The relationships among the fluidity, setting time, and pH value of hydrated magnesium silicate (MgO-SiO₂-H₂O, M-S-H) prepared by silica fume (SF) and MgO after calcination at different temperatures were investigated, and the strength and shrinkage characteristics of M-S-H cementious materials were analyzed. The effect of MgO on the hydrated products of MgO-SF and the structure of M-S-H at different calcination temperatures was investigated by X-ray diffraction and thermogravimetric analysis. The results show that the intensity of MgO diffraction peak increases, the peak width becomes narrower, the grain size increases, and the activity decreases as the calcination temperature increases. The contents of Mg(OH)₂ and M-S-H in the pure pulp prepared by calcining MgO at 1 150 ℃ are the highest, and the degree of polymerization of M-S-H silicon tetrahedron becomes the maximum value. The MgO-SF pulp and mortar slump prepared by calcining MgO at 1 150 ℃ are 129 mm and 206 mm, respectively, in accordance with the large-flow concrete. The pH value and setting time of the pulp are moderate, the mortar strength is high, and the dry shrinkage rate (ε_t) is the minimum value. ε_t is positively correlated to the change in Mg(OH)₂ content.

Chloride-induced corrosion is one of the major deterioration mechanisms of reinforced concrete that may seriously affect the durability of the structures in marine environment. The deterioration of concrete durability as a long-term process is usually investigated by lab-scale artificial acceleration simulation. However, there is no normative standard in the corresponding test methods, test systems and acceleration factors in the indoor simulation and coastal exposure research on concrete durability, thus restricting the engineering application of the research results. It is necessary for the durability of concrete structure research more practical engineering significance to establish the similarity relationship of chloride ion ingress into concrete between the coastal exposure environment and the indoor simulated environment. It could accurately evaluate the durability and predict service life of concrete structures in the marine environment. From the viewpoints of single factor and multi-factor effects, the available experimental, theoretical analysis and numerical simulation of the similarity of chloride ion ingress into concrete were introduced, respectively. The research findings on the similarity of chloride ion ingress into concrete exposed to marine environment were summarized. The relevant discussion and expectation of this subject were conducted, thus providing a basis for future theoretical research and practical engineering application.

Carbon nanotube is a kind of excellent nanomaterial. The incorporation of carbon nanotubes will affect the microstructure and macroscopic properties of cement-based materials. The research results about carbon nanotubes on the microstructure and durability of cement-based materials were analyzed. The effect of carbon nanotubes on the hydration characteristics, pore structure, micro-crack, internal interface, carbonization resistance, ion erosion resistance, frost and thaw resistance of cement-based materials and their mechanism were discussed. The results show that carbon nanotubes promote the generation of hydration products through nucleation and affect the hydration reaction rate of cement. The pore structure and internal interface of cement-based materials were optimized by the filling and bridging effects of carbon nanotubes, thus hindering the forming and expanding of micro-cracks Also, carbon nanotubes can improve the durability of the cement-based materials, such as carbonization resistance, ion erosion resistance, frost and thaw resistance via the optimization of the microstructure of the cement-based materials. At present, some further researches are thus needed since the research results of carbon nanotubes on the microstructure and durability of cement-based materials are relatively less and the relevant conclusions obtained are different.

The viscosity of Ge₁₀As₄₀Se₅₀ chalcogenide glass was investigated by fiber elongation and rotation methods. The Vogel-Fulcher-Tammann equation was proposed as an optimal fitting model after comparing to the accuracy of different equations. Ge_xAs_ySe_1-x-y glasses were compared according to the fragility, m, derived from the Angell plot. The network structure of Ge₁₀As₄₀Se₅₀ chalcogenide glass was investigated by X-ray photoelectron spectroscopy (XPS). The results show that the fragility change of Ge_xAs_ySe_1-x-y glasses follows the topological constraint theory in the range of the average coordination numbers (i.e., r=2.0-2.6). The m of Ge_xAs_ySe_1-x-y glasses decreases as r increases. However, the m does not strictly decrease as r increases when r is greater than 2.2. Based on the XPS results, Ge₁₀As₄₀Se₅₀ chalcogenide glass exists Se chain in the network structure, thus affecting the stability and results at a greater m.

TiO₂/Ti₃C₂T_x composites were synthesized by a solvothermal method with Ti₃C₂T_x as substrate and isopropanol (C₃H₈O) as an inducer. The phase composition and microstructure of TiO₂/Ti₃C₂T_x were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and ultraviolet-visible diffuse reflectance spectroscopy. The results show that anatase type TiO₂ is uniformly grown on the layered surface of Ti₃C₂T_x, thus improving the electron transport performance of TiO₂/Ti₃C₂T_x composites. The optimum photocatalytic performance of TiO₂/Ti₃C₂T_x-24 h can be obtained under the irradiation of 500 W mercury lamp (365 nm UV light), and the degradation efficiency of methyl orange (MO) is 95% for 75 min, which is 67.7% greater than that of pure TiO₂ photocatalyst.

