TiO2/硅藻土光催化氧化降解甲基橙的研究

使用经过预处理的硅藻土做载体,采用溶胶-凝胶法制备硅藻土负载二氧化钛光催化剂,利用XRD和EDS对其进行表征.通过分析光催化反应的主要影响因素,研究了硅藻土负载二氧化钛光催化剂对甲基橙的催化降解效果.结果表明：负载3次,在550℃焙烧2h,制备出的负载型催化剂催化活性较高,催化剂上的TiO2为锐钛矿结构.当催化剂投加量为lg/L,溶液初始浓度为15 mg/L,pH为3,H2O2为2 mmol/L时,对甲基橙的降解效果达到最佳.     

纳米TiO2对气相中甲醛光催化降解的研究

采用溶胶-凝胶法制备了掺杂金属离子的纳米TiO₂光催化剂,运用透射电镜和X射线衍射手段对催化剂的结构进行了表征,并将制备的光催化剂负载于不锈钢丝网、玻璃弹簧和泡沫镍板3种不同载体上,以室内空气典型污染物甲醛气体为模型反应物,研究了3种不同改性纳米TiO₂光催化剂对甲醛气体的光催化作用,3种光催化反应器的催化效率以及环境因素对光催化效率的影响,同时考察了催化剂的失活特征.结果表明:该负载型纳米TiO₂光催化剂具有较高的光催化活性,其中掺镧1.5%(质量分数)的TiO₂对甲醛的降解率最高,60 min达到91.5%,大于掺铁和掺银;泡沫镍板作为负载载体的光催化效率大于玻璃弹簧和不锈钢丝网;循环风量和不同波长紫外光对该光催化反应影响不大,反应中催化剂存在失活现象,但在清洁后能够恢复.      

卤氧化铋漂浮型光催化剂研究的新进展

卤氧化铋系列光催化剂以可见光催化效率高、原料易得和性能稳定等特点得到广泛的研究,直接应用于实际水体污染的原位修复由于其比重较大,所以存在太阳光利用率低和催化剂无法重复使用的问题。以轻质载体为基础负载制备的漂浮型卤氧化铋光催化剂,可以同时解决以上2个方面的问题,因而得到人们的关注。该文总结了近年来卤氧化铋漂浮型光催化剂研究的最新成果,主要介绍了不同轻质载体负载卤氧化铋的制备方法,如溶剂热法、醇盐水解法和冷冻干燥法等,重点概述了制备工艺对复合光催化材料结构及其催化性能的影响,并对光催化机理进行了简要的归纳。在此基础上,展望了漂浮型卤氧化铋光催化剂的发展方向,为卤氧化铋基光催化剂的实际应用提供参考。     

泡沫镍负载纳米ZnO-SnO2光催化降解三氯乙烯

采用比较简单的共沉淀法技术制备了纳米ZnO-SnO2复合氧化物光催化剂,并将其负载在泡沫镍上制成了负载型纳米光催化剂,以三氯乙烯为挥发性有机物的模型反应物,研究了反应气流速、湿度等因素对反应的影响,同时考察了催化剂的失活特征,结果表明该负载型纳米光催化剂具有较高的光催化活性,同时具有较强的抗失活性能,在205h反应中没有出现失活现象．     

焦炭负载型纳米TiO2光催化剂的制备优化试验及其降解效果分析

以焦炭为载体,Na2SiO3为粘结剂制备了负载型纳米TiO2光催化剂,通过单因素试验和正交试验优化出制备该光催化剂的最佳条件,研究分析了该催化剂在紫外灯辐照下降解亚甲基蓝染料废水的效果及影响因素。试验结果表明,煅烧3h,粘结剂浓度为20％wt,煅烧温度为400℃时制备的负载型纳米TiO2光催化剂的降解效果最好,达到80．88％。     

焦炭负载型纳米TiO2光催化剂的制备优化试验及其降解效果分析

以焦炭为载体，Na2SiO3为粘结剂制备了负载型纳米TiO2光催化剂，通过单因素试验和正交试验优化出制备该光催化剂的最佳条件，研究分析了该催化剂在紫外灯辐照下降解亚甲基蓝染料废水的效果及影响因素。试验结果表明，煅烧3h，粘结剂浓度为20％wt，煅烧温度为400℃时制备的负载型纳米TiO2光催化剂的降解效果最好，达到80．88％。     

