聚乙烯亚胺改性TiO2及光催化性能研究

纳米TiO2经3-氨丙基三乙氧基硅烷(APTES)改性后,再通过聚乙烯亚胺(PEI)单体在APTES-TiO2表面进行原位化学氧化接枝聚合,制备了基于共价键结合的PEI/APTES-TiO2纳米复合光催化材料。以甲基橙(MO)为目标降解物,研究了所制备复合材料在紫外光下和太阳光作用下的光催化性能。通过红外光谱(FTIR)、X射线衍射(XRD)、透射电镜(TEM)等对所制备的复合材料进行了表征。结果表明,TiO2经过有机改性后复合材料在紫外光和太阳光下都出现了较强的吸收,光能的利用率和光生载流子的分离效率得到提高,复合材料表现出较高的光催化活性。     

Preparation and characterization of visible-light-driven TiO2 photocatalyst Co-doped with nitrogen and erbium

A series of nitrogen and erbium co-doped TiO2 photocatalyst was prepared by sol-hydrothermal method. The structure and properties of the photocatalyst were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) method, X-ray photoelectron spectroscopy (XPS), and UV-vis diffuse reflectance spectra (DRS). The XRD and BET results showed that co-doping inhibited the increase of crystallite size and enlarged specific surface areas. XPS spectroscopy indicated nitrogen atoms were incorporated into TiO2 lattice, and erbium atoms mostly existed in the forms of Er2O3. A shift of the absorption edge to the lower energy and four absorption bands located at 654, 544, 524 and 489 nm attributed to the 4f transitions of 4I15/2 --> 4F2/9, 4I15/2 --> 4S3/2, 4I15/2 --> 2H11/2, 4I15/2 --> 4F7/2 of Er3+ were observed using DRS spectroscopy. The catalytic efficency was evaluated by the photocatalytic degradation of methyl orange (MO) under visible light irradiation. The results showed that the photocatalytic performance of the co-doped TiO2 was related with the hydrothermal temperature and the molar ratio of N/Ti, and they showed higher acitivites than pure TiO2. Results determined by fluorescence technique revealed that irradiation (lambda > 400 nm) of TiO2 photocatalyst dispersed in MO solution induces the generation of the highly active hydroxyl radicals (OH). It indicated the photocatalytic activities of TiO2 photocatalyst were correlation with the formation rate of hydroxyl radicals (OH) and other active oxygen species.     

可见光响应Pt沉积La2O3/TiO2制备及其对甲苯的光热催化去除

以钛酸四丁酯和硝酸镧为原料,采用溶胶—凝胶法制备La2O3/TiO2,通过光沉积法在La2O3/TiO2表面负载纳米Pt粒子.采用XPS、FTIR、XRD、DRS、TEM和低温氮物理吸附对光催化剂的晶体结构、光谱特征和表面结构进行表征.考察了催化剂在可见光下对甲苯的去除性能和温度对催化剂去除甲苯的影响.结果表明,沉积的Pt以单质和吸附氧的形式存在,其中以吸附氧的形式为主.Pt的掺入没有引起TiO2相结构的变化,减小了晶粒尺寸并增大了催化剂的比表面积.纳米Pt均匀地分布在La2O3/TiO2上,尺寸分布比较均一,大约为5～10nm.Pt-La2O3/TiO2的表面羟基官能团伸缩振动明显增强,比TiO2和La2O3/TiO2具有更高的可见光催化活性.Pt-La2O3/TiO2对甲苯的降解率,随着温度的升高而增大,产生了与光催化作用平行的热催化作用.气相甲苯光热催化过程不是光催化与热催化的简单叠加,而是存在协同作用.     

