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A novel rod-shaped MIL-88A(Fe)@CuS featured with sulfur vacancies (S V) were constructed as heterogeneous catalysts for activating peroxymonosulfate (PMS) for coumarin (COU) degradation. A series of x MIL@CuS were obtained according to the mass content of MIL-88A(Fe) in the composites (x , wt% = 50 %, 65 %, and 80 %). Among them, 65 % MIL@CuS hold the best performance, and realized a complete COU removal (30 μM) in 7 min (0.2 g/L 65 %MIL@CuS and 0.5 mM PMS). The degradation was much more favorable in acidic initial pH than alkaline initial pH. The calculated reaction rate constants at initial pH of 3.0, 5.0, 6.0 and 9.0 were 0.903, 0.729, 0.650 and 0.095 min−1, respectively. Electron paramagnetic resonance (EPR) analysis, radical scavenging tests and mechanism exploration indicated that the main difference in degradation under acidic and alkaline pH came from the yield of 1O 2. In initial pH = 3.0 condition, S V and lattice oxygen on 65 %MIL@CuS participated in the generation of 1O 2 , greatly increasing the content of 1O 2 (11.6 × 10−11 M) and promoting the degradation. While under initial alkaline condition (pH = 9.0), 1O 2 were basically produced from the reaction between Cu(II) and PMS, resulting in a low yield (1.7 × 10−11 M) and lower degradation. Besides, 65 %MIL@CuS maintained excellent reusability with low metal ions leaching, and the degradation exceeded 98.0 % even in the fifth run. Overall, this work provided an efficient and stable activator for activating PMS to degrade refractory organics, and managed to disclose the activation mechanisms under acidic and alkaline pH. [Display omitted] [ABSTRACT FROM AUTHOR]

Singlet oxygen (1O 2) is a reactive species for the selective degradation of stubborn organic pollutants. Given its resistance to harsh water environment, the effective and exclusive generation of 1O 2 is acknowledged as a key strategy to mitigate water production costs and ensure water supply safety. Herein, we synthesized MnO x intercalated MnFe layered double hydroxides (MF-MnO x) to selectively produce 1O 2 through the activation of PMS. The distinctive confined structure endowed MF-MnO x with a special pathway for the PMS activation. The direct oxidation of BPA on the intercalated MnO x induced the charge imbalance in the MnFe-LDH layer, resulting in the selective generation of 1O 2. Moreover, acceptable activity deterioration of MF-MnO x was observed in a 10 h continuous degradation test in actual water, substantiating the application potential of MF-MnO x. This work presents a novel catalyst for the selective production of 1O 2 , and evaluates its prospects in the remediation of micro-polluted water. [Display omitted] • MF-MnO x with confined structure was synthesized for the activation of PMS. • Selective production of 1O 2 was achieved in MF-MnO x /PMS system. • The distinctive confined structure of MF-MnO x determined the unique catalytic mechanism. • MF-MnO x /PMS system possessed satisfactory performance in resisting harsh water environment. [ABSTRACT FROM AUTHOR]

[Display omitted] • A simple heat treatment method was proposed to simultaneously introduce Sv and P doping. • The k obs value obtained by CuFe-NC-SP-2 was nearly 33 higher than that of CuFe-PBA. • CuFe-NC-SP-2/PMS system dominated by the electron transfer process (ETP) achieved 100 % removal of SDZ. • Synergistic effect of Sv (improved the adsorption energy of PMS) and P doping (accelerated the electron transport) enhanced the ETP. In this work, Prussian blue analogues (CuFe-PBA) derived copper-iron sulfides/N-doped porous carbon composite (CuFe-NC-SP- x) was prepared as an effective peroxymonosulfate (PMS) activator to degrade sulfadiazine (SDZ). A strategy that kills two birds with one stone was proposed to construct CuFe-NC-SP- x , i.e., S-etched CuFe-PBA (CuFe-PBA-S) was annealed with NaH 2 PO 2 in N 2 atmosphere to simultaneously introduce sulfur vacancy (Sv) and phosphorus doping. 40 μM SDZ was completely removed by CuFe-NC-SP-2/PMS in 20 min (0.2 g/L catalyst and 0.5 mM PMS). The k obs value obtained by CuFe-NC-SP-2 (0.48 min−1) was nearly 33 and 17 times higher than that of CuFe-PBA (0.014 min−1) and CuFe-PBA-S (0.028 min−1), respectively. Quenching tests, electron paramagnetic resonance (EPR) analysis indicated that PMS activation in the system involved radical pathway (26.1 % OH and 22.7 % SO 4 –) and non-radical pathway (17.8 % 1O 2 and 33.4 % electron transfer process). OH, SO 4 – and 1O 2 were mainly produced by S enhanced metal sites for PMS activation. The synergistic effect of Sv and P doping enabled the powerful electron transfer mechanism. Electrochemical tests and DFT calculations demonstrated that Sv existing in CuFe-NC-SP- x improved the electron donor ability and increased the adsorption energy toward PMS, and phosphorus doping accelerated the electron transport from SDZ to PMS. This work not only provides a novel strategy to synthesize a high effective PMS activator by introducing Sv and phosphorous doing in one step, but also manages to comprehensively understand the electron transfer activation mechanisms of PMS facilitated by Sv and phosphorous doping. [ABSTRACT FROM AUTHOR]

