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Cobalt-impregnated activated carbon (GAC/Co) was used to produce sulfate radical (SO ) from peroxymonosulfate (PMS) in aqueous solution (hereafter called PMS activation). We evaluated its effectiveness by examining the degradation of orange acid 7 (AO7). GAC/Co exhibited high activity to activate PMS to degrade AO7. The degradation efficiency of AO7 increased with increasing dosage of GAC/Co or PMS and elevated temperatures. pH 8 was most favorable for the degradation of AO7 by GAC/Co-activated PMS. The radical quenching experiments indicated that the reactions most likely took place both in the bulk solution and on the surface of GAC/Co. We found that SO played a dominant role in AO7 degradation. Sodium chloride (NaCl) which presents in most dye wastewater had a significant impact on AO7 degradation. Low dosages (<0.4 M) of NaCl showed a slight inhibitory effect, whereas high dosages (0.8 M) increased the reaction rate. HOCl was confirmed as the main contributor for accelerating AO7 degradation with high concentration of NaCl. In a continuous-flow reaction with an empty-bed contact time of 1.35 min, AO7 was not detected in the effluent for 0 to 18.72 L of treated influent volume (156 h) and 85% removal efficiency was still observed after 40.32 L of treated volume (336 h). Finally, the azo bond and the naphthalene structure in AO7 were destroyed and the degradation pathway was proposed. [ABSTRACT FROM AUTHOR]

Carbon nanotube (CNT) has been shown to effectively activate peroxymonosulfate (PMS) to remove contaminants, whereas controversial activation mechanisms (radical vs non-radical mechanism) were previously proposed. Here we report that radical-induced decolorization of acid orange 7 (AO7) dominated in the CNT activated PMS system, but non-radical mechanism was also involved at high Cl − concentration. CNT exhibited high activity in activating PMS to decolorize AO7. The decolorization rate of AO7 increased with increasing PMS dosages and CNT loadings, rising temperature and higher pH. Radical quenching and photoluminescence techniques confirmed the decolorization of AO7 in the CNT/PMS system was caused by the radical oxidation, which dominantly took place on the surface of CNT, rather than the bulk solution. The presence of Cl − exhibited a dual effect on AO7 decolorization. Low concentration of Cl − slightly inhibited AO7 decolorization, but further raising the concentration to above 0.1 M significantly accelerated its decolorizaition. Cl − was confirmed to react with PMS to generate HClO, which effectively bleached AO7 through non-radical process rather than radical process. The decolorization of AO7 induced from the non-radical process exhibited different degradation products and less mineralization in comparison to that derived from radical process. [ABSTRACT FROM AUTHOR]

• Selective elimination of TCs by PMS in livestock wastewater. • A kinetic model describes TCs oxidation in real livestock wastewater. • PMS-promoted TCs oxidation proceeds via non-radical process. • Theoretical calculations reveal the electrophilic attacks at ring B of TCs. • Hydroxylation dominates in the PMS-induced oxidation of TCs. Tetracyclines (TCs) discharged from livestock wastewater have received worldwide concerns owing to their potential threats to the ecosystem and human health. Advanced oxidation processes always exhibit low efficiency to remove TCs in livestock wastewater due to the radical scavenging by water matrices. Herein, we report selective elimination of TCs by peroxymonosulfate (PMS) in livestock wastewater. A kinetic model was developed to describe the rapid degradation of TCs by PMS in the real livestock wastewater. The radical scavenging study and electron paramagnetic resonance (EPR) technique excluded the contribution of radical species (e.g., SO 4 −) in the PMS-promoted oxidation of TCs. Theoretical calculations revealed the electrophilic attacks of PMS most likely located on the B-ring of TCs. Transformation product analysis further elucidated that hydroxylation dominated in the PMS-promoted oxidation of TCs, and N-demethylation also significantly contributed to chlorotetracycline (CTC) oxidation by PMS. These results demonstrate a promising strategy to eliminate TCs in livestock wastewater, because PMS shows specific reactivity towards TCs, and thus suffers less interference from the complicated water matrices. [ABSTRACT FROM AUTHOR]

• LaRuO 3 perovskites were synthesized and applied in an aqueous system. • The catalytic degradation efficiency of ARuO 3 was associated with the contact angles. • Activation mechanisms of PMS by LaRuO 3 were proposed. • LaRuO 3 perovskites exhibited high catalytic efficiency from time and mineralization rate. Sulfate radical-based technologies have been frequently applied to degrade pharmaceutical and personal care products (PPCPs). Metal-based catalysts have shown great potential for activating persulfate (PS) and peroxymonosulfate (PMS) to degrade PPCPs. In this study, a Ru-based perovskite (ARuO 3 , A = La, Ba, Ce, Sr) was synthesized by the sol–gel method and used as a catalyst to activate PMS for the degradation of carbamazepine (CBZ). Results demonstrated that the A-site cations had a significant influence on the catalytic performance of the perovskite, and the degradation efficiency of CBZ in descending order for different Ru-based perovskites was as follows: La > Ba > Sr > Ce. LaRuO 3 was selected as the optimal catalyst for CBZ degradation. LaRuO 3 efficiently activated PMS to degrade CBZ in a neutral environment. The reaction rate constant had a positive linear correlation with the concentration of PMS in a range between 0.1 mM and 0.5 mM. ESR analysis and radical quenching experiments confirmed the existence of 1O 2 , •OH, and SO 4 •− in the LaRuO 3 /PMS system, and SO 4 •− played the most significant role in decomposing CBZ. The recycling experiment and XPS spectra suggested the stability of LaRuO 3. [ABSTRACT FROM AUTHOR]

