Optimizing treatment of alcohol vinasse using a combination of advanced oxidation with porous α-Fe2O3 nanoparticles and coagulation-flocculation

One-pot hydrothermal synthesis of FeNbO4 microspheres for effective sonocatalysis

FeNbO4 sonocatalysts were successfully synthesized by a simple hydrothermal route at pH values of 3, 5, 7, 9 and 11. The catalysts were characterized by XRD, XPS, TEM, SEM, N2 adsorption and DRS to analyse the effect of pH parameters on the physicochemical properties of the materials during hydrothermal synthesis. The sonocatalytic activity of FeNbO4 microspheres was evaluated by using acid orange 7 (AO7) as the simulated contaminant. The experimental results showed that the best sonocatalytic degradation ratio (97.45%) of organic dyes could be obtained under the conditions of an initial AO7 concentration of 10 mg L-1, an ultrasonic power of 200 W, a catalyst dosage of 1.0 g L-1, and a pH of 3. Moreover, the sonocatalysts demonstrated consistent durability and stability across multiple test cycles. After active species capture experiments and calculation of the energy band, a possible mechanism was proposed based on the special Fenton-like mechanism and the dissociation of H2O2. This research shows that FeNbO4 microspheres can be used as sonocatalysts for the purification of organic wastewater, which has a promising application prospect.

Constructing a composite microfiltration carbon membrane by TiO2 and Fe2O3 for efficient separation of oil-water emulsions

Membrane-based separation technology has attracted enormous attention for oil/water emulsion treatment. Here, composite microfiltration carbon membranes (MCMs) were prepared from the precursor of phenolic resin doping with TiO2 and Fe2O3 via the processes of stereotype and pyrolysis. The functional groups, thermal stability, porous structure, microstructure, morphology, and hydrophilicity of the membrane samples were analyzed by Fourier-transform infrared spectroscopy, thermogravimetric analysis, bubble pressure method, X-ray diffraction, scanning electron microscope, and water contact angle, respectively. The effect of dopant amount on the separation performance of MCMs was investigated. The results show that a mixed matrix system is constructed by TiO2 and Fe2O3 in MCMs, which is beneficial for further optimizing the pore size, porosity, and hydrophilicity of MCMs for oily wastewater treatment by varying the dopant amount. The maximum oil rejections are achieved at 98.9% and 99.6% for MCMs with a dopant content of TiO2 and Fe2O3 at 25%, respectively. In brief, this study offers an attractive strategy for improving the separation performance of MCMs for oily wastewater.

Application, mechanism and prospects of Fe-based/ Fe-biochar catalysts in heterogenous ozonation process: A review

A growing number of novel organic contaminants have escalated the demands and challenges for water treatment technology. Advanced oxidation processes based on ozone have the advantage of strong oxidative capacity and higher efficiency, which have promising application prospects in the treatment of refractory organic contaminants. Biochar has attracted a lot of interest in recent years in wastewater treatment owing to its porous structure, portable preparation and outstanding stability. Moreover, iron species are widely used in catalytic ozonation owing to their magnetic polarization, vast abundance and low price. Despite a plethora of research on Fe-based catalysts in ozonation process, the heterogeneous catalytic ozonation with Fe-loaded biochar lacks a comprehensive compendium. This review intends to introduce the research progress on Fe-based catalysts and Fe-loaded biochar in heterogeneous catalytic ozonation progress, summarize and further explore the mechanisms and detection techniques of various active components in catalytic ozonation, as well as providing fresh insights for future research.

Mixed oxides with corundum-type structure obtained from recycling can seals as paint pigments: color stability

Green chromium and red iron oxides are technically important pigments due to their high color intensity, good dispersibility in paints, and superior hiding power. We report on the synthesis of colored pigments of mixed oxides with a corundum-type structure. The pigments are obtained via the addition of coloring ions to boehmite from recycled metallic aluminium. X-ray diffractometry (XRD) and Raman spectroscopy confirmed the crystallographic phase. Additionally, the oxidation state 3+ responsible for the greenish (chromium) and reddish (iron) coloration of the mixed oxides was confirmed by XPS and visible-light absorption measurements. The colorimetric stability of the oxides in acid and alkaline environments was evaluated. After 240 h of exposure to harsh environments, both pigments demonstrated stability and showed no strong color difference.

Enriching SO42− Immobilization on α-Fe2O3 via Spatial Confinement for Robust NH3-SCR Denitration

The application of iron oxide to NH3-SCR is attractive but largely hindered by its poor acid properties, and surface sulfation is proven to be a prominent way of enhancing the acidity. As such, the method of enriching the sulfate species on iron oxide is crucial for improving the NH3-SCR performance. In the present study, by employing ammonium bisulfate (ABS) as the source of gaseous SO2 for the purpose of trapping, we reported an effective strategy for enhancing the SO42− immobilization on α-Fe2O3 catalyst via spatial confinement in a mesoporous SBA-15 framework. Interestingly, although the presence of the mesopore channel had an adverse effect on the ABS decomposition, which was expected to produce less available SO2, the measured SO42− immobilized on α-Fe2O3 in the mesoporous SBA-15 system was significantly greater than that of the regular SiO2, demonstrating the promoting effect of the spatial confinement on the SO42− enrichment. Further characterizations of the NH3-TPD, NO oxidation, and NH3-SCR performance tests proved that, as a result of the enhanced acidity, the enrichment of SO42− on α-Fe2O3 displayed a clear correlation with the SCR activity. The results of the present study provide an effective strategy for boosting the catalytic performance of iron oxide in NH3-SCR via SO42− enrichment.