高级化学氧化工艺在制浆废水处理的应用

高级化学氧化 （ Ａｄｖａｎｃｅｄ Ｏｘｉｄａｔｉｏｎ Ｐｒｏｃｅｓｓｅｓ , 简称 Ａ Ｏ Ｐｓ） 是一项新兴的现代水处理技术, 其在处理水中难生物降解毒性有机污染物等方面具有广阔的应用前景。该文简要介绍了几种典型高级化学氧化工艺的基本原理与特点, 综述了 Ａ Ｏ Ｐｓ 技术在制浆造纸工业废水处理方面的研究进展, 并就该技术在处理高浓难降解工业有机废水方面的优势、存在的问题及发展前景作了一些评述。     

热处理对纳米TiO2光催化活性的影响

本文对纳米TiO2光催化剂在空气气氛中进行程序升温热处理,以苯酚的光催化降解反应评价光催化剂活性,以XRD、FTIR分析TiO2的晶相结构、粒子大小和表面结构随处理温度的变化情况。分析了热处理作用条件下TiO2光催化活性的变化机理。400℃条件下热处理TiO2具有最高光催化活性。适宜的表面结构、粒子大小及晶相结构是纳米TiO2光催化剂表现出较高催化活性的主要原因。     

Optical and Electrical Enhancement of Hydrogen Evolution by MoS2@MoO3 Core–Shell Nanowires with Designed Tunable Plasmon Resonance

The design of transition‐metal chalcogenides (TMCs) photocatalysts for water splitting is highly important, in which both light absorption and interfacial engineering play vital roles in photoexcited electron generation, electron transport, and ultimately speeding up water splitting. To this end, plasmonic metal nanomaterials with surface plasmon resonances are promising candidates. However, it is very difficult to enhance the light absorption and manage the interfacial engineering simultaneously, thus, resulting in suboptimal photocatalytic performance. Here, a doped semiconductor plasmon is proposed to optically and electrically enhance TMCs hydrogen evolution. With the tunability of plasmon resonance in a doped MoO₃ semiconductor via hydrogen reduction, the broadband absorption and good interfacial engineering are simultaneously demonstrated in flexible MoS₂@MoO₃ core–shell nanowire photocatalysts. Better energy‐band alignment with MoS₂ can also be realized, thereby achieving improved photoinduced electron generation. More importantly, the defects at the interface between MoO₃ and MoS₂ are effectively reduced because of precise tunability of plasmon resonance, which enhances electron transport. As a proof of concept, this optimized hybrid nanostructure exhibits outstanding H₂ evolution characteristics (841.4 μmol h^?1 g^?1), excellent stability, and good flexibility. The value is also one of the highest hydrogen evolution activity rates to date among the two dimensional‐layered visible‐light photocatalysts.     

电场辅助TiO2薄膜光催化降解甲基橙的影响

将电场引入到TiO2光催化降解甲基橙反应中,实验讨论了电场对TiO2光催化活性的影响及电场对薄膜最佳光催化活性层数的影响.结果表明:外加电场对光催化反应的影响明显,在外加电压30V时,TiO2光催化降解甲基橙的降解率提高了50%;此外,电场对催化剂TiO的最佳光催化活性层数有一定的影响,最佳光催化活性层数从无电场时的6层变为7层.     

纳米光催化材料免回收处理TNT废水

为提高纳米粒子的分散性和避免水处理时的回收程序,制备了附载型纳米复合粒子和光催化反应器。利用扫描电子显微镜（SEM）、X射线衍射图谱（XRD）和比表面积测试仪分析发现,制备的纳米TiO2／硅藻土复合粒子和纳米TiO2／SiO2复合粒子的纳米颗粒细小,比表面积和孔容积大。将纳米光催化复合材料负载于光催化反应器或直接分散于废水中,对比研究发现：重复使用6次后,前者的纳米光催化复合粒子对TNT废水的光催化降解效率保持90％以上,而后者的降解效率从97％迅速下降至50％左右。同时,红外光谱分析发现,后者处理后废水中发现有纳米光催化材料的存在;而借助于光催化反应器处理后废水中未发现有纳米光催化材料的残存,不需要额外的纳米材料回收程序。     

