可见光下氮掺杂二氧化钛对有机污染物的降解动力学研究

温和条件下以碳酸铵为氮源,采用溶胶凝胶法制备氮掺杂二氧化钛粉末,以XRD、UV-Vis漫反射吸收光谱以及BET等手段对掺杂二氧化钛进行了表征。通过吸附等温线的计算以及可见光催化活性的测定,考察了氮掺杂二氧化钛对巯基苯并噻唑的降解动力学。结果显示,实验范围内所制备的样品均为锐钛矿相,样品粒径随N／Ti配比的增加而增大;氮的掺杂产生更多的孔结构和多样孔型,增大了光催化剂对有机物的吸附能力,且氮的掺杂增强了二氧化钛在可见光区的光吸收。通过Langmuir-Hinshelwood积分动力学模型对表观速率常数、吸附平衡常数及反应速率常数的分析,表明氦的掺杂有效地改善了二氧化钛的可见光活性,其中吸附能力的增大对表观速率常数的提高有更显著的贡献。     

钇施主掺杂二氧化钛的制备及对久效磷的降解

介绍一种用五氧化二钇对TiO2进行施主掺杂来改善TiO2的光作用范围的方法,并研究用该方法制备的掺杂二氧化钛对久效磷的降解情况.钇离子以草酸盐化合物形式按比例掺杂到草酸氧钛酸中,经过结晶析出针状钇掺杂草酸氧钛酸晶体,再经过热分解和焙烧获得钇掺杂二氧化钛光催化剂粉体.钇掺杂二氧化钛光催化剂粉体中金红石矿型TiO2和锐钛矿型TiO2都分别控制为质量百分数45%和55%左右,粒度分布在0.2～0.5 μm范围,颗粒接近球形,掺钇杂量为质量百分数0.2%时光催化效果较佳,日光灯降解6 h后,久效磷的无机磷回收率达到质量百分数96.4%.     

蛋氨酸为硫源的硫掺杂二氧化钛的光催化活性

为改善二氧化钛的可见光催化活性,以蛋氨酸为硫源,在温和条件下采用溶胶-凝胶法制备了硫掺杂二氧化钛粉末。采用XRD、TEM、UV-Vis漫反射吸收光谱和XPS等方法对制备的样品进行表征,以甲基橙的光降解效果考察其可见光催化活性。结果显示：350~500℃所制备的硫掺杂二氧化钛均为锐钛矿相,600℃出现混晶,且硫的掺杂一定程度的抑制了粒径的增长和晶相的转变;硫以阳离子形式进入二氧化钛晶格中,引起光催化剂在可见光区的光吸收;掺杂样品表现出较好的可见光催化活性,且随煅烧温度的增加,催化活性逐渐降低。正交试验得出优化条件为：S/Ti物质的量配比为1.6%,煅烧温度为450℃,煅烧时间为3 h。     

钒-氮共掺杂TiO2的合成、表征及光催化性能

以偏钒酸铵作为钒源、二乙醇胺作为氮源,采用溶胶-凝胶法合成了钒-氮共掺杂TiO2.通过XRD、UV-Vis、TEM、XPS、BET等表征手段,对光催化剂的晶体结构及形貌、紫外可见光响应特性、比表面积、表面元素及存在形式进行分析,探讨钒氮共掺杂TiO2的影响机制.以苯酚为污染物,评价其在紫外光及可见光下的光催化活性.结果显示,所合成的光催化剂均为锐钛矿,钒氮共掺杂能够增大其比表面积,并使光吸收范围拓展至可见光区,N以O—Ti—N、Ti—O—N结构存在于钒氮共掺杂TiO2中,V以V5+的形式存在,钒-氮共掺杂TiO2在紫外光下对苯酚降解速率是TiO2的3.18倍,在可见光下对苯酚的降解速率为TiO2的2.56倍,重复使用7次后,钒-氮共掺杂TiO2对苯酚的降解率仍可以达到99%以上.     

