纳米四针状氧化锌晶须光催化降解甲基橙

以纳米四针状氧化锌晶须(T-ZnOw)为光催化剂,以甲基橙为染料模型化合物,研究了T-ZnOw的光催化氧化降解性能.考察了甲基橙溶液的初始浓度、催化剂用量和粒径等因素对光催化氧化降解反应的影响.研究结果表明,纳米T-ZnOw光催化氧化降解甲基橙的反应遵循一级反应动力学规律;光催化剂纳米T-ZnOw的最佳用量为2g/L,此时经60min光催化降解后,甲基橙溶液的色度剩余率仅为8%;T-ZnOw粒子直径越小,光催化活性越高,效果越好.对比实验和重复实验结果表明,纳米T-ZnOw的光催化氧化降解效果比纳米TiO2和普通球形纳米ZnO粉体更好,是一种高效、长寿的光催化剂材料.     

水解氧化锌纳米复合结构光催化降解性能研究

利用滚压振动磨在干法室温条件下制备出形状规则的纳米锌粉,在260℃下与水蒸汽接触发生水解氧化还原反应,得到氧化锌纳米复合结构.其特征是棒状和块状纳米结构共存,具有良好的分散性,氧和锌的原子比接近2:3.将这种复合纳米结构用于光催化降解甲基橙溶液,在距离40cm的20W紫外灯照射下,研究了不同初始浓度、光催化剂添加量和水解温度对氧化锌纳米复合结构光催化降解性能的影响.在50mL初始浓度为10mg/L的甲基橙溶液中,添加260℃下水解生成的氧化锌纳米复合结构400mg,在10min内降解率可达80%.以上.     

TiO_2柱撑蒙脱土的制备及其光催化性能的研究

采用TiCl4在 HCl中的水解制备TiO2柱撑蒙脱土(TiO2-PILM)纳米光催化材料,通过X射线衍射和红外光谱对其进行了表征.考察了甲基橙的初始浓度、甲基橙溶液、pH值对光催化降解效果的影响.结果表明,TiO2-PILM具有大的晶面间距,TiO2-PILM 对甲基橙有较好的光催化活性,吸附动力学数据很好地符合Lagergren二级速率方程,在甲基橙初始浓度为10mg/L、投样量为0.02g、在酸性或碱性条件时,TiO2-PILM对甲基橙的降解率较高.     

爆轰法合成纳米TiO_2及其光催化性能

采用黑索金为可爆药剂,用爆轰法制备出了类球形混晶纳米TiO2粉体,并对合成的纳米TiO2粉末进行了表征。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、纳米TiO2用量、甲基橙溶液初始pH值、超声分散和光照时间对甲基橙降解率的影响。研究表明,所制备的纳米TiO2为锐钛矿、板钛矿和金红石组成的混晶体,平均粒度约为18nm。在氧化钛浓度固定的条件下,甲基橙溶液初始浓度越高降解率越低。随着氧化钛加入量的增加,甲基橙溶液的降解率先增大后减小,而氧化钛的加入量超过40.0mg/L后,甲基橙溶液的降解率又呈升高的趋势。超声波分散的纳米氧化钛的表观反应速率明显高于未经超声波分散的氧化钛的表观反应速率。随着光催化时间的延长,光转化率逐渐升高。     

纳米二氧化钛的光催化性能研究

采用TiOSO4常温水解法制备纳米二氧化钛，以甲基橙溶液做光催化降解实验，考察各种因素对光催化降解效果的影响。结果表明：加入表面活性剂方式制备的纳米TiO2具有更大的比表面积,光催化降解效果明显；甲基橙溶液的初始浓度越低,光催化降解效果越好；锐钛晶型96．5％、金红石晶型3．5％(质量比)的混晶型纳米TiO2具有更高的光催化活性；进行过多次光催化实验的纳米TiO2经再生后仍然可保持较高的光催化活性。     

锰掺杂氧化锌纳米线的制备及其光催化性能

采用水热法制备氧化锌纳米线,并通过降解甲基橙评价其光催化活性。以聚乙二醇为模板,氯化锌和氯化锰为原料,在120℃下能获得具有纤锌立方结构的锰掺杂氧化锌纳米线,直径大约为30nm,改变聚乙二醇和氢氧化钠的量,可获得锰掺杂氧化锌纳米线阵列。此外,相比纳米线阵列,锰掺杂氧化锌纳米线具有更好的光催化性能,在120min能降解浓度为20mg／L的β甲基橙溶液。     

铁掺杂纳米TiO2的制备及其光催化性能研究

采用溶胶-凝胶法制备了掺杂Fe3 的纳米TiO2微粒,采用X光衍射仪对粉体进行了表征.以甲基橙为目标降解物,研究了Fe3 掺杂纳米TiO2光催化性能.结果表明,掺杂适量Fe3 能够提高TiO2的光催化活性,当Fe3 的掺入量为摩尔比0.41%时催化活性最高.以紫外灯为光源,降解初始浓度为20mg·L-1的250mL甲基橙溶液,催化剂0.41%(摩尔分数)Fe3 -TiO2投加量为0.5g时,甲基橙的光催化降解效果最好.     

