Effects of metal and acidic sites on the reaction by-products of butyl acetate oxidation over palladium-based catalysts

Catalytic oxidation is widely used in pollution control technology to remove volatile organic compounds. In this study, Pd/ZSM-5 catalysts with different Pd contents and acidic sites were prepared via the impregnation method. All the catalysts were characterized by means of N2 adsorption- desorption, X-ray fluorescence （XRF）, HE temperature programmed reduction （H2-TPR）, and NH3 temperature programmed desorption （NH3-TPD）. Their catalytic performance was investigated in the oxidation of butyl acetate experiments. The by-products of the reaction were collected in thermal desorption tubes and identified by gas chromatography/mass spectrometry. It was found that the increase of Pd content slightly changed the catalytic activity of butyl acetate oxidation according to the yield of CO2 achieved at 90%, but decreased the cracking by-products, whereas the enhancement of strong acidity over Pd-based catalysts enriched the by-product species. The butyl acetate oxidation process involves a series of reaction steps including protolysis, dehydrogenation, dehydration, cracking, and isomerization. Generally, butyl acetate was cracked to acetic acid and 2- methylpropene and the latter was an intermediate of the other by-products, and the oxidation routes of typical by-products were proposed. Trace amounts of 3-methylpentane, hexane, 2-methylpentane, pentane, and 2-methylbutane originated from iso4merization and protolysis reactions.     

Formation pathways of brominated products from benzophenone-4 chlorination in the presence of bromide ions

The brominated products, formed in chlorination treatment of benzophenone-4 in the presence of bromide ions, were identified, and the formation pathways were proposed.Under disinfection conditions, benzophenone-4 would undertake electrophilic substitution generating mono- or di-halogenated products, which would be oxidized to esters and further hydrolyzed to phenol derivatives. The generated catechol intermediate would be transformed into furan-like heterocyclic product. The product species were p H-dependent,while benzophenone-4 elimination was chlorine dose-dependent. When the chlorination treatment was performed on ambient water spiked with benzophenone-4 and bromide ions, most of brominated byproducts could be detected, and the acute toxicity significantly increased as well.     

Genotoxicity removal of reclaimed water during ozonation

Genotoxicity in wastewater and reclaimed water now is gaining increased attention because of genotoxins' potential damage to the ecosystem and human health. The effect of ozonation on genotoxicity in reclaimed water was investigated. It was found that ozonation decreased the genotoxicy dramatically in three tertiary treatment plants. In the further batch ozonation experiment in laboratory,secondary effluent sample used exhibited the genotoxicity of(41.1 ± 4.1) μg 4NQO/L. Ozonation with a dose of 10 mg O3/L completely removed the genotoxicity in secondary effluent. However,after ozonation, the dissolved organic carbonvalue of the sample didn't change much but the specific ultraviolet absorbance(SUVA) value dropped sharply. With the help of Fourier transform infrared spectroscopy, ozonation was found to change chemical aliphatic carbon and C–O of the dissolved arganic matter, which might be the reason of the significant decreases of SUVA and genotoxicity.     

Waste to energy—日本城市垃圾的能源化利用

<正>日本是垃圾能源化利用最发达的国家之一,垃圾分类很严格,原生垃圾是不能直接处理的。城市生活垃圾分类后,可燃组分由垃圾转运车收集送入垃圾焚烧厂,再经过机械筛选和人工分选,在焚烧炉内焚烧,产生的热能发电供给城市电网,部分余热用于一个城市公共游泳池;对于可生物降解的有机垃圾,如厨余垃圾等,进行甲烷发酵,发酵产生的沼气可以制备家用和车用燃气,也可用于发电。焚烧处理厂同时也是资源回收中心,家庭的大件垃圾如家具等,必须送回该厂处理,并交处理费。一些损     

