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Recently, free reactive manganese species (RMnS) generated via permanganate catalytic oxidation technology has been applied to contaminants abatement and sludge dewatering. This study proposed a novel free RMnS generation method in ultrasound enhanced carbon nanotube (CNTs)/permanganate process (UCP) for organics removal. Taking ciprofloxacin as a target contaminant, the removal efficiency in the UCP process (9.78 s - 1 ) was remarkably higher than that of the permanganate (0.71 s - 1 ) and CNTs/permanganate (2.57 s - 1 ) processes. CNTs could enrich manganese compounds and ciprofloxacin, and act as an electronic platform for the electronic transfer from ciprofloxacin to manganese compounds for free RMnS generation, which was revealed by DFT calculation and spectrum analysis. Meanwhile, ultrasound further regulated the generation of RMnS as it could transform the inactive solid Mn(IV) into free RMnS. In the UCP process, non-free radical modes including RMnS oxidation (49.8%) and electron transfer (23.5%) were the dominant processes for ciprofloxacin removal in the UCP process, and hydroxyl radical oxidation (13.2%), CNTs adsorption (5.5%), and PM oxidation (8.0%) also contributed to ciprofloxacin removal. Interestingly, CNTs could be well reused in the UCP process as more than 88.75% of ciprofloxacin was removed after five times reuse of CNTs. The UCP process provides a novel strategy for rapid contaminants removal in water treatment via continuous generation of free RMnS., (Copyright © 2021. Published by Elsevier Ltd.)

A novel water treatment process combining electrolysis, permanganate and ozone was tested in the laboratory. The combination showed synergistic effects in degrading various organic contaminants (like diclofenac, sulfamethoxazole, carbamazepine, etc.). A small amount of O 3 (1 mg L - 1 , 60 mL min -1 ) significantly improved the oxidation and mineralization ability of an electro-permanganate process by generating more reactive manganese species and hydroxyl radicals. The combination required less energy consumption than comparable processes. Mechanism experiments showed that the ·OH involved was mainly generated by cathode reduction, homogeneous manganese catalysis, and heterogeneous manganese catalysis of O 3 decomposition. Reactive Mn species were generated by electro-reduction, ·OH oxidation or/and O 3 activation. In situ generated Mn (Ⅳ) s plays a vital role in generating ·OH and reactive Mn species. ·OH generated by O 3 catalysis could transfer colloid Mn (Ⅳ) s to free Mn (Ⅴ) aq and Mn (Ⅵ) aq . And both the ·OH and RMnS played the dominant role for DCF removal. Increasing permanganate dosage, O 3 concentration, the current density, Cl - , or humic acid, and decreasing the pH all enhanced the degradation of diclofenac, but the presence of PO 4 3- or HCO 3 - inhibited it. Supplementing electrolysis with permanganate and O 3 might be a practical, sustainable, and economical technology for treating refractory organics in natural waters., Competing Interests: Declaration of Competing Interest The authors declare that they have no potential conflicts of interest with respect to the research, authorship or publication of this article., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Electrolysis and permanganate (PM) oxidation are two commonly used technologies for water treatment. However, they are often handicapped by their slow reaction rates. To improve the removal efficiency of refractory contaminants, we combined electrolysis with PM using an activated carbon fiber (ACF) as cathode (E-ACF-PM) for the first time to treat diclofenac (DCF) in aqueous solution. Up to 90% DCF was removed in 5 min by E-ACF-PM process. In comparison, only 3.95 and 27.35% of DCF was removed by individual electrolysis and PM oxidation at the same time, respectively. Acidic condition was more conducive to DCF removal. Surprisingly, soluble Mn(III) ( aq) formed on the surface of ACF was demonstrated as the principal oxidizing agent in E-ACF-PM process. Further studies showed that all three components (electrolysis + ACF + PM) were necessary to facilitate the heterogeneous generation of reactive Mn(III) ( aq) . Moreover, SEM images and XPS spectra of ACF before and after treatment revealed that the morphologies and elemental compositions of reacted ACF were nearly unchanged during the E-ACF-PM process. ACF can be remained active and utilized to the rapid degradation of DCF in E-ACF-PM process even after reused for 20 times. Therefore, the E-ACF-PM process may provide a novel and effective alternative on the generation of reactive Mn(III) ( aq) in situ for water treatment by green electrochemical reactions., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

