Songtian Li

Study on Degradation of Crystal Violet by UV/Fenton/Heteropolyacid System

The degradation of an azo dye crystal violet by UV/Fenton oxidation process in the presence of heteropolyacid solution has been investigated. The degradation rate is strongly dependent on the pH, initial concentrations of the dye, Fe 2+ , H 2 O 2 and phosphotungstic acid. The effect of these parameters has been studied and the optimal reacting conditions were experimentally determined. It was found to be initial pH 2.7, [H 2 O 2 ] =71 mM, [Fe 2+ ] = 0.5 mM, [dye] 0 = 20 mg/L, phosphotungstic acid concentration is 24 mg/L. Under optimal conditions, 95% degradation efficiency of dye in the presence of heteropolyacid solution was achieved after 60 min of reaction. The experimental results showed that the UV/Fenton oxidation process was an effective process for the degradation of crystal violet at low H 2 O 2 and Fe 2+ concentrations. Meanwhile, this research also proved that heteropolyacid could improve the photocatalytic efficiency in the UV/Fenton reaction as an efficient activator.

Study on Treating Dyeing and Finishing Wastewater with Combined Process of Anaerobic-PAC-SMBR

Submerged membrane bioreactor was used to investigate dyeing and finishing wastewater. Considering its unique characteristics, anaerobic process was carried out before membrane bioreactor, and powdered activated carbon was added to the reactor in order to change the property of the mixed liquor. Combination of the three processes above constituted combined process of Anaerobic-PAC-SMBR, by which the reduction of pollution indexes in wastewater during each treatment unit and the property of membrane fouling in the system were studied. The results showed that under the optimum conditions the CODCr content in effluent water was approximately 120 mg/g, removal rate of ammonia nitrogen was 93%, the chrominance was lower than 5 times, the turbidity was less than 30 FTU, and the suspended substance was zero. Addition of powdered activated carbon effectively altered the characteristic of the mixed liquor, and alleviated the membrane fouling, so it facilitated the cleaning of the membrane and the recover of the membrane flux. Combined process of Anaerobic- PAC-SMBR exhibited excellent treatment effect and stability to dyeing and finishing wastewater.

Preparation and Photocatalytic Performance of Complex Photocatalyst H3PW12O40/TiO2/Na2Ti3O7

A new carrier of catalyst-Na₂Ti₃O₇ whisker was selected and TiO₂/Na₂Ti₃O₇ was prepared by sol-gel method, then complex photocatalyst H₃PW₁₂O₄₀/Na₂Ti₃O₇ was prepared by dipping way. SEM photographs showed the production was covered well, TiO₂ was anatase type and H₃PW₁₂O₄₀ was Keggin structure. UV-vis RDS showed wavelength range unfolded red shifts. The photocatalytic activity of H₃PW₁₂O₄₀/TiO₂/Na₂Ti₃O₇ was studied in a self-made reaction devices with methyl purple as the substrate, the photocatalytic activity was researched by the decolorizing rate effect of light intensity, temperature of system, aeration volume quantum, simulant pollutant concentration, and the dosage of catalyst. The experimental results directed that the complex photocatalyst shows good activity. The decolorizing rate of methyl purple achieved over 94% when its concentration was 10 mg/L and illumination intensity was 250 W in 80 minutes. Compared to TiO₂/Na₂Ti₃O₇ the decolorizing rate was improved 32.3% (at 80 minute) and 82.4% (at 10 minute) by the photocatalyst of H₃PW₁₂O₄₀/TiO₂/Na₂Ti₃O₇.

Study on Preparation and Performances of TiO2/Potassium Titanate Photocatalyst

A new carrier of catalyst was chosen. Sol-gel method was used to preparate TiO2/potassium titanate photocatalyst. EDS shows the main peck included Ti, O, K in potassium titanate whisker. The main peak of K disappeared and the peaks of Ti, O stayed after whisker was covered. It directed that the surface of sample was covered by TiO2. The figure of UV-vis diffuse reflection shows TiO2/potassium had more stronger peak in ultraviolet area. In the reaction device of photochemistry, using middle-pressure mercury lamp as illumination, rhodamine B as simulant pollutant, the photocatalytic performance of TiO2/potassium titanate was studied. The decoloration rate of TiO2/potassium titanate which was used to deal with rhodamine B in the experiment was influenced by the pH value, light intensity, reaction temperature, aeration quantum, the dosage of catalyst and initial concentration of rhodamine B. Such conditions were chosen: pH 6, the illuminance of 250 W, the temperature of 313 K, the aeration quantum of 2.0 L/min. When the concentration of rhodamine B was 8 mg/L, the dosage of TiO2/potassium titanate was 0.01 g/L. The decoloration rate of TiO2/potassium titanate dealt with the rhodamine B reach over 95 % in 160 minutes, and compare with TiO2, the decoloration rate of rhodamine B was improved 0.50-1.91 multiple.