锶磁性光催化剂的制备和表征

以自制碳酸锶(SrCO3)和钛酸丁酯为原料,采用超声波技术制备了以锶铁氧体(SrFe12O19)为载体的锶磁性光催化剂(TiO2-SrFe12O19)。采用XRD、IR、VSM、N2吸附实验等手段研究了催化剂的表面性质和磁学特性。结果表明,该催化剂的平均晶粒尺寸在20～30nm之间,比表面积为44.8m2/g,平均孔径为7.09nm,属于介孔磁性材料;饱和磁化强度(Ms)为12.9A.m2/kg,矫顽力(Hc)为120.9kA/m,易于磁分离和重复利用。催化剂对亚甲基蓝(MB)的催化降解脱除率为94.7%,且重复使用3次,催化降解效率不低于88%,表明催化性能稳定,重复使用效果良好。     

Photocatalytic degradation of mixed pollutants in aqueous wastewater using mesoporous 2D/2D TiO2(B)-BiOBr heterojunction

There are multiple contaminants in practical wastewater;and the photodegradation of mixed pollutants is a challenge in the field of photocatalysis.Herein,we design a mesoporous 2D/2D TiO2(B)-BiOBr hetero-junction photocatalyst for the photodegradation of mixed pollutants.Such a coupling structure results in an enhancement in the disconnection of photoexcited carriers,and the increase of absorption and reaction sites.The 2D/2D TiO2(B)-BiOBr demonstrates outstanding photocatalytic activity for photode-grading rhodamine B(RhB),methyl orange(MO),tetracycline hydrochloride(TCH),and bisphenol A(BPA)simultaneously under visible light,which is 4.7.1.4,23 and 16.4 times as high as that of original BiOBr,respectively.Our work represents a possible solution to devise promising and efficient photocatalysts for the treatment of practical wastewater in the near future.     

TiO2-N-S光催化剂的制备、表征及性能研究

以胱氨酸为掺杂剂,利用溶胶-凝胶法直接制备了N、S共掺杂改性的光催化剂TiO2-N-S,借助XRD、XPS和SPS等手段对其进行了表征,并以苯酚为模型污染物考察了其在模拟太阳光下的催化活性.XRD分析表明该光催化剂为锐钛矿晶型,N、S共掺杂能有效抑制TiO2晶粒的生长,提高了晶相间转变温度.XPS显示S是以S6+形式存...     

镍、硫共掺杂纳米TiO2的制备及其可见光催化性能

为提高纳米TiO2的可见光催化活性,采用沉淀-浸渍法制备了一种新型Ni和S共掺杂TiO2纳米复合光催化剂.通过紫外-可见(UV-Vis-)漫反射、X-射线衍射(XRD)、透射电子显微镜(TEM)和X-荧光(EDX)等手段对其结晶形态、晶粒尺寸、元素掺杂量和吸光性能等进行了表征.结果显示,催化剂Ni/S/TiO2为锐钛矿晶相,平均粒径约为6～7nm,比表面积高达260.42m2/g,感光范围可拓展到可见光区,且与纯TiO2,S掺杂TiO2和Ni掺杂TiO2相比,光催化剂Ni/S/TiO2的颗粒粒径更小,比表面积更大,光吸收边红移程度更显著.以活性艳蓝198染料溶液为模拟废水,以氙光灯为光源,对光催化剂Ni/S/TiO2的催化活性进行了评价.结果表明,Ni/S/TiO2具有比纯TiO2、S掺杂TiO2和Ni掺杂TiO2更高的可见光催化活性,氙光灯照射120min,活性艳蓝198降解率可达到98.5%.     

纳米TiO_2/粉煤灰复合材料的制备及光催化性质

为了提高TiO2的光催化效果,使催化剂易于回收再利用,利用粉煤灰为载体,采用低温超声水热法制备纳米TiO2/粉煤灰复合光催化剂。借助X射线衍射(XRD)、扫描电镜(TEM)、红外(IR)和紫外-可见(UV-Vis)光谱分析对产物进行了表征,研究了TiO2加入量、超声时间等对复合物形貌、晶型和性能的影响。光催化降解亚甲基蓝的实验结果表明,由于TiO2和粉煤灰的共同作用,所得复合光催化剂的性能优于纯TiO2的光催化性能。     

Photodegradation of methyl orange by photocatalyst of CNTs/P-TiO(2) under UV and visible-light irradiation

A novel nanoscale photocatalyst CNTs/P-TiO(2) was successfully prepared by hydrothermal method. The morphology and the physicochemical properties of the prepared samples were investigated using TEM, XPS, XRD, BET, FTIR, TG-DSC and UV-vis DRS spectroscopy. The photocatalytic activity was evaluated by degradation of methyl orange (MO) dye. The results demonstrated that CNTs/P-TiO(2) nanoparticles could effectively photodegrade MO not only under UV irradiation but also under visible-light (VL) irradiation. The MO degradation performance on CNTs/P-TiO(2) was superior to that of the commercial P25. The optimal mass ratio of CNTs to P-TiO(2) in the nanocomposite catalyst was 5:100. The synergetic effect was discussed in terms of different roles played by phosphorus doping and introducing CNTs into the composite catalysts.     

