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1.
《环境化学》2017,(7)
以C球为核,钛酸四丁酯和四氯化钛为钛源,不同含量尿素为氮源,通过水热法将不同N掺杂量的TiO_2包裹在C球表面.通过控制焙烧条件,调控包在C球表面的TiO_2的晶型.X射线衍射(XRD)表明,随着焙烧温度的提高,可调控TiO_2的晶型由板钛矿/锐钛矿混晶到锐钛矿/金红石混晶最后得到单一金红石相TiO_2;X射线光电子能谱(XPS)表明,N掺杂进入了TiO_2的晶格内.可见光催化降解孔雀石绿研究表明,制备过程加入1 g尿素,煅烧温度为550℃的样品N(1)-TiO_2@C-550℃,其结构为锐钛矿/金红石混晶型,可见光催化效果最好,2 h催化效率达到75%,相比P25提高了11倍.对其可见光催化降解孔雀石绿过程中活性氧物种的捕获可知,·O-2和·OH参与了反应,其中·OH起在光催化过程中占主要作用. 相似文献
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以Ti(SO4)2为钛源、碳酸氢铵为氮源,采用均匀沉淀法制得水合沉淀物,在N2保护下对水合沉淀物进行程序升温处理,制得了不同焙烧温度的N掺杂TiO2可见光响应催化剂.以三硝基间苯二酚为目标降解物,研究了所制备微粒在可见光区及紫外光区的光催化活性.对所制备的催化剂采用X射线衍射、热重-差热分析、傅立叶变换红外光谱和紫外-可见漫反射光谱对催化剂进行表征,研究改性催化剂的晶相结构、热稳定性、表面结构和光谱特征.结果表明:N-掺杂TiO2的可见光催化活性显著提高,焙烧温度为300℃时可见光催化活性最为优异,在不降低紫外段催化能力的同时,催化剂的吸收带边红移至468nm. 相似文献
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以P掺杂的TiO2纳米颗粒为前驱体,采用水热合成法制备了系列P掺杂的TiO2纳米管.用N2吸附-脱附、透射电子显微镜(TEM)、X射线衍射(XRD)、激光拉曼光谱(Raman)、紫外可见漫反射(UV-Vis DRS)等方法对光催化材料的表面形貌、颗粒尺寸、孔结构、表面构造、吸光性能进行了分析.研究结果表明,所制备的各样品均为两端开口的纳米管形貌,管长为几十纳米到几百纳米,管外径约10 nm,内径约4 nm,管壁为多层;P掺杂后的系列TiO2纳米管仍保持锐钛矿晶型;掺杂的P可以进入到TiO2的骨架中,并形成P—O—Ti键,在TiO2禁带内引入杂质能级,降低了禁带能量,提高了TiO2的吸光性能及光生电子和空穴的分离性能.光催化甘油水溶液制氢活性评价表明,P掺杂的TiO2纳米管表现出了远高于纯TiO2管以及相同掺杂量的纳米颗粒的光催化制氢性能,2%P掺杂的样品在紫外灯和氙灯辐射下,其最高产氢速率可分别达1850μmol·(h·g)-1和335μmol·(h·g)-1.P掺杂TiO2样品光催化活性的提高与其禁带能量降低以及光生电子和空穴的分离性能增加有关. 相似文献
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以三聚氰胺和甘油磷脂酰胆碱为前驱体,通过水热法和煅烧法联合处理方式制得磷掺杂的石墨相氮化碳(PCN);利用X射线衍射(XRD)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)、紫外可见吸收光谱(UV-vis DRS)和光致发光光谱(PL)等方法分析了PCN的物相组成和光电性质。结果显示,磷掺杂提高了PCN催化剂的比表面积,降低了光生电子空穴的复合率,拓宽了可见光谱的响应范围,同时提高了催化剂的氧化性能。将PCN用于可见光催化降解抗生素磺胺噻唑(ST)时,其降解速率远高于体相石墨相氮化碳(CN),且60%PCN(60%为甘油磷脂酰胆碱与三聚氰胺的质量比)的效果最好;自由基捕获实验结果显示,羟基自由基(·OH)在整个光催化反应中占主导地位。 相似文献
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通过前掺杂法(PI)和浸渍法(IM)制备了氧化锰八面体分子筛(Octahedral Molecular Sieves,OMS-2)负载Pd(Pd/OMS-2)催化剂.采用X射线衍射(XRD)、H2-程序升温还原(H2-TPR)和N2-吸附/脱附等技术对样品进行了表征,研究了不同制备方法和不同Pd负载量对Pd/OMS-2催化剂催化氧化CO性能的影响,通过与载体OMS-2的比较研究了Pd/OMS-2催化剂的稳定性.结果表明,前掺杂法制备的Pd/OMS-2-PI催化剂活性明显优于浸渍法制备的Pd/OMS-2-IM催化剂,其T100分别为75℃和175℃.这与Pd/OMS-2-PI催化剂中OMS-2载体与Pd之间存在强相互作用有关.Pd负载量明显影响Pd/OMS-2-PI催化剂的催化活性,3Pd/OMS-2-PI催化剂(Pd=3.0wt%)催化活性最高,这是由于Pd掺杂进入OMS-2晶格结构,能活化晶格氧,而随Pd含量进一步增加,部分Pd分布在OMS-2表面.稳定性结果表明,Pd/OMS-2-PI稳定性明显优于OMS-2载体本身,这可能与Pd掺杂进入催化剂晶格,能较好稳定OMS-2结构密切相关. 相似文献
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助剂Fe添加对柱状MnO_x/PG-AC催化剂低温选择性催化还原(SCR)性能影响 总被引:1,自引:0,他引:1
《环境化学》2015,(8)
采用等体积浸渍法制备Mn Ox/PG-AC、Mn Ox-Fe Oy/PG-AC催化剂,并通过X射线衍射(XRD)、X射线光电能谱(XPS)及场发射扫描(FESEM)等表征手段分析了Fe的掺杂对催化剂低温脱硝活性的影响.分析表明,助剂Fe的加入促进活性组分锰氧化物具有更好的分散性,为催化剂提供了更多的催化活性位点,同时助剂Fe的掺杂明显调控了活性组分Mn4+/Mn3+的价态比.一定量Fe的掺杂显著提高了催化剂的低温选择性催化还原(SCR)性能.当Fe/Mn的物质的量之比为0.8时,Mn Ox-Fe Oy/PG-AC/300℃催化剂表现出最佳的低温SCR脱硝活性 相似文献
