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High-performance and energy-saving microwave (MW)-assisted catalysts are of great significance for MW-assisted treatments of wastewater. Herein, a novel nitrogen-doped reduced graphene oxide aerogel with supported nanoscale zero-valent iron (nZVI@N-rGOA) was successfully synthesized and used in the MW-assisted removal of imidacloprid (IMI) from wastewater. The resulting nZVI@N-rGOA had an open pomegranate-like multicompartment structure consisting of wrinkled flaky reticular N-rGOA walls and embedded nZVI particles, and the nZVI@N-rGOA/MW system rapidly eliminated nearly 100% of the IMI in a 10 mg/L solution within 2 min. The highly efficient MW-assisted catalytic degradation of IMI resulted from synergistic effects, including the nZVI active centres, pyridinic N sites and open pomegranate-like multicompartment structures, which facilitated MW harvesting, mass transfer of the reactants and generation of heat, electrons, holes and •OH radicals. Accordingly, the localized surface plasmon resonance and electron transfer processes enabled catalytic oxidations/reductions, respectively. This work provides a novel paradigm for designing MW-assisted catalysts for wastewater treatment. [Display omitted] • nZVI@N-rGOA had open multi-compartment structures with high MW adsorption. • nZVI@N-rGOA showed highly-efficient MW-assisted degradation of imidacloprid. • nZVI active centers and pyridinic N site facilitated active species generation. • The plasmon resonance and electron transfer processes caused the IMI degradation. [ABSTRACT FROM AUTHOR]

This study reports the introduction of nickel species into the B-site metal center of LaCoO 3 perovskite, which shows high catalytic activity for sulfafurazole (SIZ) in solution by activating peroxymonosulfate (PMS). A novel bimetallic lanthanum-based perovskite (LaCo 0.5 Ni 0.5 O 3) was designed by coprecipitation-calcination strategy, which can effectively degrade nearly 100% SIZ in 20 min by activating PMS. Density functional theory (DFT) calculations show that the interface structure of LaCo 0.5 Ni 0.5 O 3 has higher PMS adsorption capacity and faster electron transfer efficiency. Additionally, the interface structure of the B-site metal is more likely to promote PMS activation after the introduction of Ni species. Meanwhile, the Fukui index indicates the reaction sites of the active species attacking SIZ molecules and reasonably provides the possible degradation path of SIZ. This work provides an essential reference for the subsequent exploration of the catalytic mechanism of interfacial structure of heterogeneous catalysts based on PMS activation to degrade organic pollutants. [Display omitted] • The degradation of sulfafurazole by the composites was nearly 100% within 20 min. • DFT calculations explored the mechanism of catalyst-PMS interaction at the interfacial structure. • DFT demonstrated that LaCo 0.5 Ni 0.5 O 3 has higher PMS adsorption capacity and faster electron transfer efficiency. • The Co species in the LaCo 0.5 Ni 0.5 O 3 interfacial structure are more susceptible to promote PMS activation. • The DFT Fukui index pinpoints the reaction sites of SIZ structure degradation. [ABSTRACT FROM AUTHOR]

Wastewater remediation using micro/nanomotors is a hot topic, and MnO 2 based materials have become fascinating alternatives to rare noble metal-based micro/nanomotors. Herein, we demonstrate facile and large-scale synthesis of Fe-MnO 2 core-shell micromotors for antibiotic pollutant removal. Heat-treatment results in a phase transformation of MnO 2 with formation of iron oxides and partially exfoliates the MnO 2 nanoplate shell structure to promote mobility. The iron-manganese oxide micromotors exhibit an efficient removal of tetracycline antibiotics via a combination of catalytic degradation and adsorptive bubble separation. For the first time, atomic H* was found to participate in the micromotor-assisted degradation process, resulting in optimal Fenton reaction in neutral conditions with a good decontamination performance. Owing to the merits of abundance, magnetic recovery, facile fabrication, good motion, and environmental friendliness, as well as decontamination performance in a wide pH range, these core-shell micromotors demonstrate a promising candidate in practical wastewater treatment. [Display omitted] • Core-shell iron-manganese oxides micro/nanomotors (FMO-MNMs) were prepared. • FMO-MNMs present good mobility and catalytic performance in organic degradation. • Coupled catalytic degradation and adsorptive bubbles induce high removal efficiency. • Atomic H* with •OH produces better organic degradation at natural pH. [ABSTRACT FROM AUTHOR]

