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Rice hull biochar modified by ZnS nanocrystals (RBZ) was developed as an efficient absorbent for the removal of Cu(II) in aqueous solution. Response surface methodology (RSM) was applied for modeling and optimizing the performance of RBZ. The maximum adsorption capacity of RBZ toward Cu(II) through the Langmuir model fitting was 248.98 mg g−1, which was four times larger than that of rice hull biochar (RB). The adsorption kinetics of Cu(II) and XPS analysis revealed that the chemisorption process played the leading role when using RBZ. Through competition ions study, Pb(II), Cd(II), or Ca(II) can slightly reduce the adsorption of Cu(II). According to the Box Behnken design method, the analysis of variance results showed that the pH and adsorbent dosage had significant effects on the predicted responses of adsorption capacity and removal efficiency. When using the optimum conditions, pH 6, temperature 27 °C, and dosage 0.20 mg mL−1 for removing Cu(II) in solution, the maximum adsorption capacity and relatively higher removal efficiency could be obtained through the 3D response surface plots. The results demonstrated that RSM is feasible to achieve optimal conditions for adsorption capacity and removal efficiency simultaneously toward heavy metals from aqueous medium, and the interaction between them when using the biochar/ZnS composite. [ABSTRACT FROM AUTHOR]

The post-oxidation treatment (POT) is an important step in the preparation of silicon carbide (SiC) ceramic membranes via recrystallization sintering, which is generally considered to remove any possible free carbon. It is found, however, that increasing the temperature of POT improves not only the hydrophilicity and flux of SiC ceramic membranes but also their mechanical properties, chemical stability, etc. Therefore, it is necessary to study the principle of POT in order to obtain SiC ceramic membranes with optimal properties. In this study, the principle of POT was characterized via scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, synchronous thermal analysis, and metallographic microscopy. According to the principle, the conditions, such as the temperature and air flow rate, of the post-oxidation process were optimized. Under the optimized conditions, POT improved the flux of SiC ceramic membranes from 1074 to 5118 L·m−2·h−1·bar−1, increased the bending strength from 26 to 35 MPa, and provided SiC ceramic membranes with high stability under acid and alkali conditions. [ABSTRACT FROM AUTHOR]

The design and synthesis of photocatalytic materials and their application in environmental pollution control and resource recycling have been reported in many literatures. However, most photocatalytic materials contain transition metal ions, and the environmental risks of leaching 1imit the application of catalytic materials. Silicon carbide (SiC), as the representative of the third generation of semiconductor materials, has a good potential application prospect in environmental pollution prevention because of Is characteristics such as no transition metal ions, high temperature and acid-alkali resistance, strong stability and so on. In recent years, some literatures have reported the synthesis, modification and application of SiC as photocatalyst n environment and resource recycling -fields. However, few temperatures have reviewed the application progress of SiC photocatalyst. In view of the above situation, the progress in the -field of SiC photocatalysis application in recent years was reviewed in tins paper, including synthesis method, doping medication and application, and the prospects of the photocatalyst system were also prospected. [ABSTRACT FROM AUTHOR]

In this study, Z-scheme Cr2O3–Fe3O4/C hetero-nanostructure polyhedra are prepared using the amine-functionalized metal–organic framework NH2-MIL-101(Fe) as the precursor through a simple hydrothermal method and impregnation–calcination route. Systematic characterization was conducted on the phase structure, morphology, optical/electrochemical properties and the photocatalytic performance exhibited by the magnetic Cr2O3–Fe3O4/C samples. As observed from the results, Congo red (CR) degradation rates of the magnetic polyhedron-like Cr2O3–Fe3O4/C hetero-nanostructures under visible light are found to be nearly 1.86 and 1.21 times higher than those achieved by Cr2O3 and Fe3O4/C samples, respectively. Complying with the results achieved by the active specie tests, superoxide radicals could be the major active species in the CR photocatalytic degradation due to graphite carbon with high conductivity. On this basis, a model Z-scheme photogenerated carrier transfer system was developed. In the present paper, an approach for developing and designing Z-scheme hetero-nanostructure photocatalysts for purifying wastewater is presented. [ABSTRACT FROM AUTHOR]

As many countries in the world are paying increasing attention to air quality, reducing the concentration of pollutants in the air, protecting human health and improving the ecological environment have become problems that need to be solved urgently. This paper describes how ceria and cobalt tetroxide@polyacrylonitrile (CeO2/Co3O4@PAN) nanofiber membranes are produced using electrospinning technology, which have broad applications for the removal of air pollutants. Results show that CeO2/Co3O4@PAN has high electrostatic attraction to particulate matter (PM). CeO2/Co3O4@PAN membranes show better mechanical properties, thermal stability and air-purification performance than pure PAN membranes. Nanofiber membranes with 5 wt% of CeO2/Co3O4 have excellent removal efficiency: 93.4% and 94.5% for PM2.5 and PM10, respectively, and 96.2% and 98% for formaldehyde and total volatile organic compounds, respectively. They also show low pressure drops, high stability and good recyclability. This work shows that they are promising candidates as highly stable, recyclable and efficient agents for the removal of air pollutants. [ABSTRACT FROM AUTHOR]