金属氧化物降解六氯苯的活性比较及催化机理研究

以氧化铝(α-Al_2O_3、γ-Al_2O_3)、氧化钙(CaO)、过渡金属氧化物(Mn O_2、α-Fe_2O_3、γ-Fe_2O_3、Ni_2O_3、CuO)为催化剂,考察了催化剂种类、添加比例等因素对六氯苯(Hexachlorobenzene,HCB)降解效果和产物组分的影响.结果表明,催化效果随催化剂添加比例的提高显著增加.在反应温度为350℃,反应时间1 h,金属氧化物添加比例为100∶1的条件下,碱土金属氧化物CaO及过渡金属氧化物中的α-Fe_2O_3和Ni_2O_3降解活性较好,这3种氧化物对HCB的降解率分别达到65.5%、100.0%和100.0%,脱氯率D_1分别为54.4%、81.9%和77.5%.HCB降解有机产物分析结果显示,8种金属氧化物与HCB样品反应产物中均存在低氯代苯,在α-Fe_2O_3和Ni_2O_3的催化作用下有2~4氯代低氯苯检出,说明在降解过程中存在明显的逐级脱氯/加氢反应;与CaO反应后的产物中低氯代苯较少,经拉曼光谱定性分析,有无序碳的检出,说明除了脱氯/加氢还存在脱氯缩合反应.     

大渡河干海子滑坡稳定性研究

干海子滑坡位于大渡河流域,规模巨大.为研究该滑坡的稳定性,在对滑坡基本特征及变形破坏特征等深入研究的基础上,采用极限平衡法(Geo-slope软件)和有限差分法(FLAC-3D软件)对该滑坡的稳定性和应力应变特征进行了计算、模拟.稳定性计算模拟主要从深层、浅层及局部稳定三方面入手分析,计算模拟结果与滑坡的宏现地质现象均...     

用参评因子动态排序法评价环境综合质量

评价环境综合质量常用的方法是计算加权平均的综合指数,其中权重的确定又多用层次分析法（AHP）。设计以实际监测数据为依据计算两个参数yi1和yi2,并据此对各因子进行分类并排序,由此可定性确定各因子对环境总体污染的相对重要性,并判识环境污染中的关键因子、预警因子、趋好转的因子及可不必特别关注的因子;为定量确定各因子在综合评价中的权重,再依排序位次对其赋值,然后利用所赋之值进行因子间的两两比较以克服AHP法一般应用中因各人掌握标准有异而造成比较结果的不确定性,使权重确定完全建立在监测数据的客观基础上。此外,因环境污染状况随时空改变,若需对不同时段或不同区域的环境综合质量进行评价,给各因子赋予不变的权重显然不妥,而用上述思路和方法可依据实测值的差别对不同时段或不同区域的环境评价因子进行有根据的差异排序,然后再用AHP法定权,这就使不同时空环境质量的比较更为客观合理。     

游乐设施危险源、损伤、失效和故障概念辨析

针对游乐设施行业危险源、损伤、失效和故障四个概念的认知差异,通过研究相关领域这四个概念定义内涵及外延,结合游乐设施安全保障要求高、人-机-环交互频繁、运行工况复杂的特点,重新定义游乐设施这四个概念,辨析相互之间的逻辑关系,并结合游乐设施事故案例进行解析.结果表明:新定义对游乐设施危险源、失效、损伤和故障之间的关系阐述更加清晰准确,为后续的风险评价奠定良好基础.     

浅谈特种飞机任务电子系统大修

随着任务电子系统在飞机领域的广泛应用,出现了一些以任务电子系统功性能为主要作战指标的特种飞机,如预警机、电子干扰机、侦察机、指挥通信机等,其载机大修在国内已经有一套成熟的标准和体系,但是任务电子系统的大修还是空白篇幅,没有相关的指导依据,本文为特种飞机任务电子系统大修的必要性、修理周期、目的、方法提供指导性建议。     

挥发性有机废气治理技术的现状与进展

本文通过查阅文献资料,总结了当前企业挥发性有机废气产生情况、政策管理办法以及相关处理技术,并分析了未来挥发性有机废气治理政策发展趋势,旨在提高挥发性有机废气治理效率,提高空气环境质量。     

不同光波长对类石墨相氮化碳催化降解莫西沙星的机理探究

使用一种简单煅烧三聚氰胺的方法制备了类石墨相氮化碳(g-C_3N_4),研究了不同光波长对g-C_3N_4催化降解盐酸莫西沙星的影响.通过高分辨透射电子显微镜(TEM)、X射线衍射(XRD)和X射线光电子能谱仪(XPS)对材料的形貌、晶型、元素组成进行表征,证实了g-C_3N_4的成功合成.此外,通过XPS-价带谱和紫外可见漫反射(UV-DRS)图谱得到所合成g-C_3N_4的带隙(E_g=2.81 eV)和价带(E_(VB)=2.49 eV).通过不同光波长(包括365、385、420、450、485、520、595、630 nm及可见光)下g-C_3N_4对莫西沙星的降解速率来评估光催化性能.结果表明,g-C_3N_4的光催化活性依赖于辐照波长,也即速率常数(k_1)随光波长的增大而降低.活性氧(ROS)淬灭实验表明,超氧自由基(·O~-_2)在莫西沙星的光催化降解中起主导作用.     

Biological conversion pathways of sulfate reduction ammonium oxidation in anammox consortia

• The SRAO phenomena tended to occur only under certain conditions. • High amount of biomass and non-anaerobic condition is requirement for SRAO. • Anammox bacteria cannot oxidize ammonium with sulfate as electron acceptor. • AOB and AnAOB are mainly responsible for ammonium conversion. • Heterotrophic sulfate reduction mainly contributed to sulfate conversion. For over two decades, sulfate reduction with ammonium oxidation (SRAO) had been reported from laboratory experiments. SRAO was considered an autotrophic process mediated by anammox bacteria, in which ammonium as electron donor was oxidized by the electron acceptor sulfate. This process had been attributed to observed transformations of nitrogenous and sulfurous compounds in natural environments. Results obtained differed largely for the conversion mole ratios (ammonium/sulfate), and even the intermediate and final products of sulfate reduction. Thus, the hypothesis of biological conversion pathways of ammonium and sulfate in anammox consortia is implausible. In this study, continuous reactor experiments (with working volume of 3.8L) and batch tests were conducted under normal anaerobic (0.2≤DO<0.5 mg/L) / strict anaerobic (DO<0.2 mg/L) conditions with different biomass proportions to verify the SRAO phenomena and identify possible pathways behind substrate conversion. Key findings were that SRAO occurred only in cases of high amounts of inoculant biomass under normal anaerobic condition, while absent under strict anaerobic conditions for same anammox consortia. Mass balance and stoichiometry were checked based on experimental results and the thermodynamics proposed by previous studies were critically discussed. Thus anammox bacteria do not possess the ability to oxidize ammonium with sulfate as electron acceptor and the assumed SRAO could, in fact, be a combination of aerobic ammonium oxidation, anammox and heterotrophic sulfate reduction processes.