Abstract    In this study, we explored an effective and low-cost catalyst and its adsorption capacity and catalytic capacity for Methyl Orange Fenton oxidation degradation were investigated. The catalyst was directly prepared by reuse of magnetic iron oxide (Fe3O4) after saturated adsorption of vanadium (V) from waste SCR (Selective Catalytic Reduction) catalyst. The obtained catalyst was characterized by FTIR, XPS and the results showed that vanadium (V) adsorption process of Fe3O4 nanoparticles was non-redox reaction. The effects of pH, adsorption kinetics and equilibrium isotherms of adsorption were assessed. Adsorption of vanadium (V) ions by Fe3O4 nanoparticles could be well described by the Sips isotherm model which controlled by the mixed surface reaction and diffusion (MSRDC) adsorption kinetic model. The results show that vanadium (V) was mainly adsorbed on external surface of the Fe3O4 nanoparticles. The separation-recovering tungsten (VI) and vanadium (V) from waste SCR catalyst alkaline solution through pH adjustment was also investigated in this study. The results obtained from the experiments indicated that tungsten (VI) was selectively adsorbed from vanadium (V)/tungsten (VI) mixed solution in certain acidic condition by Fe3O4 nanoparticle to realize their recovery. Tungsten (V) with some impurity can be obtained by releasing from adsorbent, which can be confirmed by ICP-AES. The Methyl Orange degradation catalytic performance illustrated that the catalyst could improve Fenton reaction effectively at pH = 3.0 compare to Fe3O4 nanoparticles alone. Therefore, Fe3O4 nanoparticle adsorbed vanadium (V) has a potential to be employed as a heterogeneous Fenton-like catalyst in the present contribution, and its catalytic activity was mainly evaluated in terms of the decoloration efficiency of Methyl Orange.

Abstract  In this paper, potassium salt roasting additives were applied to extract vanadium from vanadium-titanium magnetite concentrate. Meanwhile, the mechanisms of potassium salt roasting and acid leaching kinetics were investigated. The results indicate that potassium salt roasting additives are more efficient than sodium and calcium salt and that K2SO4 works best. Under certain conditions (a dosage of K2SO4 of 4 wt %, a roasting temperature of 900 degrees C, a roasting time of 1 h, a leaching temperature of 95 degrees C, a sulfuric acid concentration of 10% (v/v), and a leaching time of 1.5 h with a liquid to solid ratio of 3 mL/g) the vanadium leaching efficiency reached 71.37%, an increase of 30.20% compared to that of blank roasting. Additionally, XRD and related SEM-EDS analyses indicated that K2SO4 fully destroyed the structure of vanadium-bearing minerals such as magnetite, and promoted the generation of soluble KVO3 to inhibit the formation of insoluble Ca(VO3)(2) in the roasting process. Furthermore, it promoted the dissolution of sphene and the release of its vanadium in the leaching process, which increased the vanadium leaching efficiency significantly. Meanwhile, leaching kinetics analyses showed that the leaching process was controlled by internal diffusion; the apparent activation energy decreased from 37.43 kJ/mol with blank roasting to 26.31 kJ/mol with potassium salt roasting. The reaction order, with regards to the sulfuric acid concentration, decreased from 0.6588 to 0.5799. Therefore, potassium salt roasting could improve mineral activity, accelerating the leaching process and reducing the dependence on high temperature and high acidity.

Abstract  High quality 2D and 3D inverse opals and hollow sphere arrays of vanadium oxide are grown on conductive substrates from colloidal polymer sphere templates formed by electrophoretic deposition or surfactant-assisted dip-coating. Inverse opals (IOs) are formed using variants of solution drop-casting, N-2-gun assisted infiltration and high-rate (200 mm min(-1)) iterative dip-coating methods. Through Raman scattering, transmission electron microscopy and optical diffraction, we show how the oxide phase, crystallinity and structure are inter-related and controlled. Opal template removal steps are demonstrated to determine the morphology, crystallinity and phase of the resulting 2D and 3D IO structures. The ability to form high quality 2D IOs is also demonstrated using UV Ozone removal of PMMA spheres. Rapid hydrolysis of the alkoxide precursor allows the formation of 2D arrays of crystalline hollow spheres of V2O5 by utilizing over-filling during iterative dip-coating. The methods and crystallinity control allow 2D and 3D hierarchically structured templates and inverse opal vanadium oxides directly on conductive surfaces. This can be extended to a wide range of other functional porous materials for energy storage and batteries, electrocatalysis, sensing, solar cell materials and diffractive optical coatings.