Synthesis and performance of novel magnetically separable nanospheres of titanium dioxide photocatalyst with egg-like structure

A magnetically separable photocatalyst TiO(2)/SiO(2)/NiFe(2)O(4) (TSN) nanosphere with egg-like structure was prepared by a unique process that combined a liquid catalytic phase transformation method, reverse micelle technique and chemical precipitation means. The prepared photocatalyst shows high photocatalytic activity for the degradation of methyl orange in water. The magnetic property measurements indicate that the photocatalyst possesses a superparamagnetic nature. It can be separated from water when an external magnetic field is added and redispersed into water solution after the external magnetic field is eliminated. It is one of the promising photocatalysts for wastewater treatment. A transmission electron microscope (TEM) and an x-ray diffractometer (XRD) were used to characterize the structure of the TSN photocatalyst. The results indicate that nickel ferrite core nanoparticles were completely encapsulated into monodisperse silica nanospheres as carrier, and titania nanoparticle aggregates were coated onto the surface of SN nanospheres, forming an imperfect TiO(2) shell for photocatalysis. The SiO(2) layer between the NiFe(2)O(4) core and the TiO(2) shell effectively prevents the injection of charges from TiO(2) particles to NiFe(2)O(4), which gives rise to an increase in photocatalytic activity. Moreover, the recycled TSN exhibits good repeatability of the photocatalytic activity.     

流化床化学气相沉积法制备CNT/Fe-Ni/TiO2及其光催化性能研究

以Fe-Ni/TiO2为催化剂,采用流化床化学气相沉积法(FBCVD)在TiO2表面原位生长碳纳米管(CNT),得到CNT/Fe-Ni/TiO2复合光催化剂.通过SEM、XRD、UV-Vis等方法表征其结构和性能,以亚甲基蓝溶液降解为模型考察其光催化性能.结果表明:Fe-Ni/TiO2催化剂在FBCVD过程中,镍主要起到了CNT生长催化活性位的作用;在生长CNT后的复合光催化剂中,比例较低的Fe3+主要作为电子俘获剂,抑制TiO2光生电子空穴的复合;Ni和CNT共同起到将电子迅速地从TiO2中导出,从而降低光生电子空穴复合几率的作用.三者的协同作用显著改善了TiO2的光催化性能.其中Fe和Ni掺杂量分别为0.25mol%和4.75mol%样品的光催化活性较高,生长CNT后得到的复合光催化剂对亚甲基蓝的降解效率较纯TiO2提高约70%.     

Non-thermal plasma-induced photocatalytic degradation of 4-chlorophenol in water

TiO(2) photocatalyst (P-25) (50mgL(-1)) was tentatively introduced into pulsed high-voltage discharge process for non-thermal plasma-induced photocatalytic degradation of the representative mode organic pollutant parachlorophenol (4-CP), including other compounds phenol and methyl red in water. The experimental results showed that rate constant of 4-CP degradation, energy efficiency for 4-CP removal and TOC removal with TiO(2) were obviously increased. Pulsed high-voltage discharge process with TiO(2) had a promoted effect for the degradation of these pollutants under a broad range of liquid conductivity. Furthermore, the apparent formation rates of chemically active species (e.g., ozone and hydrogen peroxide) were increased, the hydrogen peroxide formation rate from 1.10x10(-6) to 1.50x10(-6)Ms(-1), the ozone formation rate from 1.99x10(-8) to 2.35x10(-8)Ms(-1), respectively. In addition, this process had no influence on the photocatalytic properties of TiO(2). The introduction of TiO(2) photocatalyst into pulsed discharge plasma process in the utilizing of ultraviolet radiation and electric field in pulsed discharge plasma process enhanced the yields of chemically active species, which were available for highly efficient removal and mineralization of organic pollutants.     

