微波溶剂热法制备钼酸铋及其光催化性能

采用微波溶剂热法制备了α-Bi2Mo3O12和γ-Bi2Mo O6可见光催化剂,并用XRD、SEM、和UV-Vis等测试手段表征了试样的结构和性能,最后以氯胺磷为目标降解物考察了它们的可见光催化降解性能.结果显示,在p H值较低时产物为α-Bi2Mo3O12,p H较高时产物为γ-Bi2Mo O6,并探讨了不同产物的形成机理.光催化实验结果表明,γ-Bi2Mo O6的可见光催化活性优于α-Bi2Mo3O12;在氯胺磷初始浓度较低时,γ-Bi2Mo O6光催化降解过程符合零级动力学反应模型.在酸性或碱性条件下γ-Bi2Mo O6对氯胺磷的降解效果优于中性条件.     

N/S/SnO2-TiO2的制备及对染料的光降解活性研究

以尿素、硫脲分别作为N、S源,氯化锡作为Sn源,利用水热法合成了N/S/Sn O_2-Ti O_2产品.同时,采用XRD、SEM、XPS等技术对不同煅烧温度处理后的产品进行了表征.最后,以质量浓度为0.02 g·L~(-1)的甲基橙水溶液为模拟污染物,采用UV-vis光谱及BET分析研究了产品的光催化活性效果.实验结果表明,当煅烧温度为550℃时,水热合成出的产品结晶度较高,粒径较小,约20 nm左右.S以+6价形式进入Ti O_2晶格形成Ti—O—S键,N通过取代晶格中的O形成O—Ti—N键,Sn以Sn O_2的形式分散在Ti O_2产品中.Sn Cl4的加入不仅与C16H36O4Ti竞争水源,缓解C16H36O4Ti的水解,而且对产品有一定的分散效果.光催化活性实验结果表明,当紫外灯照射时间达到1 h时,N/S/Sn O_2-Ti O_2降解甲基橙溶液基本完成,脱色率达到95%以上.     

CuFeO2耦合过硫酸盐可见光催化降解过程及机理研究

采用水热合成法制备了CuFeO_2催化剂,并采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、X射线能谱仪(EDS)、比表面分析仪和紫外可见漫反射光谱(DRS)对CuFeO_2催化剂的晶体结构、表面形貌、组成元素、比表面积及禁带宽度等特性进行了表征分析.同时,以CuFeO_2为催化剂,加入过硫酸盐(PS),以模拟印染废水中的亚甲基蓝为目标污染物,在可见光照射下,耦合光催化技术与高级氧化技术,构建了CuFeO_2/PS/可见光(Vis)体系,并将其应用于降解亚甲基蓝染料废水.结果表明,与Cu_2O/PS/Vis、Fe_2O_3/PS/Vis体系相比,CuFeO_2/PS/Vis体系在同等条件下具有更好的降解效果.为探究该体系的最佳操作条件和适用的pH范围,系统地考察了催化剂投加量、PS投加量、pH值等因素对亚甲基蓝降解效果的影响.总有机碳含量(TOC)和重复实验表明,CuFeO_2可重复使用4次,该体系的降解效果基本不变,但矿化程度降低8.2%.电感耦合等离子体质谱(ICP-MS)实验结果表明,反应结束后溶液中残存1.7 mg·L~(-1)Cu(占CuFeO_2投加总量的0.34%)和24.9μg·L~(-1)Fe(占CuFeO_2投加总量的0.05‰),推测其来自于CuFeO_2中金属离子的溶出.此外,对反应后的CuFeO_2进行XRD和SEM表征发现,其物相组成和形貌未明显变化,表明少量的金属溶解对材料稳定性的影响较小.结合自由基掩蔽实验和CuFeO_2能带结构分析发现,该体系良好的降解效果首先得益于耦合反应过程中产生的SO_4~-·,其次是·OH,另外,还有CuFeO_2受光激发产生的光生空穴及其表面键合的Cu(Ⅰ)/Cu(Ⅱ)和Fe(Ⅱ)/Fe(Ⅲ)氧化还原对的协同作用.     

