Electro-Fenton is a promising advanced oxidation process for wastewater treatment. In this study, mesoporous carbon grafted activated carbon fibers (ACF@OMC) with different pore size were fabricated by using boric acid as the expanding agent. To study the pore structure and pore size effect on the electro-Fenton (E-Fenton) efficiency of ACF@OMC cathode materials, disordered mesoporous carbon grafted activated carbon fibers (ACF@DMC) were also prepared, and both anionic dye (Orange II) and cationic dye (Rhodamine B) were selected as target organic pollutants. Meanwhile, electro-induced generation rates of hydrogen peroxide and hydroxyl radical were measured. It was found that the E-Fenton efficiency of the cathode materials follows the increasing order of ACF@DMC < ACF@OMC-3.7 < ACF@OMC-5.4. Even after 10 consecutive experiments, the reactivity of ACF@OMC-5.4 cathode materials almost remained unchanged, indicating its promising application in practical wastewater treatment. This study gives new insights into design and preparation of carbonous materials with superior efficiency.

In this study, a novel multilayer cathode composite of ACF@rGO@OMC (ACF = activated carbon fibers, rGO = reduced graphene oxide, and OMC = ordered mesoporous carbon) with high electrical conductivity was successfully prepared. Transmission electron microscopy, electrochemical impedance spectroscopy, and cyclic voltammetry results show that the ACF@rGO@OMC composite possesses excellent properties of ordered mesoporous structure, high specific surface area, high electroactive surface area, and lower impedance. When this fabricated ACF@rGO@OMC composite electrode is applied, the reduction of oxygen to generate hydrogen peroxide was promoted from 31 to 85 mg·L–1 and the current efficiency of the electro-Fenton process was also improved from 25.0% to 40.0%. The yield of •OH had increased obviously. The ACF@rGO@OMC composite was applied for removal of phthalic acid esters using an electro-Fenton process, and it remained stable after reacting 10 times.

Magnetic material grafted with acid polyionic liquids was successfully prepared by the radical oligomerization of bis-vinylimidazolium salts on the surface of mercaptopropyl-modified silica-coated Fe3O4, and well characterized by several model technologies. The as-prepared magnetic catalyst (Fe3O4@SiO2–SH–Im–HSO4) showed high catalytic activity for the synthesis of 5-ethoxymethylfurfural (EMF) from 5-hydroxymethylfurfural (HMF) and fructose-based carbohydrates. The reaction temperature showed a remarkable effect on EMF yield. High EMF yield of 89.6% was obtained at 100 °C by the etherification of HMF. The one-pot conversion of fructose, sucrose and inulin catalyzed by Fe3O4@SiO2–SH–Im–HSO4 generated EMF with yields of 60.4%, 34.4% and 56.1%, respectively. The catalyst could be readily separated from the reaction mixture by a permanent magnet, and showed high stability in recycling experiments. This study shows a green and sustainable method for the synthesis of value-added liquid fuel from renewable resources.

A new kind of carbonic electrode material (ACF@OMC), activated carbon fibers (ACF) grafted by ordered mesoporous carbon (OMC), was prepared by developing a lay of OMC on the walls of ACF. The function of ACF@OMC cathode material was evaluated by E-Fenton degradation of brilliant red X3B (X3B), an anionic dye. The results suggest the overwhelmingly better performance of ACF@OMC than that of ACF. The structural properties of the mesoporous ACF@OMC composite are strongly related to its excellent performance.Highlights► Cable-like novel oxygen-fed gas diffusion cathode material (ACF@OMC) was prepared. ► Overwhelmingly better performance of ACF@OMC was found in E-Fenton system. ► The excellent performance of ACF@OMC is due to its ordered mesoporous structure. ► The stability makes ACF@OMC promising in sorption, energy storage and catalysis.

In this study, catalytic wet oxidation of Reactive Brilliant Red X3B (abbreviated as X3B) was studied using hydrogen peroxide as oxidant in the presence of a biomimic catalyst, iron(II) tetra(5,6-dichloro-1,4-dithiin)porphyrazine [abbreviated as FePz(dtnCl2)4]. Important factors including the solution pH, H2O2 concentration, and reaction temperature were investigated in detail to optimize the catalytic activity for the removal of X3B. Under the optimal conditions, X3B was degraded by 97.0% at pH = 2 for 240 min. Activation energy and rate constants at different reaction temperatures were calculated for the degradation of X3B in both the dark reaction and photoreaction. These results demonstrated that the catalytic activities of FePz(dtnCl2)4 for the wet oxidation of X3B could be efficiently enhanced through the synergetic effect of heat and light irradiation. Through fluorescence technology, hydroxyl radical (HO•) was detected as the main reactive oxidative species for the oxidative degradation of X3B.