7.
《环境化学》2017,(12)
分别采用前掺杂法(PI)、离子交换法(IE)和浸渍法(IM)合成了过渡金属Cu掺杂的催化剂Cu-OMS-2,通过XRD、BET、XPS、H_2-TPR等手段对催化剂的结构进行表征,并测试催化剂对甲苯的催化燃烧性能.XRD结果显示,全部掺Cu样品与单纯OMS-2晶相峰相同;XPS结果表明,Cu掺杂有效调控了Mn~(3+)/Mn~(4+)的比例,催化剂表面形成不同数量氧空位,其中前掺杂法和离子交换法制备的催化剂表面生成了更多的氧空位;H_2-TPR结果显示Cu掺杂降低了催化剂还原温度,且前掺杂法和离子交换法制备的催化剂的还原温度低于浸渍法合成的样品.因此,前掺杂法和离子交换法合成的催化剂在甲苯催化氧化中显示出较高的催化活性. 相似文献
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采用浸渍法,在相同的铁含量条件下,以硝酸铁、氯化亚铁、硫酸亚铁为前驱体制备了3种不同铁源Fe/ZSM-5分子筛催化剂.研究了铁源对Fe/ZSM-5催化剂NH_3-SCR活性的影响,并采用X射线衍射(XRD)、比表面积和孔结构(BET)、X射线光电子能谱(XPS)、氢气程序升温还原(H_2-TPR)及氨程序升温脱附(NH_3-TPD)等表征手段对催化剂的结构和理化性质进行测定.结果表明,不同的铁源对Fe/ZSM-5催化剂低温段(低于350℃)的NH_3-SCR催化性能影响较大,其低温活性顺序为:Fe(Cl)/ZSM-5 Fe(S)/ZSM-5 Fe(N)/ZSM-5.以氯化亚铁为铁源的Fe(Cl)/ZSM-5催化剂取得最佳的NH_3-SCR催化活性,在233℃时NO转化率达到90%.表征结果表明,样品Fe(Cl)/ZSM-5中形成了最多的孤立Fe~(3+)物种及中酸位数量.孤立Fe~(3+)物种有利于增强Fe/ZSM-5催化剂的低温还原性能,改性过程中形成的中等强度酸性位有利于提高催化剂低温NH_3-SCR催化性能. 相似文献
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本文利用磷酸水热法制备了多孔氮化碳(PCN-H)纳米材料,通过紫外-可见吸光光谱、扫描电子显微镜、X射线衍射、X射线光电子能谱和比表面积分析等多种手段表征催化剂的形貌、光学属性及结构特点等.在可见光照射下光催化降解除草剂莠去津,评价材料对莠去津的催化降解活性.分别测试最优化氮化碳材料在不同pH条件下对莠去津降解效率的变化,并分析催化剂用量和除草剂浓度对降解率的影响.结合活性物种捕获实验,阐述莠去津可见光降解的机理.通过材料表征结果分析,PCN-H表现为独特的多孔结构,比表面积分别是基础石墨型氮化碳(MCN)和磷酸浸泡氮化碳(PCN-S)的4.3倍和3.0倍.磷酸水热处理成功实现磷元素的掺杂,可见光利用率明显提高,1h内即可将莠去津降解率从18.4%提升至45.7%.酸性条件有助于PCN-H对莠去津催化降解.在PCN-H可见光催化降解莠去津的过程中,光致空穴和超氧自由基发挥主要作用.该方法制备的材料光能利用率高,避免了金属催化剂自身对环境的潜在污染,酸性条件下降解更为高效,有助于减轻农药污染对农业生态环境及非靶标生物造成的负面影响. 相似文献
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Chen Wang Jun Wang Jianqiang Wang Meiqing Shen 《Frontiers of Environmental Science & Engineering》2021,15(2):30
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Liyun Song Shilin Deng Chunyi Bian Cui Liu Zongcheng Zhan Shuangye Li Jian Li Xing Fan Hong He 《Frontiers of Environmental Science & Engineering》2023,17(8):96
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Radwa A. El-Salamony Enas Amdeha Nagwa A. Badawy Salwa A. Ghoneim Ahmed M. Al-Sabagh 《毒物与环境化学》2018,100(2):143-156
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. 相似文献
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Guanglong Pang Donghui Wang Yunhong Zhang Chunyan Ma Zhengping Hao 《Frontiers of Environmental Science & Engineering》2016,10(3):447-457
MnO2 microspheres with various surface structures were prepared using the hydrothermal method, and Au/MnO2 catalysts were synthesized using the sol-gel method. We obtained three MnO2 microspheres and Au/MnO2 samples: coherent solid spheres covered with wire-like nanostructures, solid spheres with nanosheets, and hierarchical hollow microspheres with nanoplatelets and nanorods. We investigated the properties