铈插层黏土负载铁催化剂在H2S选择性催化氧化过程中催化性能的研究

合成了铈插层的Laponite黏土材料(Ce-Lap),并以此材料为载体,分别负载质量分数为3%、5%、8%、10%的Fe制备Fe/Ce-Lap催化剂,通过XRD、氮气吸脱附曲线、XRF、TG、FT-IR、O2-TPD、H2-TPR、XPS等手段,对催化剂的物理化学性质进行了表征测试,并考察了催化剂在H2S选择性催化氧化反应过程中的活性.结果表明,5%的Fe/Ce-Lap在180℃时表现出最好的催化活性,能达到96%的硫产率,这归因于Fe与Ce之间的相互作用,改善了Fe3+的氧化还原能力.此外,较高的氧吸附能力及铁物种的高分散度促进了氧化反应的进行.     

电活性生物膜介导Cu2+生物还原的试验研究

电活性生物膜形成、胞外电子传递机制以及环境效应研究已成为环境领域关注的热点.通过在碳毡上富集形成生物膜,采用电化学方法对生物膜的电活性进行了表征,对电活性生物膜直接介导Cu2+的还原转化进行了初探.利用扫描电子显微镜(SEM)、能谱分析仪(EDS)、X射线光电子能谱(XPS)对Cu元素的形貌、含量以及价态进行分析,结果表明电活性生物膜能够利用乙酸作为电子供体,Cu2+作为电子受体,将Cu2+还原转化成Cu或Cu+.同时,通过激光共聚焦显微镜(LSCM)观察Cu2+对微生物的影响,结果显示Cu2+对微生物有明显的毒害作用,所以电活性生物膜介导Cu2+的转化只能在较低的铜离子浓度下进行.本研究结果将为电活性生物膜应用于环境中铜离子的固定和回收提供理论依据.     

黑木耳菌糠对Cu2+的生物吸附及其机理

针对现代工业废水中铜离子的污染及黑木耳产业链中菌糠废弃物资源化等问题,以黑木耳菌糠为吸附剂去除废水中的Cu2+.通过单因素试验确定响应面的高水平条件,并用响应面方法对其优化,确定最佳吸附条件;采用SEM-EDX、FTIR和XRD等手段对吸附前后的菌糠进行表征,初步探索了菌糠吸附的机理.结果显示:最佳单因素条件为菌糠投加量30.0 g·L-1、pH 7.0、Cu2+初始浓度75 mg·L-1、吸附时间120 min、温度25℃、转速150 r·min-1,吸附率为77.96%.响应面分析显示投加量、吸附时间和pH为显著因素.优化后投加量为31.6 g·L-1,吸附时间134 min,pH 7.0,吸附率可达80.51%,吸附符合Langmuir等温方程.菌糠表面疏松多孔,极易通过物理吸附方式吸附Cu2+,菌糠表面的氨基、羟基、酮基和羧基可以有效配位络合Cu2+.研究结果表明,黑木耳菌糠作为一种高效廉价环保的吸附剂,可用于Cu2+废水的处理.     

污泥预植重金属Cu炭化及炭中重金属的稳定性研究

提出一种污泥预植重金属炭化后固定的概念,并以重金属Cu为代表,以CuCl2的形式植入;研究了在不同Cu预植浓度、不同温度下炭化后污泥本身以及额外添加的重金属在炭中的保留率以及稳定特性,同时采用不同的浸出方法,确定与污泥炭最终处置目标相关的最大可预植量.结果表明,在污泥中Cu的预植量为0.5%(质量分数,以Cu元素计)时,经过热解炭化,90%以上的Cu都保留在污泥炭中,其固定效果与温度有关,400℃以上时,炭化温度越高,Cu越容易浸出.在污泥中预植重金属Cu存在最大容量限制,最大可预植量与污泥炭最终处置目标有关,若选择在卫生填埋场进行填埋,则Cu的预植量不宜超过0.5%.本研究提供了一种污泥包裹其他含重金属的废料共炭化实现无害化的新思路,从而达到用污泥治废的效果.     

埃及西奈地区地下水污染的水化学模拟及评估

正研究致力于调查地下水的地球化学特性,以对埃及西奈西北的地下水污染影响作出评估,使用了地理信息系统GIS、地球化学模型、以及统计学分析工具.在第四系含水层取了25个地下水样品加以分析,测出其中的主要、次要及痕量元素.研究结果可使人们对水化学特性及地下水的人为污染有更充分的了解和认识.基于这些分析,地球化学参数及不同元素的异常浓度使得尝试确定苦水中盐的来源及被污染水体的污染源成为可能.污染源主要包括废弃     

Catalytic combustion of soot over ceria-zinc mixed oxides catalysts supported onto cordierite

