Activation of sodium persulfate by magnetic carbon xerogels (CX/CoFe) for the oxidation of bisphenol A: Process variables effects, matrix effects and reaction pathways

Abstract

a b s t r a c tAn advanced oxidation process comprising sodium persulfate (SPS) and a novel magnetic carbon xerogel was tested for the degradation of bisphenol A (BPA), a model endocrine-disrupting compound. The catalyst, consisting of interconnected carbon microspheres with embedded iron and cobalt microparticles, was capable of activating persulfate to form sulfate and hydroxyl radicals at ambient conditions.The pseudo-first order degradation rate of BPA in ultrapure water (UPW) was found to increase with (i) increasing catalyst (25e75 mg/L) and SPS (31e250 mg/L) concentrations, (ii) decreasing BPA concentration (285e14,200 mg/L), and (iii) changing pH from alkaline to acidic values (9e3).Besides UPW, tests were conducted in drinking water, treated wastewater, groundwater and surface water; interestingly, the rate in UPW was always lower than in any other matrix containing several organic and inorganic constituents. The effect of natural organic matter (in the form of humic acids) and alcohols was detrimental to BPA degradation owing to the scavenging of radicals. Conversely, chlorides at concentrations greater than 50 mg/L had a positive effect due to the formation and subsequent participation of chlorine-containing radicals.Liquid chromatography time-of-flight mass spectrometry was employed to identify major transformation by-products (TBPs) of BPA degradation in the absence and presence of chlorides; in the latter case, several chlorinated TBPs were detected confirming the role of Cl-related radicals. Based on TBPs, main reaction pathways are proposed.

Impact of water matrix on the removal of micropollutants by advanced oxidation technologies

“…Hence, different water matrices containing NOM exhibit different scavenging rates, reducing the fraction of ROS available to degrade MPs, which triggers the need of considering such scavengers in the optimization of AOTs. In most cases, the MPs removal kinetics decrease with an increase in the complexity of the water matrix, since this may contain numerous non-target organic and inorganic species that compete with the target contaminants for oxidants [14]. The inhibitory effects of co-existing substances in the matrix include also light absorption and attenuation in processes utilizing UV radiation.…”

“…It may also result in the formation of less active complexes with iron species in Fentonbased processes and in the competition for catalytic active sites, catalyst deactivation by poisoning of the active sites or fouling of the surface area of the catalysts in heterogeneous catalytic processes, as well as the modification of the electrical surface charge due to the pH or ionic strength. However, it has been reported that non-target species may also act as promoters in selected AOTs [4,14]. Photosensitizers organic and inorganic species in the water matrix can promote the production of ROS by UV irradiation, leading to indirect photolysis [15].…”

Biochar-Supported FeS/Fe3O4 Composite for Catalyzed Fenton-Type Degradation of Ciprofloxacin

“…For example, the porous biochar with high specific surface area is a good adsorbent of organic pollutants [3,4], while the biochar rich in alkalis is more suitable for the precipitation of heavy metals (e.g., Pb 2+ and Cd 2+ ) [5,6]. Due to its low cost, high surface area and good stability, biochar is a promising supporting material comparable with other carbons [7,8], and has been applied to enhance the performance of iron or iron minerals in environmental remediation. First, the biochar can disperse the zero-valent iron nanoparticles and prevent their aggregation, so that the removal efficiency of heavy metals (e.g., Cr(VI) and As(V)) was significantly improved [9,10].…”

Fast Degradation of Bisphenol A in Water by Nanostructured CuNPs@CALB Biohybrid Catalysts

“…Therefore, a methodology to obtain a very fast, efficient and green strategy to eliminate BPA is mandatory. Different strategies have been described in literature; the most recent successful application has been the use of metal nanoparticles as a catalyst [9][10][11][12][13][14][15][16].…”

“…In particular, most examples have been developed using iron nanomaterials as catalysts [9][10][11][12][13] and only few examples using Cu or Cu-based materials have been applied as catalysts in this reaction [14][15][16][17][18][19][20]. For example, Zhao and coworkers 14 described the degradation of 87% BPA (20 ppm) in 180 min using a Cu-Al 2 O 3 membrane in the presence of hydrogen peroxide at neutral pHs.…”