磷钨酸对甲基橙光催化降解的初步研究

在自制的光化学反应器中,以紫外灯为光源,以磷钨酸为光催化剂,研究了其对模拟甲基橙染料废水的光催化脱色降解的影响。实验结果表明,催化剂加入量、溶液初始浓度、不同光强度是影响催化降解效果的重要因素。最佳催化条件为20 mg/L的甲基橙溶液在紫外灯(16W)辐射下,光催化剂磷钨酸用量为1.5 g/L。     

微波增强H3PW12O40／TiO2光催化降解染料和水杨酸的研究

以孔雀石绿为模型分子, 考察了微波无极灯的形状、微波功率和溶液初始浓度对光催化降解效果的影响. 并且在最佳微波反应条件下, 考察了通过溶胶-凝胶再结合程序升温水热法制备的复合材料H3PW12O40/TiO2对刚果红、酸性黑、酸性品红和水杨酸的光催化降解情况. 结果表明, 微波无极灯具有更好地增强H3PW12O40/TiO2光催化降解有机污染物的作用.     

纳米ZnO光催化降解甲基橙研究

以ZnSO4.7H2O和Na2CO3为原料,采用沉淀法制备纳米ZnO粉体。以甲基橙为研究对象,高压汞灯(主波长365nm)为光源,研究了催化剂用量、甲基橙初始浓度、光强度、电解质(Cl-、SO42-、NO3-)及pH值等对甲基橙降解率的影响。     

β-环糊精与甲基橙包合物的形成及其光催化脱色

β-环糊精与甲基橙包合物的形成及其光催化脱色     

纳米TiO2复合薄膜光催化降解甲基橙的研究

本文通过Sol-Gel工艺在载玻片表面、多孔陶瓷表面及玻璃纤维表面制得了均匀透明的纳米TiO₂复合薄膜,以甲基橙为研究对象,紫外灯为光源,研究了甲基橙初始浓度、光照时间、催化剂载体比表面、初始溶液的pH值对甲基橙降解率的影响,并比较了半导体耦合薄膜的光催化降解能力.研究结果表明:SnO₂-TiO₂复合膜相对于其它耦合膜及金属(La)掺杂膜有较高的降解率.     

多孔TiO2薄膜的表面微结构对甲基橙光催化脱色的影响

 从含聚乙二醇的钛醇盐溶胶前驱体出发,通过浸渍提拉法在玻璃表面制备了锐钛矿型多孔TiO2薄膜．随着前驱物中聚乙二醇加入量及分子量的增加,聚乙二醇热分解后在薄膜中产生气孔的数量增多,孔径增大,TiO2薄膜表面的羟基含量也增加．TiO2薄膜中引入适当大小的微孔可明显提高薄膜的光催化活性;当孔径接近400nm时,光的散射增强,透光率下降,薄膜的光催化活性降低．     

银促进的TiO2光催化降解甲基橙

 采用溶胶-凝胶和水热协同法制备了不同Ag含量的负载型Ag-TiO2样品,这些样品具有较大的比表面积和较小的粒径. 适量负载金属银后的TiO2在紫外及可见光下的光催化活性均得到提高. 银在TiO2上的最佳负载量为0.15%, 过高的负载量反而会降低TiO2光催化降解甲基橙的活性. 由于反应机理的不同,银负载对TiO2可见光下催化活性的提高要明显高于对其紫外光下催化活性的提高. 在可见光照射下,从激发态染料注入到TiO2导带的电子迅速转移到了Ag原子簇, Ag原子簇通过促进电荷分离抑制了电子和染料正离子自由基的复合,从而促进了光催化过程. 研究结果表明,有效地促进电荷分离以及激发态电子和氧气分子的反应是提高染料敏化光催化活性的关键.     

Fe3O4/SrTiO3复合光催化剂降解甲基橙

用共沉淀法制备了SrTiO3光催化剂及Fe3O4/SrTiO3复合光催化剂.通过紫外-可见漫反射光谱、XRD、SEM-EDX对其进行表征,以甲基橙为探针分子考察其光催化性能.结果表明,适量Fe3O4的掺入可明显提高Sr-TiO3光催化剂对可见光的吸收,从而增强其光催化性能;在光降解甲基橙的反应中,掺杂10%Fe3O4的SrTiO3光催化剂其催化活性是纯SrTiO3光催化剂的两倍.     

