Synthesis and Characterization of Rectorite/ZnO/TiO2 Composites and Their Properties of Adsorption and Photocatalysis for the Removal of Methylene Blue Dye

As efficient water treatment agents, a novel series of rectorite-based ZnO and TiO2 hybrid composites（REC/ZnO/TiO2） were synthesized and characterized in this study. Effects of experimental parameters including TiO2 mass ratio, solution p H and catalyst dosage on the removal of methyl blue（MB） were also conducted. The presence of a little mass ratio（2%-6%） of TiO2 highly promoted the photoactivity of REC/ZnO/TiO2 in removal of MB dye from aqueous solution, in which ZnO and REC played a role of photocatalyst and adsorbent. The promotion effects of TiO2 may result from the accelerated separation of electron-hole on ZnO. The observed kinetic constant for the degradation of MB over REC/ZnO and REC/ZnO/TiO2 were 0.015 and 0.038 min^（-1）, respectively. The degradation kinetics of MB dye, which followed the Langmuir–Hinshelwood model, had a reaction constant of 0.17 mg/（L min）. The decrease of removal ratio of MB after five repetitive experiments was small, indicating REC/ZnO/TiO2 has great potential as an effective and stable catalyst.

Microstructure and Photocatalytic Decomposition of Methylene Blue by TiO2-Mounted Halloysite, a Natural Tubular Mineral

On the basis of analysis of structure and properties, halloysite, a natural tubular mineral, was developed for an environmental treatment. TiO2 was mounted into halloysite by using hydrolysis of tetrabutyl titanate at room temperature. The adsorption and photocatalytic performance of halloysite and TiO2-mounted halloysite have been examined in methylene blue aqueous solution in the dark and under ultraviolet ray irradiation, respectively. Their performance of adsorption and photodecomposition was evaluated from the adsorbed and degraded amounts of methylene blue （MB）. Due to the mixture of adsorption and photodecomposition, the concentration of MB, organic pollution, in water decreased rapidly with TiO2-mounted halloysite powder, which is a faster reaction than that with halloysite-only adsorption. This new use of halloysite is leading to many interesting applications in the decomposition and elimination of various pollutants in air and water.

Effects of Magnetic Field on Photodegradation of Methylene Blue over ZnO and TiO2 Powders using UV-LED as a Light Source

The magnetic field effects （MFEs） are studied on photocatalytic degradation of methylene blue （MB） solution using ZnO and TiO2 particles. The UV-VIS-NIR spectrometer is used to monitor the MB concentrations, and the dependence of the reaction rate on the initial dye concentration and settling duration is studied under UV light irradiation. It is found that the MFEs exist on the heterogeneous reaction systems for both ZnO and TiO2 powders and that the extraordinary phenomenon is reproducible. For ZnO powder, the results are in good agreement with the second-order reaction kinetics following the Langmuir-Hinshelwood （L-H） model, while the reaction for TiO2 follows first-order kinetics. It enhances the photodegradation for ZnO, while it reduces or enhances the reaction for TiO2 depending on the initial dye concentrations. The MFEs become small or negligible when the same photodecomposition experiment is carried out after settling the MB solution for more than three hours for both ZnO and TiO2. It is suggested that the key factors of MFEs on photocatalytic degradation is the condition of the MB solution as well as the characteristics of photocatalysts. The alteration of the MFEs ascribed to the solution condition caused by variation of the settling time.

Mesoporous V-doped TiO_2 Nanoparticles as New Adsorbents for the Removal of Methylene Blue from Color Textile Wastewater

V-doped TiO2 nanoparticles（NPs） as dye adsorbents are synthesized by the co-precipitation method and characterized by X-ray powder diffraction, transmission electron microscope, N2 adsorption at 77 K, and X-ray photoelectron spectroscopy. The adsorption of methylene blue（MB） on the V-doped TiO2 NPs is studied in detail by varying the calcination temperature and V doping amount of the adsorbent, adsorbate concentration, adsorbent dosage, agitation rate, reaction temperature, and p H. The comparison of dye adsorption on V-doped TiO2 and parent TiO2 demonstrates that the adsorptive activity of TiO2 can be improved by V doping. The enhanced adsorptive performance can be attributed to the tremendous changes in texture, structure, and surface morphology of adsorbent. The adsorption kinetic analysis shows that the adsorption follows the pseudo-second order kinetics. The apparent activation energy for adsorption is calculated by Arrhenius formula to be 37.6 k J·mol-1, indicating that the adsorption is controlled by both of the diffusion and interfacial adsorption steps. The adsorption data are analyzed using Langmuir and Freundlich isotherms and the results indicate that the Langmuir model provides better correlation of the experimental data. The results conclusively show that the adsorption of MB is a spontaneous behavior and endothermic reaction with the ΔH value of 17.60 k J·mol-1.