三氯乙酸光催化降解过程中pH值变化影响因素的研究

研究了三氯乙酸在TiO2薄膜为催化剂的光催化反应体系中发生光催化降解反应时pH值的变化与影响因素。结果表明在反应过程中pH值不断变化呈现逐渐降低的趋势,pH值条件对三氯乙酸的光催化降解反应有一定的影响,低pH值有利于反应的进行。     

表面活性剂对光催化还原法合成纳米Ag/TiO2影响的电镜观察

在透射电子显微镜下，通过对加入表面活性剂修饰纳米TiO2粒子前后以及在不同溶胶稳定态下光催化还原合成金属纳米银簇的观察发现：适量的表面活性剂能有效改善纳米TiO2在水中的分散度，提高颗粒的稳定性．过量的表面活性剂将导致胶束的形成；在稳定的溶胶状态下，金属纳米银簇能稳定负载在纳米TiO2上，在不稳定的溶胶状态或形成胶束情况下并不能观察到金属银簇的生成。     

焙烧温度对纳米Mo-TiO2可见光催化活性的影响

用溶胶凝胶法制备Mo掺杂TiO2光催化剂,运用TG-DTA分析了光催化剂在热处理过程中发生的物理和化学变化.UV-VIS光谱显示当焙烧温度为500℃时Mo-TiO2光吸收带边红移程度最大;XRD分析表明随着焙烧温度的升高,纳米Mo-TiO2晶粒粒径增大、金红石型的含量增高.亚甲蓝溶液的光催化降解结果表明,当焙烧温度为400℃时,Mo-TiO2可见光光催化活性最好.     

Efficient Photocatalytic Nitrogen Fixation: Enhanced Polarization,Activation, and Cleavage by Asymmetrical Electron Donation to NN Bond

Photocatalytic nitrogen (N₂) fixation suffers from low efficiency due to the difficult activation of the strongly nonpolar N?N bond. In this study, a Ru–Co bimetal center is constructed at the interface of Ru/CoS_x with S‐vacancy on graphitic carbon nitride nanosheets (Ru‐Vs‐CoS/CN). Upon adsorption, the two N atoms in N₂ are bridged to the Ru–Co center, and the asymmetrical electron donation from Ru and Co atoms to N₂ adsorbate highly polarized N?N bond to double bond order. The plasmonic electric‐field‐enhancement effect enables the Ru/CoS_x interface to boost the generation of energetic electrons. The Schottky barrier between Ru and CoS_x endows the interface with electron transfer from CoS_x to Ru. The Ru‐end bound N at the Ru–Co center is preferentially hydrogenated. As a result, the Ru‐Vs‐CoS/CN photocatalyst shows an NH₃ production rate of up to 0.438 mmol g^?1 h^?1, reaching a high apparent quantum efficiency of 1.28% at 400 nm and solar‐to‐ammonia efficiency of 0.042% in pure water under AM1.5G light irradiation.     

织物负载TiO_2光催化剂的制备及活性红MS光催化动力学

实验采用溶胶一凝胶法制备纳米TiO2溶胶,棉织物经过浸渍TiO2溶胶-烘干-焙烘法处理,在织物表面低温制备TiO2薄膜.采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)等方法对样品结构和形貌进行分析和表征.在紫外灯照射下,以活性红MS为降解物,研究了制备条件包括TiO2浓度、TiO2溶胶pH值、焙烘温度和焙烘时间对薄膜光催化性能的影响.结果表明在低温下制备的TiO2主要是锐钛矿型,并且薄膜的光催化活性与处理工艺有关.在TiO2浓度为0.423 mol/L.TiO2溶胶pH值为1.67、焙烘温度为80℃、焙烘时间为2 min的条件下,活性红MS的光催化降解速率常数最大,拟合紫外光下光催化薄膜降解活性红MS为一级反应.