A ternary dual Z-scheme composite gCN/ZnFe 2 O 4 /Bi 2 S 3 (ZFO/BS) was synthesized via a facile microwave assisted process and its photocatalytic potential was explored towards visible light driven removal of 2,4,6-tricholorophenol (TCP) with subsequent peroxymonosulfate (PMS) activation. Surface-bound Fe 2 + / 3 + | s u r f. , Zn + / 2 + | s u r f. and Bi 3 + / 4 + | s u r f. were effective towards charge carrier channelization and evolution of reactive species. Highest catalytic activity was experienced for the catalyst with 10 wt% Bi 2 S 3 (ZFO/BS(10)) and 98.9% TCP was removed with 0.25 gL−1 catalyst and 1.0 gL−1 PMS, under 60 mins visible light irradiation (intensity: 80 W). Construction of dual Z-scheme heterojunction was studied using XPS and the mechanism of e-/h+ separation was elucidated. In-depth radical scavenging and EPR analysis confirmed the coexistence and relative contributions of various reactive radicals towards degradation. Plausible TCP degradation pathway was designed based on intermediate analysis. This study elucidates the superiority of dual Z-scheme ternary heterojunction towards separation of photogenerated charge carriers and mineralization of various emerging contaminants. [Display omitted] • Ternary g-CN/ZnFe 2 O 4 /Bi 2 S 3 exhibits excellent visible light driven photoactivity. • 99% TCP degradation was obtained with 0.25 gL−1 catalyst and 1 gL−1 PMS. • Dual Z-scheme heterojunction formation results most efficient charge separation. • Radical based mechanism was strongly effective for TCP degradation. • Plausible TCP degradation pathway was proposed based on identified intermediates. [ABSTRACT FROM AUTHOR]

Abstract: The nature and the extent of degradation of polyamide 6 (PA6) in the presence of layered birnessite-type manganese oxide (LMO) were analysed by thermogravimetric analysis under static air atmosphere at several heating rates between 5°C/min and 20°C/min. The samples were characterized using infrared (IR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), N2 gas adsorption–desorption and thermal analysis (TA) techniques. XRD and DTA results for LMO showed that the oxidative transformation of MnO2 was occured on heating from 300°C to 500°C. The IR spectra of Mn–O band proved the covalent character of oxygen bonding to the metal ions of the surface. The addition of LMO caused the change in the crystalline phase of PA6 from predominantly α to largely γ phase. The activation energy for degradation estimated by Kissinger method for PA6 and 10wt.% LMO/PA6 composite were found to be 213 and 118kJ/mol in static air atmosphere, respectively. The experimental results revealed that the addition of 10wt.% LMO decreased the thermal stability in static air of PA6 by about 80°C. [Copyright &y& Elsevier]

Abstract: New strategy of using ferric zeolite ZSM-5 and Y to adsorb and catalytically degrade tobacco-specific nitrosamines (TSNA) is reported in this article. These zeolites were modified by both aqueous ion-exchange with FeSO4 solution and wet-impregnation of Fe(NO3)3, and characterized by XRD, UV–vis DRS, H2-TPR and temperature-programmed surface reaction (TPSR). Apart from laboratory tests, these samples were put into tobacco rods of cigarette to assess their real performance of reducing TSNA content in smoke, and the determination of TSNA was carried out by LC–MS/MS technique with the assistance of internal-standards. The ion-exchanged zeolites are more active than their impregnated analogs, and the ferric Y zeolite could selectively reduce 26% of total TSNA in mainstream smoke of Burley type tobacco. Catalytic breaking of the chemical bond in Nof nitrosamines by zeolite is the key step of decomposition of these carcinogens. [Copyright &y& Elsevier]

