Activation of Peracetic Acid with Lanthanum Cobaltite Perovskite for Sulfamethoxazole Degradation under a Neutral pH: The Contribution of Organic Radicals

Abstract

Advanced oxidation processes (AOPs) are effective ways to degrade refractory organic contaminants, relying on the generation of inorganic radicals (e.g., •OH and SO4•−). Herein, a novel AOP with organic radicals (R-O•) was reported to degrade contaminants. Lanthanum cobaltite perovskite (LaCoO3) was used to activate peracetic acid (PAA) for organic radical generation to degrade sulfamethoxazole (SMX). The results show that LaCoO3 exhibited an excellent performance on PAA activation and SMX degradation at neutral pH, with low cobalt leaching. Meanwhile, LaCoO3 also showed an excellent reusability during PAA activation. In-depth investigation confirmed CH3C(O)O• and CH3C(O)OO• as the key reactive species for SMX degradation in LaCoO3/PAA system. The presence of Cl− (1–100 mM) slightly inhibited the degradation of SMX in the LaCoO3/PAA system, whereas the addition of HCO3− (0.1–1 mM) and humic aid (1–10 mg/L) could significantly inhibit SMX degradation. This work highlights the generation of organic radicals via the heterogeneous activation of PAA and thus provides a promising way to destruct contaminants in wastewater treatment.

Cobalt doped graphitic carbon nitride as an effective catalyst for peracetic acid to degrade sulfamethoxazole

“…S4,† the purging of N 2 had a negligible impact on SMX removal in Co–CN/PAA system, indicating that the role of ˙CH 3 and CH 3 OO˙ to SMX degradation could be ignored. 19 Besides, ˙OH was proved to be absent in reported cobalt-based PAA systems. 9,11,14 Thus, the dominant reactive species for SMX removal in Co–CN/PAA system might be CH 3 C(O)O˙ and CH 3 C(O)OO˙.…”

“…S4, † the purging of N 2 had a negligible impact on SMX removal in Co-CN/PAA system, indicating that the role of cCH 3 and CH 3 OOc to SMX degradation could be ignored. 19 Besides, cOH was proved to be absent in reported cobalt-based PAA systems. 9,11,14 Thus, the dominant reactive species for SMX removal in Co-CN/PAA system might be CH In spite of the fact that the second-order rate constant between MeOH and R-Oc is unknown, previous studies had proved that MeOH could efficiently scavenge R-Oc.…”

“…Similar results were also found in previous publications. 14,18,19 S1, † the weight percentage of cobalt in Co-CN measured by EDS enhanced from 2.38% to 22.53% when the dosage of Co(NO 3 ) 2 $6H 2 O increased from 0.05 to 0.5 g. As presented in Fig. 7a, with increasing cobalt doping content in Co-CN, the SMX removal efficiency in Co-CN/PAA system increased from 51.7% to 99%, and the corresponding k obs within 240 s enhanced from 0.0021 to 0.015 min À1 .…”

“… 14 As a result, cobalt-based heterogeneous catalysts have been proposed in PAA systems to overcome the shortcomings induced by homogeneous cobalt ion, such as cobaltosic oxide (Co 3 O 4 ), 14 cobalt ferrite (CoFe 2 O 4 ) 18 and lanthanum cobaltite perovskite (LaCoO 3 ). 19 However, the above cobalt-based heterogeneous catalysts possess unsatisfactory catalytic efficiency and poor dispersibility in aqueous solution with inevitable leaching of cobalt ion. Therefore, it is essential to find a proper way that can promote the catalytic efficiency and restrain the leaching of cobalt ion to improve the cobalt-based catalysts.…”

Degradation of Benzotriazole UV Stabilizers in PAA/d-Electron Metal Ions Systems—Removal Kinetics, Products and Mechanism Evaluation

“…Peracetic acid (PAA) is a long-known disinfectant and effective oxidant of organic micropollutants [ 53 , 54 , 55 , 56 ]. In recent studies, UV irradiation [ 57 , 58 , 59 , 60 ], d-electron metal ions [ 61 , 62 , 63 , 64 ], or heterogeneous activators [ 65 , 66 , 67 , 68 , 69 , 70 , 71 ] have been used as PAA activators. So far, no information is available on the removal procedures of benzotriazole UV stabilizers.…”