A novel heterogeneous manganese/graphitic carbon nitride (Mn 3 O 4 -CN) catalyst for activating peroxymonosulfate (PMS) was successfully assembled using alkali precipitation. The g-C 3 N 4 improved the composite's surface morphology, micro-porous structure, surface area, and particle size distribution, and an electron-rich center with Mn site was created. The Mn 3 O 4 -CN/PMS system exhibited high efficiency and stability when the solution pH varied from 3.0 to 9.0, with more than 90% of p-acetaminophen (ACT) removal in 30 min under experimental conditions. A possible reaction mechanism was proposed, primarily involving electron transfer from Mn (II) and Mn (III) to PMS along with the generation of·O 2 - and 1O 2 , and the degradation of ACT was attributed to the 1O 2. Specifically, the degradation rate of phenolic compounds varied with their molecular structure in the following order: ACT > bisphenol A (BPA) > p-cresol (MP) > p-chlorophenol (CP) > phenol (Ph) > p-nitrophenol (NP). Further, the density functional theory (DFT) calculations indicated that the phenols' degradation efficiency was related to their adsorption energy and Bader charge value. These results improved our understanding of the manganese-based PMS non-radical dominated process and provided a method for predicting the degradation performance of phenols for the first time. [Display omitted] • Mn 3 O 4 -CN exhibited promoting effect on ACT degradation in the PMS activation system. • The PMS activation coordinated with the Mn valence change. • Electron transfer between ACT and high valence Mn renewed the catalyst surface. • ACT degradation was primarily attributed to 1O 2. • The structure-dependence degradation of phenols in the PMS system was confirmed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Zero-valent copper supported on polyurethane foam (Cu-NC) was fabricated. • 1.85% Cu loading (Cu-NC) demonstrated the best performance for TTC removal. • H 2 O 2 (65.0 μM) was generated in situ with presence of Cu-NC suspension. • High degradation efficiency (74.1–94.2%) was maintained in the pH 3.0–11.0 range. • Activation of PMS by Cu(I) produced HO• via outer sphere interaction. The occurrence of tetracycline (TTC) in the environment can exacerbate microbial selection pressure and trigger bacterial resistance, raising potential risks to the ecosystem and public health. Here, we report that copper supported polyurethane foam (Cu-NC) can efficiently activate PMS to degrade TTC. Results demonstrated that the degradation rate of TTC was 91.3% and the pseudo first-order kinetic constant of 0.0762 min−1 was achieved after 40 min reaction at pH 5.0. Activation of PMS by Cu-NC was proposed to proceed via two sequential processes, which was different from the conventional mechanism for sulfate radical generation. Cu0 initially reacts with dissolved oxygen to generate H 2 O 2 and Cu(I) (s) in situ in the solid form. Then Cu(I) (s) solves the relative instability of low-valent transition metal ions in aqueous solution, thus improving the activation efficiency of PMS. A novel mechanism for Cu(I) (s) activation of PMS to generate HO• was proposed and elucidated through outer-sphere interaction (electrostatic bonding) and acid-base theory. Superoxide radical and Cu0 accelerate the Cu(II)/Cu(I) redox, overcoming the rate-limiting step in Fenton-like reaction. Cu-NC showed an excellent cycling stability (80.8% removal efficiency after fifth run) in PMS activation with low Cu ion leaching (＜0.2 mg/L). The Cu-NC/PMS system also exhibited satisfactory removal of TTC in the presence of various water matrices. This study can deepen the understanding of the generation of HO• in the PMS activation process and provide a promising strategy for pollutants degradation in wastewater treatment. [ABSTRACT FROM AUTHOR]

• PMS exhibits specific and high reactivity towards HRAs. • HRAs oxidation by PMS proceeds via a non-radical process. • PMS-promoted HRAs degradation is unaffected by water matrices. • Thioether sulfur in HRAs (except RXTD) is oxidized to sulfoxide product. • Ecotoxicity of HRAs is remarkably reduced after PMS oxidation. Peroxymonosulfate (PMS) is an appealing oxidant for organic contaminant destruction relying on radical generation after activation. Herein, we report PMS-promoted rapid degradation of histamine H 2 -receptor antagonists (HRAs) through non-radical process for the first time. Five commonly used HRAs, i.e., ranitidine (RNTD), cimetidine (CMTD), famotidine (FMTD), nizatidine (NZTD) and roxatidine (RXTD), were examined their reactivity towards PMS. Results show that HRAs (except RXTD) exhibit high reactivity towards PMS, with apparent second-order rate constants from 403 to 872 M−1s−1 at pH 7.0. Radical scavenging experiments excluded the contribution of radicals to PMS-promoted degradation of HRAs, and this non-radical process was unaffected by the real water matrices. Structure-activity assessment and theoretical calculation indicated that the thioether sulfur in HRAs (except RXTD) was the main reactive site for PMS oxidation. Transformation product analysis further elucidated oxidation of the thioether sulfur to sulfoxide product through an oxygen atom transfer process. Moreover, the thioether sulfur on the straight chain was more susceptible to oxygen transfer with PMS than that on the thiazole ring of HRAs. Toxicity evaluation indicated the ecotoxicity of HRAs could be remarkably reduced after PMS oxidation. Hence, this work provides a promising strategy to rapidly remove HRAs and significantly reduce their toxicity in water treatment. Image, graphical abstract [ABSTRACT FROM AUTHOR]