Low-temperature CO oxidation over Au-doped 13X-type zeolite catalysts: preparation and catalytic activity

Au-supported 13X-type zeolite (Au/13X) was synthesized using a common deposition–precipitation (DP) method with a solution of sodium carbonate as a precipitate agent. Further testing was conducted to test for catalytic oxidation of CO. A study was conducted on the effects of different preparation conditions (i.e., chloroauric acid concentration, solution temperature, pH of solution, and calcinations temperature) on Au/13X for CO oxidation. In respect to the catalytic activity, the relationship between different the preparation conditions and gold particles in 13X zeolite was analyzed using X-ray diffraction, TEM and XPS. The activity of Au/13X catalysts in CO oxidation was dependent on the chloroauric acid concentration. From XRD results, a higher chloroauric acid concentration induced larger gold nanoparticles, which resulted in lower catalytic activity. Results revealed that higher temperatures induced higher Au loading, homogeneous deposit, and smaller gold clusters on the support of 13X, resulting in higher CO activity. Furthermore, a pH of 5 or 6 generated greater amounts of Au loading and smaller Au particles on 13X than at a pH of 8 or 9. This may be a result of an effective exchange between Au(OH)2Cl2- and Au(OH)₃Cl^- on specific surface sites of zeolite under the pH’s 5 and 6. The sample calcined at 300°C showed the highest activity, which may be due to the sample’s calcined at 200°C inability to decompose completely to metallic gold while the sample calcined at 400°C had larger particles of gold deposited on the support. It can be concluded from this study that Au/13X prepared from a gold solution with an initial chloroauric acid solution concentration of 1.5 × 10^-3 mol·L^-1 gold solution pH of 6, solution temperature of around 90°C, and a calcination temperature of 300°C provides optimum catalytic activity for CO oxidation.     

三维电极电催化氧化法处理废水的研究进展

综述了近几年国内外在三维电极电化学反应器方面的最新研究进展,分析了电源的输出形式、阴阳极板的布置方式、粒子电极的填充方式等因素对废水处理效果的影响,探讨了碳纳米材料等新材料在粒子电极载体上的应用,最后介绍了三维电极法与其他技术联用的最新研究,并指出了三维电极法存在的问题及今后的研究方向。     

EDI装置工业应用问题及应对措施

根据河南某电厂电去离子（EDI）装置在调试、运行中发生了断水烧坏模块、树脂包被有机物污染和余氯氧化导致树脂破碎等诸多问题,通过对EDI模块的抽检和整套工艺的系统性分析,找出了产生问题的原因,采取了增加多重流量保护、清洗系统隔离及余氯检测等措施,对EDI树脂包进行了更换和修复,恢复了EDI装置的离子交换性能。通过一年多的运行观察,该套装置运行稳定,产水水质优良。     

超超临界锅炉高温管道内壁氧化皮的研究进展

分析了国内外超超临界锅炉高温管内氧化皮的研究现状,对高温受热面管内氧化皮的分析方法进行了归类,指出了目前的研究存在的不足之处。对目前的试验研究给予了建议,为进一步对高温管道的抗氧化性研究提供了发展方向,同时对提高机组的安全稳定运行具有重要的意义。     

均匀设计法优化造纸黑液的湿式氧化法处理工艺

通过均匀设计实验,对造纸黑液进行湿式氧化处理,数据回归得到CODCr、吸光度、浊度的回归方程,各回归方程显著,氧分压对造纸黑液各指标影响最大;研究反应过程中反应温度、氧分压、进水pH值、进水浓度、搅拌强度、反应时间对造纸黑液湿式氧化(WAO)处理的影响,6因素优化的操作条件依次为:180℃、3.0MPa、7.25、5500mg/L、500r/min、60min;在优化的操作条件下,造纸黑液的CODCr、CODCr去除率为1661mg/L、69.8%,吸光度、脱色率为0.63、96.3%,浊度、浊度去除率为661NTU、74.8%.均匀设计法在造纸黑液WAO处理中得到了较好的应用.     

Application of electrochemical reactor divided by cellulosic membrane for optimized simultaneous removal of phenols,chromium, and ammonia from tannery effluents

The post treatment of simulated tannery wastewater was evaluated in an electrochemical oxidation process under galvanostatic conditions. A continuous flow reactor divided by a cellulosic membrane consisted of Ti/SnO₂–Sb anodes and iron cathodes was used. Central composite design and response surface methodology (RSM) were applied to investigate the effects of six operational parameters, namely initial concentration of total phenols (TPh), total chromium (TCr), total ammonia nitrogen (TAN), flow rate (Q), current intensity (I), and electrode surface area (A). Effectiveness of the innovative cellulosic membrane was proven by considerable pH variations in the anolyte and catholyte chambers. A faster removal rate was observed for TPh and TAN, followed by TCr. The treatment level was very sensitive to Q and I in the studied ranges. RSM showed the removal efficiencies of 78.14%, 63.42%, and 86.09% for TPh, TCr, and TAN, respectively, are achieved under optimal conditions with consumption of only 9.03 kWh m^?3 electrical energy. Chlorinated compounds such as chloroform, 2,4-dichlorophenol, and chlorobenzene were detected as the degradation intermediates. According to the obtained results, electrolysis in the divided cell with cellulosic membrane is a practical, cost-effective method for advanced treatment of tannery effluents.     