纳米TiO2/硅藻土光催化降解蒽醌染料废水的研究

为提高光催化剂的稳定性,选取硅藻土为载体,以钛酸四异丙酯为前驱物,采用溶胶-凝胶法制备了TiO2/硅藻土光催化剂,并利用XRD、SEM、FT-IR等技术对其进行表征.以蒽醌染料弱酸性艳蓝RAW为目标降解物,考察了TiO2/硅藻土的光催化活性、最佳pH值范围及催化剂重复使用对光催化活性的影响.结果表明,所制备的TiO2为锐钛矿和金红石混晶型,平均粒径11nm,通过控制硅藻土加入量可以得到负载均匀的光催化剂.所制备的TiO2/硅藻土具有较强的光催化活性,对弱酸性艳蓝RAW的降解效果好于商品Degussa P25型TiO2,最佳pH值为4.0.该催化剂性质稳定,重复使用15次后,催化活性仅降低12.4%.     

活性炭负载型TiO_2光催化降解采油废水的研究

采用溶胶-凝胶法制备了活性炭负载型的TiO2复合光催化剂,通过SEM和XRD对其进行表征,并利用采油废水的COD去除率来考察自制TiO2/AC复合催化剂对采油废水的处理效果。结果表明:活性炭表面负载了均匀的纯锐钛矿型TiO2薄膜,其晶粒尺寸为24.0 nm;TiO2/AC复合催化剂对采油废水中大多数有机物有不同程度的光催化降解;处理后采油废水COD去除率可达65.3%。     

金属泡沫镍负载纳米TiO2光催化降解空气中甲醛

研究金属泡沫镍表面负载改性TiO2光催化剂对室内空气主要污染物甲醛的降解。采用溶胶一凝胶法制备了掺杂金属离子的纳米TiO2光催化剂，将其负载于泡沫镍板上，以室内空气典型污染物甲醛为模型反应物，研究3种不同改性纳米TiO2对甲醛的光催化作用．并讨论金属镧离子的最佳掺杂比例以及环境因素对光催化效率的影响。同时考察催化剂的失活特征。结果表明，该负载型纳米光催化剂对甲醛气体具有较高的光催化活性。掺镧TiO2对甲醛的降解率最高。最佳掺杂比例为1．5％。该催化剂存在失活现象。但在清洁后能够恢复。     

脉冲放电等离子体协同TiO_2/沸石去除甲醛的实验研究

脉冲放电等离子体和催化剂联用处理甲醛是一种新型的高级氧化技术,实验采用线-筒式脉冲放电协同制备的负载型TiO_2/沸石催化技术去除甲醛,进行了脉冲放电分别协同沸石、TiO_2、TiO_2/沸石三种催化剂去除甲醛的对比实验,实验结果表明:在一定实验条件下,采用溶胶-凝胶法制备负载型催化剂,当焙烧温度为450℃,焙烧时间为2 h时,制备的负载型TiO_2/沸石光催化剂具有更强的催化活性,与脉冲放电等离子体协同效应加强,对甲醛的去除率明显高于脉冲放电协同沸石、TiO_2的效率。     

低温等离子体协同催化处理VOCs的研究进展

针对成分复杂且极易挥发的挥发性有机物(VOCs),传统的大气治理技术很难将其完全去除,而低温等离子体技术利用O·、·OH、N·和O₃等强氧化性物质可高效降解VOCs。简述了低温等离子体单独降解VOCs反应机理,等离子体与催化剂的协同作用,并分析了催化剂位置对降解效率的影响。其中,重点分析了不同催化剂的协同作用,主要包括贵金属催化剂、复合金属催化剂、过渡金属催化剂、钙钛矿催化剂和光催化剂等,深入分析了其对VOCs的降解机理,并总结了这些催化剂用于处理VOCs的降解效果及影响因素,最后提出了低温等离子体技术协同催化降解VOCs目前存在的问题及未来的研究和发展方向,可为实际工业废气的治理提供参考。     

Combined effects of adsorption and photocatalysis by hybrid TiO2/ZnO-calcium alginate beads for the removal of copper