Abstract  The study investigated photocatalytic water splitting for O₂ production under visible light irradiation using neodymium vanadium oxide (NdVO₄) and vanadium oxide (V₂O₅) hybrid powders. The results in a sacrificial agent of 0.01 M AgNO₃ solution were obtained, and the highest photocatalytic O₂ evolution was 2.63 μmol/h, when the hybrid powders were prepared by mixing Nd and V at a volume ratio of 1:3 at a calcination temperature of 350 °C for 1 h. The hybrid powders were synthesized by neodymium nitrate and ammonium metavanadate using the glycothermal method in ethylene glycol at 120 °C for 1 h. The hybrid powders consisted of two shapes, NdVO₄ nanoparticles and the cylindrical V₂O₅ particles, and they possessed the ability for photocatalytic oxygen (O₂) evolution during irradiation with visible light. The band gaps and structures of the hybrid powders were analyzed using UV-visible spectroscopy and transmission electron microscopy.

Abstract  Vanadium oxides supported on mesoporous SBA-15 catalysts with different vanadium loadings were studied in the oxidative desulfurization (ODS) of dibenzothiophene as a model sulfur compound. The catalytic activity was improved when SBA-15 framework was modified by adding Al and Ga. Structural and textural characterization of the catalysts were performed by means of XRD, N-2 adsorption, UV-Vis -DRS, XPS, NMR, TEM, Raman, TPR and Py-FTIR. UV-Vis DRS and Raman demonstrated that highly dispersed vanadium VOT4-3 species are responsible for the high activity in the sulfur removal. The Ga modified support with an intermediate V/Si ratio of 1/30 was the most active catalyst for ODS of DBT, using hydrogen peroxide as oxidant and acetonitrile as solvent. 100% of DBT elimination was attained at a short time in mild conditions. Gallium and aluminum incorporation into the support modified successfully the nature of the SBA-15 surface by generating Bronsted and Lewis acidity. The interaction between the acid sites with the active vanadium sites improved the activity of the catalysts. The high dispersion depended on the vanadium loading and on the nature of the support. The more acidic support allowed better dispersion of the vanadium species due to stronger interaction metal-support. The reusability of the catalysts indicates that vanadium oxide supported on mesoporous SBA-15 modified with Ga and Al are potential catalysts for the ODS of dibenzothiophene. (C) 2017 Elsevier Inc. All rights reserved.

Abstract  Seven chiral dioxidomolybdenum(VI) complexes with tridentate Schiff bases were synthesized by mono condensation of S(+)-1-amino-2-propanol with salicylaldehyde and its derivatives. One- (H-1, C-13) and two-dimensional (COSY, gHSQC and NOESY) NMR, IR, CD and UV-Vis spectroscopy were used for detailed characterization of the new molybdenum(VI) compounds. After optimization of the reaction conditions, the catalytic activities of these complexes were tested for the oxidation of olefins, i.e. styrene and cyclohexene, with aqueous 30% H2O2 or tert-butyl hydroperoxide (TBHP) as an oxidant. Moreover, the molybdenum(VI) Schiff base complexes were also able to catalyze the oxidation of prochiral sulfides [PhSR (R = Me, Bz)] to optically active sulfoxides in the presence of aqueous 30% H2O2. (C) 2016 Elsevier Ltd. All rights reserved.

Abstract  Bulk VO2 (B) nanobelts with high quality have been fabricated via a simple one-step hydrothermal route and found to possess intrinsic peroxidase-like activity. The catalysts with excellent affinity to hydrogen peroxide (H2O2) and 3,3',5,5'-tetramethylbenzidine (TMB) could be used for the colorimetric assay of H2O2 and glucose.