催化臭氧氧化降解水溶液中亚甲基蓝的动力学研究

以废啤酒酵母为原材料、采用吸附-活化法制备得到负载过渡金属铁的活性炭(Fe/AC),对Fe/AC吸附亚甲基蓝(MB)性能和催化臭氧氧化MB效果进行了评价。Fe/AC对MB的吸附符合Langmuir等温吸附模型;20℃,pH=7的条件下,Fe/AC对MB的最大吸附量达到107.43 mg/g。吸附MB达到平衡的Fe/AC催化臭氧氧化降解水中MB,30 min内MB的转化率达到99%以上,5 h后总有机碳(TOC)的降解率达到70%。结合Fe/AC吸附MB特性和催化臭氧氧化MB行为,将Langmuir等温吸附模型分别与近似一级和二级反应动力学模型进行耦合,构建了Langmuir-Kinetic近似一级和近似二级耦合模型,均能较好地拟合MB转化率的动力学数据,但对体系的TOC去除率动力学数据的拟合度较低。     

污泥浓度对生物海绵铁体系中Fe~0的腐蚀影响研究

通过单因素实验,研究了不同活性污泥浓度对海绵铁体系中铁离子浓度变化的影响。结果表明:随着反应的进行,反应器泥水混合液中Fe(Ⅱ)和TFe浓度在不断升高,与活性污泥浓度成正相关性;pH值也呈现升高趋势,活性污泥浓度越高,pH值变化的越小;试验还发现海绵铁释铁过程包括生物腐蚀和化学腐蚀,生物腐蚀的影响要远远大于化学腐蚀。     

胡敏酸改性膨润土钝化污染土壤Pb&Cd及机理

通过盆栽试验,探讨了胡敏酸改性膨润土对重金属铅、镉污染土壤的钝化效果及机理。结果表明,铅、镉污染土壤中施加胡敏酸改性膨润土能显著降低小白菜中Pb、Cd的含量,在添加Cd(3 mg/kg)/Pb(250 mg/kg)污染土壤和Cd(1 0 mg/kg)/Pb(5 00 mg/kg)污染土壤上小白菜地上部分Pb含量分别比对照降低19.08%和47.91%,Cd含量分别比对照降低9.79%和14.89%。土壤本身对添加的重金属Pb/Cd有一定的耐受力和自我净化能力,在添加重金属后,添加的Pb/Cd元素大部分直接转化为较为稳定的碳酸盐结合态和铁锰氧化结合态。相关性分析显示小白菜的鲜重与小白菜Pb/Cd含量极显著负相关,进一步说明胡敏酸改性膨润土是通过提高小白菜的生物量,从而降低Pb/Cd在小白菜中的含量。     

河南省秸秆能源化利用研究

在日益严峻的能源短缺和环境污染的双重压力下,进行秸秆能源化的开发和利用对于河南新型城镇化建设具有重大战略意义。河南秸秆资源丰富,但秸秆能源化利用尚处于初级阶段,利用率非常低,只有健全秸秆收储体系,改进各种秸秆能源化利用方式的技术性能,加强应用和推广,提升秸秆能源化利用的经济效益,加大对秸秆能源化利用相关主体的引导和扶持,提供政策和资金支持,才能为河南秸秆能源化发展提供良好的环境。     

德国工厂实践“互联网化”第四次工业革命开端

如果有人说“工厂会解决当前全球面临的问题”,您可能会觉得这是在说大话。但现在真有一个国家正在努力实现这一宏伟概念,这个国家就是德国。 现在,德国政府提出了高技术战略“工业4．0”,并开始推进这个产官学一体项目。如果用一个词来概括这个概念,那就是“互联工厂”。     

浅析湖泊环境中凤尾莲的化感作用

综述了凤尾莲抑藻化感作用及其对其他植物的影响,凤尾莲化感物质及其作用机理,其他植物对凤尾莲的化感作用。认为在下一步的工作中,应着重对凤尾莲化感作用涉及到的生理、生化和生态机制开展研究。