[Display omitted] Peroxymonosulfate activation via heterogeneous catalyst was broadly applied for the treatment of PPCPs. In this work, a novel material of Epigallocatechin-3-gallate (EGCG) fuctionalized Mn 3 O 4 nano-octahedra (E@MO) was synthesized and utilized for the degradation of carbamazepine. Various technologies such as X-ray diffraction, Fourier transform-infrared spectroscopy, Scanning electron microscope, Transmission electron microscope, Brunauer-Emmett-Teller and X-ray photoelectron spectroscopy were employed for the characterization of the as-synthesized catalyst. The results depicted that under the conditions of CBZ concentration 5 mg/L, PMS concentration 1 mM, catalyst dosage 0.2 g/L, initial pH 5.8 and 25 °C, the targeted pollutant could be totally degraded in 60 min with a rate constant of 0.0622 min−1. When temperature raised to 45 °C, CBZ was removed completely in 20 min and the rate constant (0.1668 min−1) was 2.59 times than that of 25 °C, implying the degradation process was an endothermic reaction. Scavenging experiments and EPR analysis confirmed the main reactive oxygen species generated in the reaction were sulfate radical (SO 4 • ) and hydroxyl radical (•OH), while SO 4 • serviced as the leading role. Due to the reduction property of EGCG, compared with bare Mn 3 O 4 , the CBZ degradation was markably enhanced and the degradation reaction were accurately matched with the pseudo first-order kinetics equation. The possible twelve intermediates produced in the decomposition of CBZ were identified by HPLC-MS/MS, their ecotoxicity were evaluated and compared by ECOSAR model. Together with the consequences, the degradation mechanism of CBZ in the E@MO/PMS system was propounded. [ABSTRACT FROM AUTHOR]

• Oxygen vacancies enriched CoAl-LDH@CoS x hollow flowers was synthesized. • CoAl-LDH@CoS x exhibited excellent catalytic activity for sulfamethoxazole degradation. • 1O 2 was identified as the primary reactive species in the oxidation process. In this study, oxygen vacancies enriched cobalt aluminum hydroxide@hydroxysulfide (CoAl-LDH@CoS x) hollow flowers was synthesized by in-situ etching of CoAl-LDH using sodium sulfide solution. The analysis of SEM, EDS, XRD, and XPS were used to characterize the samples. The as-synthesized 0.2CoAl-LDH@CoS x displayed higher catalysis performance of sulfamethoxazole (SMX) degradation via the activation of PMS than the pristine CoAl-LDH. 98.5 % of SMX (40 μM) was eliminated with 0.1 g/L 0.2CoAl-LDH@CoS x and 0.3 mM PMS at pH 6.0 in 4 min. The degradation fitted with the pseudo-first-order reaction kinetics well with rate constant of 0.89 min−1 for 0.2CoAl-LDH@CoS x /PMS system and 0.55 min−1 for CoAl-LDH/PMS system. Singlet oxygen (1O 2) was verified as dominant reactive oxygen species responsible for SMX degradation via quenching tests. Mechanism investigation suggested that the oxygen vacancies, redox cycles of Co(II)/Co(III) and S 2 2−/(S2− and sulfate species) on the surface of 0.2CoAl-LDH@CoS x were crucial for PMS activation. In addition, the plausible degradation pathways of SMX were proposed by analysis of the SMX degradation intermediates. This study not only reveals that 0.2CoAl-LDH@CoS x is an efficient catalyst to activate PMS for SMX degradation, but also shed a novel insight into development of heterogeneous catalysts with oxygen vacancies. [ABSTRACT FROM AUTHOR]