and catalytic activities of formaldehyde oxidation at room temperature. Crystalline structures of MnO2 are the main factor affecting the catalytic activities of these samples, and γ-MnO2 shows high catalytic performance. The excellent redox properties are responsible for the catalytic ability of γ-MnO2. The gold-supported interaction can change the redox properties of catalysts and accelerate surface oxygen species transition, which can account for the catalytic activity enhancement of Au/MnO2. We also studied intermediate species. The dioxymethylene (DOM) and formate species formed on the catalyst surface were considered intermediates, and were ultimately transformed into hydrocarbonate and carbonate and then decomposed into CO2. A proposed mechanism of formaldehyde oxidation over Au/MnO2 catalysts was also obtained. 相似文献
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Zheng Wang Bingru Zhang Fengting Li 《Frontiers of Environmental Science & Engineering》2007,1(4):454-458
The objective of this study was to prepare a new photocatalyst with high activities for degradation of organic pollutants. Coupled ZrO2/ZnO photocatalyst was prepared with a simple precipitation method with cheap raw materials zinc acetate and zirconium oxychloride, and was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Reactive brilliant red X-3B was used as a model compound to investigate the photocatalytic activity of synthesized catalysts in water under 254 nm UV irradiation. Results show that the optimal calcination temperature and coupling molar ratio of Zr were 350°C And 2.5%, respectively. At the calcination temperature of 350°C, ZrO2 was dispersed on the surface of hexagonal ZnO in the form of amorphous clusters. The particle size of ZrO2/ZnO decreased with the decrease of calcination temperature and the increase of Zr coupling amount. ZrO2/ZnO has better photocatalytic activity for degradation of reactive brilliant red (RBR) X-3B than pure ZnO and P25-TiO2. 相似文献
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以锐钛矿TiO2(P25)为载体采用原位生长法负载锰氧化物制备了Mn/TiO2催化剂,再以等体积浸渍-煅烧法对该催化剂掺杂氧化铈制备Ce(x)Mn/TiO2-y催化剂用以烟气低温SCR脱硝.在固定锰负载量(质量分数为8%)的基础上,考察了铈掺杂量(铈锰摩尔比)、煅烧温度对催化剂SCR脱硝性能的影响.采用TEM、BET、XRD和XPS等手段表征了催化剂的理化结构特性.结果发现,当Ce/Mn的摩尔比例为1.0,煅烧温度为300℃时,Ce(1.0)Mn/TiO2-300催化剂在150—300℃温度范围内、10500—27000 h-1的空速范围内,能够保持90%以上的NO转化率.理化性能分析结果表明,煅烧温度对催化剂的微观形貌影响显著,随着煅烧温度的升高,Ce(1.0)Mn/TiO2-500催化剂活性物种颗粒集聚明显、比表面积降低,且锰氧化物价态分布偏向于低价态;铈的掺杂有助于Ce(1.0)Mn/TiO2-300催化剂活性物种在载体表面的均匀分散,可以促进产生更多的Mn4+物种和更多的吸附氧,有利于催化剂低温SCR脱硝性能的提升. 相似文献
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改性斜发沸石处理高浓度氨氮废水 总被引:2,自引:0,他引:2