TiO_2/polyaniline composites:An efficient photocatalyst for the degradation of methylene blue under natural light

Polyaniline （PAn） sensitized nanocrystalline TiO2 composites （TiO2/PAn） were successfully prepared and used as an efficient photocatalyst for the degradation of dye methylene blue （MB）. The results showed that PAn was able to sensitize TiO2 efficiently and the composite photocatalyst could be activated by absorbing both the ultraviolet and visible light （λ： 190 ～ 800 nm）, whereas pure TiO2 absorbed ultraviolet light only （λ 〈 380 nm）. Under the irradiation of natural light, MB could be degraded more efficiently on the TiO2/PAn composites than on the TiO2 Furthermore, it could be easily separated from the solution by simple sedimentation.

String and Ball-Like TiO_2/rGO Composites with High Photo-catalysis Degradation Capability for Methylene Blue

Novelthree-dimensionalstring and ball-like titanium dioxide/reduced graphene oxide, TiO_2/rGO(STG) composites were prepared using a one-step hydrolysis process followed by a low-temperature hydrothermaltreatment. The STG composites exhibited excellent photo-catalytic degradation performance for methylene blue owing to a good synergistic effect between TiO_2 and rGO. The STG composites with 1.0 wt% of rGO loading exhibited the highest removalrate of 86.0% for methylene blue and its reaction rate constant(5.27 × 10^(-3) min^(-1)) was much higher than those of pure string and ball-like TiO_2(ST). In addition, the STG composites also showed an outstanding capability for the photo-catalysis degradation of other cationic dyes. In addition, a possible photo-catalytic degradation mechanism for the STG composite was postulated, in which~?O_2^- and~·OH were the main oxidizing groups. This work of fers new insights into a better design and preparation of novelcomposite materials for the removalof organic dyes.

Photocatalytic Degradation of Methylene Blue with Side-glowing Optical Fiber Deliverying Visible Light

The side-glowing optical fibers (SOFs) were chosen as the conducting medium of endogenous light; and 20 mg·L-1 methylene blue was chosen as the target to be degraded. The SOF is made up of quartz core with a silicon cladding, which can emit light through side surface more uniformly and transmit light for longer distance to avoid attenuation of light by liquid medium. The filament lamp was chosen as visible light source. Different reaction conditions, such as the presence of optical fiber or not, the quantity of SOF, light irradiation intensity were tested by measuring the methylene blue degradation of methylene blue. The results show that suitable reaction conditions were 1.167 g·L-1 Ag + /TiO 2 with 7% (by mass) of Ag + doped in TiO 2 , and 500 roots of SOF (30 cm length in solution). The photocatalytic degradation efficiency under 300W lamp irradiation for 8h was about 97%. And the photocatalytic degradation efficiency of methylene blue degradation was proportional to SOF quantity, light irradiation intensity and catalytic dosage within a certain range. Compared with general UV and visible light SOFs could save a huge amount of energy and cost, in the potential applications in dealing with organic pollutants on a large scale.

Influence of H-Type and L-Type Activated Carbon in the Photodegradation of Methylene Blue and Phenol under UV and Visible Light Irradiated TiO₂

Photodegradation of methylene blue (MB) and phenol (Ph) on TiO2 in presence of H-type and L-type activated carbons (AC) was studied. Photodegradation of MB and Ph were studied under two different lamps and results were compared against those obtained on a commercial TiO2. Apparent first order rate constant for the degradation of MB was higher in presence of any AC in comparison of TiO2 alone while only in presence of ACco2-800phenol was photodegradated in shorter irradiation time than that required by TiO2. It can be concluded that TiO2 enhances its photoactivity by a factor up to 8.7 in the degradation of MB in presence of AC and this effect is associated to the specific surface properties of AC.

