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The nanosized Fe3O4 catalyst was synthesized via a modified reverse coprecipitation method and characterized by means of a scanning electron microscope (SEM) and an X-ray diffraction (XRD) analysis...

The characteristics and influencing factors for dinitrotoluene degradation by nano-Fe3O4-H2O2 were studied, and the nano-scale Fe3O4 catalyst was prepared by the coprecipitation method, with dinitrotoluene wastewater as the degradation object. The results showed that the catalytic reaction system within the pH value range of 1 to 9 could effectively degrade dinitrotoluene, and the optimal pH value was 3; with the increase of catalyst dosage, the degradation efficiency and the catalytic reaction rate of dinitrotoluene grew as well. The optimal catalyst dosage was 1.0 g/L when the H2O2 dosage was within the range of 0 to 0.8 mL/L; the degradation efficiency and reaction rate grew with the increase of H2O2 dosage. With further increase of H2O2 dosage, degradation efficiency and reaction rate decreased; under the best conditions with the H2O2 dosage of 0.8 mL/L, the catalyst concentration of 1 g/L and the pH value of 3 at room temperature (25 °C), the degradation rate of the 100-mg/L dinitrotoluene in...

The aim of this work was to study the retention and separation of 4BS dye from aqueous solution using N-doped TiO2 (N-TiO2) ceramic membrane. An N-TiO2 sol was synthesized by the sol–gel technique and applied to a ceramic membrane to synthesize a composite membrane. XRD analysis confirmed that the N-TiO2 had an anatase structure. SEM images revealed that the TiO2 particles with a diameter of 7–9 nm had been loaded on a ceramic support to form the nanoporous composites. 4BS dye containing aqueous solution was treated by the composite membranes. The operating conditions studied were the dye concentration, solution pH, the pressure and velocity of cross flow. With the coupling of photocatalysis and membrane separation, the retention rate of 99% for dye and the higher permeation flux (over 96%) were obtained. The composite membranes were found to be stable and to perform reproducibly.

This research measured the effectiveness of Si-FeOOH as a type of heterogeneous Fenton-like catalyst made from alkaline precipitation methods, in catalyzing the degradation of 2,4-dichlorophenol (2,4-DCP) wastewater. Factors including catalyst dosage, pH, and hydrogen peroxide dosage were investigated, showing: with an initial concentration of 2,4-dichlorophenol at 100 mg/L, a dosage of catalyst at 0.1 g/L, a dosage of H2O2 at 1.5 ml/L, pH at 5 and indoors temperature at 25 ± 1 °C, the degradation rate of 2,4-dichlorophenol, CODCr and TOC has reached 94.21%, 83.67%, and 76.11%, separately. Comparisons were made with FeOOH used as catalyst, showing that Fenton-like Si-FeOOH is a better catalyst than FeOOH.

The catalytic activity of carbon nanotubes-supported vanadium oxide (V2O5/CNTs) catalysts in the selective catalytic reduction (SCR) of NO with NH3 at low temperatures (≤ 250 °C) was investigated. The effects of V2O5 loading, reaction temperature, and presence of SO2 on the SCR activity were evaluated. The results show that V2O5/CNTs catalysts exhibit high activity for NO reduction with NH3 at low-temperatures. The catalysts also show very high stability in the presence of SO2. More interestingly, their activities are significantly promoted instead of being poisoned by SO2. The promoting effect of SO2 is distinctly associated with V2O5 loading, particularly maximized at low V2O5 loading, which indicated the role of CNTs support in this effect. The promoting effect of SO2 at low temperatures suggests that V2O5/CNTs catalysts are promising catalytic materials for low-temperature SCR reactions.

The aim of this work was to study the preparation of SiC-supported V2O5 catalysts and the kinetics on selective catalytic reduction for NO with NH3 on the catalysts. Using incipient wetness impregnation methods, vanadium oxide was applied to silicon carbide to prepare a SiC-supported vanadium oxide. X-ray photoelectron spectroscopy analysis confirmed that V2O5 existed in the prepared materials. Using the prepared materials as catalysts, selective catalytic reduction for NO by NH3 has been analyzed, and reaction kinetics on the catalysts was studied at 150–300 °C. The obtained results showed that the reduction reaction on the catalysts is close to zero-order kinetics with respect to NH3, first-order with respect to NO, and half-order to O2. Apparent activation energy for the reduction reaction was found to be 38 kJ mol−1. The prepared materials are stable and reusable.