Modified substrates as outer heterogeneous catalysts was employed to reduce the soot generated from incomplete combustion of diesel or diesel/biodiesel blends, a process that harms the environment and public health. The unique storage properties of ceria(CeO2) makes it one of the most efficient catalysts available to date. Here, we proposed that ceria-based catalysts can lower the temperature at which soot combustion occurs; more specifically, from 610℃ to values included in the diesel exhausts operation range(300–450℃). The sol-gel method was used to synthesize mixed oxide-based catalysts(CeO2:ZnO); the resulting catalysts were deposited onto cordierite substrates. In addition, the morphological and structural properties of the material were evaluated by XRD, BET, TPR-H2, and SEM. Thermogravimetric(TG/DTA) analysis revealed that the presence of the catalyst decreased the soot combustion temperature by 200℃ on average, indicating that the oxygen species arise at low temperatures in this situation, promoting highly reactive oxidation reactions. Comparative analysis of soot emission by diffuse reflectance spectroscopy(DRS) showed that catalyst-impregnated cordierite samples efficiently oxidized soot in a diesel/biodiesel stationary motor: soot emission decreased by more than 70%.     

钛板SCR脱硝催化剂的制备及性能研究

选用钛板作为催化剂的骨架,预先在钛板表面制备二氧化钛涂层,再浸渍活性组分以制备催化剂。用SEM结合能谱分析的方式表征催化剂表面性能,通过固定床实验来测试不同NO负荷、不同温度、不同O2含量、二氧化硫、水蒸气等烟气条件对脱硝效率的影响,并对该催化剂的抗冷热性能和稳定性进行了测试。     

Heterogeneous Fenton-like degradation of 4-chlorophenol using iron/ordered mesoporous carbon catalyst

Ordered mesoporous carbon supported iron catalysts(Fe/OMC) were prepared by the incipient wetness impregnation method and investigated in Fenton-like degradation of 4-chlorophenol(4CP) in this work. XRD and TEM characterization showed that the iron oxides were well dispersed on the OMC support and grew bigger with the increasing calcination temperature. The catalyst prepared with a lower calcination temperature showed higher decomposition efficiency towards 4CP and H2O2, but more metals were leached. The effect of different operational parameters such as initial pH, H2O2 dosage, and reaction temperature on the catalytic activity was evaluated. The results showed that 96.1% of 4CP and 47.4% of TOC was removed after 270 min at 30°C, initial pH of 3 and 6.6 mmol/L H2O2. 88% of 4CP removal efficiency was retained after three successive runs, indicating Fe/OMC a stable catalyst for Fenton reaction. 4CP was degraded predominately by the attack of hydroxyl radical formed on the catalyst surface and in the bulk solution due to iron leaching. Based on the degradation intermediates detected by high performance liquid chromatography, possible oxidation pathways were proposed during the 4CP degradation.     

Photocatalytic removal of NO and NO2 using titania nanotubes synthesized by hydrothermal method

In this study, the photocatalysts of titania nanotubes(TNTs) were synthesized at different calcination temperatures using commercial Degussa TiO2(P25) as a precursor. The materials were then characterized by BET, SEM, TEM, and XRD analyses. The photocatalytic reactions with NO and NO2 under UV-A irradiation were both performed. The results showed that the photocatalytic reaction rate of NO was much faster than that of NO2, and the conversion of NO2 to nitrate was the rate-limiting step for photocatalytic removal of NOx if the nitrate produced cannot be removed continuously from the photocatalyst surface. For TNTs calcined at different temperatures, a significant enhancement was observed on the total NOx removal efficiency by TNT calcined at 500°C for both NO and NO2 photocatalytic reaction, which could be attributed to its high anatase crystallinity as well as high surface area. These two factors affect primarily on the NO2conversion step in which the high anatase crystallinity could be responsible for the high efficiency at the beginning, while the high surface area could be accounted for retaining this high efficiency from nitric acid poisoning during the test period.     

Combination of heterogeneous Fenton-like reaction and photocatalysis using Co-TiO2 nanocatalyst for activation of KHSO5 with visible light irradiation at ambient conditions

A novel coupled system using Co–Ti O2 was successfully designed which combined two different heterogeneous advanced oxidation processes, sulfate radical based Fenton-like reaction（SR-Fenton） and visible light photocatalysis（Vis-Photo）, for degradation of organic contaminants. The synergistic effect of SR-Fenton and Vis-Photo was observed through comparative tests of 50 mg/L Rhodamine B（Rh B） degradation and TOC removal. The Rhodamine B degradation rate and TOC removal were 100% and 68.1% using the SR-Fenton/Vis-Photo combined process under ambient conditions, respectively. Moreover, based on XRD, XPS and UV-DRS characterization, it can be deduced that tricobalt tetroxide located on the surface of the catalyst is the SR-Fenton active site, and cobalt ion implanted in the Ti O2 lattice is the reason for the visible light photocatalytic activity of Co–Ti O2. Finally, the effects of the calcination temperature and cobalt concentration on the synergistic performance were also investigated and a possible mechanism for the synergistic system was proposed. This coupled system exhibited excellent catalytic stability and reusability,and almost no dissolution of Co2＋was found.