Abstract  The primary objective of the current work is to estimate the association of ejaculate levels of 20 toxic and essential metals and sperm quality parameters in 148 adult men. Materials: Ejaculate volume, absolute and relative sperm count, sperm motility and vitality were assessed in semen samples of 148 men according to the WHO manual. At the same time, concentration of 20 toxic and essential metals (Al, As, Be, Bi, Cd, Co, Cr, Cu, Fe, Hg, I, Li, Mn, Mo, Ni, Pb, Se, Sn, V, Zn) was estimated in ejaculate samples using inductively coupled plasma mass spectrometry. Results: The results show that the increase in seminal liquid volume was accompanied by a significant 37% decrease in sperm copper content. At the same time, the normalization of the ejaculate volume resulted in a 26, 50, and 31% decrease in seminal Mn, Mo, and Ni concentration, respectively. An increase in sperm count was accompanied with a significant 36% decrease in semen Pb content. At the same time, a significant 25% increase in semen vanadium content was observed after normalization of the relative sperm count. Investigation of sperm motility indicated that this parameter was not significantly associated with semen metal levels. A significant 29% increase in selenium ejaculate levels was associated with an increase in sperm vitality. Correlation analysis revealed direct significant interrelation between sperm quality and seminal cobalt and selenium levels, whereas reverse correlation of the parameters was observed with copper, beryllium and lead levels. Conclusions: i) Selenium is characterized by a positive relationship with sperm count, motility and vitality; ii) Relative sperm count is directly associated with seminal vanadium levels;, iii) Ejaculate cadmium, tin and lead concentrations are negatively interrelated with sperm quality; iv) Present study failed to reveal any significant connection between seminal zinc levels and the sperm parameters analyzed.

Abstract  By adding alkaline ashes through injection to weathered mine waste pH increased approximately 3 units, trace element was immobilized and flow rate decreased due to formation of hard pans. Reduction in trace element concentrations was around 96.9-99.6 % for copper, 94.7-99.7 % for zinc and 22.9-99.8 % for cadmium. For lead the best reduction was 97.3 % and the worst-393 % (increase). MSWI ashes performed worst with low buffering capacity and increase in vanadium and molybdenum concentrations.

Abstract  The mechanisms of the many-electron oxidation of water by a chemical model of the manganese oxidase cofactor in photosynthesis photosystem II (manganese(IV) clusters) and nitrogen reduction in chemical models of nitrogenase cofactor (vanadium(II) and molybdenum(III) clusters) were considered. The hypothesis was suggested according to which polynuclear enzyme cofactors and their functional chemical models performed two important functions, catalyzed noncomplementary processes and effected many-substrate concerted reactions with decreased activation energies.

Abstract  The influence of the oxydiacetate (ODA) and thiodiacetate (TDA) ligands on the physicochemical and biological properties of the oxidovanadium(IV) ternary complexes of the VO(L)(B) type, where L denotes ODA or TDA and B denotes 2,2'-bipyridine (bipy) or 1,10-phenanthroline (phen), has been investigated. The stability of the complexes in aqueous solutions, assessed based on the potentiometric titration method, increases in the following direction: VO(TDA)(bipy) < VO(ODA)(bipy) < VO(TDA)(phen) < VO(ODA)(phen). Furthermore, the influence of the TDA and ODA ligands on the antioxidant activity of the oxidovanadium(IV) complexes toward superoxide free radical (O2•-), 2,2'-azinobis(3-ethylbenzothiazoline-6 sulfonic acid) cation radical (ABTS+•) and 2,2-diphenyl-1-picrylhydrazyl radical (DPPH•) has been examined and discussed. The reactivity of the complexes toward O2•- increases in the following direction: VO(TDA)(phen) < VO(TDA)(bipy) ≈ VO(ODA)(bipy) < VO(ODA)(phen). The antioxidant activity against ABTS+• and DPPH• free radicals is higher for phen complexes, whereas the thiodiacetate complexes are more reactive than are the corresponding oxydiacetate ones. Finally, herein, the cytoprotective activity of the complexes against the oxidative damage generated exogenously by hydrogen peroxide in the hippocampal neuronal HT22 cell line (the MTT and LDH tests) is reported. In a low concentration (1 μM), the cytoprotective action of thiodiacetate complexes is much higher than that of the corresponding oxydiacetate complexes. However, in the higher concentration range (10 and 100 μM), the antioxidant activity of the complexes is overcompensated by their cytotoxic effect.