Photocatalytic degradation of organic pollutants in TiO2/UV/O3 system has been ascribed to the hydroxyl radicals mediated oxidation process. In this paper, TiO2 nanotubes (TNTs) were prepared by hydrothermal treatment of P25 TiO2 in NaOH solution, which was characterized by TEM, XRD and nitrogen adsorption–desorption isotherms. Adsorption and photocatalytic degradation of Brilliant Red X-3B (X3B), an anionic azo dye, in TiO2 suspensions using O2 and O3 as oxidants, TNTs and P25 TiO2 as photocatalysts, respectively. The maximum adsorption of X3B on the surface of TNTs is 3 times higher than that of P25 TiO2, and TNTs showed superior photocatalytic activity than P25 TiO2 under identical conditions. Ozonation and photocatalytic oxidation are involved in the degradation of X3B in TiO2/UV/O3 system. However, only photocatalytic oxidation is responsible for the degradation of X3B in TiO2/UV/O2 system. Compared with O2, O3 is a more efficient oxidant in degradation of X3B in TiO2/UV system. Quenching experiments showed that photocatalytic degradation of X3B, whatever in TiO2/UV/O3 or TiO2/UV/O2 system, is through direct holes oxidation, reflecting the importance of adsorption on the degradation of organic pollutant. It is the first example showing the direct hole oxidation of organic pollutant in TiO2/UV/O3 system.Graphical abstractHighlights► The first example showing the direct hole oxidation of organic pollutant in TiO2/UV/O3 system. ► Adsorption is important on the degradation pathway of organic pollutant in TiO2. ► Ozonation and photocatalytic oxidation are involved in TiO2/UV/O3 system. ► Compared with P25 TiO2, TiO2 nanotubes showed higher photocatalytic activity.

•Nitric oxide improves tall fescue behaviors against Cd2+ toxicity.•Nitric oxide affects Cd2+ absorption in tall fescue.•Nitric oxide alleviates Cd2+ toxicity in tall fescue photosystem II on electron donor side.Tall fescue (Festuca arundinacea) possesses remarkable prospects in heavy metal phytoremediation. Nitric oxide (NO) plays multifunctional roles in plant growth, development and the regulation of cellular mechanisms. In this study, we evaluated the potential use of tall fescue for cadmium (Cd) phytoremediation and the contribution of NO to the process. Different concentrations of Cd2+ were applied to study the toxic effects of Cd2+ and its absorption in tall fescue. Sodium nitroprusside (SNP) was used as exogenous NO donor and NG-nitro-l-arginine-methyl ester (L-NAME) was used as a NO synthesis inhibitor to evaluate the role of NO in tall fescue phytoremediation. The tall fescue growth parameters and photosystem II (PSII) activities were determined. The performance of the tall fescue was inhibited by an increase in the Cd2+ concentration. The SNP treatment improved the behaviour of tall fescue against Cd2+ stress, while the L-NAME treatment led to the opposite results in certain cases. Additionally, SNP treatment reduced the Cd2+ contents of the tall fescue shoots. The study of OJIP curves showed that Cd2+ treatment possessed negative effects on PSII grouping and NO treatment could alleviate Cd2+ toxicity on PSII. Moreover, JIP test depicted toxic effect of Cd2+ upon tall fescue and the protective role of NO against heavy metal stress. Overall, the tall fescue exhibited high tolerance to Cd2+ stress and NO protected the fescue from Cd2+. Cd2+ toxicity in the tall fescue PSII is primarily localized on the electron donor side. NO alleviated Cd2+ toxicity on the PSII electron donor side, which may be due to its role in the regulation of the level and toxicity of reactive oxygen species.

In this paper, gold nanoparticles on highly ordered TiO2 nanotube arrays (Au/TNTA) were prepared via electrochemical anodic oxidation method followed by photodeposition. The prepared samples were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS). Photocatalytic degradation of Rhodamine B(RhB) under simulated sunlight irradiation were carried out. The experiment results showed that the photocatalytic activity of TNTA was greatly enhanced after loading of gold. Both hydroxyl radicals (·OH) and holes are involved in the degradation of RhB.

Magnetic material grafted with acid polyionic liquids was successfully prepared by the radical oligomerization of bis-vinylimidazolium salts on the surface of mercaptopropyl-modified silica-coated Fe3O4, and well characterized by several model technologies. The as-prepared magnetic catalyst (Fe3O4@SiO2–SH–Im–HSO4) showed high catalytic activity for the synthesis of 5-ethoxymethylfurfural (EMF) from 5-hydroxymethylfurfural (HMF) and fructose-based carbohydrates. The reaction temperature showed a remarkable effect on EMF yield. High EMF yield of 89.6% was obtained at 100 °C by the etherification of HMF. The one-pot conversion of fructose, sucrose and inulin catalyzed by Fe3O4@SiO2–SH–Im–HSO4 generated EMF with yields of 60.4%, 34.4% and 56.1%, respectively. The catalyst could be readily separated from the reaction mixture by a permanent magnet, and showed high stability in recycling experiments. This study shows a green and sustainable method for the synthesis of value-added liquid fuel from renewable resources.