稀土La3+掺杂Bi2WO6光催化降解活性艳红X-3B的研究

采用水热合成法制备稀土元素La3+掺杂Bi2WO6光催化剂并考察其对染料废水中活性艳红X-3B的光催化活性.通过X射线衍射、场发射扫描电镜、紫外-可见漫反射光谱、N2物理吸附-脱附等手段对合成材料的结构、形貌、光吸收等物理化学性能进行表征.结果表明,La3+掺杂量为5%时,其结晶度好、颗粒均匀、具有较强的可见光吸收性能,且比表面积比纯Bi2WO6提高30%以上,对X-3B的去除效果最好.另外,催化剂投加量、X-3B初始浓度、反应溶液pH等因素对La3+掺杂Bi2WO6光催化降解X-3B均有重要影响.     

Bi2WO6可见光催化降解活性艳红X-3B的研究

采用水热合成法制备Bi2WO6催化剂,并通过XRD,UV-vis DRS等手段对其进行表征;以活性艳红X-3B为目标污染物,研究催化剂量、X-3B初始浓度、反应溶液pH值以及H2O2等因素在可见光辐射下对其光催化降解效果的影响.结果表明,所制备的Bi2WO6催化剂结晶度好,具有较强的可见光吸收能力;最佳催化反应条件为: X-3B初始浓度20mg/L,Bi2WO6用量2g/L, pH5.18(原始pH值).在此条件下,光照60min,对X-3B的去除率可达到86%;加入2mL/L 30%的H2O2,光照30min,降解率可达到96%以上,降解反应符合一级反应动力学.光催化反应可以有效地破坏X-3B的发色基团偶氮结构使其脱色,但在所设定的反应时间(80 min)内X-3B不能被完全矿化,反应过程中有中间产物生成.     

纳米复合GeO2/TiO2的制备及光催化性能研究

采用改进的Sol-gel方法,制备了一种新型的单分散椭球形微孔结构的纳米GeO2/TiO2复合光催化剂,并用TG-DTA、XRD、XPS、UV-vis、FT-IR、TEM、BET等手段进行了表征.以难生化降解的染料罗丹明B为目标降解物,采用HPLC测定不同光照时间下催化剂对染料降解的情况,考察了催化剂的光催化活性结果表明,改进的Sol-gel法制得的复合光催化剂具有明显的孔结构,而且比表面积大、粒径小、粒径分布窄、分散性好;与适量GeO2复合后能够有效提高TiO2纳米粒子的光催化活性;复合光催化剂的最佳制备条件为GeO2摩尔含量为0.1%,煅烧温度为400℃,所制得的GeO2/TiO2光催化活性比纯TiO2有显著提高.     

TiO2纤维光催化降解X-3B影响因素研究

采用溶胶-凝胶法及水蒸汽活化热处理工艺制备了15%(质量分数)SiO2掺杂的TiO2纤维,并利用SEM、XRD和HRTEM对其结构进行了表征.同时,以活性艳红X-3B染料水溶液为降解对象,研究了热处理温度、溶液pH值、紫外光源、溶液浓度等因素对TiO2纤维光催化活性的影响.结果表明,所制得的TiO2纤维为锐钛矿相,直径约为5～10μm;其最佳热处理温度为700℃,且在强酸(pH=2)或强碱(pH=14)条件下均表现出良好的光催化活性,并对不同浓度的X-3B溶液都有良好的降解效果,同时TiO2纤维也具有良好的可重复使用性.     

纳米TiO2的凝胶网格沉淀法制备及其光催化性能

以明胶为反应介质,采用凝胶网格沉淀法制备纳米TiO2光催化剂,利用TG-DTA、XRD、TEM、FT-IR、UV-Vis、FL等分析测试手段对制备过程、样品的结构和性能进行了研究.结果表明,利用凝胶网格沉淀法不仅能够控制纳米微粒的晶相和大小,而且可防止沉淀物相互聚集和团聚,获得的纳米微粒粒径更小,分散性更好.以染料罗丹明B溶液为目标降解物,1h的降解率为98%.最佳光催化剂的合成条件为8%明胶浓度、650℃煅烧2h.     