BiOCl/TiO2的氯化改性及其新式光生自由基催化反应

采用溶胶凝胶法制备了BiOCl/TiO₂复合催化剂,透射电镜（TEM）照片显示,两种半导体分布均匀、相互连接,形成的异质结可以为电子传导提供有效通道.经过氯化处理的复合材料具备更强的光催化能力,在紫外光条件下对苯的降解率达到90%,是原BiOCl/TiO₂的2倍、纯TiO₂的10倍.本文利用X射线光电子能谱、红外光谱和电子顺磁共振,对表面氯化的机理进行研究.结果表明,氯元素以Ti—Cl的方式吸附在催化剂表面,在光照条件下光生空穴夺取一个电子,使其生成氯自由基,进而配合超氧、羟基,构成一种新型的三自由基光催化体系,使催化降解能力大幅提升.最后,利用实验方法得到了光生氯自由基的直接证据,并构建了该体系的光催化反应机理.     

改性Ti/SnO2-Sb电极催化降解1,4-二氯苯废水试验研究

采用聚合物前驱体法制备了未掺杂、掺杂Cu、掺杂Bi、掺杂Ni的4种Ti/Sn O2-Sb电极,运用SEM和XRD分析电极表面形貌及结构,通过线性极化扫描、循环伏安等测试考察其电化学性能,同时进行1,4二氯苯(p-DCB)降解实验进一步探究电极的电催化氧化特性.SEM和XRD结果表明,掺杂金属可改善电极表面形貌,增大其比表面积;电化学测试表明,Ti/Sn O2-Sb电极的析氧电位并未因金属掺杂而有明显改变,掺杂金属后,Ti/Sn O2-Sb电极具有更优的电催化活性和稳定性.p-DCB降解实验表明,改性Ti/Sn O2-Sb电极对p-DCB的降解效率明显提高,其中Ti/Sn O2-Sb-Cu电极的电催化处理效果最优,电解2 h后p-DCB的去除率即达到87.6%,且p-DCB的降解反应遵循一级反应动力学规律.     

Mo源改性石墨相氮化碳(g-C3N4)活化过一硫酸盐可见光降解罗丹明B的性能研究

分别以钼酸钠（MA）和乙酰丙酮钼（MC）作为钼（Mo）源,采用热聚合法合成不同类型Mo-C₃N₄材料（MACN和MCCN）,并通过XRD、SEM、XPS、UV-Vis DRS等表征技术探究不同Mo源的引入对g-C₃N₄晶体结构和光学性质的影响.结果表明,Mo的引入增大了g-C₃N₄的晶格间距,以MC为Mo源合成的MCCN催化剂具有更大的比表面积、更宽的可见光响应范围和更低的能带宽度.将所合成的催化剂应用于耦合过一硫酸盐（PMS）可见光催化降解罗丹明B （RhB）研究,发现在催化剂浓度为0.5 g·L^-1、PMS浓度为1 mmol·L^-1、罗丹明B浓度为10 mg·L^-1的条件下,MCCN-4/PMS/Vis催化体系在25 min内对RhB的降解率高达94.1%,分别是MCCN-4/Vis和单独PMS催化体系的5.6和19.2倍,并且RhB光催化降解过程符合一级动力学方程.为进一步探索MCCN/PMS/可见光（Vis）催化体系的最佳工艺条件,系统考察了Mo的掺杂量、催化剂投加量、PMS浓度、污染物浓度、pH值等实际因素对RhB降解效果的影响.同时,循环实验表明,MCCN-4复合催化剂具有良好的稳定性和可重复性,3次循环之后仍保持89.1%的RhB降解率.此外,捕获实验和电子自旋共振测试（ESR）结果表明,在MCCN/PMS/Vis催化体系下,光生空穴（h⁺）和超氧自由基（·O₂^-）作为主要活性物种参与了RhB的降解.     