二铁取代硅钨酸盐光解引发甲基橙的脱色

合成了SiW10Fe2的季胺盐(Fe2POM),并对其结构进行了表征.以Fe2POM为催化剂,研究了甲基橙的起始浓度、催化剂添加量、不同pH值等因素对光脱色速率的影响.利用异丙醇作为·OH捕获剂,探讨了甲基橙在Fe2POM-H2O2体系中的光化学脱色规律和机制.结果表明:体系在较宽的pH范围内具有高的光脱色活性,40—160mg/L初始质量浓度范围内,甲基橙的脱色速率随初始浓度降低而升高,脱色过程符合表观一级反应动力学规律.各体系的光脱色活性依次为:Fe2POM-H2O2单纯的Fe2POM>单纯的光照.     

孔道结构H3PW12O40/TiO2的制备及其可见光光催化降解水溶性染料的性能

 采用溶胶-凝胶方法制备了孔道结构复合材料H3PW12O40/TiO2,采用ICP-AES,UV/DRS,31P MAS NMR,TEM和N2吸附等技术对其组成和结构进行了表征. 结果表明,催化剂中活性组分H3PW12O40的基本骨架结构未发生改变,H3PW12O40的担载量为22.29%,催化剂平均粒径为40 nm,具有双孔结构,其平均微孔和介孔孔径分别为0.61和3.06 nm. 考察了催化剂可见光光催化降解6种水溶性染料的性能. 结果表明,6种染料均可不同程度地被降解和矿化. 通过对染料中性红的光催化降解实验,比较了H3PW12O40/TiO2,Degussa P-25和锐钛矿结构TiO2的可见光光催化活性,其中,H3PW12O40/TiO2活性最高,且催化剂最易分离,可循环使用.     

Photocatalytic decolorization of methyl orange solution with potassium peroxydisulfate

Increasing environmental pollution caused by toxic dyes due to their hazardous nature is a matter of great concern. It has been generally agreed that methyl orange (MO) can be effectively degraded in aerated K₂S₂O₈ homogeneous reaction system using near-UV irradiation. In this paper photocatalytic degradation of MO solutions with K₂S₂O₈ was investigated, with particular attention on the possible underlying mechanisms. This report has shown decolorization efficiency of MO increases with the increasing of the dosage of the catalyst. There is no optimal amount of catalyst in our case, where special attention was paid on the nature of the photocatalyst itself. The current research revealed that the decolorization reaction is a pseudo first-order reaction when the concentration of MO is below 20 mg L⁻¹ and the decolorization reaction is zero-order reaction when the concentration of MO is above 100 mg L⁻¹, but the Langmuir-Hinshewood kinetic model does not describe this. The influence of IO₄⁻, BrO₃⁻ and H₂O₂ were investigated in detailed. Several observations indicate that the mechanism is not involved in hydroxyl radical attacks in MO degradation with K₂S₂O₈ by UV irradiation. The possible underlying mechanisms are direct oxidation of the MO by S₂O₈²⁻ and hydrogen attraction by SO₄^•−.      

RETRACTED ARTICLE: Kinetic and anion degradation products study on photocatalytic degradation of reactive orange 5 solution with phosphotungstic acid

Increasing environmental pollution caused by toxic dyes is a matter of great concern due to their hazardous nature. So it is crucial to develop processes which can destroy these dyes effectively. It has been generally agreed that reactive orange 5 (KGN) can be effectively degraded in aerated phosphotungstic acid (HPA) in a homogeneous reaction system using near-UV irradiation. In this paper, photocatalytic degradation of reactive orange 5 solutions with phosphotungstic acid was investigated, especially more attention was paid to the kinetic model and the anion degradation products. The results revealed that the photocatalytic degradation reaction of KGN with HPA in a homogenous solution can be described by Langmuir-Hinshelwood equation and Langmuir-Hinshewood kinetic model described it well. The reaction manifested the first order with lower concentration(⩽30 mg L⁻¹) with the limiting rate constant and the adsorption constant in this case being 0.8098 mg L⁻¹ min⁻¹ and 4.359 10⁻² L mg⁻¹, respectively. The degradation mechanism of KGN with HPA is different from that with TiO₂, the anion products of the two reaction systems are the same. The difference in degradation mechanism of KGN with HPA from that with TiO₂ is caused by the nature of the photocatalyst.      

