Highly efficient degradation of phenolic compounds by Fe(II)-activated dual oxidant (persulfate/calcium peroxide) system. (July 2022)

• Record Type: Journal Article
• Authors: Masud, Md Abdullah Al; Kim, Do Gun; Shin, Won Sik
• Is Part Of: Chemosphere. Volume 299(2022)
• Publication Date: 2022-07
• Subjects: Calcium peroxide -- Dual oxidant -- Natural groundwater -- Persulfate -- Radical; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2022.134392
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: This study demonstrates the feasibility, reaction mechanisms, and potential of practical applications of a dual oxidant (DuOx) system comprising calcium peroxide (CP) and persulfate (PS) catalyzed using Fe(II) [PS/CP/Fe(II)]. The DuOx system was superior in phenol degradation to single oxidant systems, i.e., PS/Fe(II) or CP/Fe(II), with 95.5% phenol removal under an optimum condition of a phenol/PS/CP/Fe(II) molar ratio of 1/1/5/6 ([Phenol]0 =0.5 mM). Based on scavenger studies and electron spin resonance (ESR) spectroscopy, the phenol removal in the DuOx system was barrierless, with negative activation energy assisted by robust reactive species. The phenol degradation results in the presence of methanol, t -butanol, l -histidine, and NaN3 . The ESR spectroscopy indicates that phenol degradation is attributed dominantly to 1 O2 generated by recombining O2 − and radicals, such as hydroxyl (HO ) and sulfate (SO4 − ). The performance of the DuOx system was highly efficient in pH 3–11, up to 10 mM Cl −, SO4 2−, or NO3 −, and up to 50 mg/L humic acids but was strongly suppressed by more than 10 mM HCO3 − and H2 PO4 − . In addition, the DuOx system was efficient in phenol removal in natural groundwater as well as removing and mineralizing other phenolic compounds (PCs) such as bisphenol A, chlorophenol, dichlorophenol, trichlorophenol, and nitrophenol. These results provide insights into the reactions induced by the DuOx system and confirm its applicability of in situ chemical oxidation in refractory organic pollutants. Graphical abstract: Image 1 Highlights: Dual oxidant (CaO2 /PS) system was highly efficient for phenolic compound degradation. Both radical and nonradical ROS caused phenol degradation in PS/CP/Fe(II). 1 O2 was dominant in organic pollutant degradation in PS/CP/Fe(II). PS/CP/Fe(II) performance was excellent in natural groundwater.