光催化氧化处理垃圾渗滤液的研究

通过实验 ,研究分析了不同催化剂 ( Ti O2 、Zn O)、p H值、光照时间对垃圾渗滤液光催化氧化的影响 ,得出 :Ti O2 光催化氧化效果明显优于 Zn O的效果 ,Ti O2 光催化氧化对 CODCr的去除率为 72 % ;p H值对光催化氧化影响不大 ,p H值为 5～ 9均可 ;光照时间 6 0 min效果最好。     

Bi2WO6/UiO-66复合材料的制备与光催化性能研究

以冰乙酸作为模板剂,采用溶剂热法制备了一种Bi₂WO₆/UiO-66复合光催化剂,探究了不同UiO-66掺杂量对其光催化性能的影响,通过XRD、FTIR、SEM、N₂吸附-脱附、UV-Vis DRS、PL等手段对复合材料进行表征,以有机染料罗丹明B（RhB）作为目标降解物评价复合材料的光催化性能. 结果表明,该复合材料在可见光下光催化降解RhB时具有很强的活性. 经过4次循环实验,光催化剂的催化活性没有明显降低. 通过自由基捕获实验证明起主要作用的活性物质为空穴（h⁺）,并提出了可能的光催化降解机理为：UiO-66均匀分布在Bi₂WO₆的表面,增大了复合材料的比表面积,Bi₂WO₆光生电子转移到UiO-66的表面,降低了电子空穴复合率,h⁺则位于Bi₂WO₆表面,直接氧化有机物达到净化效果.     

pH对高锰酸钾氧化降解苯胺类化合物动力学的影响

以苯胺和对氯苯胺为目标污染物,在假一级动力学实验条件下(KMn O4初始浓度是目标有机物初始浓度的10倍),考察了p H对KMn O4氧化降解苯胺类化合物的动力学的影响.发现在KMn O4氧化降解苯胺类化合物的过程中存在明显的自催化现象,推测这种自催化现象可能是由于原位生成的Mn Ox在其表面络合目标污染物,从而促进了KMn O4对污染物的氧化速率.对不同p H条件下KMn O4氧化苯胺类化合物的动力学数据进行了假一级拟合获得假一级反应速率常数(kobs),通过KMn O4浓度与kobs进一步得到的二级反应速率常数k″(M-1·s-1)随p H的增加先升高后降低,在苯胺和对氯苯胺各自的p Ka附近时达到最大,即文献中提出的类抛物线现象.笔者之前提出的质子传递模型可以很好地拟合KMn O4氧化苯胺和对氯苯胺的二级反应速率常数随p H的变化趋势.     

钛基石墨烯复合材料的制备及其光催化还原Cr（VI）的研究

通过改进的Hummers法制备氧化石墨烯(GO),再将氧化石墨烯和钛酸四丁酯作为初始反应物,利用溶剂热法制备Ti O_2/RGO纳米复合材料.利用SEM、TEM、XPS、XRD等分析手段对Ti O_2/RGO纳米复合材料进行表征,考察其在可见光照射条件下光催化还原水中Cr(Ⅵ)的效能,并对光催化还原机制进行了初步探讨.结果表明,Ti O_2/RGO复合材料的光催化还原能力与单一Ti O_2(P25)相比有了显著提高;复合材料中RGO含量、溶液p H值、催化剂投加量、Cr(Ⅵ)初始浓度均对光催化还原过程有所影响,当复合材料中RGO含量比例为2%、溶液p H值为2,催化剂投加量为40 mg时,光催化还原Cr(Ⅵ)的效率可达98%.光催化还原Cr(Ⅵ)的过程是吸附过程和光催化还原过程的共同作用结果,RGO不但提高了复合材料的吸附能力,还作为复合材料的电子导体,抑制了光生电子-空穴对的复合,增强了复合材料的光催化性能.经过5次循环使用后,复合材料的光催化还原效率仍然保持在90%左右.     