CdS-TiO2复合光催化剂可见光下降解黄连素

采用沉积法制备CdS-TiO2复合光催化剂,利用UV-Vis DRS、XRD等方法对其进行表征,并在可见光下对黄连素废水进行处理,考察了催化剂投加量、黄连素初始浓度、黄连素初始pH值对黄连素去除率的影响.研究结果表明,在常温下制备的CdS-TiO2复合光催化剂,对可见光有较好的响应能力;在催化剂投加量1.5 g.L-1,黄连素初始浓度80 mg.L-1的条件下,催化剂对黄连素的去除效果显著,可达80%以上.pH对反应的影响不大.该催化剂循环使用3次仍具有较高的光催化活性与化学稳定性.     

绢云母负载N掺杂纳米二氧化钛的制备及性能研究

以绢云母为载体,采用水解-沉淀法制备出了绢云母负载纳米TiO2粉体(TiO2/M),以尿素为氮源,采用后掺杂法制得具有可见光响应的N掺杂TiO2/M.采用XRD,XPS,SEM,DUV等手段对样品进行了性能表征;并以日光色镝灯为光源,甲基橙为模拟污染物检测其光催化活性.研究了N的掺杂对粉体中TiO2晶相结构,粒度和光催化性能的影响.结果表明,绢云母与TiO2通过桥氧相连形成包覆层,N的掺杂抑制了TiO2晶粒的长大,减缓锐钛矿向金红石相的转变,同时N的掺杂形成Ti—O—N键,形成新的能级结构,使样品对光的吸收边红移至440—550 nm,具有明显的可见光响应,对甲基橙的光催化降解率与没有掺N的样品相比,最高可达1.6倍.     

基于席夫碱反应合成氮掺杂的碳活化PMS降解双酚A

基于石墨相氮化碳(g-C3N4)的热聚合形成过程和席夫碱反应,本文将尿素和2-萘甲醛作为前驱体,经一步热聚合反应制备了氮掺杂的碳材料(NCN-x),并以其作为催化剂活化过一硫酸盐(PMS)来降解双酚A(BPA).在催化剂特性研究部分,利用SEM、XRD、FTIR以及XPS对其表面形貌、结构与元素组成进行分析.结果 表明...     

铂掺杂二氧化钛的制备及光催化乳酸制氢的研究

采用溶胶-凝胶法和甲醛还原法制备了Pt/TiO2光催化剂,并采用XRD对其结构进行了表征.当焙烧温度为500℃时,制备的纳米二氧化钛为纯锐钛矿相;在二氧化钛表面沉积少量的铂对二氧化钛的晶相和粒径几乎没有影响,但可以使二氧化钛光催化的产氢性能提高近10倍.以乳酸为电子供体,对影响其光催化产氢的因素进行了详细地考察.研究结果表明,光催化分解乳酸产氢的最佳条件为焙烧温度500℃、焙烧时间2 h、载铂量0.8%、催化剂用量0.14 g·L-1和pH 1-2.     

磺胺甲噁唑在磷钨酸/二氧化钛复合膜上的光催化降解

以典型抗生素类药物磺胺甲噁唑(SMZ)为目标物,模拟太阳光下研究其在磷钨酸/二氧化钛(H3PW12O40/TiO2)复合膜上的光催化降解行为,并对其可能的降解机理进行探讨.通过一系列的条件实验确定H3PW12O40/TiO2复合膜光催化降解SMZ的最佳实验条件为:H3PW12O40掺杂量为7.7%、污染物初始浓度为50 mg·L-1、溶液pH值为5.5.此时,H3PW12O40/TiO2复合膜表现出最强的光催化活性,其动力学常数为0.453 h-1,为纯TiO2膜的3.0倍;模拟太阳光照射12 h后,复合膜对SMZ的矿化度可达66.6%,是纯TiO2膜的1.25倍.     