WO3/g-C3N4异质结光催化剂的制备和光催化活性探究

采用水热合成和煅烧法制备高催化活性的WO₃/g-C₃N₄材料,并用于酸性橙G废水的降解.同时,采用X射线衍射、漫反射光谱、傅立叶变换红外光谱、扫描电镜和氮吸附-脱附测试、X光子能谱和光致发光光谱方法对复合材料进行了表征.降解实验表明,复合材料的光催化性能比单一WO₃和g-C₃N₄高,且Z型光催化剂WO₃/g-C₃N₄在WO₃与g-C₃N₄质量比为3∶10时具有最高的光催化活性,在105 min内对20 mg·L^-1酸性橙G的光降解效率达98%,反应速率是单一g-C₃N₄的5倍.采用自由基捕获剂分别对体系中的·OH、·O₂^-和h⁺进行捕获实验,结果表明,·OH、·O₂^-和h⁺共同参与了光催化降解反应,其中,h⁺是Z型WO₃/g-C₃N₄光催化的主要活性物质.复合催化剂具有良好的重复利用性,在3次循环试验后光降解效率仍达90%.     

In_2TiO_5纳米带的静电纺丝法制备及光催化性能

以酞酸丁酯(Ti(OC_4H_9)_4)、硝酸铟(In(NO3)3)和聚乙烯吡咯烷酮(PVP-K30)为原料,采用静电纺丝技术制备了In_2TiO_5纳米带.利用X射线衍射(XRD)、扫描电子显微镜(SEM)、紫外-可见漫反射光谱(UV-vis DRS)和氮气吸附-脱附等温线(BET)等技术对样品进行了表征.考察了In_2TiO_5纳米带在光催化降解罗丹明B(RhB)、甲基橙(MO)、亚甲基蓝(MB)和左氧氟沙星(LEV)过程中的应用性能,研究了不同离子型物质、溶液的pH和MB起始浓度对In_2TiO_5纳米带光催化活性的影响.结果表明:In_2TiO_5纳米带具有正交晶系结构,禁带宽度为3.47 eV,比表面积为20.71 m~2·g~(-1),可应用于4种不同离子型物质的光催化降解,发现光催化效果与被降解物质的表面带电性质有关.在紫外光照射下,90 min,对MB的降解率达98.1%,其降解过程服从一级动力学模型.     

TiO2/Ti光电极电助光催化降解甲草胺的研究

采用阳极氧化法制备了TiO₂/Ti光电极,并通过电助光催化的方法研究了恒电流法和恒电压法对甲草胺的降解效率.实验证实了在光催化和电催化之间存在协同效应,反应溶液中加入Na₂SO₄电解质后,SO₄^2-可以被价带空穴氧化成强氧化性的S₂O₈^2-,继而可以氧化处理物质,提高甲草胺的降解效率.实验结果表明：甲草胺在羟基自由基的作用下通过羟基化作用和脱烷作用,发生断键、开环等一系列的氧化还原反应,最终生成CO₂和H₂O等无机小分子物质.     

硫毒化NH3-SCR脱硝催化剂再生方式的构建及机制研究

以CeTi复合氧化物负载NH₄HSO₄(模拟SO₂毒化催化剂)为研究对象,并向其中掺杂Mo作为改性组分,研究了硫毒化催化剂的再生过程与机制.与热再生相比,冷等离子体在再生毒化后催化剂的过程中显现出独特的优势.通过对再生后催化剂的物理化学性质表征及优化再生气氛,确认了冷等离子再生催化剂的优点：不仅能够保持催化剂物相结构的稳定,还可促进催化剂表面NH₄HSO₄的低温分解和硫物种的脱附.虽然冷等离子体再生后的催化剂NH₃-SCR反应活性下降,但可通过纯O₂气氛中焙烧的方式,实现对催化剂物理化学性质的重构和催化活性的再生.通过此研究,初步建立了催化剂“毒化-再生-重构”的基本构效关系,为硫中毒NH₃-SCR脱硝催化剂的再生提供了可行性方案.     

