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In this study, Fenton-like chain reaction is constructed by coupling nanoscale tungsten powders (nW0) and peroxydisulfate (PDS). The nanoscale tungsten powders/peroxydisulfate (nW0/PDS) system exhibits a high oxidation efficiency toward diverse pollutants and expands the effective pH range up to 9.8. Results reveal •OH and sulfate radical (SO 4 •−) were confirmed to be responsible for 4,4′-ethylidenebisphenol (EBP) degradation, especially •OH. The corrosion process of nW0 results in the in-situ production of H 2 O 2 and the transient-state tungsten species (W (x, x < VI)), initiating the reaction of H 2 O 2 and tungsten species to generate •OH. PDS can accelerate nW0 corrosion to enhance the Fenton-like reaction, and can be activated by tungsten species (nW0 and W (x, x < VI)) to produce •OH and SO 4 •−. Integrated the analysis results of LC-QTOF-MS/MS, EBP degradation pathways were proposed. This study reveals the high oxidation efficiency over a wide pH range in the nW0/PDS system and provides new insight into the tungsten species induced Fenton-like reaction. [Display omitted] • The nW0/PDS system exhibits high oxidation efficiency over a wide pH range. • The stepwise oxidation between nW0 and dissoved oxygen in-situ produces H 2 O 2. • •OH and SO 4 •− are generated by the tungsten species induced Fenton-like reaction. • PDS accelerates the corrosion of nW0 and the Fenton-like reaction. • Degradation process of EBP was proposed based on LC-QTOF-MS/MS results. [ABSTRACT FROM AUTHOR]

A novel "ferrate/percarbonate (Fe(VI)/SPC) co-oxidation process" was used to treat ciprofloxacin (CIP) and various micropollutants (MPs), which owned better performance than mixture of Fe(VI), Na 2 CO 3 and H 2 O 2. The mechanism investigation found that the low-concentration H 2 O 2 (1–2 µM) released by SPC can promote the high-valent iron intermediates (Fe(IV)/Fe(V)) of Fe(VI) to the MP oxidation, and Fe(VI) products can also activate SPC to produce hydroxyl radical (·OH). The interactive activation of Fe(VI) and SPC was realized, which retained the high selectivity of Fe(VI) to electron-rich pollutants, and also made up the oxidation of electron-deficient pollutants through •OH, improving the degradation effect of various MPs by 20–30%, and the rate constant was increased by 1 to 3 times. Moreover, non-purgeable organic carbon (NPOC) determination confirmed that •OH participation reduced the NPOC value of CIP from 5.43 mg/L to 4.37 mg/L. The transformation pathway of CIP showed that Fe(VI)/SPC resulted in more hydroxylation intermediates of CIP than Fe(VI) alone. Acute toxicity assays found that the photoinhibition rate of CIP treated with Fe(VI) alone was 14.5%, while the sample treated with Fe(VI)/SPC showed no significant photoinhibition effect, which proved that the new process had good detoxification properties for CIP. [Display omitted] • The interaction between SPC and Fe(VI) formed both·OH and Fe(IV)/Fe(V). • Low-concentration H 2 O 2 released by SPC improved the electron utilization of Fe(VI). • The·OH enables CIP to generate hydroxylation products possessing reduced toxicity. • SPC/Fe(VI) process is suitable for oxidation of electron rich and electron deficient pollutants. [ABSTRACT FROM AUTHOR]

Among all homogeneous catalysts, cobalt ions show the highest catalytic performance for the activation of peroxymonosulfate (PMS). Herein, we report a Co2+/PMS/H 3 BO 3 system that can effectively generate reactive oxygen species (ROS) with ultra–low Co2+ dosage (5 μg/L). Co2+/PMS/H 3 BO 3 system showed ultrafast reactivity and wide applicability for various pollutants. Sulfamethoxazole (SMX, 2 mg/L) could be completely removed within 5 min, and the corresponding k obs reached up to 1.1239 min−1. The introduction of H 3 BO 3 significantly promoted the generation of ROS. The turnover frequency (TOF) calculated through dividing k obs by the cobalt ions concentration is as high as 224.78 min−1, which is much higher than most of the current research. Through a series of theoretical and experimental analyses, the complex of H 2 BO 3 −–MS (HSO 5 B(OH) 3 –) was inferred to be the key substance that led to the excellent performance of the system. This work provides new insights into the Co2+/PMS system in the presence of borate buffer. [Display omitted] • Trace cobalt(II) (5 μg/L) can efficiently activate PMS in the presence of boric acid. • The corresponding k obs value reached up to 1.1239 min−1 in Co2+/PMS/H 3 BO 3 system. • H 2 BO 3 −-PMS was the key substance that caused the excellent performance of the system. • Co2+/PMS/H 3 BO 3 system showed wide applicability for various pollutants. • This study provides novel insights into the Co2+/PMS system in borate buffer. [ABSTRACT FROM AUTHOR]

Iron-based PAA activation process is a promising advanced oxidation process for water decontamination which depends on Fe(II) as the main reactive site for PAA activation, resulting in various reactive oxidative species (ROSs) generation. For practical application, the impact of water matrix chloride ion (Cl−) on ROSs production and contaminants removal should be carefully considered. In this study, it's found that the introduction of Cl− (0.1–10 mM) could significantly enhance the reaction rate of the rapid stage (k obs1) up to 2.15 times at the initial pH of 4.25 in the Fe(II)/PAA system. Further studies demonstrated that the improved removal capacity of NAP resulted from Cl− induced R-O• generation as indicated by the exposure dose of R-O• increasing from 7.74 × 10−11 M•s to 1.44 × 10−10 M•s, rather than chlorine-containing radicals' generation. DFT calculation results suggested that the formed Fe(II)-Cl− complexes could easily activate PAA to generate more ROSs for NAP removal. Moreover, Fe(II)/PAA treatment can alleviate the biological toxicity of pollutants via both the Escherichia coli test and toxicity assessment. The obtained new knowledge manifested that Cl− can boost ROSs generation and conversion in iron-based PAA systems, providing guidance for the efficient decontamination of chlorine-containing sewage with PAA-based AOPs. [Display omitted] • The presence of Cl− promotes NAP removal in the Fe(II)/PAA system at pH 3.0–9.0. • Cl− accelerates PAA depletion due to the formation of complex ([FeCl(H 2 O) 5 ]+ or [FeCl(OH)(H 2 O) 4 ]). • Cl− induced R-O• generation to become the dominant ROS in Fe(II)/PAA system. • Fe(II)/PAA/Cl− treatment can reduce the biological toxicity of wastewater. [ABSTRACT FROM AUTHOR]