Effect of Dispersity and Porous Structure of TiO2 Nanopowders on Photocatalytic Destruction of Azodyes in Aqueous Solutions

Photocatalytic activity of TiO2 nanopowders of anatase modification with various particle sizes and specific surface areas has been studied in the process of photocatalytic decolorization of aqueous solutions of methylene blue and direct blue 2C azodyes. By means of scanning electron microscopy and low-temperature N2 adsorption method, it was found that TiO2 nanopowders have the particles size of 5-120 nm with the specific surface area of 15-120 m2·g^-1. The used TiO2 samples are characterized by mesoporous structures with average pore size of 4.3-14.9 nm. The photocatalytic activity of TiO2 was evaluated via decolorization of azodyes solutions. It was shown that the efficiency of decolorization symbatically changes with the dye adsorption value on TiO2 surface and the degree of decolorization rises when the surface area of TiO2 nanopowders increases. It was found that TiO2 photocatalytic activity essentially depends on adsorption interactions between the dye molecules and catalytic active centers on TiO2 surface, and these interactions, in turn, are greatly affected by pH of the solution.     

Mesoporous Structure and Photocatalytic Activity of Doped Polyanilines

Photocatalytic activity of doped polyaniline nanopowders with different molar ratio of An/O （aniline~oxidizer） has been studied in the process of photocatalytic decolorization of aqueous solutions of methylene blue. By means of scanning electron microscopy and low-temperature N2 adsorption method, it was found that doped PANI （polyaniline） nanopowders have the particles size of 30-50 nm with the specific surface area of 20-35 m2.g＂~. It was found that PANI photocatalytic activity essentially depends on molar ratio of An/O and adsorption interactions between the dye molecules and catalytic active centers on PANI surface and these interactions are greatly affected by pH of the solution 9.2. An optimum of the synergetic effect is found for an initial molar ratio of aniline to oxidizer equal to 0.8.     

Synthesis of MIL-53(Fe)/MWCNTs Hybrid Material with Enhanced Efficiency for Photocatalytic Degradation of Rhodamine B

BMIL-53(Fe)/MWCNTs hybrid material was prepared via the solvethermal synthesis method. The resulting samples were characterized by X-ray diffraction, FT-IR spectroscopy, scanning electron microscopy, UV-Vis absorption spectroscopy,the Brunauer–Emmet–Teller method, and photoluminescence spectroscopy. The result showed that the introduction of multiwalled carbon nanotubes to the MIL-53(Fe) can increase the surface area of the composites, suppress the recombination of photogenerated electron-hole pairs and promote the electron transfer process. The hybrid material showed optimal photocatalytic performance in the degradation of Rhodamine B under the irradiation of ultraviolet and natural light.     

硫掺杂g-C3N4多孔纳米片的制备及其光催化降解性能研究

Abstract: In this study, sulfur-doped porous g-C3N4 nanosheets (CN-T-U 1.75) have been synthesized successfully by one-step calcination using urea and thiourea as the precursors. CN-T-U 1.75 exhibited excellent photocatalytic performance for Rhodamine B (RhB) degradation under visible light irradiation, with the kinetic reaction rate constant of 0.01838 min-1. Analysis of the characterization results showed that CN-T-U 1.75 had a larger specific surface area, and the doping caused a change in the energy band structure. Moreover, the catalytic mechanism analysis shows it could produce two oxidation groups of ?O2- and ?OH to degrade pollutants synergistically.     