MWNTs/TiO2对典型氯苯类化合物的光催化降解研究

研究复合光催化剂MWNTs/TiO2对典型氯苯类有机化合物光催化降解动力学及主要光降解路径.结果表明,同一初始浓度和相同光催化降解实验条件下,60min时典型氯苯类有机化合物的光降解率均达到90%以上.其中六氯苯和五氯苯的光催化降解速率常数分别为0.0664h-1和0.0670h-1,其大小明显高于其它氯苯类化合物.1,二氯苯的光催化降解反应速率常数仅为0.0430h4--1,在典型氯苯类化合物中最小.三氯苯的3种同分异构体——1,3-三氯苯、24-三氯苯和1,5-三氯苯的光催化降解速率常数分别为0.0547h2,1,,3,-1、0445h0.-1和0.0439h-1.六氯苯的主要光催化降解路径为:HCB→PeCB→1,2,3,5-TeCB→1,2,4-TCB→1,4-DCB.     

Reaction mechanism and metal ion transformation in photocatalytic ozonation of phenol and oxalic acid with Ag+/TiO2

Photocatalytic ozonation of phenol and oxalic acid （OA） was conducted with a Ag^＋/TiO2 catalyst and different pathways were found for the degradation of different compounds. Ag^＋ greatly promoted the photocatalytic degradation of contaminants due to its role as an electron scavenger. It also accelerated the removal rate of OA in ozonation and the simultaneous process for its complex reaction with oxalate. Phenol could be degraded both in direct ozonation and photolysis, but the TOC removal rates were much higher in the simultaneous processes due to the oxidation of hydroxyl radicals resulting from synergetic effects. The sequence of photo-illumination and ozone exposure in the combined process showed quite different effects in phenol degradation and TOC removal. The synergetic effects in different combined processes were found to be highly related to the properties of the target pollutants. The color change of the solution and TEM result confirmed that Ag＋ was easily reduced and deposited on the surface of Tit2 under photo-illumination, and dissolved again into solution in the presence of ozone. This simple cycle of enrichment and distribution of Ag^＋ can greatly benefit the design of advanced oxidation processes, in which the sequences of ozone and photo-illumination can be varied according to the needs for catalyst recycling and the different properties of pollutants.     

Graphene TiO2 nanocomposites with high photocatalytic activity for the degradation of sodium pentachlorophenol

A series of graphene–TiO2photocatalysts was synthesized by doping TiO2 with graphene oxide via hydrothermal treatment. The photocatalytic capability of the catalysts under ultraviolet irradiation was evaluated in terms of sodium pentachlorophenol（PCP-Na） decomposition and mineralization. The structural and physicochemical properties of these nanocomposites were characterized by X-ray diffraction, N2adsorption–desorption, transmission electron microscopy, scanning electron microscopy, Ultraviolet–visible diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, electron paramagnetic resonance spectra, and Fourier-transform infrared spectroscopy. The graphene–TiO2nanocomposites exhibited higher photocatalytic efficiency than commercial P25 for the degradation of PCP-Na, and 63.4% to 82.9% of the total organic carbon was fully mineralized. The improved photocatalytic activity may be attributed to the accelerated interfacial electron-transfer process and the significantly prolonged lifetime of electron-hole pairs imparted by graphene sheets in the nanocomposites. However,excessive graphene and the inhomogeneous aggregation of TiO2 nanoparticles may decrease photodegradation efficiency.     

Ni2P/Bi2MoO6复合材料的制备及可见光催化活性

分别制备了花状Bi₂MoO₆和片状Ni₂P,采用研磨、水热及超声的方式将两种材料复合,考察了负载方式、负载率和溶液pH值对其可见光下降解亚甲基蓝（MB）的影响;利用XRD、XPS、FTIR、SEM、PL和UV-Vis等测试手段表征了样品的微观结构、形貌和光学性质;研究表明Ni₂P作为助催化剂,可加速电子空穴对分离,显著提高Bi₂MoO₆的光催化活性,其中当Ni₂P负载率为4%时,TOC去除率为64.28%,降解速率为纯Bi₂MoO₆的2倍,且将Ni₂P/Bi₂MoO₆复合催化剂循环利用3次后,同实验条件下降解率为94%,证明复合催化剂稳定性好.     

