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Fenton-like processes have gained widespread acceptance due to their high oxidative potential and environmental compatibility. In this study, a composite of graphitized carbon and nZVI (GC-nZVI) was synthesized and applied toward the degradation of bisphenol A (BPA) in water. The morphological structure and stability of GC-nZVI were evaluated using different characterization techniques including X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Our results showed that the catalytic graphitization of carbon occurred simultaneously with the carbothermal reduction of iron oxide, and ZVI was distributed uniformly on the carbon material. Excluding the adsorption effect, there was almost no degradation of BPA using GC-nZVI only. However, in the presence of H 2 O 2 and UVA radiation, BPA was rapidly degraded. The synergistic effect of the photo-Fenton process carried out in the presence of H 2 O 2 showed that 90% of BPA degradation was obtained after 60 min using only 50 mg L–1 of GC-nZVI and 0.5 mM of H 2 O 2 at pH 6. The generation of HO• has been demonstrated using chemical competition experiments and the photo-Fenton process, which could eliminate 66% of BPA within 15 min under the same conditions. Finally, recycling experiments have shown that after three cycles of BPA and H 2 O 2 addition, a degradation efficiency of 71% was achieved over 60 min. The GC-nZVI/H 2 O 2 /UVA system demonstrated great potential for advanced oxidation processes and had good application prospects in the treatment of actual wastewater. [Display omitted] • GC-nZVI was synthesized via a carbothermal reduction and metal-catalyzed graphitization process. • GC-nZVI mediated photo-Fenton degraded BPA under near-neutral conditions. • Multiple H 2 O 2 additions allowed for the continued degradation of BPA in our recycling experiments. • A proposed degradation pathway for BPA has been presented. [ABSTRACT FROM AUTHOR]

This paper outlines the synthesis and application of a sustainable composite for the photo-Fenton-like degradation of caffeine, bisphenol A, and simazine. The phase, morphology, optical and magnetic properties of the samples were evaluated by different characterization techniques. The composite of Fe 2.5 Co 0.3 Zn 0.2 O 4 and copper-chromium layered double hydroxide (CuCr-LDH) was determined to be the most favorable photocatalyst in the photo-Fenton-like process when compared with Fe 3 O 4 , Fe 2.5 Co 0.3 Zn 0.2 O 4 , CuCr-LDH, and Fe 3 O 4 /CuCr-LDH composite. Studying the efficiency of the photo-Fenton-like degradation process in the presence of the Fe 2.5 Co 0.3 Zn 0.2 O 4 /CuCr-LDH composite revealed a degradation rate constant of caffeine twice more than the sum of those obtained for the individual processes. This ascribes to the synergistic effect by which the photo-generated electron-hole from the catalyst and the efficient reduction of Fe3+, Cu2+, etc. during the photo-Fenton-like reaction is accelerated. Moreover, under the optimal condition and after 120 min of heterogenous photo-Fenton-like process at natural pH, > 90% of pollutants mixture was decomposed. The experiments fulfilled in near-real conditions demonstrated I) the high stability and magnetically recoverability of the photocatalyst and II) the proper degradation performance of the applied heterogenous photo-Fenton-process in the removal of pollutant mixture in different water bodies and in the presence of chloride and bicarbonate ions. [Display omitted] • Co 0.3 Zn 0.2 Fe 2.5 O 4 /CuCr-LDH composite as sustainable photocatalyst was synthesized. • Photo-Fenton-like process showed a synergetic effect in degradation of pollutants. • Under the optimal condition almost 90% of pollutants mixture was degraded. • 68% of TOC removal was observed for the pollutants mixture after 4 h of process. • Different water types and available inorganic ions showed a low inhibiting effect. [ABSTRACT FROM AUTHOR]

The present work describes, for the first time, the use of a new and strong complexing agent, ethylenediamine-N,N'-disuccinic acid (EDDS) in the homogeneous Fenton process. The effect of H2O2 concentration, Fe(III)-EDDS concentration, pH value, and oxygen concentration on the homogeneous Fenton degradation of bisphenol A (BPA) used as a model pollutant, was investigated. Surprisingly, the performance of BPA oxidation in an EDDS-driven Fenton reaction was found to be much higher at near neutral or basic pH than at acidic pH. Inhibition and probe studies were conducted to ascertain the role of several radicals (e.g., •OH, HO2•/O2•-) on BPA degradation. This unexpected effect of pH on Fenton reaction efficiency could be due to the formation of HO2• or O2•- radicals and to the presence of different forms of the complex Fe(III)-EDDS as a function of pH. Indeed, the reduction of Fe(III)-EDDS to Fe(II)-EDDS is a crucial step that governs the formation of hydroxyl radical, mainly responsible for BPA degradation. In addition to its ability to maintain iron in soluble form, EDDS acts as a superoxide radical-promoting agent, enhancing the generation of Fe(II) (the rate limiting step) and therefore the production of •OH radicals. These results are very promising because they offer an important new treatment option at higher range of pH values and more particularly at pHs encountered in natural conditions. [ABSTRACT FROM AUTHOR]