The use of nanosized titanium dioxide(TiO_2) and zinc oxide(ZnO) in the suspension form during treatment makes the recovering and recycling of photocatalysts difficult.Hence,supported photocatalysts are preferred for practical water treatment applications.This study was conducted to investigate the efficiency of calcium alginate(CaAlg) beads that were immobilized with hybrid photocatalysts,TiO_2/ZnO to form TiO_2/ZnO-CaAlg.These immobilized beads,with three different mass ratios of TiO_2:ZnO(1:1,1:2,and 2:1) were used to remove Cu(Ⅱ) in aqueous solutions in the presence of ultraviolet light.These beads were subjected to three cycles of photocatalytic treatment with different initial Cu(Ⅱ) concentrations(10-80 ppm).EDX spectra have confirmed the inclusion of Ti and Zn on the surface of the CaAlg beads.Meanwhile,the surface morphology of the beads as determined using SEM,has indicated differences of before and after the photocatalytic treatment of Cu(Ⅱ).Among all three,the equivalent mass ratio TiO_2/ZnO-CaAlg beads have shown the best performance in removing Cu(Ⅱ) during all three recycling experiments.Those TiO_2/ZnO-CaAlg beads have also shown consistent removal of Cu,ranging from 7.14-52.0 ppm(first cycle) for initial concentrations of10-80 ppm.In comparison,bare CaAlg was only able to remove 6.9-48 ppm of similar initial Cu concentrations.Thus,the potential use of TiO_2/ZnO-CaAlg beads as environmentally friendly composite material can be further extended for heavy metal removal from contaminated water.     

负载型催化剂光催化氧化五氯苯酚钠的效果

研究以TiO₂ 为基本活性组分、空心玻璃珠为载体、硅酸钠为粘合剂的负载型催化剂的制备技术 .选取五氯苯酚钠 (PCP-Na)为处理对象 ,结合对催化剂比表面和晶型结构的表征 ,对制备的催化剂进行筛选评价 .实验结果表明 :在适当的条件下 (二氧化钛、空心玻璃珠、40%硅酸钠溶液重量比为 4∶20∶2,650℃下烧 3h)所制备的C3型催化剂不仅光催化活性高 ,且负载牢固 ,易与水分离 .对初始COD_Cr=400mg·L^-1,PCP-Na=10mg·L^-1的反应液 ,在光照强度为 30kW·m^-2下 2hCOD_Cr去除率大于 65% ,PCP-Na去除率大于 92%.试验进一步探讨C3型催化剂投加量、反应液初始浓度、供氧量对催化反应的影响 .     

甲基橙在镧掺杂二氧化钛表面的吸附研究

以钛酸丁酯为原料,采用溶胶-凝胶法成功制备了一系列La^3＋-TiO2光催化剂。通过XRD对催化剂进行了表征,XRD光谱结果表明所制得的TiO2光催化剂晶型结构为锐钛矿型。考察了pH值对甲基橙在纯TiO2光催化剂表面的吸附以及掺杂量对吸附的影响,通过紫外-可见光吸收光谱分析得出碱性或中性条件下的吸附较好。镧（La^3＋）掺杂量的TiO2对甲基橙的吸附实验表明,La^3＋的掺杂显著提高了甲基橙在TiO2催化剂表面的吸附能力,随着La^3＋掺杂量的增加,吸附能力逐渐增强。     

Graphitic carbon nitride-based photocatalysts in the applications of environmental catalysis

Semiconductor photocatalytic technology has shown great prospects in converting solar energy into chemical energy to mitigate energy crisis and solve environmental pollution problems. The key issue is the development of high-efficiency photocatalysts. Various strategies in the state-of-the-art advancements, such as heterostructure construction, heteroatom doping, metal/single atom loading, and defect engineering, have been presented for the graphitic carbon nitride (g-C₃N₄)-based nanocomposite catalysts to design their surface chemical environments and internal electronic structures to make them more suitable for different photocatalytic applications. In this review, nanoarchitecture design, synthesis methods, photochemical properties, potential photocatalytic applications, and related reaction mechanisms of the modified high-efficiency carbon nitride-based photocatalysts were briefly summarized. The superior photocatalytic performance was identified to be associated with the enhanced visible-light response, fast photoinduced electron-hole separation, efficient charge migration, and increased unsaturated active sites. Moreover, the further advance of the visible-light harvesting and solar-to-energy conversions are proposed.     

