A new two-dimensional layered mesoporous kaolinite based photocatalysis composite with strong visible light response and high photocatalytic efficiency was successfully prepared by acid-base etching and thermal polymerization, using mesoporous kaolinite (PK) as carrier and dicyandiamide as precursor. The crystal structure, molecular composition, microstructure, specific surface area, pore structure, and photochemical properties of the photocatalytic composites were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, specific surface area test, UV-Vis absorption spectroscopy, electrochemical impedance spectroscopy and other detection methods. The results show that when the mass ratio of PK to g-C₃N₄ (GCN) is 1∶3, the prepared PK/GCN-3 composite has a larger specific surface area (25.9 m²/g) and a wider visible light absorption threshold (517 nm). The apparent reaction rate constant of PK/GCN-3 in terms of the degradation of Rhodamine B dye was 5 times that of pure GCN after 6 h visible light irradiation.

Noting the extensive application of minerals in catalysts and the urgent solution to address the global greenhouse problem caused by the too fast release of CO₂, TiO₂-attapulgite (ATP) was prepared by using a sol-gel method, on which Ni-Ru catalyst was loaded through impregnation for CO₂ methanation. Performances of the samples with different contents of Ru and Ni were compared, while the influence of CO₂ intake rate was especially studied and the reaction mechanism was explored by using in-situ IR spectroscopy. It was found that the bimetallic catalyst had excellent low temperature activities, whereas the effect of Ru was more pronounced. Among the catalysts prepared, 5Ni-1Ru-TiO₂-ATP has the best catalytic effect, with the CO₂ conversion rate reaching 47.9% at 350℃ and the highest (59.6%) at 400℃. Compared with the catalyst without Ru prepared under the same conditions, the conversion rate at 350℃ was increased by 31.8%, and at 400℃ by 26.5%. Excessive intake rate leads to insufficient gas-solid contact and poor catalytic effect. The composite catalyst followed a reaction path with CO* radicals as the intermediate.

Acid leaching, alkali leaching and alkali leaching combined with hydrothermal process were used to control the pore structure of stellerite, while the pore structure characteristics, phase composition, micro morphology, chemical composition and humidity controlling performance of stellerite samples were systematically evaluated. The acid treatment led to an increase in the number of micropores and mesopores of 2-10 nm, while the alkali treatment resulted in an increment in the number of mesopores of 2-50 nm. The combined process of alkali leaching and hydrothermal allowed the pore structure regulation of stellerite at lower alkali concentrations. The moisture absorption capacity of the stellerite was increased as the number of micropores was increased, while the moisture release behavior was enhanced if the number of the 10-50 nm mesopore and macropore was raised. In the relative humidity range of 33-75%, the balance of moisture absorption and desorption of the alkali treated samples was better than that of those the acid treated ones. After leaching with 3 mol/L hydrochloric acid solution, 5 mol/L sodium hydroxide solution and 0.6 mol/L sodium hydroxide solution hydrothermal reaction, the 12 h moisture control capacities reached 4.44%, 5.41% and 3.72% respectively, which were 4.62 times, 5.84 times and 3.71 times respectively higher than that of the untreated stellerite.

Diatomite samples were prepared at different calcination temperatures, with Linjiang diatomite as raw material. Pore structures of the diatomite and calcined samples were characterized by using the low-temperature nitrogen adsorption and the mercury intrusion technologies. With these experimental data, fractal characteristics of the diatomite and the calcined samples were analyzed with FHH model, Menger sponge model and thermodynamic relations model. It was found that the diatomite contained mainly mesoporous and macropores. With increasing calcination temperature, specific surface area and mesoporous volume of the diatomite samples were decreased, while the proportion of the macropores was increased. At the same time, the sample surface roughness was reduced or the surface became smoother and smoother. When the calcination temperature was lower than 600℃, fractal dimension of the mesopore volume and heterogeneity of the mesoporous structure were decreased with increasing calcination temperature. The deformation of the mesoporous structure and the mesoporous volume fractal dimension was seriously accelerated after calcining at 1000℃. When the calcination temperature was higher than 600℃, the fractal dimension of the macroporous pores was reduced, while the roughness and inhomogeneity of macropore surface of the samples were decreased.

Monoclinic pyrrhotite (M-Pyr) was derived from pyrite through thermal decomposition in nitrogen atmosphere with controlled temperature and time, which was used to activate sodium persulfate (PDS) for the degradation of oxytetracycline (OTC). The effects of initial concentration of OTC, initial solution pH value, contents of PDS and M-Pyr on OTC degradation were studied. The contents of PDS and M-Pyr had a positive effect on the OTC removal rate, while the effect of the initial OTC concentration was negative. Specifically, 99% of OTC was degraded in the M-Pyr/PDS system with pH=6-7, ρ (M-Pyr) =0.1 g/L and c(PDS)=1.0 mmol/L. The removal rate of OTC was 86.5% after recycling for two times, where the relatively poor recyclability might be attributed to the corrosion of M-Pyr and the formation of intermediate product to occupy the active sites. Sulfate radical and hydroxyl radical were the main active species in the M-Pyr/PDS system.