Synergistic effect of N- and F-codoping on the structure and photocatalytic performance of TiO2

Three types of TiO₂ nanostructures were synthesized via a facile hydrolysis method at 195 °C. Effects of the preparation method and doping with N and F on the crystal structure and photocatalytic performance of TiO₂ were investigated. The nanomaterials were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller porosimetry, ultraviolet–visible diffuse reflectance spectroscopy and fluorescent emission spectra. Their photo-catalytic activity was examined by the photodegradation of methylene blue in aqueous solution under both ultra-violet and visible light irradiation. The results show that nitrogen and fluorine co-doped anatase TiO₂ had the characteristics of a smaller crystalline size, broader light absorption spectrum and lower charge recombination than pure TiO₂. Most importantly, more efficient photocatalytic activity under both ultra-violet and visible light was observed. The obtained N–F-TiO₂ nanomaterial shows considerable potential for water treatment under sunlight irradiation.     

Visible light responsive N-F-codoped TiO2 photocatalysts for the degradation of 4-chlorophenol

Visible light responsive N-F-codoped TiO₂ photocatalysts exhibit a higher catalytic activity than N-doped TiO₂ for the degradation of 4-chlorophenol due to the synergistic effect of nonmetal elements.     

TiO2表面沉积Ag粒子及其可见光下降解含盐废水中的苯酚

为了制备可见光激发下能高效降解含盐废水中有机物的光催化剂,首次以商用TiO_2光催化剂(P25)为载体,利用吸附相反应技术一步获得了Ag沉积的可见光响应复合光催化剂.同时,通过XPS、TEM、HRTEM及紫外可见漫反射光谱图,结合多种高含盐水体系中苯酚的光催化降解过程,研究了不同Ag沉积对催化剂可见光活性的影响.结果发现,吸附平衡后P25表面富含水的吸附层可作为反应和粒子的生成场所,生成量子尺寸的Ag粒子.另外,在吸附层中生成的Ag粒子均匀分布于P25表面并与之紧密结合,并在TiO_2晶格结构中引入晶格交错结构.Ag与TiO_2的表面等离子体共振效应和晶格交错结构共同提升了催化剂的可见光响应和电荷的分离效率,增强了催化剂对苯酚的可见光催化性能.在含盐废水体系中,盐离子数量越多,催化剂在可见光下降解苯酚过程受到的干扰越大.     

TiO2复合催化剂弱光催化降解模拟海水中苯酚及其催化活性的影响

为了获得适用于海水中有机污染物光降解催化剂,分别选用纳米SiO_2粒子和氧化石墨烯GO为载体,利用吸附相反应技术并结合热处理过程制备了基于TiO_2的复合催化剂,研究了弱光(光强小于1mW·cm~(-3))激发下复合催化剂光催化降解模拟海水中苯酚.结果表明,吸附相反应技术结合焙烧得到的La~(3+)掺杂TiO_2-SiO_2,表面亲水性较强和对苯酚吸附能力较弱,难以克服盐离子的干扰并有效降解模拟海水中高浓度苯酚.而吸附相反应技术结合醇溶剂热还原处理后,La~(3+)掺杂TiO_2-SiO_2催化剂表面亲水性显著减弱,但该催化剂在模拟海水中不能形成稳定的悬浮体系.吸附相反应技术得到的TiO_2-GO和La~(3+)掺杂TiO_2-GO中,TiO_2粒子粒径小于10nm且均匀负载于GO的表面.醇溶剂热还原处理可使TiO_2形成晶型结构,从而提高其催化活性,同时还能将GO表面的含氧基团还原,降低催化剂表面亲水性.从而提升催化剂对苯酚的吸附能力和对盐离子的抗干扰能力.另外,还原GO与小粒径TiO_2粒子紧密结合,使光生电子能很快转移至还原GO表面,增大光生电荷分离率,进一步提升催化剂的光降解性能.     