Preparation of Cu-BiVO4 and Its Photocatalytic Properties for Desulfurization of Model Oil

A photocatalyst Cu-BiVO4 was synthesized by the hydrothermal method and was characterized by XRD, UV-vis DRS, and N2 adsorption-desorption measurement. The catalytic activity of the Cu-BiVO4 samples was studied on desulfurization of thiophene dissolved in n-octane, which was used as a model light oil, via photocatalytic oxidation reaction under illumination by visible light. The catalyst characterization results indicated that the loading of Cu on the catalyst did not change the crystal phase of BiVO4, and the crystallinity of the Cu-BiVO4 sample was found to be better at pH=7. The Cu-BiVO4 samples presented a significant bathochromic shift of the absorption band in the visible region, and the absorption intensity increased for the composite catalyst. The desulfurization experiments showed that the Cu-BiVO4 sample prepared at a pH value of 7 had a better catalytic activity. Under proper operating conditions, the desulfurization rate of the model compound achieved by Cu-BiVO4 sample prepared at pH=7 could reach as high as 90%.     

Preparation of WO_3/C Composite and Its Application in Oxidative Desulfurization of Fuel

The WO_3/C composite was successfully prepared by calcination of a mixture of WO_3 and g-C_3N_4 at 520 ℃. The as-synthesized samples were analyzed by X-ray diffraction(XRD), electronic differential system(EDS), scanning electron microscopy(SEM), infrared spectrometry(IR) and the Brunner-Emmet-Teller(BET) techniques. The WO_3/C composite, in comparison with the WO_3 and C_3N_4, features smaller particle size, bigger surface area and higher desulphurization performance. The influence of the reaction temperature, the catalyst dosage, the reaction time, the oxidant dosage, the sulfide type and the extractant dose on desulfurization reaction was studied. The results showed that the WO_3/C composite revealed a higher desulfurization activity than the WO_3. The desulfurization rate could reach up to 95.8% under optimal conditions covering a catalyst dosage of 0.02 g, a H_2O_2 amount of 0.2 mL, a 1-ethyl-3-methylimidazolium ethyl sulfate(EMIES) amount of 1.0 mL, a reaction temperature of 70 ℃ and a reaction time of 180 min. After five recycles, the desulfurization activity of catalyst did not significantly decline.     

Fe2O3复合BiOCl的制备及其光催化性能研究

Fe2O3 was synthesized by the solvothermal method, and the synthesized Fe2O3 was added in the process of preparing BiOCl by hydrolysis, and then Fe2O3/BiOCl photocatalytic materials with different composite ratios were prepared. The optimal Fe2O3/BiOCl (1Fe/50Bi) sample showed a highest photocatalytic efficiency for cationic dyes (Rhodamine B) and anionic dye (methyl orange) degradation irradiated with visible light, as compared with that of a bare BiOCl catalyst. Meanwhile, radical capturing experiments indicated that the photo-induced holes (h+) is the main active species. X-ray powder diffraction and ultraviolet-visible diffuse reflectance spectroscopy were used to characterize the structural and optical properties, which proved that Fe2O3 was successfully composited to the BiOCl surface and effectively reduced the bandgap of BiOCl. More importantly, the optimal 1Fe/50Bi sample shows the highest photocatalytic efficiency for tetracycline (TC) degradation (98%) irradiated with visible light, as compared with that of a bare BiOCl catalyst. Consequently, the Fe2O3/BiOCl photocatalyst have potential applications in environmental purification.     

Surface Structure,Spectroscopic and Photocatalytic Activity Study of Polyaniline/TiO2 Nanocomposites

PANI （polyaniline） as a promising conducting polymer and photosensitizer has been used to prepare PANI/TiO2 （polyaniline/TiO2） nanocomposite as photocatalyst. TiO2 nanoparticles with size of 5-100 nm were encapsulated by PANI via the ＂in situ＂ polymerization of aniline on the surface of TiO2 nanoparticles. IR, SEM, EPR techniques were used to characterize the mechanism of electron interaction in PANI/TiO2 nanocomposite. The resulting PANI-modified TiO2 composites exhibit significantly higher photocatalytic activity than that of neat PANI on degradation of MB （methylen blue） aqueous solution under UV irradiation.     