Photodegradation of atrazine and ametryn with visible light using water soluble porphyrins as sensitizers

The photodegradation of the herbicides atrazine and ametryn with visible light in aerated neutral aqueous solutions and 5, 10, 15, 20-tetrakis (2,6-dichloro-3-sulfophenyl) porphyrin or 5, 10, 15, 20-tetrakis (4-sulfophenyl) porphyrin as sensitizers are reported for the first time. Our findings show that the degradation percentage reached 30% for atrazine and 63% for ametryn. The final photoproducts were characterized as dealkylated s-triazines. Photolysis of the pesticides in the presence of a singlet oxygen quencher showed only a minor contribution of this type of mechanism, while a bimolecular quenching reaction between the triplet state of the sensitizer and the pesticides is excluded by flash photolysis studies. It is proposed that the mechanism may involve the formation of a superoxide radical anion from the triplet state of the sensitizer and molecular oxygen, followed by a radical decomposition pathway. Selected article from 1st International Meeting on Photochemistry, Photocatalysis and Environmental Applications, Agadir, 2006, organised by Prof. Dr. Ait Ichou, University Ibn Zohr, Agadir, Morocco     

Effects of visible light radiation on macrophyte litter degradation and nutrient release in water samples from a eutrophic shallow lake

Visible light is a major fraction of the solar spectrum; however, information on visible light radiation of macrophyte detritus is lacking. In this study, we conducted a microcosm experiment to assess the effects of visible light radiation on degradation of two litter species: Potamogeton malaianus (P. malaianus) and Phragmites australis (Ph. australis). This research represents an investigation of mass loss, microbial activity and nutrients released over a period of 168 days. Overall, we found that visible light radiation had significant effects on litter decomposition, but it did not affect the microbial activities which degrade cellulose and lignin. The decomposition rate order of the three components in P. malaianus and Ph. australis in treatments was: cellulose?>?hemicellulose?>?lignin. The visible light radiation mainly affected the degradation of lignin, which is the primary compound in litter susceptible to photodegradation. The exposure to visible light radiation up to 17.6?Wm^?2 stimulated the dissolved organic carbon release and reduced the molecular weight to less reactive. Meanwhile, no obvious difference in nutrient contents (TP, TN, NO₃–N, NO₂–N, and NH₃–N) was observed among different visible light intensities. The results of this study contribute to better understanding of the photochemical behaviour of macrophyte litter in shallow lakes.     

Photodegradation of fungicide triadimefon and pesticide pirimicarb in aqueous TIO2 suspension

Two agrochemicals composed of nitrogen‐containing heterocyclic ring, triadimefon and pirimicarb, were degraded photocatalytically. The disappearance and TOC elimination rates of triadimefon were close to those of pirimicarb, whereas the photolysis of triadimefon was 4 times slower than that of pirimicarb. For triadimefon its aromatic moiety degraded quickly and Cl^‐ was released immediately, while triazole moiety degraded slowly. The formation rates of NH⁺ ₄ and NO₃ ^‐ by the degradation of triazole moiety were influenced by the rest of the molecule. The difference between disappearance and TOC elimination rates of both triadimefon and pirimicarb were far larger than those of aromatic compounds.     

太湖水体光学特征及其对水中初级生产力的影响

对太湖梅梁湾水体实测结果表明 :在水体表面 ,UV -C的强度较小 ,只有 10 -5μE·m-2 ·s-1数量级 ;UV -B的强度随着波长的增加而呈现递增的趋势 ;UV -A的强度较强 ,达 10 -2 μE·m-2 ·s-1数量级 ,并且在水体中衰减较快 ,衰减系数 (Kd)可以达到 12 .5m-1。可见光在水体中Kd 可达 8.2m-1。在水下 0 .5m处 ,紫外线不足表面光强的 1% ,可见光是表面光强的 2 0 %左右。初级生产力在表面相对较小 ,在水下 0 .2m处最大 ,且随水深的增加而减少 ;在水体中直接测定发现 ,0 .2m处溶解氧值较高。初级生产力的这种分布是水体中紫外光与可见光共同作用的结果。     