Effects of Experimental Conditions and Kinetics of Photodegradation of Methylene Blue over TiO2

The authors investigated the catalytic activity of TiO2 for methylene blue（MB） degradation under solar light.The reaction parameters such as reaction time,TiO2 content,temperature,pH,MB concentration and light irradiation were in attention.Then,the experimental data was analyzed to investigate the adsorption order and adsorption model.The results indicate that the optimum conditions for the removal of MB are a TiO2 content of 0.5 g/L,0.50 mg/L MB solution,a temperature of 30 ℃ and reaction time of 60 min.It was found that the amount of MB removal was decreased when the pH and temperature increased.This suggests that the removal process is exothermic.However,the solar light irradiation plays a vital role in enhancing the removal amount of MB.In the dark reaction,the ability of TiO2 to remove MB was increased when the pH increased.The kinetics studies confirm that the adsorption of MB is the Pseudo-second-order.And the adsorption model was fitted with the Freundlich isotherm.

Characterization and photocatalytic activity for methylene blue degradation of iron-deposited TiO_2 photocatalyst

Iron deposited TiO 2 was prepared by photo reducing ferric ions. The photocatalytic activity of methylene blue degradation was enhanced after TiO 2 was deposited with iron, and the optimum n (Fe)/ n (Ti) is 0.25%. TiO 2 and iron deposited TiO 2 are anatase and rutile, and anatase is the dominant crystalline phase. In all samples, the XRD patterns indicate that there are no characteristic peaks of iron to be detected. XPS confirms that Fe 3+ and Fe 2+ are present on the surface of 0.5% iron deposited TiO 2, however they are not susceptible to XRD detection. The thermodynamics analysis shows that the alternative possibility of reduction from the Fe 3+ /Fe 2+ couple seems plausible, but Fe 2+ can not be reduced to Fe. The fluorescence intensity weakens after iron is deposited on TiO 2, because iron deposited traps photo generated electrons and holes. The fluorescence intensity order of TiO 2 and iron deposited TiO 2, from strong to weak, is in good agreement with that of photocatalytic reactiveness TiO 2 and iron deposited TiO 2, from low to high.

Pt@TiO2-SiO2复合纳米纤维的制备及其光催化性能研究

TiO2材料是近年来一种常用的光催化材料。为了提高TiO2材料对染料分子的吸附以及改善其在可见光区的光催化性能,本文通过静电纺丝法和溶胶凝胶法制备了Pt掺杂的TiO2-SiO2复合纳米纤维,通过SEM、XRD、BET、UV-vis等方法对材料进行表征,以亚甲基蓝模拟污染物进行光催化降解动力学实验。实验结果显示[m(Pt)∶m(TiO2)]=0. 328%时显现出最佳的光催化性能,对溶液中的亚甲基蓝的降解率达到了99%。

Novel EPS/TiO2 Nanocomposite Prepared from Recycled Polystyrene

The synthesis and characterization of a new nanocomposite material that was prepared from recycled expanded polystyrene (EPS) and titanium dioxide (TiO2) is reported here. The EPS was obtained from chemical reagent box insulation. To obtain the nanocomposite, these materials were dispersed in a solvent, mixed with TiCl4 and heated. The resulting new material was characterized with SEM, TEM, TGA, BET, Raman and IR techniques. The Raman and IR spectra provided complementary information regarding the structure of the nanocomposite. The Raman spectra were used to identify the crystalline structure of TiO2 in the nanocomposite. In contrast, the IR spectra were used to identify the organic portion of the nanocomposite. The TEM images indicated that the nanocomposites had an average particle size of 6 - 12 nm. In addition, the adsorption and photocatalytic properties of the new material were evaluated. The EPS/TiO2 nanocomposite was efficient at degrading methylene blue (MB) dye solutions under UV irradiation. Furthermore, according to thermal analysis, this material had greater polymer stability due to the incorporation of TiO2.