Organic silicon waste residue was used as silicon source to prepare MCM-41 mesoporous silica by using alkali fusion and hydrothermal reaction method. The effect of alkali fusion time and liquid-solid ratio on extraction rate of the silicon source was evaluated, while the effect of CTAB/SiO₂ molar ratio on structure of the mesoporous silica was detailly explored. Besides, adsorption performance of the MCM-41 toward Rhodamine B (RhB) was comprehensively studied. It was found that the MCM-41 possessed highest degree of ordered mesoporous structure, after calcining for 2 h, with the liquid-solid ratio of 50∶1 mL/g, and CTAB/SiO₂ molar ratio of 1∶0.3. Accordingly, the specific surface area, pore size and pore volume of the sample were 783.23 m²/g, 2.529 nm and 0.7479 cm³/g, respectively. In addition, the RhB could be effectively removed with MCM-41, with the maximum efficiency to be 295.23 mg/g. Isotherm and kinetic studies revealed that the RhB removal process could be well fitted with Langmuir and pseudo-second-order kinetic models. Meanwhile, owing to its spontaneous and exothermic adsorption, MCM-41 exhibited a high recyclability.

Two typical montmorillonite samples, with layer charge densities of 0.342 and 0.439, measured by using alkylammonium method, were selected in this study. The effects of layer charge density on the two-dimensional (2D) exfoliation of montmorillonite and the surface electrical properties of the nanosheets after exfoliation were studied. The mechanisms of the exfoliation and hydration swelling ability of montmorillonite were explained using molecular dynamics simulation. It was found that montmorillonite with relatively low layer charge density exhibited stronger hydration and swelling ability and thus was easier to be exfoliated into 2D nanosheets. The exfoliated 2D nanosheets from the montmorillonite with higher layer charge density had larger electronegativity per unit area. The lower layer charge density of montmorillonite, the weaker adsorption of water molecules on the surface of montmorillonite crystal layer, the stronger interlayer cation hydration and greater hydration swelling ability, could be used to explain the fact that the montmorillonite with low layer charge density was more easily exfoliated into 2D nanosheets.

4A zeolite was prepared by using calcination and hydrothermal method with weathered granite sand tail mud as silicon and aluminum sources. The optimal calcination temperature was determined to be 600℃. Based on the single-factor experiment, in terms of cation exchange capacity, according to the experimental design principle of central composite, NaO₂/SiO₂, H₂O/NaO₂, crystallization temperature and crystallization time were all optimized. The optimum parameters were determined to be Na₂O/SiO₂=1.42, H₂O/Na₂O=61.00, crystallization temperature of 90.89℃, and crystallization time of 8.16 h. The corresponding optimum was 198.50 mmol/100 g. The as-obtained 4A zeolite was characterized by using scanning electron microscopy and X-ray diffraction, indicating that it was highly crystallized. The removal mechanism of NH₄⁺-N from the solutions with the 4A zeolite was attributed to the ion exchange and NH₄⁺-N adsorption on the 4A zeolite, which could be well described with the pseudo-second-order kinetic model and the Langmuir model. In addition, the maximum adsorption capacity to NH₄⁺-N was calculated to be 102.04 mg/g. Therefore, this 4A zeolite could be used as highly efficient adsorbents to remove NH₄⁺-N from water.

Si₃N₄/BaAl₂Si₂O₈(BAS) composite ceramics were prepared by a novel freeze gelation method. The flexural strength, flexural modulus, flexural fracture and microstructures of Si₃N₄/BAS composite ceramics were investigated at different temperatures (i.e., 25-1 400℃) and BAS contents (i.e., 7.5%-40.0%, in mass fraction). The results show that the high-temperature mechanical properties of Si₃N₄/BAS composite ceramics can be improved via the increasing of BAS content. At 1 400℃ and 40% BAS, the flexural strength and flexural modulus of Si₃N₄/BAS composite ceramics are 241 MPa and 92 GPa, respectively. At 25-1 400℃ and 30%-40% BAS, Si₃N₄/BAS composite ceramics become a rigid fracture mode, and the sintered body is mainly composed of β-Si₃N₄ and BAS without Si₂N₂O. In air, the testing samples show a surface oxidation phenomenon at 1 500℃, but the samples are not oxidized at <1 400℃.

As the ideal candidate materials for high-temperature structure parts in aeronautics and astronautics domain, SiC/SiC composites possess some advantages, e.g., heat-resistant, oxidation resistance, ablation resistance and heat shock resistance. Interphase is one of critical factors affecting the performances of SiC/SiC composites. According to the interphase design philosophy of ceramics matrix composites, the interphases of SiC/SiC composites are divided into four kinds, i.e., layered structure, refractory oxide, rare metal salts and multiple components ceramics. In this review, the species and styles of interphase, modifying effects on mechanical and oxidation resistance properties, influence factors on the properties and mechanisms and some existing problems were represented, and the proper perspectives were proposed.