Kinetic Modeling of the Photocatalytic Reduction of Cr（VI） in the Presence of Dye Using Composite Photocatalyst

The photocatalytic properties of surface TiO2 supported zeolite in a semi batch reactor for the reduction of Cr（VI） in the presence of methyl orange dye were investigated. The prepared composite photocatalyst was characterized by SEM-EDS （scanning electron microscopy and energy dispersive spectroscopy）. The effects of operating parameters such as the pH and concentration of Cr（VI） in the absence and presence of dye were evaluated. The Cr（VI） reduction was more efficient in the ternary system （Cr（VI）/dye/TiO2-zeolite） than that of the corresponding binary system （Cr（VI）/TiO2-zeolite）. The extent of metal reduction after 210 min of irradiation was 68% at pH = 3 for the ternary system. In order to optimize the effectiveness of the composite photocatalyst on the photocatalytic reduction of Cr（VI）, kinetics and isotherm models were applied. The kinetics of Cr（VI） in the presence of dye on TiO2/zeolite composite photocatalyst followed the pseudo-first-order model while the equilibrium data correlated reasonably well with Freundlich isotherm.     

二次重建法制备具有大孔容高比表面的大孔-介孔γ-Al2O3

Through improving the aging process during synthesis of the support, γ-Al2O3 with large pore volume and high surface area was synthesized by a facile secondary reforming method. The synthesis parameters, such as the reaction temperature, the first aging temperature and the second aging temperature, were investigated. The textural properties of γ-Al2O3 were characterized by means of N2 adsorption-desorption isotherms, X-ray powder diffractometry(XRD), scanning electron microscopy(SEM), Fourier transform infrared(FTIR) spectroscopy and thermogravimetry(TG). The experimental results indicated that AACH and amorphous AlOOH were the precursors of alumina, which were formed via precipitation from solutions after reaction of aluminum sulphate with ammonium hydrogen carbonate. The precursor nanocrystallites grew and re-assembled during the secondary reforming process, which resulted in an increased pore size and pore volume and a decreased bulk density. The as-synthesized γ-Al2O3 materials featured meso/macroporosity, large pore volume(2.175 cm3/g), high surface area(237.8 m2/g), and low bulk density(0.284 g/mL).     

Ag/BiVO_4脱氮光催化剂的制备与表征

以硝酸铋为铋源、偏钒酸铵为钒源,采用水热法制备了Ag掺杂改性的粉体钒酸铋(Ag/BiVO4)催化剂,采用XRD,UV-Vis DRS,SEM等手段对其理化性能进行了表征,并以模拟含氮油品为目标降解物,在可见光下评价其光催化脱氮性能。表征结果显示,Ag掺杂不会改变BiVO4催化剂典型的单斜白钨矿结构,可提高Ag/BiVO4催化剂对可见光的吸收能力,从而使其催化性能明显优于未改性的BiVO4催化剂,对模拟油品中的吡啶表现出良好的可见光降解效果。对于50 mL吡啶含量为50μg/g的模拟油品,当Ag掺杂量(理论计算值)为5%(w)时,催化剂最佳用量为0.05 g,在可见光下照射2.5 h,模拟油品中吡啶的降解率可达86.7%。     

ZnO/mpg-C3N4复合光催化剂的制备及其可见光催化性能

采用简单溶剂热法成功合成了具有高可见光催化活性的ZnO/mpg-C₃N₄复合光催化剂。利用XRD、TEM、FT-IR、UV-Vis等手段对样品的结构、形貌及光学性能进行了表征,并以亚甲基蓝(MB)作为目标污染物,对ZnO/mpg-C₃N₄进行了光催化降解评价实验。结果表明,采用溶剂热法合成的ZnO/mpg-C₃N₄复合光催化剂中,ZnO颗粒较均匀地分散在mpg-C₃N₄上,与纯ZnO及mpg-C₃N₄相比,可见光催化活性明显提高。当mpg-C₃N₄质量分数为80%时,ZnO/mpg-C₃N₄复合光催化剂的光催化活性最高,为纯mpg-C₃N₄的2.3倍。     