Abstract  Water from La Pampa, Argentina, was used for washing and cooking rice to examine the in-situ impact of using naturally-contaminated water for food preparation on the elemental dietary intake. Whilst washing with the control tap water (28 μg/L As) reduced the concentration of As in rice by 23%, the use of different well waters (281-1144 μg/L) increased As levels significantly (48-227%) in comparison with the original concentration in the rice (0.056 µg/g). Cooking the rice at a low water-to-rice ratio (2:1) using modern methods increased the levels of As in the cooked samples by 2-3 orders of magnitude for both pre-washed and un-washed rice. Similar trends were observed for vanadium. Although the levels of manganese, iron, copper, zinc and molybdenum in rice were reduced during washing and cooking for most water samples, the molybdenum concentration in the cooked rice doubled (2.2-2.9 µg/g) when using water containing >1 mg/L Mo.

Abstract  Reductive leaching of vanadium from spent vanadium catalysts for sulfuric acid production by sulfur dioxide, with the use of weakly acidic aqueous solutions of sulfurous acid, is studied. It is shown that the rate and completeness of vanadium leaching is related to the presence of admixtures of polyvalent metals. For catalyst with high iron content (1.5%) the effect of different parameters on the kinetic of vanadium dissolution was determined. The acquired data was analyzed for correspondence to the mathematical models for heterogeneous processes. The best description of the leaching process is given by the model which assumes the process limitation by diffusion of two reactants trough the insoluble layer of forming product. It was found that these reactants are hydrogen and vanadyl ions reaction orders for which are 0.48 and -0.7, respectively. Temperature increase has a significant effect on the leaching rate (activation energy is 49.24 kj.mol(-1)). This value of activation energy can be explained by the change in permeability of the film of insoluble product with temperature increase, which improves diffusion rate of reactants. (C) 2016 Elsevier B.V. All rights reserved.

Abstract  Oxo-vanadium(IV) Schiff base complex supported on MCM-41 as an organic-inorganic hybrid heterogeneous catalyst was synthesized with post-grafting of MCM-41 with 3-aminoropropyltrimethoxysilane and subsequent reaction with 3,4-dihydroxybenzaldehyde and then complexation with oxo-vanadium acetylacetonate salt. The catalyst was analysed using a series of characterization techniques such as Fourier transform infrared spectroscopy, small-angle X-ray diffraction, nitrogen absorption isotherm, transmission electron microscopy and thermogravimetric analysis. The data collected provided evidence that the vanadium complex was anchored onto MCM-41. High catalytic activity of this catalyst was observed in the oxidation of various sulfides and thiols (into sulfoxides and disulfides, respectively) with urea hydrogen peroxide as oxidant in high to excellent yields and selectivity under mild conditions. The heterogeneous catalyst could be recovered easily and reused several times without significant loss in catalytic activity and selectivity. Copyright (c) 2015 John Wiley & Sons, Ltd.

Abstract  A new atomic layer deposition (ALD) process for V2O5 using ozone (O-3) as oxidant has been developed that resulted in crystalline V2O5 thin films which are single-phase and orthorhombic on various substrates (silicon, Au-coated stainless steel, and anodic aluminum oxide (AAO)) without any thermal post-treatment. Within a fairly narrow temperature window (170-185 degrees C), this low temperature process yields a growth rate of similar to 0.27 angstrom/cycle on Si. It presents good uniformity on planar substrates. Excellent conformality enables deposition into high aspect ratio (AR) nanopores (AR > 100), as needed for fabrication of three-dimensional (3D) nanostructures for next generation electrochemical energy storage devices. V2O5 films obtained using O-3-based ALD showed superior electrochemical performance in lithium cells, with initial specific discharge capacity of 142 mAh/g in the potential range of 2.6-4.0 V, as well as excellent rate capability and cycling stability. These benefits are attributed primarily to the crystallinity of the material and to fast transport through the thin active storage layers used.