Cu/Fe-layered doubled hydroxide (CuFe LDH) prepared by a coprecipitation method was used to degrade methylene blue (MB) and ammonia as a heterogeneous photoactivator of NaClO. The micro-morphology, reaction kinetics and degradation mechanism were investigated. The layered structure of the samples with Cu/Fe molar ratios from 2∶1 to 4∶1 was analyzed. The catalyst with Cu/Fe molar ratio of 3∶1 exhibits the optimum performance under given conditions (i.e., catalyst dosage of 0.5 g/L and NaClO of 0.075 mL), and the pseudo-first-order rate constant of 30 mL MB (100 mg/L) is 7.9 times greater than that without any catalyst. 30 mL ammonia (100 mg/L) at the catalyst dosage of 3 g/L and NaClO of 0.3 mL can be degraded by 99.5% within 1 min, compared to that of 66.6% without any catalyst. Based on the radical quenching experimental results, the superoxide radicals are the dominant reactive oxidants, and also involve chlorine radicals and hydroxyl radicals. The results by electrochemical impedance spectra and X-ray photoelectron spectroscopy reveal that the photoelectrons can accelerate the in-situ regeneration of reaction activity sites on the surface of catalyst and increase the separation efficiency of photo-induced charges in CuFe LDH/NaClO/light system, resulting in the improved degradation of waste water pollutants.

Different rare earth ions (i.e., Nd³⁺, Y³⁺, Eu³⁺) doped BiVO₄ nanocrystals were synthesized by a chemical protocol method. The phase composition, crystal structure, morphology, local structure, surface chemistry and spectral properties of the nanocrystal samples were investigated by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, ultraviolet-visible diffusion reflective spectroscopy and photoluminescence spectroscopy. The results show that the sizes of different ion-doped BiVO₄ crystals are in nanoscale, the BiVO₄ nanocrystals doped with different ions have a tetragonal crystal structure. and the obtained nanocrystals have regular morphologies and clear profiles, indicating that the obtained nanocrystals have a good crystallization performance and exhibit a certain degree of lattice distortion. Raman peaks of doped BiVO₄ nanocrystals appear at about 247, 367, 763 and 855 cm^-1, which are consistent with the characteristic vibration frequencies of BiVO₄ structure with tetragonal phase. UV-visible diffuse reflectance spectrum shows that the internal electronic structure of the BiVO₄ nanocrystals changes after doping ions, the band gap energies of BiVO₄, Eu:BiVO₄, Y:BiVO₄ and Nd:BiVO₄ nanocrystal are 2.50, 2.74, 2.90 and 2.94 eV, respectively, indicating that doping different ions could regulate the band gap of the semiconductor nanocrystals. Based on the results by photoluminescence spectroscopy, the minimum luminescence intensity of Eu:BiVO₄ nanocrystals is obtained, showing the minimum electron hole recombination efficiency, which is suggested that the Eu:BiVO₄ nanocrystals has higher photocatalytic activity. The maximum luminescence intensity of Y:BiVO₄ nanocrystal is obtained, thus having the maximum electron hole recombination efficiency.

Calcium polyphosphate (CPP) was modified via the Schotton-Baumann acylation reaction using 12-aminododecanoic acid (12-AA) and acryloyl chloride as main raw materials. The effects of hydrothermal reaction time and 12-AA dosage on the modification process of CPP were investigated. They were characterized by Fourier infrared spectroscopy, X-ray diffraction and scanning electron microscopy. The particle size, contact angle and thermal stability of CPP were also determined. The results show that the yield of CPP-modified increases with increasing the hydrothermal reaction time and 12-AA content. In the acylation process, the pH value decreases as the reaction time increases until stable (i.e., a weak acidity, pH 6.2). A greater yield (i.e., 56.70%) and the smaller particle size (i.e., 588.3±119.7 nm) of modified CPP are obtained when a molar ratio of CPP to 12-AA is 1∶3 and the reaction time is 12 h. The contact angle before and after the modification increases from 2 to 61.41 degrees. Based on the results by thermogravimetric analysis, the CPP has a good thermal stability with little mass loss at <592.92 ℃. However, the modified CPP still has a good thermal stability and shows an obvious mass loss at 426.68-461.66 ℃.

ATP/g-C₃N₄ (graphitic carbon nitride) consisting of g-C₃N₄ film in-situ growth on the surface of attapulgite (ATP) rod was prepared via a hydrothermal process. Then ATP/g-C₃N₄ was used as a carrier to uniformly load LaCoO₃ nano-particles to prepare Z-scheme ATP/g-C₃N₄/LaCoO₃ heterojunction photocatalysts. The samples obtained were characterized by X-ray diffraction, transmission electron microscopy, ultraviolet-visible, photoluminescence, Brunauer-Emmett-Teller, specific surface area analysis and photo electrochemical analysis. The oxidative removal ability of ATP/g-C₃N₄/LaCoO₃ at different loadings of LaCoO₃ to benzothiophene (DBT) in model gasoline was investigated under visible light. The results show that ATP/g-C₃N₄/LaCoO₃ composites dramatically enhance the visible light response, the absorption capacity and the separation of photogenerated electron-hole pairs, compared to ATP/g-C₃N₄ andLaCoO_3. After 150-min irradiation, the desulfurizing rate of 50%-ATP/g-C₃N₄/LaCoO₃ can achieve 85.3%.

The SiO₂ in the molybdenum tailings is purified by high-temperature heating and pickling, and the surface is modified with methylhydrogen-containing silicone oil and dimethyl diethoxysilane(DDS).The results show that the impurities such as calcium and magnesium can be effectively removed, and the purified content of silicon oxide can reach 84.3%. When methyl hydrogen-containing silicone oil is used as a modifier, the activation degree of modified slag can reach 77.6%, and the maximum contact angle can reach 116°. Methyl hydrogen-containing silicone oil can be effectively grafted onto the surface oftailing particles. When dimethyl diethoxy silane is used as a modifier, the activation degree can reach 95%, the contact angle can reach 130°, and dimethyl diethoxy silaneis uniformly coated on the surface of tailing particles. The application of modified molybdenum tailings silica in ammonium hydrogen phosphate extinguishing agent shows that it can improve the water repellency of ammonium hydrogen phosphate extinguishing agent.