壳聚糖-CdS复合纳米粒子对甲基橙的光催化降解作用

用反相微乳液法制备了壳聚糖-CdS复合纳米粒子,并考察了复合纳米粒子用量、光照条件和溶液pH值等因素对光催化降解甲基橙的影响.结果表明:在100 mL质量浓度为20 mg/L的甲基橙溶液中加入0.30 g复合纳米粒子,可以达到较好的光催化降解效果;甲基橙在光催化降解过程中最大吸收波长464 nm处的吸收峰迅速减弱,并最终消失,且在258 nm和455 nm处出现了新的吸收峰,说明甲基橙发生了降解;溶液pH值对光催化降解甲基橙有一定的影响,在弱酸性条件下降解效率较高;复合纳米粒子比普通CdS降解效率高,2 min时高出50%,400 min时高出21.3%.初步提出了复合纳米粒子光催化降解机理,复合纳米粒子的吸附作用是光催化降解作用的前置步骤.     

掺铁纳米氧化锌的制备及其光催化性能

采用共沉淀法制备了纯纳米ZnO和掺铁纳米ZnO,并用X射线衍射光谱进行了表征。用紫外灯作为光源,甲基橙溶液为光催化反应模型降解物,研究了ZnO及掺铁ZnO的光催化性能,并考察了前驱体焙烧温度、铁掺杂量、底物浓度、光照时间以及pH对降解率的影响。结果表明,掺杂铁离子提高了ZnO的光催化活性,400℃热处理的掺杂铁0.5%(质量比)的ZnO的光催化性能最好;当甲基橙初始浓度为5mg/L,光照时间3h,掺杂铁0.5%(质量比)的ZnO粉末对甲基橙的降解率达到84%;掺铁纳米ZnO在弱酸性条件下的催化效果比碱性条件下更好。     

金属网表面ZnO纳米棒的可控制备及其光催化性能

采用晶种诱导法,以硝酸锌为前驱体在金属网表面成功制备ZnO纳米棒光催化材料,用XRD、SEM等进行表征,并采用甲基橙溶液模拟废水,研究该材料的光催化降解性能。探讨了水浴合成ZnO纳米棒时,生长液浓度、反应温度等因素对光催化性能的影响。结果表明,80℃水浴反应4h,生长溶液浓度为100mmol/L,制备得到的ZnO纳米棒光催化活性较佳,光催化反应2h甲基橙溶液的降解率可达99%。     

Cd/CdS光催化降解甲基橙的研究

采用胶体化学法制备表面富镉的Cd／CdS纳米粒子为催化剂对水溶液中甲基橙的光催化降解进行了研究。探讨了光催化反应机理,讨论了光催化剂用量,双氧水的用量,试液的pH值,光照时间与甲基橙脱色率的关系。实验结果表明,当甲基橙起始浓度为20mg／L,Cd／CdS用量为0．500g,双氧水用量为5．88mmol／L,pH值为7．0时,光照6h,甲基橙的脱色率可达到95．5％。     

WO_3-TiO_2纳米材料的制备及其光催化性能

采用溶胶-凝胶法制备WO3-TiO2纳米复合材料,并用透射电镜和X射线衍射对所制备材料进行表征和分析。以WO3-TiO2纳米材料为光催化剂对甲基橙进行光催化降解处理,研究WO3的掺杂量、煅烧温度、光照时间等因素对甲基橙降解率的影响。结果表明:在紫外灯照射下,使用w(WO3)=3%、550℃下煅烧得到的WO3-TiO2纳米复合粉体0.02 g,甲基橙溶液20 mL(ρ=5 mg/L,pH=4),光催化3 h后,甲基橙降解率达到94.93%。     

石墨/TiO2复合光催化剂的制备和性能

以石墨和纯的TiO₂为原料,采用球磨工艺制备了石墨/TiO₂复合光催化剂。使用XRD、SEM、TEM、XPS和DRS等手段对其性能进行了表征。以甲基橙为模拟污染物,研究了石墨掺入量、球磨时间对复合光催化剂光催化活性的影响。结果表明,石墨/TiO₂复合光催化剂具有锐钛矿结构,球磨后TiO₂(101)面的衍射峰宽化并右移,TiO₂成为200 nm左右的不规则球状颗粒,在其表面均匀分布着石墨。TiO₂晶粒的Ti-O键的结合能变高,且表面有缺陷产生,使其在可见光区具有显著的吸收。石墨掺入量为5%、球磨时间为12 h的石墨/TiO₂样品对甲基橙具有优异的光催化降解效果,在70 min的降解时间内甲基橙的降解去除率可达95.08%。石墨/TiO₂复合光催化剂的光催化反应速率常数k为0.043035 min^-1,是纯TiO₂的2.64倍。     

TiO2／膨胀石墨复合材料的制备及光催化性能的研穷

采用快速升温法制备出以膨胀石墨为载体的TiO2／膨胀石墨光催化剂，用SEM及XRD对其表面形貌及结构进行表征，研究了光催化剂在紫外光照射下的催化能力，探讨了目标降解物溶液的初始浓度及其pH值对光催化剂的降解能力的影响。结果发现，负载量为10％的光催化剂对40mg／L的亚甲基兰溶液5h的光降解率达到58．83％，甲基橙为51．12％。     