Abstract  Concomitant generation of reactive oxygen species during tissue inflammation has been recognised as a major factor for the development and the maintenance of hyperalgesia, out of which H2O2 is the major player. However, molecular mechanism of H2O2 induced hyperalgesia is still obscure. The aim of present study is to analyse the mechanism of H2O2-induced hyperalgesia in rats. Intraplantar injection of H2O2 (5, 10 and 20 µmoles/paw) induced a significant thermal hyperalgesia in the hind paw, confirmed by increased c-Fos activity in dorsal horn of spinal cord. Onset of hyperalgesia was prior to development of oxidative stress and inflammation. Rapid increase in phosphorylation of extracellular signal regulated kinase (ERK) was observed in neurons of dorsal root ganglia after 20 min of H2O2 (10 µmoles/paw) administration, which gradually returned towards normal level within 24 h, following the pattern of thermal hyperalgesia. The expression of TNFR1 followed the same pattern and colocalised with pERK. ERK phosphorylation was observed in NF-200-positive and -negative neurons, indicating the involvement of ERK in C-fibres as well as in A-fibres. Intrathecal preadministration of Src family kinases (SFKs) inhibitor (PP1) and MEK inhibitor (PD98059) prevented H2O2 induced augmentation of ERK phosphorylation and thermal hyperalgesia. Pretreatment of protein tyrosine phosphatases (PTPs) inhibitor (sodium orthovanadate) also diminished hyperalgesia, although it further increased ERK phosphorylation. Combination of orthovanadate with PP1 or PD98059 did not exhibit synergistic antihyperalgesic effect. The results demonstrate SFKs-mediated ERK activation and increased TNFR1 expression in nociceptive neurons during H2O2 induced hyperalgesia. However, the role of PTPs in hyperalgesic behaviour needs further molecular analysis.

Abstract  Cold VCl3-plasma is employed for the preparation of highly dispersed vanadium oxide clusters on nanosized zeolite. Different types of zeolites, such as EMT, FAU (z.X), and Beta, are used. The activity of the prepared catalysts is studied in the selective photooxidation of methanol under polychromatic visible and UV irradiations. The physicochemical properties and catalytic performance of plasma-treated zeolite Beta (P-V2O5@Beta) catalyst is compared with zeolite Beta (V2O5@Beta) and amorphous silica (V2O5@SiO2) impregnated vanadium oxide catalysts. Pure V2O5 is used as a reference material. The set of catalytic data shows that plasma-prepared zeolite Beta based catalyst displays the highest activity. Complementary characterization techniques including XRD, N2-sorption, FTIR, ionic exchange, pyridine adsorption, Raman, NMR, TPR, and EDX-TEM are used to study the impact of the preparation approach on the physicochemical properties and catalytic performance of photocatalysts.

Abstract  Inositol and phytic acid have been employed as organic additives of the positive electrolyte for all-vanadium redox flow battery (VRFB) to improve its stability and electrochemical reversibility. Thermal stability of the V(V) electrolyte could be improved by both inositol and phytic acid additives. The results of cyclic voltammetry (CV), steady polarization curve and electrochemical impedance spectroscopy (EIS) show that the electrochemical activity of the electrolyte with additives is improved compared to the blank one. The diffusion coefficient of V(IV) species with inositol has been increased from 0.71-1.16 x 10(-6) to 3.11-5.15 x 10(-6) cm(2) s(-1) and the exchange current density was raised from 2.8 x 10(-3) to 11.7 x 10(-3) A cm(-2). Moreover, electrochemical results suggest that the positive electrolytes with organic additives have better cycling stability. The VRFB employing positive electrolyte with inositol as additive exhibits excellent charge-discharge behavior with an average energy efficiency of 81.5% at a current density of 30 mA cm(-2). The UV-visible spectroscopy confirms that new substances in V(V) electrolyte are not formed with both inositol and phytic acid additives. (C) 2012 Elsevier Ltd. All rights reserved.

Abstract  New oxovanadium(V) complexes with 2-[hydroxy(diaryl)methyl]-8-hydroxyquinoline ligands were synthesized. These compounds were found to be efficient tandem catalysts of oligomerization of hex-1-ene and alkylation of toluene, which leads to the mixture of hexyl-, dihexyl-, and trihexyltoluenes with the conversion of the starting alkene more than 99%.

Abstract  This work aims to explore the mechanism of photocatalytic degradation of gaseous 1,2-dichlorobenzene (o-DCB) over vanadium pentoxide (V2O5) hollow spheres. To this end, flower-type V2O5 hollow microspheres with diameters of about 700-800 nm were obtained with the assistance of carbon-sphere templates, and then tested in the photodegradation of o-DCB under visible light (lambda > 400 nm). Due to its strong adsorption capacity and large specific surface area, the V2O5 hollow structure showed high photocatalytic activity in the degradation of gaseous o-DCB under visible light. Furthermore, the o-DCB degradation mechanism was investigated by using in situ Fourier transform infrared (FTIR) spectroscopy, and the intermediates, such as o-benzoquinone-type and organic acid species, and final products (CO2 and H2O) were also confirmed. Then, the reaction pathways over V2O5 were proposed. The outstanding performance indicated that the photocatalysts could be applied to air purification for Chlorinated Volatile Organic Compound (Cl-VOC) removal.