采用NaOH碱熔法对缙云斜发沸石进行处理,采用正交实验对碱熔法改性沸石的最佳条件进行了选择;并对改性前后的沸石进行粉末X射线衍射(XRD)、电感耦合等离子体发射光谱法(ICP-AES)和扫描电镜(SEM)表征;详细研究了所得改性沸石在氨氮废水处理中的净化性能.结果表明,处理沸石的水热温度对氨氮去除效果的影响最显著;碱熔法处理可使缙云斜发沸石转变为低硅铝比的Na-P型分子筛,它对氨氮废水的NH4+-N具有优异的吸附性能.当改性沸石投加量为5 g,对100 mL浓度为1000 mg.L-1氨氮溶液,氨氮去除率可达77.8%,改性沸石吸附NH4+-N是一快速吸附过程,且能较好地符合Langmuir吸附等温模式,偏向于单分子层的吸附. 相似文献
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Yuchao Shao Jun Zhao Yuyang Long Wenjing Lu 《Frontiers of Environmental Science & Engineering》2023,17(10):119
Converting biomass materials to humic acid is a sustainable method for humic acid production and achieve biomass valorization. A two-step hydrothermal treatment method was adopted in this study to produce humic acid from corn stalks. In the first step of the process, hydrochar was prepared at different hydrothermal temperatures and pH values. Their chemical properties were then analyzed, and the hydrochar-derived humic acids were produced under alkaline hydrothermal conditions (denoted as HHAalk). The hydrochar, prepared under high temperature (200 °C) and strong acidic (pH 0) conditions, achieved high HHAalk yields (i.e., 67.9 wt% and 68.8 wt% calculated based on weight of hydrochar). The sources of HHAalk formation were as follows: 1) production in the hydrochar preparation stage, and 2) increment under the alkaline hydrothermal treatment of hydrochar. The degree of hydrochar unsaturation was suggested as an indicator for evaluating the hydrochar humification potential under alkaline hydrothermal conditions. This study provides an important reference for the preparation of suitable hydrochar with high hydrothermal humification potential. 相似文献
20.
Caiting Li Qun Li Pei Lu Huafei Cui Guangming Zeng 《Frontiers of Environmental Science & Engineering》2012,6(2):156-161
A series of CeO2 supported V2O5 catalysts with various loadings were prepared with different calcination temperatures by the incipient impregnation. The catalysts were evaluated for low temperature selective catalytic reduction (SCR) of NO with ammonia (NH3). The effects of O2 and SO2 on catalytic activity were also studied. The catalysts were characterized by specific surface areas (SBET) and X-ray diffraction (XRD) methods. The experimental results showed that NO conversion changed significantly with the different V2O5 loading and calcination temperature. With the V2O5 loading increasing from 0 to 10 wt%, NO conversion increased significantly, but decreased at higher loading. The optimum calcination temperature was 400°C. The best catalyst yielded above 80% NO conversion in the reaction temperature range of 160°C–300°C. The formation of CeVO4 on the surface of catalysts caused the decrease of redox ability. 相似文献