BiVO4/SBA-15光催化氧化苯乙烯制苯甲醛

为提高BiVO4的光催化活性，通过浸渍法将BiVO4负载于SBA-15介孔分子筛上合成BiVO4/SBA-15催化剂，采用X射线衍射（XRD）、N2吸附-脱附等手段对合成催化剂结构进行表征；在400 W金卤灯照射下，以BiVO4/SBA-15为催化剂进行苯乙烯氧化反应，考察反应条件对氧化性能的影响。结果表明：BiVO4的负载未破坏SBA-15的介孔结构，且均匀分散在其表面；与BiVO4催化剂相比，BiVO4/SBA-15的光催化活性有显著提高，在反应温度为70 ℃、反应时间为2.5 h、n（苯乙烯）：n（丙酮）：n（过氧化氢）=1:2:3.5、m（BiVO4/SBA-15）：m（苯乙烯）=10%的光催化条件下，苯乙烯转化率达到90.31%，苯甲醛选择性达到70.65%。     

g-C3N4/Ti-MOF复合材料的合成及其光催化性能

采用快速微波合成法合成了Ti-MOF(MOF,金属有机骨架材料),并在其基础上合成新型可见光响应光催化剂g-C3N4/Ti-MOF。通过X射线衍射、扫描电镜、EDS能谱仪、傅里叶变换红外光谱、N2吸附-脱附和紫外-可见漫反射光谱等手段对其进行表征,同时光催化还原Cr(Ⅵ)研究g-C3N4/Ti-MOF的光催化性能。结果表明,g-C3N4/Ti-MOF复合光催化剂在150 min内能还原92%的Cr(Ⅵ),远远高于g-C3N4和Ti-MOF;同时g-C3N4/Ti-MOF复合光催化剂经过4次循环实验后仍能保持较稳定的光催化活性。最后提出了g-C3N4/Ti-MOF复合材料光催化还原Cr(Ⅵ)的可能机理。     

改性纳米二氧化钛光催化降解水中微量溶解性亚甲基蓝

以TiCl4,(NH4)2SO4为主要原料,采用溶胶-凝胶法制备了SO42-/TiO2光催化剂,利用X射线衍射仪对所制备试样进行了表征,并将其用于光催化降解水中微量亚甲基蓝。结果表明,SO24-离子的掺杂修饰,使纳米TiO2结构明显改善。确定出亚甲基蓝溶液降解的最佳工艺条件为:紫外光照射下,在石英试管中,亚甲基蓝的初始浓度为6～9mg/L,催化剂投加量为1.0～1.5g/L。     

碘掺杂g-C3N4光催化剂的制备及催化性能

采用热聚合法,以尿素为前驱体,碘化氨为掺杂剂,制备出不同碘离子掺杂量的可见光催化剂石墨相氮化碳（g C3N4）。对碘掺杂g C3N4催化剂（Ix C3N4）进行X射线衍射（XRD）、扫描电镜（SEM）、透射电镜（TEM）、傅里叶变换红外光谱（FT IR）、X光电子能谱（XPS）、紫外 可见漫反射（UV Vis）、N2吸附、电子荧光光谱（PL）、电化学阻抗（EIS）等表征,分析了催化剂的形貌、结构、光学和电学性能。以4 硝基苯酚为目标污染物进行光催化降解实验,选取最佳碘掺杂量的I002 C3N4催化剂进行重复性实验。结果表明,碘离子的引入没有改变g C3N4的原始形貌和结构,掺杂后的样品拓宽了g C3N4对可见光的吸收范围,降低了光生电子 空穴对的复合率;掺杂最佳碘离子量的催化剂I002 C3N4在2 h内对4 硝基苯酚的降解率达到84%,重复4次实验后,降解率仍能达到80%。     

微波法合成TiO2及其光催化降解有机废水研究

以硫酸钦、聚乙烯毗咯烷酮(PVP)、乙二醇(EG)为原料,采用微波法制备了TiO2光催化剂.在间歇式光催化反应器内,用亚甲基蓝溶液模拟有机废水,在高压汞灯光照下,研究TiO2光催化剂对亚甲基蓝的光催化降解过程.利用X射线衍射(XRD)、扫描电子显微镜(SEM)和傅立叶变换-红外光谱(FT-IR)测试技术,对TiO2光催...     

