Herein, by using a simple co-precipitation method Al-doped magnetite spinel nanoparticle encapsulated in the carbon matrix Fe(Fe0.69Al0.31)2O4@C was synthesised and its catalytic activity was examined as a heterogeneous Fenton catalyst towards the catalytic wet peroxide oxidation (CWPO) of antibiotic pollutant 20 ppm ciprofloxacin (CIP) in batch and continuous reactors. Under the optimized conditions, 0.5 g center dot L-1 Fe(Fe0.69Al0.31)2O4@C in batch reactor mineralized 51 % of CIP was achieved within 180 min at 50 degrees C and pH 3 by utilizing 1.2 mM or 4S H2O2 (S = stoichiometry; 47 mol H2O2:1 mol CIP) which is significantly less concentration compared to other heterogeneous Fenton catalysts. Impressive long-lasting catalytic activity was demonstrated in the up-flow fixed bed reactor, for 110 h with 44 % TOC removal and less than 1 ppm Fe leaching in the effluent water. Kinetic studies on the rate of decomposition of H2O2 revealed that Fe(Fe0.69Al0.31)2O4@C effectively decomposed the H2O2 like the homogeneous Fenton catalyst. The XPS results confirmed the influence of Al on iron ions in the magnetite structure through a substantial shift in higher binding energy for Fe3+ and introduced a more electropositive character on the Fe3+(delta+) that successively expedites the kinetically slow Fe3+ reduction reaction with H2O2 to produce HOO center dot. The pi electrons of the graphitic carbon facilitate the electron transfer between the carbon matrix and Fe(Fe0.69Al0.31)2O4 nanoparticles to enhance the CIP degradation. The acute toxicity assessment studies validated the non-toxic nature of the effluent water obtained from batch and continuous reactors. A degradation pathway was proposed based on the eleven intermediate products identified using LC-HRMS analysis.

Al substituted magnetite was identified as a promising heterogeneous Fenton catalyst for CWPO of 200 ppm phenol in a continuous system under mild conditions (pH 5, 40 °C, 0.1 ml min−1, 1.2S H2O2) for 500 h with 80% TOC conversion, 1 ppm Fe leaching.

A facile strategy developed for the fabrication of composite material comprising mesopores and representing an iron oxide core/encapsulated in carbon nanodisk shell using Fe-based MOF as precursor. Catalytic carbonization of Fe2+ coordinated 1,4,5,8 -naphthaleneteracarboxylic dianhydride MOF at 725 degrees C under N-2 atmosphere followed by air treatment at 300 degrees C yielded Fe3O4 nanoparticles encapsulated in mesoporous carbon matrix (FeMCNA-300). The XRD and N-2 adsorption studies confirm the presence of Fe3O4 nanoparticles and mesopores in the carbon matrix, respectively. MOF precursor generates mesopores of narrow pore size distribution without aid of structure directing agent in the carbon shell through straightforward catalytic reduction of core iron oxide. FeMCNA-300 demonstrated outstanding catalytic activity towards the degradation of 150 ppm of methylene blue (MB) dye in water with 84% TOC conversion in 15 min at room temperature. MB and oxidant H2O2 interact with iron oxide nanoparticles through confined mesoporous channel in the FeMCNA-300 carbon nanodisk. This permits the generated OH center dot at the surface of magnetite nanoparticles to instantly oxidize the MB molecules adsorbed in the close proximity. FeMCNA-300 under ultra-sonication decolourise MB completely with high TOC conversion of about 84% at maximum iron leaching of 2% up to five successive recycles. (C) 2017 Elsevier Inc. All rights reserved.

Iron grafted over mesoporous silica (8 wt %Fe/SBA‐15) is a sustainable, efficient heterogeneous iron catalyst for direct arylation of biphenyl methane C(sp3)−H and benzene C(sp2)−H bonds. The selective extraction deposition (SED) technique was adopted to graft iron easily over the mesoporous support SBA‐15 by using LaFeO3 as an iron precursor. The synthesized catalyst has been characterized by EPR spectroscopy, diffuse reflectance UV/Vis spectroscopy, and temperature programmed reduction (TPR) analysis to understand the coordination environment and state of oxidic iron species grafted over the mesoporous SBA‐15. TPR results confirm the presence of isolated, clustered, oligomeric oxidic iron species in the catalyst. The adopted SED technique is highly successful for grafting 8 wt % iron into the mesopores of SBA‐15 without forming iron oxide particles. Unlike homogeneous iron, the 8 wt %Fe/SBA‐15 catalyst does not need support from an electron‐withdrawing group and additives to carry out arylation of benzene and could be successfully recycled five times.