Application of novel copolymer-TiO(2) membranes for some textile dyes adsorptive removal from aqueous solution and photocatalytic decolorization

Novel low density polyethylene-grafted-poly(4-vinylpyridine-co-acrylamide) (LDPE-g-P(4-VP/AAm)) films were prepared by means of gamma-radiation-induced graft copolymerization as support for photocatalytic application. Nanometer-sized TiO(2) particles were immobilized to the grafted LDPE via dip coating technique. The efficiency of immobilized photocatalyst is tested on two target pollutants (textile azo dyes: Remazol red RB-133 (RR RB 133) and reactive blue 2 (RB2)). The efficient photocatalytic ability as reflected in determined photobleaching rate of both dyes was observed and is comparable to that for the non-supported TiO(2) used in a typical slurry photoreactor. The LDPE-g-(4-VP/AAm) copolymers supported TiO(2) photocatalyst has the practical advantages of easy separation and removal from the polluted environment. It could be a viable technique for the safe disposal of textile wastewater into the water streams.     

多孔矿物载体对纳米TiO2复合材料光催化脱色性能的影响

以多孔矿物沸石、硅藻土、高岭石和坡缕石为载体,采用TiCl4水解法制备了纳米TiO2/多孔矿物复合光催化材料。采用XRD分析了材料的成分和结构,采用甲基橙染料废水评价并对比了材料的光催化性能。研究表明,复合材料中纳米TiO2均为锐钛矿结构,且矿物载体结构未被破坏。由于沸石、硅藻土和坡缕石具有很好的吸附性能,制备的材料在光照初期即对甲基橙染料废水表现出很好的脱色效果。高岭石由于吸附性能相对较弱,导致材料对甲基橙染料废水的脱色效果不佳。     

Photocatalytic pretreatment of oily wastewater from the restaurant by a vacuum ultraviolet/TiO2 system

The present study aims at investigating the performance of a vacuum ultraviolet (VUV, 185 nm) and TiO(2) oxidation system for the pretreatment of oily wastewater from restaurant. The influence of irradiation time, pH, dissolved oxygen (DO), the dosage of TiO(2) and the initial chemical oxygen demand (COD) concentration on COD removal efficiency was ascertained and optimum process conditions for stable and effective operation were determined. Under the optimum conditions of irradiation 10 min, initial COD 3981 mg/L, TiO(2) 150 mg/L, pH 7.0 and flow rate of air 40 L/h, the process of VUV and TiO(2)/VUV achieved removal efficiencies of COD, BOD(5) and oil as 50±3%, 37±2%, 86±3%, and 63±3%, 43±2%, 70±3%, respectively. The biodegradability factor f(B) of the wastewater was determined as 1.56 which indicated that the VUV/TiO(2) process improved the biodegradability of the oily wastewater significantly. Results clearly indicate that VUV/TiO(2) photolysis tends to destruct parts of COD, BOD(5), and ammonia, as well as enhances the biodegradability of the oily wastewater simultaneously. Thus, this technique could be used as a pretreatment step for conventional biological treatment of oily wastewater.     

Synergy between surface adsorption and photocatalysis during degradation of humic acid on TiO2/activated carbon composites

A photocatalyst comprising nano-sized TiO(2) particles on granular activated carbon (GAC) was prepared by a sol-dipping-gel process. The TiO(2)/GAC composite was characterized by scanning electron microscopy (SEM), X-ray diffractiometry (XRD) and nitrogen sorptometry, and its photocatalytic activity was studied through the degradation of humic acid (HA) in a quartz glass reactor. The factors influencing photocatalysis were investigated and the GAC was found to be an ideal substrate for nano-sized TiO(2) immobilization. A 99.5% removal efficiency for HA from solution was achieved at an initial concentration of 15 mg/L in a period of 3h. It was found that degradation of HA on the TiO(2)/GAC composite was facilitated by the synergistic relationship between surface adsorption characteristics and photocatalytic potential. The fitting of experimental results with the Langmuir-Hinshelwood (L-H) model showed that the reaction rate constant and the adsorption constant values were 0.1124 mg/(L min) and 0.3402 L/mg. The latter is 1.7 times of the calculated value by fitting the adsorption equilibrium data into the Langmuir equation.     