Synthesis and properties of B–Ni–TiO 2 /g-C 3 N 4 photocatalyst for degradation of chloramphenicol (CAP) under visible light irradiation

Firstly, B, Ni co-doped TiO2 (B–Ni–TiO2) was prepared by sol–gel method, g-C3N4 was prepared by calcination method. Secondly, B–Ni–TiO2/g-C3N4 composite photocatalysts were prepared by heating reflux method. The physical and chemical properties of the composite photocatalysts were characterized by XRD, XPS, UV–Vis, FT-TR, SEM, PL and TEM, HRTEM. The effect of different photocatalysts on the degradation of chloramphenicol was investigated. After the combination of g-C3N4 and B–Ni–TiO2, the separation efficiency of photo-generated electrons and holes can be accelerated and the photocatalytic activity can be improved. When the ratio of g-C3N4 and B–Ni–TiO2 was 1:4, the degradation rate of chloramphenicol by the composite photocatalyst was up to 95%. After five photocatalytic degradation experiments, the photocatalytic activity of the composite photocatalyst was not significantly reduced, the result showed that the composite photocatalyst had better stability and regeneration performance. The ·O2− was responsible for the photodegradation activity were determined and a possible mechanism was proposed.

Preparation Complex Photocatalyst of Modified TiO2/K2Ti6O13 by Tungstosilicic Acid and Study its Degradation of Methyl Orange

With potassium titanate (VI) whisker as carrier, and silicotungstic acid (H4SiW12O40) as modified reagent, the compound photocatalyst H4SiW12O40/TiO2/K2Ti6O13 was prepared by sol-gel-dipping method. UV-vis spectra showed that the compound photocatalyst had strongly responded to UV light and had some absorbency of visible light. The photocatalytic activity was evaluated by degradation of methyl orange under UV light. The photocatalytic influences of initial concentration of methyl orange, the dosage of catalyst, pH value, temperature, intensity of light were investigated. The results indicate that the photocatalyst of H4SiW12O40/TiO2/K2Ti6O13 has higher photocatalytic activity. The degradation rate of methyl orange could reach over 85 % under the experimental conditions.

Preparation, Characterization and Photocatalysis Properties of Visible Spectral Response Photocatalyst CoPcS/TiO2/K2Ti4O9

Photocatalyst CoPcS/TiO2 was prepared by sol-gel method. Composite CoPcS/TiO2/K2Ti4O9 was prepared by dipping. It was incandesced at various temperatures and modification effect was compared. The results showed that optical absorption of sample incandesce at 423K occurred significant red-shift. Light absorption width extended from ultraviolet region to visible region, especially there was an intensive absorption between 600 nm and 680 nm. X-ray diffraction spectrogram showed that TiO2 in sample still maintained anatase crystal form. Under the illumination of visible light, photocatalysis degradation experiment was taken with Orange II as simulated pollutants. Decoloration rate of Orange II was much improved. The rate can reach 85% in 300 minutes.

Study on Determination of Trace Cu (II) by Sodium Diethyldithiocarbamate Chelating Resin Preconcentration and Thin Layer Resin Phase Spectrophotometry

A new method to determine trace Cu(II) by sodium diethyldithiocarbamate chelating resin preconcentration and thin layer resin phase spectrophotometry has been developed. The method has a high sensitivity (ε 435=3.6×105 L•mol-1•cm-1), which is 33 times higher than that of liquid phase spectrophotometry. It has a good selectivity (most coexisting ions can not influence of determination) and an ideal precision (30 μg Cu(II), n=6, RSD=1.67%). The content of Cu(II) in water, high purity rare earth and its oxide has been determined, the detection limit of Cu(II) is 5.3 μg•L-1, the linear range is 0~7.2 μg•mL-1.

Preparation of Loading TiO2/Hollow Pearls Photocatalyst and Its Photocatalytic Activity

The loading photocatalyst of TiO2/hollow pearls was prepared by sol-gel method and hollow pearls as carrier. The results indicate that the approach of TiO2 loading on hollow pearls is viable. The scanning electron microscope (SEM) images show that the coating layer is symmetrical on the hollow pearls; the UV-vis DRS shows that TiO2/hollow pearls has strong absorption in the UV range, and the absorption is not notable change in visible range. The photocatalytic experiment was carried out under UV light irradiation with degradation Malachite Green. The loading photocatalyst of TiO2/hollow pearls obtained better photocatalytic activity which the degradation rate could reach over 70% under the experimental conditions.

Study on Determination of Trace Fe(II) in Environmental Samples by Thin Layer Resin Phase Spectrophotometry

A new method for the determination of Fe(II) by thin layer resin phase spectrophotometry in alkali condition has been reported. The complex anion formed by Fe(II) and VA is absorbed on the 717# resin and Fe can be determined by making thin layer. The method has a high sensitivity (ε620=3.0×105 L•mol-1•cm-1), which is 15 times higher than that of liquid phase spectrophotometry. It has been proved a satisfactory precision (5.0μg Fe(II), n=6, RSD=1.8%). The trace Fe(II) in natural water has been determined, the recovery is 97%～98%.