Abstract: We report for the first time the use of Fe(III)-EDDS (EDDS: ethylenediamine-N,N′-disuccinic acid) complex as an iron source in a homogeneous photo-Fenton system. The performance of this system was followed through the formation of the e degradation of 2,2-bis-(4-hydroxyphenyl)propane (BPA). It was observed that Fe(III)-EDDS can enhance the efficiency of both ion and BPA degradation especially near neutral pH. The effect of H2O2 concentration, Fe(III)-EDDS concentration, pH value and oxygen concentration on the BPA degradation during this photo-Fenton system was investigated. It was observed that O2 is an important parameter affecting the efficiency of this process not only due to its reactivity with BPA but also because of its effect on the iron species present in solution. Comparison with iron complexes of oxalate, citrate and EDTA have demonstrated that Fe(III)-EDDS is a very efficient iron source for this photo-Fenton process. This work also demonstrates that Fe(III)-EDDS plays a positive role in the photo-Fenton system, especially at higher pHs, and makes this system an encouraging method for the treatment of organic pollutants in the natural environment. [Copyright &y& Elsevier]

In this paper, the degradation of three endocrine-disrupting chemicals (EDCs): bisphenol A (BPA), 17β-estradiol (E2) and 17α-ethinylestradiol (EE2) by manganite (γ-MnOOH) activated peroxymonosulfate (PMS) was investigated. Preliminary optimisation experiments showed that complete degradation of the three EDCs was achieved after 30 min of reaction using 0.1 g L−1 of γ-MnOOH and 2 mM of PMS. The degradation rate constants were determined to be 0.20, 0.22 and 0.15 min−1 for BPA, E2 and EE2, respectively. Combining radical scavenging approaches, Electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS) analyses, we revealed for the first time that about 40% of EDCs degradation can be attributed to heterogeneous electron transfer reaction involving freshly generated Mn(IV), and 60% to sulfate radical degradation pathway. The influence of various inorganic ions on the γ-MnOOH/PMS system indicated that removal efficiency was slightly affected by chloride and carbonate ions, while nitrate and nitrite ions had negligible impacts. The application of γ-MnOOH/PMS system in real sewage treatment plant water (STPW) showed that degradation rate constants of EDCs decreased to 0.035–0.048 min−1 and complete degradation of the three EDCs after 45 min. This study provides new insights into the reactivity of combined γ-MnOOH and PMS, and opens new ways for the application of Mn-bearing species in wastewater treatment technologies. [Display omitted] • γ-MnOOH/PMS system is able to degrade efficiently EDCs in different water matrix. • A reaction mechanism considering the oxidative species involvement was determined. • Complete removal of EDC was reached in real sewage treatment plant water. • High mineralization efficiency was achieved in STPW. [ABSTRACT FROM AUTHOR]

In the present work we investigate the activation efficiency of H 2 O 2 and S 2 O 8 2− using UVA and UVB radiation. Bisphenol-A (BPA) is used as model pollutants to estimate the oxidative process efficiency in simulated and real sewage treatment plant waters. Particular attention is paid to the BPA removal efficiency and to the radical mechanism involvement considering the effect of typical inorganic water constituents (carbonates and chloride ions) and organic matter. Despite a detrimental effect observed when carbonate ions are in solution using both hydrogen peroxide and persulafate, the presence of high chloride ions concentration was found to improve BPA removal using S 2 O 8 2− as radical precursor. This enhancement, investigated combining chemical kinetic model approach and laser flash photolysis experiments, is attributed to the formation of hydroxyl radical and chlorine radical species from sulfate radical. Different transformation products are identified by means of GC–MS and HPLC-MS analyses. Moreover, experiments using sewage treatment plant water (STPW) spiked with BPA are performed in order to assess the efficiency of oxidative processes in a simulated treatment systems activated using UVA + UVB radiations. [ABSTRACT FROM AUTHOR]

[Display omitted] • Promising degradation efficiency of pollutants in sewage treatment plant water. • Predominant non-radical pathway in PDS-containing systems. • Predominant sulfate radical pathway in PMS-containing systems. • SO 4 •−, •OH and 1O 2 were generated in both CuFe 2 O 4 -PDS/PMS systems. • Correlation between XPS and radical quenching investigations. Copper ferrites (CuFe 2 O 4) nanopowder was prepared via hydrothermal method followed by annealing at 500 °C, and XRD, SEM, XPS and UPS were employed for its characterization. CuFe 2 O 4 was tested for the catalytic degradation of bisphenol A (BPA) in the dark and under UVA light, both in the presence of peroxymonosulfate (PMS) or peroxydisulfate (PDS) as radical precursor under natural pH of 6.2. While the individual photo-induced processes i.e. , photocatalysis (using CuFe 2 O 4 alone) and photolysis of either PMS or PDS, exhibited limited efficiencies in BPA degradation, a significant increase of performance was observed by combining CuFe 2 O 4 and UVA light with either PMS or PDS with a synergy effect of 3.8 and 34.1, respectively. Under the optimal conditions, employing 0.5 g/L of nanopowder, the degradation constant of 25 µM BPA was 0.211 min−1 with 2 mM of PMS and 0.018 min−1 with 2 mM of PDS, and resulted in the complete degradation of BPA within less than 20 min. The activation mechanism of PMS and PDS using CuFe 2 O 4 was elucidated, revealing sulfate radicals as the primary reactive species in PMS-containing systems, whereas a predominantly non-radical pathway was observed in the presence of PDS. Indeed, advanced spectroscopic techniques indicated that surface copper played an important role in the non-radical pathway. Furthermore, the CuFe 2 O 4 /PMS/UVA system exhibited high performance in the degradation of different phenolic compounds including BPA, phenol and p-nitrophenol in real water matrices. These achievements were observed across different real water matrices with a particular emphasis on sewage treatment plant water. [ABSTRACT FROM AUTHOR]