Solar photocatalytic decomposition of two azo dyes on multi-walled carbon nanotubes (MWCNTs)/TiO2 composites

Multi-walled carbon nanotubes (MWCNTs)/TiO₂ composite photocatalysts with high photoactivity were prepared by sol-gel process and further characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), and UV-vis absorption spectra. Compared to pure TiO₂, the combination of MWCNTs with titania could cause a significant absorption shift toward the visible region. The photocatalytic performances of the MWCNTs/TiO₂ composite catalysts were evaluated for the decomposition of Reactive light yellow K-6G (K-6G) and Mordant black 7 (MB 7) azo dyes solution under solar light irradiation. The results showed that the addition of MWCNTs enhanced the adsorption and photocatalytic activity of TiO₂ for the degradation of azo dyes K-6G and MB 7. The effect of MWCNTs content, catalyst dosage, pH, and initial dye concentration were examined as operational parameters. The kinetics of photocatalytic degradation of two dyes was found to follow a pseudo-first-order rate law. The photocatalyst was used for seven cycles with photocatalytic degradation efficiency still higher than 98%. A plausible mechanism is also proposed and discussed on the basis of experimental results.     

Rubber sheet strewn with TiO2 particles:Photocatalytic activity and recyclability

A new method for the preparation of rubber sheet strewn with titanium dioxide particles (TiO₂-strewn sheet) is presented. This simple and low cost method is based on the use of TiO₂ powder (Degussa P25) being strewn onto the sheet made from rubber latex (60% HA) through a steel sieve. The characteristic of the TiO₂-strewn sheet was studied by using scanning electron microscopy/energy dispersive X-ray spectrometer (SEM/EDS) and X-ray diffractometer (XRD) techniques. The photocatalytic activity of TiO₂-strewn rubber sheet was evaluated using Indigo Carmine (IC) dye as a model for organic dye pollutant in water. The results showed that the TiO₂-strewn sheet could degrade IC dye solution under UV light irradiation. The effects of pH, initial concentration, and the intensity of UV light on the photodegradation were also investigated. Kinetics of the photocatalytic degradation was of the first-order reaction. The used TiO₂-strewn sheet can be recovered and reused. The recycling uses did not require any cleaning between successive uses and no decline in the photodegradation efficiency was observed compared with freshly prepared TiO₂-strewn sheet.     

上转换发光剂掺杂纳米TiO2的制备及可见光降解乙基紫的研究

合成了一种新型含有稀土金属Er的上转换发光剂40CdF₂·60BaF₂·1.6Er₂O₃,此上转换发光剂在488 nm可见光的激发下,产生了5个波长均小于387 nm的上转换紫外光发射峰.采用超声波分散的方法制备出了上转换发光剂掺杂的纳米TiO₂可见光光催化剂.利用X-射线衍射(XRD)及透射电镜(TEM)对催化剂进行了表征.以乙基紫染料为研究对象,研究了在(三基色灯下发出的)可见光的照射下该可见光光催化剂的催化降解性能,并与未掺杂的纳米TiO₂粉末的催化性能进行了对比.结果表明,作为掺杂成分的上转换发光剂可有效地将可见光转化为紫外光并被纳米TiO₂粉末吸收利用,在可见光照射12.0 h后乙基紫降解率达到了99.68%,大大高于未掺杂纳米TiO2时的降解率.     