介孔TiO2光催化降解亚甲基蓝性能研究

以CTAB为模板导向剂,采用溶胶-凝胶法制备介孔TiO 2材料,以亚甲基蓝为降解底物,研究了光催化材料对亚甲基蓝的光催化活性,考察不同CTAB浓度及煅烧温度、光照时间对TiO 2光催化降解性能的影响。实验结果表明,随着CTAB的加入,所制样品的光催化活性均有所提高,紫外光照60 min后,500℃制备的,CTAB浓度为0.14 mol/L的介孔TiO 2光催化剂对亚甲基蓝的光催化率达到92.9%。

Simulated-sunlight-activated photocatalysis of Methylene Blue using cerium-doped SiO_2/TiO_2 nanostructured fibers

Cerium-doped SiO2/TiO2 nanostructured fibers were fabricated by electrospinning technology. The prepared fibers were characterized by thermogravimetric analysis （TGA）, scanning electron microscopy （SEM）, X-ray diffraction （XRD） and Fourier transform infrared spectroscopy （FT-IR）. Using the fibers as catalysts, photoeatalytic degradation of Methylene Blue （MB） aqueous solution was carded out under simulated sunlight. The 0.2% Ce doping proved to be the optimal concentration for the doping of TiO2/SiO2, compared to other Ce-doped molar concentrations. The 0.2% Ce-doped SiOdTiO2 fibers exhibited higher photocatalytic activity than industrial Degussa P25 and the samples doped with only Ce or SIO2. The reasons for improving the photocatalytic activity were also discussed. Several operational parameters were studied, which showed that the photocatalytic efficiency of MB was influenced by parameters such as the initial dye concentration, the initial pH, inorganic anions, and so on. In addition, the influences of an electron acceptor and a radical scavenger suggested that OH was the dominant photooxidant during the photocatalytic process. The reuse evaluation of the fibers indicated that their photocatalytic activity had good stability.

One-step synthesis of N-doped metal/biochar composite using NH_3-ambiance pyrolysis for efficient degradation and mineralization of Methylene Blue

A series of new biochar-supported composite based on the combination of biochar and metallic nanoparticles(NPs)were produced through single-step pyrolysis of FeCl_3–Ti(OBu)_4 laden agar biomass under NH_3 environment.The physiochemical properties of composites were characterized thoroughly.It has found that heating temperature and N-doping through NH_3-ambiance pyrolysis significantly influence the visible-light sensitivity and bandgap energy of composites.The catalytic activities of composites were measured by degradation of Methylene Blue(MB)in the presence or absence of H_2O_2 and visible-light irradiation.Our best catalyst(N–TiO_2–Fe_3O_4-biochar)exhibits rapid and high MB removal competency(99.99%)via synergism of adsorption,photodegradation,and Fenton-like reaction.Continuous production of O_2U^-and UOH radicles performs MB degradation and mineralization,confirmed by scavenging experiments and degradation product analysis.The local trap state Ti^(3+),Fe_3O_4,and N-carbon of the catalyst acted as active sites.It has suggested that the Ti^(3+)and N-doped dense carbon layer improve charge separation and shuttle that prolonged photo-Fenton like reaction.Moreover,the catalyst is highly stable,collectible,and recyclable up to 5 cycles with high MB degradation efficiency.This work provides a new insight into the synthesis of highly visible-light sensitized biocharsupported photocatalyst through NH_3-ambiance pyrolysis of NPs-laden biomass.

Enhanced photocatalytic activity of Gd3+ doped TiO2 and Gd2O3 modified TiO2 prepared via ball milling method

Gd^3+/TiO2 and Gd2O3/TiO2 nanoparticles were prepared by ball milling method.The effects of Gd^3+ion and Gd2O3 on the structure and optical property of TiO2 were studied by XRD and UV-vis DRS.Specific surface area was determined by Brunauer-Emmett-Teller(BET)method.The morphology and elemental composition were characterized by SEM-EDS.XPS was used to determine the surface compositions and chemical character of elements.The sample sizes and microstructures were observed by TEM.The photocatalytic activities of TiO2 nanoparticles modified with rare earth metal gadolinium(Gd^3+ion or Gd2O3)were evaluated by degradation of methylene blue(MB)under UV light.Experimental results indicate that 2,5 mol%Gd^3+/TiO2 shows the best photocatalytic activity compared with Gd2O3/TiO2 and pure TiO2.The existence of gadolinium can exhibit the aggregation and induce lattice distortion of TiO2 obtained from XRD,SEM and TEM results.The band gap energy of 2.5 mol%Gd^3+/TiO2 decreases to3.07 eV and it leads to visible light absorption response which can be seen from UV-vis absorption spectra.The surface area of 2.5 mol%Gd^3+/TiO2 equals to 85.8 m^2/g and average crystal size is 21.1 nm.EDS and XPS analyses reveal that gadolinium can be introduced either into TiO2 lattice or adsorbed on the surface of TiO2.The content of surface OH groups in 2.5 mol%Gd^3+/TiO2 is 50,88%(1.55 times higher than that of pure TiO2)and the content of lattice oxygen decreases to 11.26%.The MB(25 mg/L)degradation reaction rate constants of 2,5 mol%Gd^3+/TiO2,0.5 mol%Gd2O3/TiO2 and pure TiO2 were0.0713,0.0588 and 0.0263 min^-1,respectively.The degradation rates of rhodamine B(30 mg/L)in 60 min are 97,9%,90.1%and 84.6%for 2,5 mol%Gd^3+/TiO2,0.5 mol%Gd2O3/TiO2 and pure TiO2,respectively.