多基质时厌氧氨氧化菌、异养反硝化污泥活性及抑制特征

以厌氧氨氧化污泥(AAOB)和各种有机物混合,AAOB分别与异养甲醇反硝化菌和城市污水处理厂活性污泥相混合为研究对象,考察了多种基质(醇类、糖类)时自养、异养反硝化菌群的活性及其相应的抑制特征.结果表明,醇类有机物对AAOB的活性有明显抑制作用,甲醇的抑制性最强,当甲醇为5.48mmol/L时,AAOB活性了损失2/3.而乙酸钠对AAOB有一定的促进作用,另外,葡萄糖、乳糖和蔗糖等糖类有机物对AAOB的影响较小.此外,试验发现经驯化的甲醇反硝化菌能利用各种醇类完成异养短程反硝化.对于活性污泥,利用乙酸钠实现短程反硝化的能力优于甲醇、乙醇、葡萄糖和乳糖.混合试验中,正丙醇导致AAOB和甲醇反硝化菌混合菌群中AAOB活性下降,并且在与甲醇反硝化菌的竞争中处于劣势.乙酸钠对于AAOB和活性污泥混合菌群中AAOB的影响较小.     

巯基硅烷改性氧化石墨对砷的吸附性能

为提高氧化石墨(GO)对砷的吸附能力,以3-巯基丙基三甲氧基硅烷为改性剂,制备了巯基改性的氧化石墨(GO-SH),考察其对水中砷的吸附性能.采用单因素实验法考察了初始pH值、吸附剂投加量、温度等对吸附效果的影响,拟合了吸附等温线,并研究了吸附动力学和吸附热力学规律.实验结果表明,在最优条件下,GO-SH对初始浓度为4 mg.L-1的砷去除率达到97.7%;吸附等温线符合Langmuir和Freundlich模型,45℃时由Langmuir模型得到的饱和吸附量(Qm)为24.45 mg.g-1;吸附动力学符合准二级模型,内扩散模型符合高浓度砷的吸附动力学;热力学研究表明,吸附过程是自发吸热的反应,以化学吸附为主.     

不同加热方式下催化氧化甲苯的性能研究

研究考察了微波单模腔、多模腔与传统电炉三种不同加热方式下甲苯的催化氧化性能,分析不同加热方式下进出口气体温度和固定床反应温度的变化,并对实验前后的Cu-Mn-Ce/TiO2-分子筛催化剂进行了扫描电镜、X射线衍射和比表面积等表征测试.研究表明,相同工艺条件下电炉加热、微波多模腔与单模腔加热对甲苯的去除效率分别为77%、83%和94%,对应的床层反应温度为265℃、215℃和145℃,微波加热的选择性、"热点效应"和偶极极化作用提高了甲苯的降解效率并降低其氧化温度和工艺处理能耗,微波单模腔内高的能量密度显著提高了甲苯的氧化效率并降低反应温度.催化剂表征发现,微波加热对催化剂结构与活性组分的分布几乎没有影响,而电炉加热则导致催化剂表面烧结与活性组分团聚,微波加热下催化剂更大的比表面积有利于甲苯的吸附与氧化降解.     

响应面法在催化湿式氧化降解异佛尔酮中的应用

以Ru/TiZrO2为催化剂,采用催化湿式氧化法降解异佛尔酮废水,选择反应温度、氧气分压、反应时间、催化剂用量、初始pH为影响因素,以TOC去除率为响应值,采用响应面法研究影响因素及其交互作用对响应值的影响,建立二次多项式回归方程模型,并采用后退回归法进行模型精简.结果表明,反应时间和反应温度及其交互作用对TOC去除率影响极显著(P≤0.01);反应时间的二次项对TOC去除率影响显著(P≤0.05).随着反应温度的升高和反应时间的延长,TOC去除率逐渐提高.最后对模型进行验证,实验值与预测值具有很好的一致性,说明模型具有可靠的预测性,将该模型应用到催化湿式氧化中合理可行.质谱和离子色谱检测到异佛尔酮的降解产物主要为有机酮与小分子羧酸,由此提出对反应机理和降解途径的假设.