Hexavalent chromium Cr(VI) pollution makes has a harmful impact on human health and the ecological environment. Photocatalysis reduction technology exhibits low energy consumption, high reduction efficiency and stable performance, and is playing an increasingly important role in chromium pollution control. Graphite-phase carbon nitride has been used to reduce Cr(VI) to the less harmful Cr(III) due to its visible light catalytic activity, chemical stability and low cost. However, it has a low specific surface area and fast recombination of electron–hole pairs, which severely restrict its practical application. In this work, a TiO₂-modified poly(triazine imide) (PTI) square nanotube was prepared by the one-step molten salts method. The results showed the PTI had a square hollow nanotube morphology, with an about 100–1000 nm width and 60–70 nm thickness. During the formation of the PTI square tube, TiO₂ nanoparticles adhere to the surface of the square tube wall by strong adsorption, and eventually form a PTI/TiO₂ heterojunction. The PTI/TiO₂-7 wt% heterojunction exhibited very good Cr(VI) reduction efficiency within 120 min. The enhanced photocatalytic activity was mainly attributed to the efficient separation and transport of photo-induced electron–hole pairs and the high specific surface area in the heterojunction structure.

Introducing oxygen vacancies into zirconia is an effective strategy to enhance its light absorption and photocatalytic performance. However, the cost-efficient preparation of oxygen-deficient zirconia (ZrO_2-x) remains challenging, which severely limits its broad application. In this study, flash sintering treatment was presented to fabricate ZrO_2-x bulk in a very short time of 90 s. It was found that oxygen vacancies were introduced into ZrO₂ bulk through electrochemical reduction reactions. The as-prepared ZrO_2-x with black color exhibited the excellent optical absorption capability, small band gap (2.09 eV for direct and 1.67 eV for indirect), and reduced conduction band energy, which is ascribed to the generation of oxygen vacancies and reduction of Zr cations. The as-prepared ZrO_2-x showed the remarkable photocatalytic activity due to the excellent solar light absorption and low recombination rate of electron-hole pairs. Flash sintering treatment provides a cost-efficient approach for rapidly fabricating ZrO_2-x bulks with high concentration of oxygen vacancies, which can also be applied to other materials.

Aged asphalt can enormously affect the performance of asphalt pavement and cause serious environmental hazards. Microcapsule-modified asphalt is one of the effective means to improve the anti-aging ability of asphalt. In this work, novel sustained-release microcapsules containing rejuvenator were prepared by the solvent evaporation method. The morphology of the microcapsules was characterized by scanning electron microscopy (SEM). The sustained-release properties of the microcapsules were investigated by static thermogravimetric analysis. The physical properties such as penetration, ductility, softening point, and Brookfield viscosity of the original asphalt and microcapsule-modified asphalt were studied. In addition, the viscoelasticity of the original asphalt and microcapsule-modified asphalt was investigated by means of a dynamic shear rheometer (DSR). The results show that the prepared microcapsules have a smooth surface and a complete encapsulation with an average particle size of 60 μm. After the heating treatment (above 140 °C), a large number of micropores were formed on the shell surface of microcapsules, which provided a structural basis for the sustained-release of rejuvenator. The release rate of the rejuvenator was obviously slowed down by the microcapsules. The aging behavior of sustained-release microcapsules containing rejuvenator-modified asphalt can be greatly improved. The enhanced anti-aging properties of sustained-release microcapsule-modified asphalt are attributed to the functions of the rejuvenator which can be slowly released from the micropores on the microcapsules’ surface, after which the light components lost in the original asphalt can be supplemented.

This study aimed to utilize the hydration characteristics of cement through wet grinding techniques to efficiently and conveniently prepare a stable C-S-H seed suspension, providing key parameters and a scientific basis for their large-scale production, which ensures the stability of the C-S-H suspension during production, transportation, and application. This preparation aimed to mitigate the adverse effects of high-volume silica fume on the early mechanical properties of high-performance cement concrete. The properties of C-S-H seed were characterized in detail by SEM, XRD, and TD. In the concrete performance test, silica fume was used to replace part of the cement, and different contents of C-S-H seed were added to test its effect on the compressive strength of concrete, with XRD and SEM used to analyze the performance differences. The results show that the particle size and hydration degree of cement no longer developed after 90 min of wet grinding. Polycarboxylate ether (PCE) superplasticizer can increase the fluidity of the crystal C-S-H seed suspension when the content exceeds 1.5%. When the content of PCE exceeded 2%, the C-S-H seed suspension precipitated. Adding 5% C-S-H seed can increase the compressive strength of cement concrete by 10% under the condition of reducing the amount of cement and increasing the amount of silica fume. And Ca(OH)₂ (CH) was produced by cement hydration consumed by silica fumes to generate C-S-H gel, by which the concrete became denser with more strength. However, when the amount of C-S-H seed exceeded 7%, the compressive strength of the concrete decreased.

The present research is carried out to inspect the influence of nano-OvPOSS (octavinyl oligomeric silsesquioxane) with different particle sizes on styrene-butadiene-styrene (SBS) modified asphalt through the method of molecular dynamics simulation. This nanomaterial is investigated for the first time to be used in asphalt modification. With the construction of modified asphalt simulation models and the analysis of their mixing energy, radius of gyration (R_g), radial distribution function (RDF), ratio of free volume (RFV), heat capacity, bulk modulus, and shear modulus, this study elucidates the influence of nano-OvPOSS on the compatibility between SBS and asphalt, on the structure of SBS as well as that of asphalt molecules and on the temperature stability and mechanical properties of SBS modified asphalt. The results show that nano-OvPOSS not only is compatible with SBS as well as with asphalt, but also is able to improve the compatibility between SBS and asphalt. Nano-OvPOSS is able to reinforce the tractility of branched chains of SBS and make SBS easier to wrap the surrounding asphalt molecules. The free movement space of molecules in the SBS modified asphalt system also shrinks. Moreover, the addition of nano-OvPOSS into SBS modified asphalt results in higher heat capacity, bulk modulus, and shear modulus of modified asphalt. All of these effects contribute to a more stable colloidal structure as well as more desirable temperature stability and deformation resistance of the modified asphalt system. The overall results of the study show that nano-OvPOSS can be used as a viable modifier to better the performance of conventional SBS modified asphalt.