Visible light driven mineralization of spiramycin over photostructured N-doped TiO2 on up conversion phosphors

A novel visible light-active photocatalyst formulation(NdT/OP) was obtained by supporting N-doped TiO_2(NdT) particles on up-conversion luminescent organic phosphors(OP). The photocatalytic activity of such catalysts was evaluated for the mineralization process of spiramycin in aqueous solution. The effect of NdT loading in the range 15–60 wt.% on bulk and surface characteristics of NdT/OP catalysts was investigated by several chemicophysical characterization techniques. The photocatalytic performance of NdT/OP catalysts in the removal of spyramicin from aqueous solution was assessed through photocatalytic tests under visible light irradiation. Total organic carbon(TOC) of aqueous solution,and CO and CO_2 gas concentrations evolved during the photodegradation were analyzed. A dramatic enhancement of photocatalytic activity of the photostructured visible active NdT/OP catalysts,compared to NdT catalyst,was observed. Only CO_2 was detected in gas-phase during visible light irradiation,proving that the photocatalytic process is effective in the mineralization of spiramycin,reaching very high values of TOC removal. The photocatalyst NdT/OP at 30 wt.% of NdT loading showed the highest photocatalytic activity(58%of TOC removed after 180 min irradiation against only 31% removal after 300 min of irradiation of NdT). We attribute this enhanced activity to the high effectiveness in the utilization of visible light through improved light harvesting and exploiting. OP particles act as "photoactive support",able to be excited by the external visible light irradiation,and reissue luminescence of wavelength suitable to promote NdT photomineralization activity.     

可见光激发下模拟海水中四环素光降解的机制和路径

为了探明海水体系中多相光催化降解污染物的机制和路径,研究了在可见光激发下不同介孔TiO₂光催化降解纯水和模拟海水中四环素(TC)的过程,明确了不同盐离子对光催化降解过程的影响.结合自由基捕获实验,电子自旋共振(ESR)光谱和中间产物分析研究了光降解污染物的主要活性物种和模拟海水中TC降解途径.结果表明,模拟海水中TC光催化过程会受到显著抑制,手性介孔TiO₂催化剂对TC光降解反应速率相比其在纯水体系降低了70%左右,而非手性TiO₂光催化剂在海水体系中几乎不能降解TC.模拟海水中阴离子对光降解过程影响较小,但Mg²⁺和Ca²⁺存在会显著抑制光催化过程.无论在纯水还是模拟海水中,可见光激发后催化剂产生的活性物种都是空穴为主,因此模拟海水中降解路径与纯水体系中相同.盐离子不会抑制活性物种的产生,但Mg²⁺和Ca²⁺会富集在TC分子中电负性强的原子周边,阻碍空穴等对TC分子中电负性强原子的攻击,从而抑制了光催化降解效率.     

Synthesis, crystal structure, photodegradation kinetics and photocatalytic activity of novel photocatalyst ZnBiYO4

ZnBiYO₄ was synthesized by a solid-state reaction method for the first time. The structural and photocatalytic properties of ZnBiYO₄ were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and UV-Vis diffuse reflectance. ZnBiYO₄ crystallized with a tetragonal spinel structure with space group I41/A. The lattice parameters for ZnBiYO₄ were a = b = 11.176479 Å and c= 10.014323 Å. The band gap of ZnBiYO₄ was estimated to be 1.58 eV. The photocatalytic activity of ZnBiYO₄ was assessed by photodegradation of methyl orange under visible light irradiation. The results showed that ZnBiYO₄ had higher catalytic activity compared with N-doped TiO₂ under the same experimental conditions using visible light irradiation. The photocatalytic degradation of methyl orange with ZnBiYO₄ or N-doped TiO₂ as catalyst followed first-order reaction kinetics, and the first-order rate constant was 0.01575 and 0.00416 min^-1 for ZnBiYO₄ and N-doped TiO₂, respectively. After visible light irradiation for 220 min with ZnBiYO₄ as catalyst, complete removal and mineralization of methyl orange were observed. The reduction of total organic carbon, formation of inorganic products, SO₄^2- and NO₃^-, and evolution of CO₂ revealed the continuous mineralization of methyl orange during the photocatalytic process. The intermediate products were identified using liquid chromatography- mass spectrometry. The ZnBiYO₄/(visible light) photocatalysis system was found to be suitable for textile industry wastewater treatment and could be used to solve other environmental chemical pollution problems.