Microwave Chemical Method Research Articles

Preparation and properties of sliver and nitrogen co-doped TiO2 photocatalyst

TiO2 photocatalysts co-doped with different content of Ag and N were prepared by sol–gel method combined with microwave chemical method. The samples were analyzed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscope (TEM), ultraviolet–visible diffuse reflectance spectrum (UV–vis) and photo-luminescence emission spectrum (PL). The photocatalytic activity was investigated by photocatalytic degradation of methylene blue (MB) under irradiation of fluorescent lamp. The results indicate that Ag and N co-doping can restrain the increase of grain size, broaden the absorption spectrum to visible light region, and inhibit the recombination of the photo-generated electron–hole pairs. Moreover, the photocatalytic activity of Ag–N–TiO2 in MB degradation is remarkable improved. The degradation rate of the sample with Ag:TiO2=0.05at%, N:TiO2=18.50wt% in 5h is 93.44%, which is much higher than that of Degussa P25 (39.40%).

Removal of Nickel and Vanadium from Crude Oil by Microwave-Chemical Method. I. Chemical Method

WY series demetalizers, some types of thiocarbamate, were synthesized by organic amine (diethylene triamine and triethylene tetramine), carbon disulfide, and sodium hydroxide and used to remove nickel and vanadium from crude oil. WY-1 demetallizer has excellent removal of nickel and vanadium efficiency for Shengli crude oil and Iran crude oil. The nickel and vanadium removal efficiency of Shengli crude oil reached 43.41 and 41.63% at the dosage of WY-1 500 mg/L, reaction time 30 min, and reaction temperature 70°C. With the dosage of WY-1 and increasing reaction time and reaction temperature, the nickel and vanadium removal efficiency of crude oil increased.

Application of Experimental Teaching in University Education of Inorganic Material Specialty English

In the paper, the experimental teaching is adopted to the inorganic material specialty English to promote the English comprehensive ability and professional skills of students. The experiment is to prepare sepiolite nanofibers by means of the microwave chemical method using natural sepiolite samples as raw materials. Through the experiment, the English practical ability and skills of students are developed.

Influence of praseodymium and nitrogen co-doping on the photocatalytic activity of TiO 2

TiO 2 nanoparticles co-doped with different doping concentration of Pr and N were prepared by sol–gel method combined with microwave chemical method. The samples were characterized by XRD, FT-IR, UV–vis, TEM, XPS, PL, and the photocatalytic activity were investigated by photocatalytic degradation of methylene blue (MB). The results indicate that Pr and N ions incorporate into the lattice of TiO 2, co-doping restrains the increase of grain size, broadens the absorption region to visible light, and inhibits the recombination of the photo-generated electrons and holes. Moreover, the photocatalytic activity of Pr–N-TiO 2 is remarkable improved due to the synergistic effect of the co-doped ions. The degradation rate of MB in 6 h is 92.81%, which is much higher than that of Degussa P25 (45.01%).

Preparation and Properties of Expanded Vermiculite/Gypsum Thermal Insulation Boards

In this paper, thermal insulation boards comprising expanded vermiculite and gypsum were manufactured by casting and compression molding methods respectively. The effects of flake size and preparation methods of expanded vermiculite (EV), ratio of calcined gypsum/EV and molding methods on thermal and mechanical properties were discussed. The results indicated that the thermal conductivity (λ) and compressive strength of the boards decreased with the increase of flake size, and increased as the ratio of calcined gypsum/EV rose, and the density of the boards increased linearly with the increasing ratio. Compared to compression molding, casting technique can make insulating materials with higher thermal conductivity, compressive strength, and lower water content. The boards containing EV expanded by microwave chemical method presented a better thermal insulating property (λ=0.091W•m-1•K-1) relative to the ones filled with microwave exfoliated EV (λ=0.107W•m-1•K-1). The prepared materials can be used for heat, acoustical insulation and moisture adjustment.

First-principles study on anatase TiO2 codoped with nitrogen and praseodymium

The crystal structures, electronic structures and optical properties of nitrogen or/and praseodymium doped anatase TiO2 were calculated by first principles with the plane-wave ultrasoft pseudopotential method based on density functional theory. Highly efficient visible-light-induced nitrogen or/and praseodymium doped anatase TiO2 nanocrystal photocatalyst were synthesized by a microwave chemical method. The calculated results show that the photocatalytic activity of TiO2 can be enhanced by N doping or Pr doping, and can be further enhanced by N+Pr codoping. The band gap change of the codoping TiO2 is more obvious than that of the single ion doping, which results in the red shift of the optical absorption edges. The results are of great significance for the understanding and further development of visible-light response high activity modified TiO2 photocatalyst. The photocatalytic activity of the samples for methyl blue degradation was investigated under the irradiation of fluorescent light. The experimental results show that the codoping TiO2 photocatalytic activity is obviously higher than that of the single ion doping. The experimental results accord with the calculated results.

Preparation of Expanding Vermiculite by Chemical and Microwave Methods

Based on the characters of expanding and layer adsorbing of vermiculite，industrial vermiculite samples from Weili Mine of Xinjiang Province were expanded by both chemical and microwave chemical methods. The influences to the exfoliation ratio of different parameters such as concentration of hydrogen peroxide, power of the microwave, heating time, ratio of solid-liquid, immersion time were discussed. And the expanded mechanism of vermiculite was also analyzed. The results indicate that the expanded times increase with the increasing of concentration of hydrogen peroxide, and the best expanding point appears when the concentration of hydrogen peroxide is 30%. The solid-liquid ratio of vermiculite and hydrogen peroxide has little effect on the expanding of vermiculite. The vermiculite samples could be expanded 8.5 times by heated 2 min under 800W microwave power after immersion for 12 h when the concentration of hydrogen peroxide is 30%. As a result, the vermiculite could be expanded because of the oxygen pressure produced by the decomposition of hydrogen peroxide into the vermiculite interlayer. When using the microwave chemical method, the pressure of both oxygen and interlayer water lead to the increases of the expanded times. And exfoliation vermiculite plays an important part in energy-saving and environmental treatment.

Study on Demulsification of Crude Oil Emulsions by Microwave Chemical Method

The demulsifying and separating experiments of crude oil emulsion were performed by using the heating method, the thermal chemical method, the microwave radiating method, and the microwave chemical method separately. The water content of this emulsion was 78 v/v%, and the type was water‐in‐oil (w/o). The influence tendencies of the key factors on demulsification effect were explored by changing the heating temperature, the demulsifier amount used and the microwave radiating time in this paper. With the microwave chemical experiments on the self‐made emulsions of different water content, the demulsification rate and separation efficiency were explored. The type of these emulsions were oil‐in‐water (o/w), water‐in‐oil (w/o) and the multiple type, related to the water content scopes which were less than 30 v/v%, more than 70 v/v% and between them, respectively. The separation effect by the microwave chemical method for the high water content crude oil emulsion was better than that of emulsion with lower water content. For the crude oil used in this experiment, the result could be obtained that the separation efficiency was about 95 v/v% under the conditions of 50 ppm of demulsifier, 10 seconds radiation time, and 1 minute settling time for the microwave chemical method.