Preparation of novel hybrid nanomaterials based on LaFeO3 and phosphotungstic acid as a highly efficient magnetic photocatalyst for the degradation of methylene blue dye solution

Novel magnetic hybrid nanomaterials 1 (LaFeO₃.Fe₃O₄@SiO₂-NH₂/PW₁₂) were synthesized by supporting phosphotungstic acid (H₃PW₁₂O₄₀; PW₁₂) on LaFeO₃.Fe₃O₄ nanomaterials through sono-assisted method. The synthesized nanomaterials were fully characterized by using FT-IR, XRD, UV–vis, BET-BJH, VSM, SEM, and TEM analyses. FT-IR, XRD, and UV–vis confirmed successful synthesis of nanomaterials. The SEM and TEM images revealed spherical morphology with core-shell structure for hybrid nanomaterials 1 . VSM results confirmed the magnetic property of hybrid nanomaterials 1 and suggested it as easily recyclable photocatalyst for removal of organic dyes from aqueous solution. The photocatalytic activity of hybrid nanomaterials 1 has been studied over the degradation of methylene blue (MB) and methyl orange (MO) solution under UV–vis light irradiation. Importantly the hybrid nanomaterials 1 showed outstanding degradation efficiency for MB solution in comparison with bare LaFeO₃.Fe₃O₄ and PW₁₂. The photocatalytic activity was enhanced mainly due to the high efficiency in separation of electron–hole pairs induced by the remarkable synergistic effects of LaFeO₃.Fe₃O₄ and PW₁₂ semiconductors. After the photocatalytic reaction, the nanocomposite can be easily separated from the reaction solution and reused several times without loss of its photocatalytic activity. Trapping experiments indicated that hole (h_VB⁺) and ^•OH radicals were the main reactive species for dye degradation in the present photocatalytic system. On the basis of the experimental results and estimated band gaps, the mechanism for the enhanced photocatalytic activity was proposed.     

Hydrophilic Fe3O4 nanoparticles prepared by ferrocene as high‐efficiency heterogeneous Fenton catalyst for the degradation of methyl orange

Hydrophilic Fe₃O₄ nanoparticles were prepared with ferrocene as an iron source via the thermal decomposition method and their catalytic response towards methyl orange was investigated. The effects of the pH, temperature, H₂O₂ dosage, catalyst dosage and initial dye concentration on the degradation of methyl orange were researched in detail. Furthermore, the stability of the catalyst was evaluated by measuring the degradation rate in eight successive cycles. The study demonstrates that methyl orange can be completely degraded i.e., a 99% degratation rate was obtained within 3 min. This excellent catalytic activity is attributed to the small size and good dispersibility of the nanoparticles, which stimulate the rapid and massive generation of reactive oxygen species in the heterogeneous Fenton reaction. In addition, the magnetic separation of the catalyst offers great prospects for fast and economical decontamination of dye polluted water.     

铁锌柱撑膨润土催化剂的制备及其对甲基橙废水的光催化降解性能

采用微波辐照促进的溶胶浸渍法制备了铁锌柱撑膨润土催化剂;用制备的催化剂对甲基橙溶液在可见光照射下进行降解,探讨了铁负载量、H2O2质量浓度、溶液初始pH、反应时间和催化剂投加量对甲基橙降解率的影响,并考察了催化剂的重复利用性能.结果表明,在pH为3、H2O2质量浓度100mg/L、催化剂投加量1.5g/L、反应时间为2h条件下,甲基橙降解率可达97%.     

Effect of a long-term exposure of anatase TiO2 powder doped with surface-located Sb3+ ions to UV radiation on its photocatalytic activity

Ultraviolet photocatalytic experiments on the kinetics of decolorization of methyl orange and the ¹²¹Sb Mössbauer characterization of the title catalyst were performed. The stereochemically active electronic lone pair of Sb³⁺ was found to completely deactivate the neighboring oxygen vacancy as a recombination center towards the photogenerated electrons and holes.     

Synthesis of methyl orange using ionic liquids

Two ionic liquids were synthesized, each system consisting of the 1-hexyl-3-methylimidazolium ion ([hmim]⁺) as the cation and either hexafluorophosphate ([PF₆]⁻), or perchlorate ([ClO₄]⁻) as the anions. This study involves the synthesis of methyl orange (4-[[(4-dimethylamino)phenyl]-azo] benzene sulfonic acid sodium salt) using the ionic liquids as replacement solvents for the reaction. The advantage of using ionic liquids as substitutes for organic solvents includes: recyclable/reclaimable solvents, stabilization of intermediates and higher product yields. The 1-hexyl-3-methylimidazolium derivatives can be used for syntheses conducted at low temperatures and are less toxic than typical organic solvents.     

Effect of charge balance vacancies on the ultraviolet photocatalytic activity of Fe3+-doped anatase

1. Download : Download high-res image (112KB)
2. Download : Download full-size image