Strong enhancement on dye photocatalytic degradation by ball-milled TiO2:A study of cationic and anionic dyes

TiO2 particles with desirable properties were produced by undergoing specific durations of ball milling.Characterizations of the TiO2 particles before and after ball milling were investigated via X-ray diffraction（XRD）, Brunauer-Emmett-Teller（BET）, particle size analysis, zeta potential, and scanning electron microscope（SEM）. The equilibrium adsorption data were well fitted to Langmuir, Freundlich, and Dubinin-Radushkevich（D-R） isotherms. Compared to the as-received TiO2（mean particle size d150= 0.78μm, specific surface area = 88.17 m^2g-1, pore volume = 0.41 cm^3g-1）, the 60 min ballmilled TiO2（d50= 0.55 μm, specific surface area = 99.48 m2g-1, pore volume = 0.48 cm3g-1） enhanced the adsorption quantity of congo red and methylene blue from 10.4 mg g-1to 13.6 mg g-1, and from17.0 mg g-1to 22.2 mg g-1, respectively; and also improved the kinetic rates from k = 0.1325 to 0.2193, and k = 0.0944 to 0.1553, respectively. Dye adsorption and degradation efficiency of congo red was enhanced in acidic p H range（2–5.14）, and methylene blue was enhanced in alkaline p H range（7.58–12）.

纳米TiO_2光催化性能研究进展及其影响因素探讨

阐述了TiO2的光催化机理及影响TiO2光催化活性的因素,并综述了近年来TiO2光催化的改性研究方法,最后指出了纳米TiO2光催化剂的不足和研究发展的重点,以期推动纳米TiO2光催化技术的工业化进程。

液相沉积法制备光催化活性TiO_2薄膜和纳米粉体

采用液相沉积法 ,在 3 5℃通过向六氟钛酸铵水溶液中添加硼酸和结晶诱导剂锐钛矿型TiO2 纳米晶 ,沉积出具有光催化活性的TiO2 薄膜和纳米粉体 .用XRD ,AFM ,阶梯仪 ,UV vis ,BET法对TiO2 薄膜和粉体的沉积条件、结构、厚度和性能进行了测定和表征 ,并用亚甲兰的降解 ,评价了TiO2 薄膜和纳米粉体的光催化活性 .结果表明 ,当反应物六氟钛酸铵与硼酸的摩尔比为 1∶2～ 1∶4时 ,沉积的粉体和薄膜含有锐钛矿相TiO2 ;经 3 0 0℃热处理的TiO2 薄膜和纳米粉体具有最高的光催化活性 ,它的光催化活性是未经热处理前的 5倍 .本文还解释了经 3 0

溶胶液浓度和镀膜层数对TiO_2薄膜光催化活性的影响

作者用sol gel法制备了不同浓度、不同层数的锐钛矿纳米TiO2 薄膜。利用薄膜对亚甲兰溶液的光催化降解作用 ,研究了溶胶液浓度、镀膜层数及两者间的相互关系对薄膜光催化性能的影响。发现并非浓度越大、镀膜层数越多、膜的光催化性能越好。不同浓度的溶胶液匀有各自催化性能最佳的膜层数 ,超过该层数后膜的催化性能降低。浓度大的膜在层数较少时催化性能好 ,浓度小的膜随层数增加 。