Strategies for improving the photocatalytic performance of metal-organic frameworks for CO2 reduction: A review

Photocatalytic CO₂ reduction is an appealing strategy for mitigating the environmental effects of greenhouse gases while simultaneously producing valuable carbon-neutral fuels. Numerous attempts have been made to produce effective and efficient photocatalysts for CO₂ reduction. In contrast, the selection of competitive catalysts continues to be a substantial hindrance and a considerable difficulty in the development of photocatalytic CO₂ reduction. It is vital to emphasize different techniques for building effective photocatalysts to improve CO₂ reduction performance in order to achieve a long-term sustainability. Metal-organic frameworks (MOFs) are recently emerging as a new type of photocatalysts for CO₂ reduction due to their excellent CO₂ adsorption capability and unique structural characteristics. This review examines the most recent breakthroughs in various techniques for modifying MOFs in order to improve their efficiency of photocatalytic CO₂ reduction. The advantages of MOFs using as photocatalysts are summarized, followed by different methods for enhancing their effectiveness for photocatalytic CO₂ reduction via partial ion exchange of metal clusters, design of bimetal clusters, the modification of organic linkers, and the embedding of metal complexes. For integrating MOFs with semiconductors, metallic nanoparticles (NPs), and other materials, a number of different approaches have been also reviewed. The final section of this review discusses the existing challenges and future prospects of MOFs as photocatalysts for CO₂ reduction. Hopefully, this review can stimulate intensive research on the rational design and development of more effective MOF-based photocatalysts for visible-light driven CO₂ conversion.     

不同煅烧温度制备的Mn、N掺杂TiO2光催化性能研究

以MnSO4·H2O为锰源,尿素为氮源,采用溶胶-凝胶法制备不同锻烧温度的纯TiO2、Mn-TiO2及Mn-N-TiO2光催化剂,利用X射线衍射、紫外-可见光漫反射光谱及电子自旋共振等技术对样品形貌和结构进行表征,并以罗丹明B的光催化降解为模型反应,考察不同锻烧温度对其光催化活性的影响.结果表明,Mn、N成功掺入TiO2后,有利于提高光催化剂的热稳定性,抑制锐钛矿相向金红石相转化,且光吸收拓展到可见光区域.Mn、N共掺杂样品比单Mn掺杂样品具有更高的光催化活性,400℃下锻烧的Mn-N-TiO2在可见光下对罗丹明B的降解具有最高的光催化活性,光照2h降解率达到100%.高温锻烧Mn-N-TiO2和Mn-TiO2样品在紫外光照射30min后对罗丹明B的降解率在90%以上.     

高效负载型光催化剂制备及其加铂修饰技术

通过光催化氧化五氯苯酚钠实验,结合对催化剂晶型结构、比表面积的表征分析,优化钛酸四丁酯水解制备TiO₂负载型催化剂并加铂修饰的制备条件:R值、烧结温度、粘合剂添加量、空心玻璃珠粒径大小及催化剂中铂含量,从而制备出高效、实用的负载加铂修饰型半导体光催化剂.实验结果表明,当R=10,温度为650℃烧结1h,TiO₂∶硅酸钠∶空心玻璃珠=10∶2.5∶20(W),铂在催化剂中的重量百分比为1.4%～1.6%,空心玻璃珠的粒径为0.5mm时,所制备的加铂修饰负载型催化剂催化活性、使用寿命和牢固度均比较理想.用该催化剂做光催化实验,当反应液初始五氯苯酚钠浓度为100mg/L、pH值为6.5,催化剂投加量为2g/L,通氧气量为1.6mL/s,光照强度为30kW/m²时,五氯苯酚钠2 h光催化氧化率达92.0%.     

In situ preparation of visible-light-driven carbon quantum dots/NaBiO3 hybrid materials for the photoreduction of Cr(VI)

In this study, different carbon quantum dots (CQDs)/NaBiO₃ hybrid materials were synthesized as photocatalysts to effectively utilize visible light for the photocatalytic degradation of contaminants effectively. These hybrid materials exhibit an enhanced photocatalytic reduction of hexavalent chromium (Cr(VI)) in the aqueous medium. Zero-dimensional nanoparticles of CQDs were embedded within the two-dimensional NaBiO₃ nanosheets by the hydrothermal process. Compared with that of the pure NaBiO₃ nanosheets, the photocatalytic performance of the hybrid catalysts was significantly high and 6 wt.% CQDs/NaBiO₃ catalyst exhibited better photocatalytic performance. We performed the first-principles density functional theory calculations to study the interfacial properties of pure NaBiO₃ nanosheets and hybrid photocatalysts, and confirmed the CQDs played an important role in the CQDs/NaBiO₃ composites. The experimental results indicated that the enhanced reduction of Cr(VI) was probably due to the high loading of CQDs (electron acceptor) on NaBiO_3, which made NaBiO₃ nanomaterials to respond in visible light and significantly improved their electron-hole separation efficiency.