Comparative study of Bisphenol A degradation via heterogeneously catalyzed H2O2 and persulfate: Reactivity, products, stability and mechanism

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2019-08, Vol.369, p.470-479
• Main Authors: Xu, Ximeng, Zong, Shaoyan, Chen, Weiming, Liu, Dan
• Format: Article
• Language: English
• Subjects: Coal fly ash; H2O2; Heterogeneous AOPs; Magnetite; Persulfate; Surface reaction
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2019.03.099

[Display omitted] •Degradation of BPA was investigated by ·OH - and SO4·--AOPs.•The TOC removal rate achieved 36% and 24% for the catalyzed H2O2 and persulfate.•BPA followed different transformation pathways in two systems.•The less radical scavenging may led to the higher removal of BPA by catalyzed H2O2.•The magnetic fly ash presented good structural stability during the recycle runs. In this study, H2O2 and persulfate (PS) were both proved to be heterogeneously catalyzed by the Fe3O4 nanoparticle supported on coal fly ash for reactive oxidation species (ROS). The two heterogeneous advanced oxidation processes (AOPs) were systematically investigated, and the system with H2O2 exhibited higher reactivity for Bisphenol A (BPA) elimination and total organic carbon (TOC) reduction. The two systems were comprehensively compared in terms of degradation kinetics, transformation way, water matrix species and catalyst stability. Systems with H2O2 and PS can remove 100% and 80.2% of the BPA after 120 min (0.22 mmol/L), respectively([H2O2] = 22 mmol/L, [PS] = 22 mmol/L). The oxidant efficiency in system with H2O2 was obviously higher probably due to the less radical scavenging. A mechanism was proposed that the interface interactions between solid and liquid phase will affect the collision among molecular of oxidants and catalyst, as well as the lifetime of radicals during the their diffusion process. The quenching experiments demonstrated that the primary radical species in two systems were ·OHand SO4·-/·OH, respectively, thus causing the different BPA degradation pathways and by-products. The catalyst presented good structural stability and relatively low Fe leaching in both systems during the recycle. The valence state transformation from Fe2+ to Fe3+ after the reaction explained the gradual catalytic activity loss. In the tap water and municipal wastewater, the system with PS was less influenced by the real water matrix due to the lower university of SO4·- toward organics.