Ag-BiVO_4催化剂的制备及其用于光催化氧化噻吩

采用水热法合成了可见光催化剂Ag-BiVO4,并对其进行了XRD和UV-Vis DRS表征。以噻吩的正辛烷溶液为含硫模型化合物溶液,考察了Ag-BiVO4催化剂前体的pH、Ag-BiVO4催化剂用量和空气流量等工艺条件对脱硫率的影响,研究了Ag-BiVO4催化剂光催化氧化噻吩的性能。表征结果显示,Ag的掺杂没有改变BiVO4的晶相,在Ag-BiVO4催化剂前体的pH为7的条件下制备的Ag-BiVO4催化剂(Ag-BiVO4(pH=7))结晶度较好,吸收边带明显红移,禁带宽度窄于纯BiVO4。实验结果表明,Ag-BiVO4(pH=7)催化剂活性最高,在空气流量为300 mL/min、Ag-BiVO4(pH=7)催化剂加入量为1.0 mg/L、400 W金卤灯照射180 min的条件下,脱硫率可达95%。     

掺杂型光催化剂Ag-BiVO_4的制备及其光催化降解含酚废水的研究

研究了掺杂型可见光催化剂Ag-BiVO4的制备及其光催化氧化降解含酚废水的工艺条件。采用水热法制备了Ag-BiVO4,并对其进行X射线衍射、紫外-可见漫反射等手段表征;以含酚废水为降解目标,考察了催化剂前驱体的pH值、催化剂用量和空气流量等工艺条件对降解率的影响,研究了Ag-BiVO4催化剂光催化氧化苯酚的性能。结果表明,Ag的掺杂延伸了BiVO4的可见光吸收范围,吸收边带明显红移,能隙禁带宽窄于纯BiVO4,而Ag的掺杂没有改变BiVO4的晶相,在中性条件下制备的Ag-BiVO4催化剂晶型较完整,可见光催化活性最高。在空气通入量为200mL/min、Ag-BiVO4(pH=7)催化剂加入量为0.5mg/L时,400W金卤灯照射150min,对含酚废水的去除率可达93%。     

Synthesis of silica nanoparticles from blast furnace slag as cost-effective adsorbent for efficient azo-dye removal

Synthesis of silica nanoparticles (NSBFS) from commercial blast furnace slag (BFS) and its efficiency to remove methylene blue (MB) from water as well as the desilicated blast furnace slag (DBFS) were investigated in this study. The sorbent materials were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), N₂ adsorption-desorption isotherms, dynamic light scattering (DLS), scanning electron microscopy (SEM), and Energy Dispersive X-ray Analysis (EDAX). Different physiochemical parameters such as initial pH of the dye, sorbent dosage, contact time, and initial dye concentration were studied. The pseudo-first-order and pseudo-second-order models were applied to evaluate the kinetic mechanism of the adsorption process. The results show that the process follows the pseudo-second-order kinetics using NSBFS or DBFS. The adsorption equilibrium values were obtained using Langmuir and Freundlich equations, Langmuir model showed the best correlation indicate that NSBFS and DBFS are homogeneous surface. The batch adsorption experiments showed that the maximum sorption was observed at pH?=?10 and 8 and the maximum uptake capacities (qm) for MB were 80.8 and 109.8?mg/g using DBFS and NSBFS, respectively.