高活性氮掺杂介孔二氧化钛的合成及性能研究

采用水热法, 以聚乙二醇(PEG)为模板, N,N-二甲基甲酰胺为氮源, 制备了氮掺杂的介孔二氧化钛。并用X射线粉末衍射(XRD)、傅立叶红外光谱(FTIR)、BET、透射电子显微镜(TEM)、紫外一可见漫反射谱(DRS)和X射线光电子能谱(XPS)等技术手段对制备样品进行了表征。结果表明: 所合成的样品具有锐钛矿结构,直径约20 nm, 并且具有一定的可见光活性。以甲基橙(MO)为光降解模型, 样品在可见光区表现出了较好的催化活性, 这取决于烷氧基和氮掺杂的协同效应。     

Organic-inorganic hybrid materials based on polyaniline/TiO(2) nanocomposites for ascorbic acid fuel cell systems

Polyaniline was grafted onto a mixture of rutile and anatase TiO(2) nanoparticles by in situ chemical oxidative polymerization. These nanocomposites were characterized by carbon, hydrogen and nitrogen (CHN) analysis, x-ray diffraction (XRD), Fourier transform infrared (FTIR), ultraviolet-visible (UV-vis), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis. FTIR and UV-vis confirm the formation of polyaniline on TiO(2) nanoparticles. The TEM shows that the composites consist of PANI and TiO(2) nanoparticles. Compared to the neat polyaniline, PANI/TiO(2) composites show a higher capacitance and also a higher activity per mass of polyaniline. Since the PANI/TiO(2) composites are stable during the electrooxidation of ascorbic acid, they can be used as an alternative catalyst for direct ascorbic acid fuel cells.     

Photodegradation of an azo dye using immobilized nanoparticles of TiO2 supported by natural porous mineral

Natural mordenite, replacing the synthetic zeolites, has been employed as the support of TiO2, and its photocatalytic activity has been examined in methyl orange (MO) aqueous under UV light. AFM, TEM, XRD, FTIR and fluorescence spectra have been used to reveal the loading effects of TiO2 on mordenite. The results show that the photocatalytic degradation (PCD) reaction rates are sharply increased by natural zeolite supports. Since mordenite is photo-inert, the PCD-enhancement is mostly caused by the bonding effects of Ti-O-Si and Ti-O-Al. Moreover, another two distinct natural zeolites have been employed as the supports of TiO2, in order to check the universality of PCD-enhancement effect of natural zeolites on TiO2. And the factors of PCD reaction on TiO2-zeolite, such as pH and catalyst dose, have been investigated.     

Nanocomposite of Cu-TiO2-SiO2 with high photoactive performance for degradation of rhodamine B dye in aqueous wastewater

The nanocomposite of Cu-TiO2-SiO2 photocatalyst have been prepared by a sol-gel method, which is used for the degradation of Rhodamine B (RB) as a probe that is notorious organic compound present in dyes wastewater. Morphological and structural characteristics of the Cu-TiO2-SiO2 nanocomposite were studied with low temperature N2 adsorption (BET), X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-vis diffuse reflectance spectroscopy (DRS). The Fourier transformed infrared spectroscopy (FT-IR) analysis shows the enhanced chemical bonding of O-Ti and O-Ti-O after the composition of Cu and SiO2 species into TiO2. It is found that the Cu-TiO2-SiO2 nanocomposite exhibits much higher photocatalytic activity under both UV light and visible light irradiation as compared with that over commercial titania (Degussa P25) toward the dyes wastewater containing RB. The photodegradation rate of RB (5 mg/L) can reach above 95.0% under sunlight after 3 h. The addition of SiO2 not only inhibites the crystal growth and anatase-to-rutile transformation of TiO2 nanocatalyst, but also enhances the adsorption of organic compounds. Cu-doping extends the light response to the visible region. Synergetic effects between Cu-SiO2 and TiO2 have been investigated, which provides a good way and material in the degradation field of dyes wastewater.