. In conclusion, the potential of sulfate radicals-based technology for degrading organic contaminants has been demonstrated.

Generation of oxidative radicals by advanced oxidation processes (AOPs) in wastewater treatment: a mechanistic, environmental and economic review

“…In fact, SO 2− 4 has been identified in surface and groundwater in concentrations up to 630 mg L −1 and 230 mg L −1 , respectively, and previous works in the field have proven to generate SO •− 4 at lower SO 2− 4 concentrations (i.e., 150 mg L −1 ) via electrochemical treatment (Farhat et al, 2015;Petrovic, 2016, 2017). (Arellano et al, 2019).…”

Degradation of Various Organic Coatings via UV‐Generated Sulfate Radicals

“…As the coatings are composed of organic molecules or polymers, it is anticipated that various organic coatings are possible to be degraded through advanced oxidation processes that have been previously developed. In this work, the exposure of an aqueous ammonium persulfate (APS, (NH 4 ) 2 S 2 O 8 ) solution to UV light induces the generation of SO 4 ⋅ − , leading to the chemical degradation of various organic coatings in the aqueous solution [9,14] . To the best of our knowledge, this is the first strategy for demonstrating the degradation of organic coatings using radicals.…”

“…In this work, the exposure of an aqueous ammonium persulfate (APS, (NH 4 ) 2 S 2 O 8 ) solution to UV light induces the generation of SO 4 *À , leading to the chemical degradation of various organic coatings in the aqueous solution. [9,14] To the best of our knowledge, this is the first strategy for demonstrating the degradation of organic coatings using radicals. In a proof-of-concept, we demonstrated the degradation of two types of organic coatings, including LbL assembled coating and PDA coating, which were formed with distinct intermolecular interactions, by utilizing UV-generated SO 4 *À .…”

Effects of Persulfate Activation with Pyrite and Zero-Valent Iron for Phthalate Acid Ester Degradation

“…Advanced oxidation processes (AOPs) are promising alternatives for in-situ degradation of organic pollutants [12][13][14]. Persulfate (PS) activation has more advantages because of higher redox potential (E 0 = 2.01 V), stability in subsurface environment, and cost-efficiency [15,16].…”