TiO2-石墨烯（Gn）复合材料光催化降解O3研究

通过改性Hummer法及溶胶凝胶法,制备出TiO2-石墨烯光催化复合材料.经吸附-光催化活性实验选出光催化活性最高的含C量为1.5%(质量分数)的TiO2-石墨烯复合材料,并在自行设计的模拟大型客机环境的气相光催化反应器中,进行O3光催化降解实验研究.结果表明,TiO2-石墨烯复合光催化材料在较短时间内对O3有较高的降解效率,且其光催化活性显著优于纯TiO2材料.初始O3浓度为(0.150～0.200)×10-6时,复合光催化剂受紫外光激发60 min的光催化降解率为66.12%,初始O3浓度为(0.950～1.000)×10-6时,其光催化降解率约为77%,较低浓度时((0.100～0.150)×10-6),O3去除率也能达到45.45%.此外,通过探讨光催化材料的重复使用性能,表明复合光催化剂重复使用4次以内,其对O3的光催化降解率保持基本稳定.     

Cu改性石墨相氮化碳(g-C3N4)光催化灭活铜绿微囊藻的效能与机理研究

通过热聚合法制备不同比例Cu掺杂g-C₃N₄复合光催化材料,利用XRD、SEM/EDX、FT-IR、UV-Vis DRS、PL、XPS等技术对复合材料的形貌结构和光学性能进行表征,研究了复合材料对藻细胞的光催化灭活效果.结果表明,Cu掺杂改性可有效促进g-C₃N₄材料表面光生电子-空穴的分离,增强其对可见光的利用率,进而提升其光催化效率;随着Cu掺杂比例的增大,Cu-C₃N₄对藻细胞的灭活效果则越好.进一步研究发现,H₂O₂和·O^-₂是Cu-C₃N₄光催化灭藻过程中起主要作用的活性物质,会损伤藻细胞的形态结构、抗氧化酶系统和光合系统,导致藻细胞大量死亡.     

ZnTiO3-TiO2复合光催化剂的制备及光催化降解有机污染物机制分析

TiO_2光催化剂因无毒无害而在光催化降解污染物领域有巨大潜力.但由于TiO_2的光生电子空穴复合较快,量子效率较低,限制了它的广泛使用.在本研究中,通过溶胶-凝胶(Sol-Gel)法制备了ZnTiO_3-TiO_2异质结复合光催化剂,分析了配比和煅烧温度对材料光催化性能的影响,以甲基橙(MO)溶液为模拟污染物进行光催化降解,探讨了其催化效果及效率提升的机制.结果表明,在紫外光照射下,ZnTiO_3与TiO_2比值为0. 3时,在600℃下煅烧3 h后,其催化效果最佳且表现出良好的化学稳定性.通过光电流测试和电子自旋共振波谱仪的检测结果,证明复合光催化剂的光生电子和空穴复合率降低,从而提高了光催化活性.     

Surface modification of polypropylene non-woven fibers with TiO2 nanoparticles via layer-by-layer self assembly method: Preparation and photocatalytic activity

Polypropylene (PP) meltblown fibers were coated with titanium dioxide (TiO₂) nanoparticles using layer-by-layer (LbL) deposition technique. The fibers were first modified with 3 layers of poly(4-styrenesulfonic acid) (PSS) and poly(diallyl-dimethylammonium chloride) (PDADMAC) to improve the anchoring of the TiO₂ nanoparticle clusters. PDADMAC, which is positively charged, was then used as counter polyelectrolyte in tandem with anionic TiO₂ nanoparticles to construct TiO₂/PDADMAC bilayer in the LbL fashion. The number of deposited TiO₂/PDADMAC layers was varied from 1 to 7 bilayer, and could be used to adjust TiO₂ loading. The LbL technique showed higher TiO₂ loading efficiency than the impregnation approach. The modified fibers were tested for their photocatalytic activity against a model dye, Methylene Blue (MB). Results showed that the TiO₂ modified fibers exhibited excellent photocatalytic activity efficiency similar to that of TiO₂ powder dispersed in solution. The deposition of TiO₂ 3 bilayer on the PP substrate was sufficient to produce nanocomposite fibers that could bleach the MB solution in less than 4 hr. TiO₂-LbL constructions also preserved TiO₂ adhesion on substrate surface after 1 cycle of photocatalytic test. Successive photocatalytic test showed decline in MB reduction rate with loss of TiO₂ particles from the substrate outer surface. However, even in the third cycle, the TiO₂ modified fibers are still moderately effective as it could remove more than 95% of MB after 8 hr of treatment.     