• Copper-immobilized carbon nanofibers (Cu-CNF- x) was firstly synthesized from PAN and Copper phthalocyanine. • The addition of BO 3 − successfully mitigated the issue of water acidification resulting from PMS usage. • BO 3 − significantly enhanced the adsorption energy (E ad) of PMS onto Cu-CNF- x , raising it from 0.43 eV to 4.75 eV. • BO 3 − greatly augmented the utilization efficiency of PMS and facilitated the generation of H 2 O 2 in the Cu-CNF- x /PMS system. • The mechanism involved in BO 3 −/Cu-CNF- x /PMS system was proposed. In this work, perborate (BO 3 −) was applied to promote the degradation of sulfadiazine (SDZ) in copper-immobilized carbon nanofibers (Cu-CNF- x) activated peroxymonosulfate (PMS) system. Results showed that in BO 3 −/Cu-CNF-3/PMS ternary system, 100% of SDZ (40 μM) could be efficiently eliminated in 5 min with 0.1 g/L Cu-CNF-3, 1 mM BO 3 − and 1 mM PMS; while Cu-CNF-3/PMS and BO 3 −/PMS systems only achieved 58.4% and 47.3% degradation in 30 min. In initial pH range of 5.0–9.0, the ternary system removed over 92.6% of SDZ, and the treated solution pH maintained neutral, effectively relieving the water acidification introduced by PMS. Electron paramagnetic resonance analysis and radical scavenger tests evidenced the production of SO 4 −•, •OH, 1O 2 and H 2 O 2 BO•O•−. Mechanisms analysis proposed the activation process as follows: initially, BO 3 − promptly activated PMS to generate H 2 O 2 BO•O•− via electrophilic substitution reaction, and H 2 O 2 was produced due to the decomposition of BO 3 −; thereafter, PMS was activated by Cu-CNF- x to yield SO 4 −•, •OH and 1O 2 ; the obtained H 2 O 2 was then utilized by Cu-CNF- x to produce •OH and 1O 2 as well. Density functional theory (DFT) calculations showed that the adsorption energy (E ad) between PMS and Cu-CNF- x was 0.43 eV. BO 3 − greatly increased the E ad of PMS on Cu-CNF- x by ten times to 4.75 eV, which extremely promoted the PMS activation. This work provided a novel strategy of BO 3 −/Cu-CNF-3/PMS for the efficient degradation of refractory organic pollutants, and managed to understand the synergistic role of BO 3 − to PMS based heterogeneous catalytic processes. [ABSTRACT FROM AUTHOR]

[Display omitted] • PMS/PBO catalytic system was first proposed for the degradation of BPA. • Strong electrophilic H 2 O 2 BO 2 was proposed as an unreported active substance. • Electrophilic substitution was considered as the key step of catalytic reaction. • DFT calculation was employed to reveal the activation mechanism. Although sulfate radical (SO 4 •−) based advanced oxidation processes (AOPs) is promising for the removal of stubborn organic contaminations, low utilization efficiency of peroxymonosulfate (PMS) has practically troubled the potential application of this water treatment technology. In this study, a novel strategy for ultrafast PMS decomposition was proposed using solid peroxyborate (PBO) as the catalyst. Over 80 % of PMS can be rapidly activated within 1 min. strong electrophilic H 2 O 2 BO 2 rather than commonly recognized species was considered as the reactive species causing BPA degradation. Through thermodynamic DFT calculation, the catalytic mechanism was thoroughly clarified as the electrophilic substitution reaction between protonated perboric acid (H 4 BO 4 +) and ionized PMS (SO 5 2-). Universality experiments showed that PMS/PBO system was a promising, efficient, and eco-friendly process for the degradation of selective contaminants. This work sheds novel lights on the mechanism of electrophilic substitution induced PMS activation, and provides a new idea for environmental remediation. [ABSTRACT FROM AUTHOR]