Abstract: A micrometer-sized, nanostructured, flower-like Co3O4–CeO2 composite oxide was synthesized by an ethylene-glycol-mediated process. The composite oxide was an assembly of polycrystalline nanoparticles, with a typical mesoporous structure. The composite''s catalytic activity in 1,2,4-trichlorobenzene degradation was evaluated using a pulsed-flow microreactor–gas chromatography system, and compared with that of quartz sand, commercial CeO2, commercial Co3O4, and a Co3O4/CeO2 equimass mixture. The composite oxide was a promising catalyst for 1,2,4-trichlorobenzene degradation. This is attributed to the structural features of the composite oxide with a high specific surface area and a high total pore volume, and the synergistic effect between the two composite phases. The easy creation of high-mobility active oxygen on CeO2 and the easy cleavage of Cot the interface of the two components promote reactivity of Co3O4 in 1,2,4-trichlorobenzene degradation. Pulsed catalytic theory suggests a first-order reaction between the composite oxide and 1,2,4-trichlorobenzene, with an apparent activation energy of about 27kJ/mol, and degradation on the Co3O4–CeO2 composite oxide would occur easily. [Copyright &y& Elsevier]

Developing an in-situ soil remediation technology for simultaneous catalytic degradation of contaminants and nitrogen supplementation is of great importance but remains challenging. Herein, MgFe-LDH engineered biochar (MB) was successfully synthesized by using a simple co-precipitation method. The as-prepared materials were used as catalysts for the first time to activate urea-hydrogen peroxide (UHP) to degrade antibiotic sulfamethoxazole (SMX) and provide nitrogen. The enhanced degradation efficiency of SMX (91%) were mainly attributed to •OH and 1O 2 -mediated oxidation. Pot experiments showed MB/UHP significantly decreased the SMX concentration from 6.47 to 2.10 mg kg−1 and simultaneously increased NH 4 +-N and NO 3 --N concentration. The optimal quantitative-structure-activity-relationship model for 19 antibiotics suggested the dipole moment, energy of the highest occupied molecular orbital, and bond order were the intrinsic influencing factors. This study not only provides a green remediation technology but also offers a theoretical basis for estimating the removal rate of unexplored antibiotics. [Display omitted] • A green soil remediation technology involving MgFe-LDH-catalytic UHP was developed. • The technology used for simultaneous soil antibiotic degradation and N supply. • The developed QSAR offers a theoretical basis to estimate unexplored antibiotics. [ABSTRACT FROM AUTHOR]

Abstract: A lanthania modified MgO catalyst, La-MgO, has been developed and characterized by adsorption methods, X-ray diffraction method (XRD), scanning electron microscopy (SEM), temperature-programmed desorption of ammonia (NH3-TPD) and CO2 (CO2-TPD). The La-MgO has been proved to be a highly efficient and stable dehydrochlorination chemsorbent; moreover, it shows prominent catalytic degradation ability for a typical PVC-containing polyolefins (polypropylene/polyvinyl chloride), i.e., higher degradation rate and superior liquid quality, which will be very useful in the recycling of chlorine-containing waste plastics. [Copyright &y& Elsevier]

Abstract: In this study, thermal degradation of additive-free polypropylene powder over different type of zeolite catalysts was investigated. BEA, ZSM-5 and MOR with different surface areas, pore structures, acidities and Si/Al molar ratios were used as solid catalysts for degradation of polypropylene (PP). Degradation rate of the PP over zeolites was studied by thermogravimetric analysis (TGA) employing four different heating rates and apparent activation energies of the processes were determined by the Kissinger equation. The catalytic activity of zeolites decreases as BEA>ZSM-5a (Si/Al=12.5)>ZSM-5b (Si/Al=25)>MOR depending on pore size and acidity of the catalysts. On the other hand, initial degradation is relatively faster over MOR and BEA than that over both ZSM-5 catalysts depending on the apparent activation energy. It can be concluded that acidity of the catalyst is the most important parameter in determining the activity for polymer degradation process as well as other structural parameters, such as pore structure and size. [Copyright &y& Elsevier]