碘铈共掺杂纳米TiO_2的制备及可见光光催化性能

采用溶胶凝胶法制备了不同原料比例碘铈共掺杂纳米TiO2催化剂,运用X射线光电子能谱（XPS）,X射线衍射（XRD）,透射电镜（TEM）等检测手段对催化剂进行了初步表征.结果表明,经过450℃煅烧处理得到的TiO2、铈掺杂TiO2以及碘铈共掺杂TiO2催化剂均为锐钛矿相,掺杂的Ce和I原子可能以I—Ce—O及O—Ti—I等键合方式进入TiO2晶格内部,此外,I-Ce离子共掺杂能有效降低TiO2表面的电子-空穴对的复合.以染料罗丹明B（Rhodamine B,RhB）和无色小分子水杨酸（Salicylic acid,SA）为降解的目标化合物,发现碘铈共掺杂的最佳物质的量之比为nCe∶nI∶nTi=0.04∶0.05∶1,即I0.05Ce0.04TiO2催化剂在可见光照射下（λ〉420 nm）降解目标化合物其光化学活性明显优于单掺铈的TiO2催化剂和未掺杂的TiO2.该催化反应涉及到空穴氧化,并伴有羟基自由基（.OH）、超氧自由基（O2.-）及H2O2等氧化物种的产生.     

One-step ball milling-prepared nano Fe2O3 and nitrogen-doped graphene with high oxygen reduction activity and its application in microbial fuel cells

• Nano Fe₂O₃ and N-doped graphene was prepared via a one-step ball milling method. • The maximum power density of Fe-N-G in MFC was 390% of that of pristine graphite. • Active sites like nano Fe₂O₃, pyridinic N and Fe-N groups were formed in Fe-N-G. • The improvement of Fe-N-G was due to full exposure of active sites on graphene. Developing high activity, low-cost and long durability catalysts for oxygen reduction reaction is of great significance for the practical application of microbial fuel cells. The full exposure of active sites in catalysts can enhance catalytic activity dramatically. Here, novel Fe-N-doped graphene is successfully synthesized via a one-step in situ ball milling method. Pristine graphite, ball milling graphene, N-doped graphene and Fe-N-doped graphene are applied in air cathodes, and enhanced performance is observed in microbial fuel cells with graphene-based catalysts. Particularly, Fe-N-doped graphene achieves the highest oxygen reduction reaction activity, with a maximum power density of 1380±20 mW/m² in microbial fuel cells and a current density of 23.8 A/m² at –0.16 V in electrochemical tests, which are comparable to commercial Pt and 390% and 640% of those of pristine graphite. An investigation of the material characteristics reveals that the superior performance of Fe-N-doped graphene results from the full exposure of Fe₂O₃ nanoparticles, pyrrolic N, pyridinic N and excellent Fe-N-G active sites on the graphene matrix. This work not only suggests the strategy of maximally exposing active sites to optimize the potential of catalysts but also provides promising catalysts for the use of microbial fuel cells in sustainable energy generation.     

Visible light sensitive activated carbon-metal oxide (TiO2, WO3, NiO,and SnO) nano-catalysts for photo-degradation of methylene blue: a comparative study

Four composites of metal oxide doped with activated carbon with a metal oxide weight of 20% were prepared using mechano-mixing method. The nano-catalysts were characterized by N₂-adsorption–desorption, X-ray diffraction analysis, transmission electron microscopy, Fourier-transform infrared spectroscopy, UV-diffuse reflectance, and photoluminescence spectroscopy. Photo-catalytic degradation of methylene blue dye under UV 254 nm and visible light was examined. In general, prepared catalysts are more active for degradation of dye under visible light than UV, reaching 96% within 180?min irradiation using the SnO catalyst. Photo-degradation of methylene blue followed pseudo first order reaction mechanism with a rate constant of 14.8?×?10^?3?min^?1, and the time required for removal of 50% of dye was 47?min.     

油酸铵改性的高活性TiO2/V-TiO2复合光催化剂的制备及光催化降解甲基橙的研究

采用溶胶-凝胶法,将经过油酸铵改性的掺钒二氧化钛粉末投入到纯TiO2溶胶中,烘干、煅烧,制得带有n-n异质结半导体结构的复合型高活性掺钒二氧化钛光催化剂,并通过XRD、TEM、XPS等技术对样品进行了表征。通过对甲基橙溶液的光催化降解实验来考察TiO2/V-TiO2催化剂的光催化活性。结果表明：TiO2/V-TiO2复合催化剂拥有比纯TiO2更高的光催化活性。其中,V的掺杂摩尔分数为0.5%、TiO2：V-TiO2的质量比为10∶1的最佳复合催化剂,其光催化活性是纯TiO2的5.1倍。