In this study, La 3+ (ion)/La(OH) 3 -W/La(OH) 3 -EW-loaded magnetic cationic hydrogel (MCH) composites were fabricated in situ and characterized to investigate the effects of lanthanum species on phosphate adsorption. The corresponding maximum P adsorption capacities of MCH-loaded La 3+ (ion) (MCH-La 3+ (ion)), La(OH) 3 -W (MCH-La(OH) 3 -W), and La(OH) 3 -EW (MCH-La(OH) 3 -EW) were 70.5 ± 2.67, 69.2 ± 3.5, and 90.2 ± 2.9 mg P/g, respectively. Furthermore, for MCH-La(OH) 3 -EW, the P adsorption capacity was maintained relatively stable and high at pH 4.5-11 because of the ligand exchange, electrostatic interactions, and Lewis acid-base interactions. The enhanced adsorption of P was achieved over a wide pH range, as well as in the presence of competing anions (including Cl - , NO 3 - , SO 4 2- , HCO 3 - and SiO 4 4- ). Moreover, the exhausted MCH-La(OH) 3 -EW could be easily regenerated by a NaOH-NaCl desorption agent with above 72% adsorption capacity remained during five recycles. The column adsorption capacity of MCH-La(OH) 3 -EW reached ∼3500 bed volumes (BV) (∼67.7 mg P/g) as the concentration of P decreased from 5 mg/L to 0.1 mg/L. The ATR-IR, Raman, and XPS deconvolution results revealed that both MCH and lanthanum compounds, including La 3+ (ion), La(OH) 3 -W and La(OH) 3 -EW, contributed to the phosphate adsorption because of the electrostatic interactions between -N + (CH 3 ) 3 and phosphate, as well as the formation of LaPO 4 ·xH 2 O., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

• Electronic polarization and defect engineering modification enhanced intrinsic PMS activation. • ACO-O V @PES membrane/PMS system achieved flow-through removal of contaminants. • The highly accessible SO 4 ·−, · OH, and 1O 2 were the responsible reactive species. • DFT calculations revealed PMS activation promotion by dual-modification strategy. The application of Fenton-like membrane reactors for water purification offers a promising solution to overcome technical challenges associated with catalyst recovery, reaction efficiency, and mass transfer typically encountered in heterogeneous batch reaction modes. This study presents a dual-modification strategy encompassing electron polarization and defect engineering to synthesize Al-doped and oxygen vacancies (O V)-enriched Co 3 O 4 spinel catalysts (ACO-O V). This modification empowered ACO-O V with exceptional performance in activating peroxymonosulfate (PMS) for the removal of organic contaminants. Moreover, the ACO-O V @polyethersulfone (PES) membrane/PMS system achieved organic contaminant removal through filtration (with a reaction kinetic constant of 0.085 ms−1), demonstrating outstanding resistance to environmental interference and high operational stability. Mechanistic investigations revealed that the exceptional catalytic performance of this Fenton-like membrane reactor stemmed from the enrichment of reactants, exposure of reactive sites, and enhanced mass transfer within the confined space, leading to a higher availability of reactive species. Theoretical calculations were conducted to validate the beneficial intrinsic effects of electron polarization, defect engineering, and the confined space within the membrane reactor on PMS activation and organic contaminant removal. Notably, the ACO-O V @PES membrane/PMS system not only mineralized the targeted organic contaminants but also effectively mitigated their potential environmental risks. Overall, this work underscores the significant potential of the dual-modification strategy in designing spinel catalysts and Fenton-like membrane reactors for efficient organic contaminant removal. [Display omitted] [ABSTRACT FROM AUTHOR]