Abstract  The TiO2/MoO3 and TiO2/V2O5 thin-film nanoheterogeneous photocatalysts obtained by mechanochemical activation of oxides were studied by using the test reactions of probing dye photooxidation, EPR spectroscopy, X-ray diffraction, and atomic force microscopy. It was shown that mechanochemical synthesis yields nanoheterostructures of the oxide-oxide type, in which optimum conditions were created for photogeneration of charge carriers and their accumulation and thus opens up an opportunity of obtaining photocatalytic systems with prolonged oxidative activity.

Abstract  The steam reforming of toluene has been studied on three catalysts with vanadium (0.9, 1.75, 3%) derived from hydrotalcites precursors (Mg/Al molar ratio 3) in the temperature range 400-500 degrees C. Catalysts were characterized by BET, XRD, SEM, TEM, FT-IR and then a correlation between physico-chemical characteristics and catalytic activity for toluene steam reforming has been done. The results showed that the catalyst with 3% V, with polyvanadate species, achieves the best catalytic activity, with a toluene conversion of 77.5%, at 500 degrees C, and a H-2 composition of 57%. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Abstract  A rapid and efficient procedure for the preparation of various aryl-14H-dibenzo[a,j]xanthenes was reported. The method developed produced excellent yields via one-pot condensation of beta-naphthol with various aryl-aldehydes in the presence of Keggin vanadium substituted heteropolyacid, H5PW10V2O40, as catalyst under solvent free conditions. The present methodology therefore offered several advantages but not limited to excellent yields (82%-98%), short reaction times (30-50 min), mild reaction conditions, simple work-up, as well as the utilization of cheap and environmentally benign catalyst in the absence of organic solvents.

Abstract  A comparison between unassisted and calcium fluoride-enhanced leaching demonstrated that calcium fluoride can markedly boost the efficiency and accelerate the rate of vanadium leaching from stone coal. Analysis methods were adopted to identify the mechanism of calcium fluoride-enhanced vanadium leaching from stone coal, including Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES), valence state of vanadium, X-ray Diffractometry (XRD), X-ray Photoelectron Spectroscopy (XPS), F-19 liquid Nuclear Magnetic Resonance (NMR), Scanning Electron Microscope (SEM) and thermodynamics. The whole calcium fluoride-enhanced vanadium leaching process was that calcium fluoride reacted with sulfuric acid and then generated HF(aq); calcite was dissolved into the acid; chlorite and phlogopite were thoroughly disintegrated and subsequently generated quartz, M+, Mg2+, [SiF6](2-), [AlF5](2-) and Al3+; the released V(III) was oxidized to VO2+ by O-2 from the air. It is the procedure that fluorine combined with aluminum and silicon in the lattice of vanadium-bearing phlogopite to generate [SiF6](2-) and [AlF5](2-) that facilitated the vanadiumleaching from stone coal. This generation decreased the Delta G degrees of phlogopite disintegration, declined the effect of chemical reaction on vanadium leaching, accelerated the leaching rate of vanadium and boosted the leaching efficiency of vanadium. (C) 2015 Elsevier B.V. All rights reserved.

Abstract  Peroxophosphotungstate (PW) anions were successfully immobilized on the surface of clicked graphene oxides and used as heterogeneous catalysts for the epoxidation of various olefins using H2O2 as oxidant. Graphene oxide (GO) was functionalized with azide groups through both grafting and tethering methods Then, supported ionic liquids were formed on the surface of GO through the Cu (I)-catalyzed azide-alkyne cycloaddition (CuAAC) click reaction. The clicked GO supported ionic liquids were used as appropriate supports for the immobilization of PW anions. Characterization of the prepared materials by various physicochemical methods showed that PW anions have been successfully immobilized on the surface of clicked GOs. Catalytic activities of these heterogeneous catalysts were evaluated in the epoxidation of olefins which showed that not only the catalysts are active, but also they could be reused several times without significant loss of their activities.