Peroxymonosulfate (PMS) activation induced by tricobalt tetroxide spinel (Co 3 O 4) has been confirmed as a typical Haber-Weiss reaction, while free radicals were once considered as the dominated reactive species in the previous studies. However, the catalytic mechanism of the spongy Co 3 O 4 driven PMS activation was surprisingly found as a radical/nonradical mixed process rather than a pure radical process in the present work. The important role of sulfate radical (SO 4 −) was confirmed through the quenching experiments. Despite the inhibition of furfuryl alcohol (FFA) and 1,4-benzoquinone (BQ) on degradation was generally accepted as the evidence to support the existence of 1O 2 and O 2 −, additional experiments using methyl phenyl sulfoxide (PMSO) as the indicator indeed verified high-valent-cobalt-oxo rather than 1O 2 and O 2 − dominated the very early reaction stage. Notably, instead of homogeneous Co3+, heterogeneous Co(IV) = O on catalyst surface was believed to be responsible for the oxidation of organics. Spongy Co 3 O 4 not only possessed stronger catalytic ability than commercial Co 3 O 4 (k [spongy Co3O4] = 0.74 min−1, k [Co3O4] = 0.08 min−1), but also owned preferable stability. The performance of catalytic system was barely affected by the solution pH under the near neutral condition. Besides, little suppression of the widely existing anions on the degradation indicated the potential application of spongy Co 3 O 4 /PMS system. This study provides a reliable oxidation technology for the removal of organic pollutants, and sheds new light on the cobalt oxide triggered PMS activation process. • Spongy Co 3 O 4 was successfully synthesized for PMS activation. • Spongy Co 3 O 4 /PMS system (0.74 min−1) exhibited 9 times higher degradation than commercial Co 3 O 4 /PMS system (0.08 min−1). • Co(IV) O was considered as the main reactive species instantaneously produced and consumed in the very early reaction. • The oxidation of SO 4 − existed throughout the reaction process. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hexagonal CoOOH microplate (B-CoOOH) was firstly synthesized from CoAl-LDH. • B-CoOOH/PMS (0.60 min−1) exhibited 12 times higher degradation than CoOOH/PMS (0.05 min−1). • Oxygen vacancies rather than Co species redox pairs contributed to PMS activation. • TOC removal of 97.5% was achieved in 80 min with PMS dosage of 0.6 mM. Cobalt oxyhydroxide (CoOOH) has received much attention as a environmental friendly mineral for activating peroxymonosulfate (PMS) for organics elimination in environment remediation. Yet, it suffered from unsatisfactory catalytic activity. This work presents a facile self-sacrifice method to synthesize highly effective hexagonal CoOOH microplate (B-CoOOH) from cobalt aluminum layered double hydroxide (CoAl-LDH). 40 μM of sulfamethoxazole (SMX) was 100% eliminated in 6 min in the presence of 0.1 g/L B-CoOOH and 0.3 mM PMS. B-CoOOH/PMS system achieved a high degradation (0.60 min−1), which was 12 times higher than CoOOH/PMS system (0.05 min−1). Besides, B-CoOOH also displayed satisfactory recyclability during the repeating tests, excellent physicochemical stability with low cobalt ions leaching (0.05 mg/L), and high mineralization efficiency (97.5% of TOC removal). Quenching tests signified the dominant role of 1O 2 in SMX degradation. Mechanisms exploration revealed that the abundant oxygen vacancies (O V) on B-CoOOH acted as the electron donator in PMS activation process, which differed from previous report, in which Co species redox pairs was responsible for activating PMS and producing reactive oxygen species. In the initial stage of PMS activation, the dissolved oxygen in solution contributed to the generation of 1O 2 , while in the later stage PMS was regarded as the main precursor for the 1O 2 formation. This study provides a convenient approach for the synthesis of cobalt oxyhydroxide with excellent catalytic activity, and sheds a new insight into the indispensable role of O V in heterogeneous catalysis. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sulfur vacancies-enriched CuS@MIL-101(Fe) sphere was fabricated. • CuS@MIL-101(Fe) realized a rate constant of 0.577 min−1, which was 11.1 and 17.0 times of CuS and MIL-101(Fe), respectively. • CuS@MIL-101(Fe) exhibited satisfactory stability and recyclability for COU degradation. • •OH and 1O 2 were identified as the predominant ROS. For improving the catalytic activity and recyclability of CuS in Fenton-like reaction processes, novel sulfur vacancies-enriched CuS@MIL-101(Fe) was constructed, characterized, and examined as heterogeneous catalysts for activating peroxymonosulfate (PMS) to degrade coumarin (COU). Thanks to the redox pairs of Fe3+/Fe2+, Cu+/Cu2+, S2−/S 2 2−/S0/sulfate species, copper-iron synergistic effect and sulfur vacancies, the CuS@MIL-101(Fe) realized a complete removal of COU (30 μM) in 10 min with reaction rate constant of 0.577 min−1, which was 11.1 and 17.0 times of CuS and MIL-101(Fe), respectively. The effect of various experimental conditions (i.e., initial pH, CuS@MIL-101(Fe) dosage, PMS concentration, and background anions) on COU degradation was discussed, and the stability and versatility of CuS@MIL-101(Fe) was studied as well. Radical scavenging experiments and electron paramagnetic resonance (EPR) spectroscopy identified •OH and 1O 2 as the main reactive oxygen species (ROS). Finally, the possible mechanism of higher COU degradation efficiency in the CuS@MIL-101(Fe) activated PMS system and the degradation pathways were also deeply explored. Consequently, this work provided a novel insight into construction of sulfur vacancies-enriched heterogeneous catalysts for efficiently activating PMS for refractory organic pollutants elimination. [ABSTRACT FROM AUTHOR]