• PS was effectively activated by PDI nanosheets for BPA removal under visible light. • Separation of electron/hole pairs and generation of oxidative species were enhanced. • The mechanism of PDI/PS/Vis system was elucidated. • PDI/PS/Vis system shows non-selectivity and high stability. • High mineralization and low biotoxicity validated the potential of the system. A novel PDI/PS/Vis system was constructed and the photocatalytic activity of PDI with various degrees of self-assembly was explored. Perylene diimide (PDI) as photocatalysts possesses excellent charge separation efficiency and the electron injection from the PDI to persulfate (PS) can produce active species more efficiently. With the PDI/PS/Vis system, 5 mg/L bisphenol A (BPA, 50 mL) could be completely removed in 15 min with 0.5 g/L photocatalyst and 1.5 mM PS under visible light (λ>420 nm). Nearly 71.1 % of BPA was mineralized after 1 h degradation. Radical quenching tests and electron paramagnetic resonance (EPR) spectra revealed that h+, ·O 2 −, ·OH and SO 4 ·- all contributed to organics elimination with radical process. Based on the results of theoretical calculations and toxicity assessment, BPA will eventually be converted into non-toxic ring-opening products. Therefore, the highly efficient PDI/PS/Vis system has great potential for application in water environment remediation. [ABSTRACT FROM AUTHOR]

• Metal-free biochar from Boehmeria nivea fiber was an efficient carbocatalyst. • Electron transfer acceleration was achieved by graphitization and N-doping on biochar. • Graphitization and N-doping regulated non-radical pathway for TC degradation. • Active sites of PGBF-N in PMS activation for TC degradation were proposed. • TC degradation by PGBF-N/PMS system suffer less interference from (in)organics. Advanced oxidation has great promise in the degradation of organic pollutants, but the high preparation requirements, adjustment difficulty, high cost, potential hazard, and low repeatability of catalysts limit the practical applications of this technology. In this study, a metal-free biochar-based catalyst derived from biomass fiber was prepared assisted by graphitization and nitrogen incorporation (PGBF-N). The heterogeneous catalysis of peroxymonosulfate (PMS) was triggered by PGBF-N with degradation rate 7 times higher than that of pristine biochar. The high catalytic efficiency was attributed to the accelerated electron transfer originated from the high degree of graphitization and nitrogen functionalization of PGBF-N, in which the non-radical pathways containing carbon-bridge and singlet oxygen-mediated oxidation were elucidated as the predominant pathways for tetracycline degradation, instead of the dominant role of radical pathway in pristine biochar. Vacancies and defective edges formed on sp2-hybridized carbon framework as well as the nitrogen doping sites and ketonic group of PGNF-N were considered as possible active sites. The excellent degradation rate in actual water indicated that the PGBF-N/PMS system dominated by non-radical pathway exhibited a high anti-interference ability to surrounding organic or inorganic compounds. This study provides a facile protocol for converting biomass fiber into functional catalyst and enables underlying insight in mediating dominated degradation mechanism of heterogeneous catalysis by biochar fiber. [ABSTRACT FROM AUTHOR]

• Development of microporous and hierarchical pore system ZSM-23 zeolites. • Evaluation of degradation of the UHMWPE over microporous and hierarchical ZSM-23. • Hierarchical zeolites exhibit higher catalytic activity in UHMWPE degradation. • Hierarchical zeolites demonstrated lower energy level in UHMWPE degradation. The catalytic degradation of ultra high molecular weight polyethylene was studied in the presence of microporous and hierarchical ZSM-23 zeolites by thermogravimetric analysis. The ZSM-23 was synthesized using different structure-directing agents and subsequently subjected to post-synthesis treatment. The materials characterization were carried out by dispersive energy X-ray spectrometry, X-ray diffraction, temperature programmed desorption of ammonia and nitrogen adsorption-desorption measurements. The obtained zeolites were physically mixed with polymer in the proportion of 30 %wt and submitted to thermogravimetric analyses at heating rates of 5, 10, 20 and 30 °C.min−1. The average activation energy for the process was determined from the model-free kinetic proposed by Flynn-Wall-Ozawa. The modified zeolites presented a secondary porosity, which reflected in high values of external surface area and acidity, and demonstrated higher conversion efficiency and lower energy level required in polymer degradation compared to the parent samples. [ABSTRACT FROM AUTHOR]