酞菁钴/MCM-41的制备及其可见光催化性能

以MCM-41分子筛为载体,采用浸渍法将酞菁钴负载到分子筛上以氙灯为光源降解甲基橙溶液。对负载型酞菁钴催化剂进行FT-IR、XRD、SEM表征,结果表明所制催化剂负载效果良好,且分子筛结构未发生改变。以甲基橙溶液为模拟处理对象,研究催化剂的催化性能,考察了光照、酞菁钴负载、催化剂用量等因素对催化效果的影响。结果表明,氧气充足时,在光照条件下、0.04g负载型酞菁钴催化剂处理200mL的0.05g/L甲基橙溶液能够有很好的处理效果,2h降解率能够达到98.3%,且重复利用4次后降解率仍能达到90%。     

Preparation and characterization of ZnO-graphene composite photocatalyst

ZnO is one of potential semiconductor materials in photocatalytic field, and appears to be a suitable alternative to TiO2, due to its photochemical properties and photodegradation mechanism similar to TiO2. Graphene is a single 2D carbon sheet with large specific surface and excellent electric conductivity. The combination of ZnO and graphene could extremely improve the photocatalytic activity of ZnO. Herein we prepared ZnO-graphene nanocomposite photocatalyst using graphite and ZnO by a facile one-step hydrothermal method. During the hydrothermal reactions, both of the reduction of graphene oxide and loading of ZnO were occurred simultaneously and the desired product was obtained. The as-prepared ZnO-graphene photocatalyst exhibited extraordinaire photocatalytic properties. Results of photocatalytic degradation of methyl orange show that the photocatalysis efficiency of the composite was significant enhanced, compared to pure ZnO. This work could provide new avenue for the fabrication of ZnO-carbon based composites, facilitating their application in pollutions degradation issues.     

Two-step preparation of Ag/tetrapod-like ZnO with photocatalytic activity by thermal evaporation and sputtering

A two-step method to synthesize metal–semiconductor heterostructure photocatalyst is presented in this research. Based on the tetrapod-like zinc oxide (T-ZnO) deposited by thermal evaporation, Ag/T-ZnO heterostructure is synthesized by RF magnetron sputtering method in this two-step preparation technique. The structure and the photocatalytic properties of the Ag/T-ZnO were studied in detail. The Ag/T-ZnO heterostructure exhibits better photocatalytic activity than that of the pure T-ZnO and there is an optimum sputtering time and sputtering power for the heterostructure's photocatalytic activity. The essential photocatalytic mechanism of this heterostructure have been discussed and the enhanced photocatalytic activity indicates the feasibility of this novel two-step method which may be developed to a promising synthesis technique.     

Preparation, characterization and activity evaluation of Ag2Mo4O13 photocatalyst

Ag(2)Mo(4)O(13) photocatalyst was prepared by the hydrothermal method using AgNO(3) and (NH(4))(2)MoO(4) as raw materials in one step. The Ag(2)Mo(4)O(13) photocatalyst was characterized by X-ray powder diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) analysis, N(2) adsorption measurements, and terephthalic acid photoluminescence (TA-PL) probing technique. The photocatalytic activity of the photocatalyst was evaluated by photocatalytic oxidation of methyl orange and photocatalytic reduction of nitrobenzene. The results showed that, the optimum catalyst concentration is 3 g/L, and the optimum optical thickness is 49.4. When the reaction solution was illuminated for 60 min and 10 h, and the amount of photocatalyst was 2.0 g/L, the methyl orange conversion and aniline yield were 76.4% and 63.3%, respectively. The effect of different heat treatment conditions on the photocatalytic activity of the photocatalyst was also investigated. The best preparation condition is heat treatment at 500°C for 10 h. Compared with those photocatalysts prepared at any other conditions, the photoabsorption wavelength range of the photocatalyst calcined at 500°C for 10 h extends greatly towards visible light and it also improves the utilization of the total spectrum. The mechanisms of influence on the photocatalytic activity were also discussed.     

Comparison of dye degradation efficiency using ZnO powders with various size scales

ZnO powders with various size scales (mean diameter size: 10, 50, 200 and 1000nm) have been prepared by two different preparation methods, thermal evaporation method and chemical deposition method, and examined as photocatalysts for the UV-induced degradation of methyl orange in water solution. ZnO nanoparticle with diameter size 50nm prepared by thermal evaporation method showed the highest photocatalytic activity. In addition, the tetrapod ZnO nanopowders had the higher efficiency than irregular ZnO particles. However, the smallest 10nm ZnO nanoparticle prepared by chemical deposition method indicated the lower efficiency contrast to 200nm ZnO powders prepared by thermal evaporation method. The results indicated preparation method was the decisive factor rather than size and morphology. Moreover, the effect of catalyst loading, pH value and the initial dye concentration on the final degradation efficiency were discussed through the photocatalytic experiments using 50nm ZnO nanoparticle as photocatalyst.