A recyclable heterogeneous catalyst has been successfully developed for application in a Fenton-type advanced oxidation process without adding external H2O2. LaFeO3 was prepared from Fe(NO3)3·9H2O and La(NO3)·6H2O by a simple sol-gel method and its catalytic efficiency was evaluated for mineralization of 4-chlorophenol using a Fenton-like process. The mineralization process was carried out under ultrasonication in presence of heterogeneous LaFeO3 catalyst with H2O2 that was produced during ultrasonication. The mineralization process was monitored through total organic carbon (TOC) analysis. Very importantly, utmost 5-fold synergism was evidenced by the ultrasound mediated LaFeO3-catalyzed system. Besides, more than twofold synergism was observed by combining the ultrasound assisted LaFeO3 catalytic process and potassium persulfate (KPS) assisted advanced oxidation process. It is worth to mention that complete mineralization (∼96%) of 4-chlorophenol (initial concentration of 1.25×10-4M) was observed within 1h in the presence of LaFeO3 (0.5gL-1) and KPS (1.0mmol) under ultrasonication (40kHz). Even after four cycles, the activity of LaFeO3 remained intact which proved its recyclability. Extremely reusable heterogeneous LaFeO3 catalyst makes the system more interesting from both economic and environmental points of view.

Functionalization of silica-gel by immobilization of iron ions at its surface was carried out through a novel method – selective extraction–deposition (SED) in acidic solution using LaFeO3 orthoferrite with perovskite structure as a solid precursor. Isolated Fe-ions produced as a result of precursors decomposition in acidic aqueous solution were trapped by silica surface silanols. The presence of iron in the only one state of isolated surface ions over 2wt%Fe/SiO2 material at the Fe content corresponded to surface silanols concentration was confirmed using ESR, Mossbauer spectroscopy, UV Raman, FTIR and XPS techniques. Catalytic performance of 2wt% Fe/SiO2 was examined toward catalytic wet peroxide oxidation (CWPO) of phenol in up flow fixed bed reactor at pH 4, 80°C, LHSV 6h−1 with 200ppmw phenol and 1300ppmw hydrogen peroxide in water. It was demonstrated that mixing of LaFeO3 with silica-gel gives an advanced catalytic material with high activity (TOC removal of 90%) and stability without iron leaching. This effect is due to dynamic behavior of iron that includes its SED–leaching–condensation along the catalysts layer. In this case, the LaFeO3 has a multiple function–active catalytic component, precursor of iron ions and buffer controlling the pH along the catalysts layer.

The formation of polycrystalline tin oxide nanoparticles (NP) and nanowires was investigated using nanocasting approach included solid–liquid strategy for insertion of SnCl2 precursor and SBA-15 silica as a hard template. HR-TEM and XRD revealed that during the thermal treatment in air 5nm tin oxide NP with well defined Cassiterite structure were formed inside the SBA-15 matrix mesopores at 250°C. After air calcination at 700°C the NP assembled inside the SBA-15 mesopores as polycrystalline nanorods with different orientation of atomic layers in jointed nanocrystals. It was found that the structure silanols of silica matrix play a vital role in creating the tin oxide NP at low temperature. The pure tin chloride heated in air at 250°C did not react with oxygen to yield tin oxide. Tin oxide NP were also formed during the thermal treatment of the tin chloride loaded SBA-15 in helium atmosphere at 250°C. Hence, it is well evident that silanols present in the silica matrix not only increase the wetting of tin chloride over the surface of SBA-15 favoring its penetration to the matrix pores, but also react with hydrated tin chloride according to the proposed scheme to give tin oxide inside the mesopores. It was confirmed by XRD, N2-adsorption, TGA-DSC and FTIR spectra. This phenomenon was further corroborated by detecting the inhibition of SnO2 NP formation at 250°C after inserting the tin precursor to SBA-15 with reduced silanols concentration partially grafted with tin chloride.

Numerical simulations of the 3D reacting flow in a model supersonic combustor with kerosene as the fuel have been carried out. The combustor entry Mach number is nominally 2.5. Tetrahedral grids with wall y(+) less than 75 have been used. Details of the flow field inside the combustor such as contours of static pressure, static temperature, species mass fraction, reaction rate and Mach number are discussed. Also, the variation of metrics such as combustion efficiency and total pressure loss along the length of the combustor are presented. Predicted values of wall static pressure along the top wall of the combustor are compared with previously reported experimental data. The calculations over predict the pressure rise due to combustion in the cavity region, but the overall pressure rise is predicted well.