Preparation, characterization and application of CuCrO2/ZnO photocatalysts for the reduction of Cr(VI)

The delafossite CuCrO₂ elaborated by sol-gel from 40 nm diameter colloid is optically active in the visible region. It is characterized physically and photoelectrochemically. The microstructure is fairly homogenous with a mean crystallite size of ca. 2 μm. The optical gap (1.30 eV), determined from the diffuse reflectance, is well suited to the sunlight spectrum. The Mott Schottky plot is characteristic of P-type conductivity with a flat band potential of -0.26 V_SCE. As application, the photoreduction of chromate is successfully achieved in air-equilibrated suspension CuCrO₂/ZnO (1/1). CuCrO₂ is photoactivated by visible light and the electrons in the conduction band (-1.34 V_SCE) are injected to ZnO. In the presence of salicylic acid, a conversion of Cr(VI) to Cr(III) of 57% is obtained under optimal conditions (pH 3 at 25℃, 5×10^-4 mol/L) because of the HCrO₄^- dark adsorption onto ZnO (4HCrO₄^- + 3C₇H₆O₃ + 18O₂ + 16H⁺ → 4Cr³⁺ + 21CO₂ + 19H₂O, ΔG⁰ = -557 kcal/mol). Prolonged illumination is accompanied by a deceleration in the photoactivity owing to the competitive water reduction, an issue of energetic concern. The hetero-system exhibits self sensitization for hydrogen production with an evolution rate of 149 μmol/(hr·g).     

Ce/TiO2/g-C3N4异质结的制备及光催化降解PFOA反应机制

采用溶胶凝胶-超声混合法制备了铈/二氧化钛/石墨相氮化碳（Ce/TiO₂/g-C₃N₄）异质结催化剂，通过透射电子显微镜（TEM）、X-射线粉末衍射仪（XRD）、傅里叶变换红外光谱仪（FTIR）和紫外-可见分光光度计（UV-Vis）等表征了复合材料的结构、晶相、活性基团和光吸收性能，并考察了可见光下该催化剂对模拟全氟辛酸（PFOA）废水的降解效果.结果表明，Ce/TiO₂/g-C₃N₄分散性好，粒径小于20 nm，金属Ce的掺入及TiO₂/g-C₃N₄异质结的生成，有效抑制了光生电子和空穴对的复合，使复合光催化剂禁带宽度减小，光吸收范围增大，光催化性能得到明显提升.在pH值为2，PFOA浓度为4 mg·L^-1，催化剂投加量为1 g·L^-1的条件下，可见光照射180 min后，可降解94.4%的PFOA，脱氟率为38.6%.降解过程符合准一级反应动力学，速率常数为0.522 h^-1.通过HPLC-MS分析降解产物，同时结合氟元素物料平衡的计算结果，认为降解机制主要是以阴离子形式存在的PFOA吸附至表面带有大量正电荷的催化剂表面后，在光生空穴和活性自由基的作用下，以自由基机理逐步脱去CF₂生成短链的PFCAs，同时生成氟离子.     

Bi2MoO6/纳米棒ZnO异质结对MB的可见光-压电协同降解性能研究

采用水热法合成了一系列不同负载率的Bi₂MoO₆/纳米棒ZnO复合光催化剂.通过XRD、FT-IR、SEM、TEM、XPS、UV-Vis、EPR和PL等分析技术对合成的样品进行表征.在光/超声波条件下,以亚甲基蓝（MB）为目标降解物评价其压电-光催化性能.结果表明：Bi₂MoO₆/ZnO纳米棒（BZ-0.6）的降解速率常数约为ZnO传统光催化的9.25倍,其性能提升的主要原因在于ZnO的压电效应与Bi₂MoO₆/ZnO界面形成的异质结的耦合,有效地促进了电子和空穴的分离和转移.此外,同实验条件下,循环利用5次后Bi₂MoO₆/ZnO复合光催化剂降解率仍保持良好的稳定性.