[Display omitted] • Core-shell CoAl-LDH@CoFe-PBA was synthesized from CoAl-LDH via a self-sacrificed method. • CoAl-LDH@CoFe-PBA exhibited outstanding performances to PMS activation for SMX degradation. • The generation routes of reactive oxygen species at acidic and alkaline pH was explicated. • The SMX degradation mechanism in CoAl-LDH@CoFe-PBA/PMS system was proposed. • Degradation pathway and toxicity assessment of intermediates was investigated. Novel cobalt aluminum layered double hydroxide@cobalt aluminum Prussian blue analogs (CoAl-LDH@CoFe-PBA) nanosheet was synthesized via a self-sacrificed method from CoAl-LDH. The morphology and physicochemical properties characterization showed that CoAl-LDH@CoFe-PBA nanosheets were hexagon shape with diameter of 100 nm. Peroxymonosulfate (PMS) activation via CoAl-LDH@CoFe-PBA towards sulfamethoxazole (SMX) degradation was systematically examined. The catalytic system showed a satisfactory SMX degradation efficiency (over 80%) with the initial pH range of 3.0–9.0. In particular, only ~8 min was required to achieve 98% of SMX (40 μM) degradation with 0.1 g/L CoAl-LDH@CoFe-PBA and 0.3 mM PMS. Besides, the underlying reaction mechanism and generation routes of various reactive oxygen species (ROS) with varied initial pH was explicated by the electron paramagnetic resonance (EPR) and quenching tests. The surface-bound •OH and 1O 2 were responsible for SMX degradation at acidic pH, and 1O 2 was mainly produced from O 2 •−. At alkaline pH, SO 4 •− and 1O 2 co-contributed to the degradation, while 1O 2 was generated from O 2 •− and SO 4 •−. Oxygen vacancy in the inner space of the catalyst was considered as key electron donors involved in O 2 •− production. In addition, nine major degradation intermediates of SMX were identified and the possible degradation pathways were further proposed accordingly. [ABSTRACT FROM AUTHOR]

[Display omitted] • Prussian blue analogues@MXene composite (PBA@MXene) was fabricated. • PBA@MXene exhibited excellent catalytic activity for coumarin degradation. • Alkaline condition was more favorable for coumarin degradation. • Lewis-acid sites on MXene was crucial for PMS activation. In this study, with two dimensional MXene as the substrate, Prussian blue analogues@MXene composite (PBA@MXene) was fabricated and utilized as a heterogeneous catalyst for the oxidative degradation of coumarin (COU) based on peroxymonosulfate activation. The initial pH strongly affected the degradation process, and the alkaline pH was beneficial to the COU degradation than the acidic pH. The kinetic rate constants were determined to be 0.030, 0.055, 0.121 and 0.246 min-1at pHs of 3.0, 5.0, 6.6 and 10.0, respectively. The TOC removal efficiency achieved at pH 10.0 was 70.9% in 20 min reaction time. Radical scavengers tests showed that in the presence of 500 mM tert-butyl alcohol (TBA), the rate constant was gradually enhanced from 0.004 to 0.040 min−1 with increasing the solution pH from 3.0 to 10.0; while with the addition of 500 mM Methanol (Me), the rate constants were determined to be 0.002, 0.001, 0.002, and 0.002 min−1 at pHs of 3.0, 5.0, 6.6, and 10.0, respectively. Mechanism study indicated that the differences in COU degradation at different pHs could be mainly ascribed to the unsaturated Ti-C-O (Lewis-acid site) and terminal F-Ti on the catalyst surface. This work not only demonstrated that 1.2PBA@MXene was a promisingly effective catalyst for PMS activation for COU degradation, but also clearly spelled out the role of Lewis-acid sites of MXene in MXene-based catalysts. [ABSTRACT FROM AUTHOR]