Aerosol effects on ozone concentrations in Beijing: A model sensitivity study

Most previous O₃ simulations were based only on gaseous phase photochemistry. However, some aerosol-related processes, namely, heterogeneous reactions occurring on the aerosol surface and photolysis rate alternated by aerosol radiative influence, may affect O₃ photochemistry under high aerosol loads. A three-dimensional air quality model, Models-3/Community Multi-scale Air Quality-Model of Aerosol Dynamics, Reaction, Ionization, and Dissolution, was employed to simulate the effects of the above-mentioned processes on O₃ formation under typical high O₃ episodes in Beijing during summer. Five heterogeneous reactions, i.e., NO₂, NO₃, N₂O₅, HO₂, and O₃, were individually investigated to elucidate their effects on O₃ formation. The results showed that the heterogeneous reactions significantly affected O₃ formation in the urban plume. NO₂ heterogeneous reaction increased O₃ to 90 ppb, while HO₂ heterogeneous reaction decreased O₃ to 33 ppb. In addition, O₃ heterogeneous loss decreased O₃ to 31 ppb. The effects of NO₂, NO₃, and N₂O₅ heterogeneous reactions showed opposite O₃ concentration changes between the urban and extra-urban areas because of the response of the reactions to the two types of O₃ formation regimes. When the aerosol radiative influence was included, the photolysis rate decreased and O₃ decreased significantly to 73 ppb O₃. The two aerosol-related processes should be considered in the study of O₃ formation because high aerosol concentration is a ubiquitous phenomenon that affects the urban- and regional air quality in China.     

饮用水原水中微量阿特拉津去除方法试验研究

饮用水中微量有机物的污染是关系饮用水生态安全的重要问题。以饮用水中微量的内分泌干扰类除草剂阿特拉津为研究对象,分别采用微生物降解技术和光催化氧化技术对其进行降解,考察温度对阿特拉津降解效果的影响。研究结果表明：阿特拉津浓度为1 mg/L时,3种温度条件下,除锰功能菌MB4对阿特拉津均有明显的去除效果,降解时间为7 d时,阿特拉津的去除率达到65%。底物浓度为200 μg/L,3种温度条件下,活性炭负载二氧化钛（TiO₂/PAC）催化剂光降解阿特拉津30 min时,其去除率均达到90%。光催化氧化技术协同微生物降解技术在饮用水中微量的内分泌干扰物的去除中有广阔的应用前景。     

负载型混晶相TiO2光催化剂的低温制备及其光催化活性

以蒙皂石为载体,钛酸四丁酯为前驱物,在较低温度下由溶胶凝胶法制备得到负载型TiO₂光催化剂。研究了理论负载量、固定化温度、干燥、焙烧温度对TiO₂/蒙皂石复合光催化剂光催化性能的影响。采用XRD分析技术对复合材料进行了表征。结果表明,负载的TiO₂以锐钛矿-金红石的混晶相存在。当TiO₂理论负载量为15 mmol/g、溶胶反应温度为25℃、干燥温度为70℃时,TiO₂/蒙皂石复合光催化剂对偶氮染料光催化反应1 h降解率达93.40%。该制备技术的特点是在省去高温焙烧的条件下,制备出光催化活性高的负载型光催化剂。     

复合顺序对三维花状TiO_2-FeOOH复合材料吸附及光催化性能的影响

以TiCl_4为钛源、Fe(NO_3)3·9H_2O为铁源,采用分子自组装法在活性炭表面制备了不同复合顺序的TiO_2-FeOOH复合材料,研究了其对甲基橙的吸附和光催化性能。实验结果表明,TiO_2-FeOOH复合材料由锐钛矿TiO_2和α-针铁矿复合层组成,并呈直径为200~300 nm的三维花状多级结构,这种独特的多级结构有利于实现吸附与光催化的协同作用。UV-Vis吸收光谱显示TiO_2与FeOOH的复合减小了TiO_2的禁带宽度,但TiO_2/FeOOH/AC、TiO_2/FeOOH/AC和TiO_2/AC对质量浓度为10 mg/L的甲基橙溶液处理6 h后,溶液脱色率分别为78.8%,33.9%,57.5%,表明复合顺序对TiO_2-FeOOH复合材料的界面电子传递过程及光催化性能有重大影响。     

氧化铜晶体的制备及其光催化性能的表征

以硫酸铜为铜源,氢氧化钠为沉淀剂,乙醇-水溶液为分散体系,通过一步沉淀制备得到氧化铜晶体。并以紫外光照时间、pH值、亚甲基蓝浓度为基础,研究了氧化铜光催化剂对亚甲基蓝的催化活性。结果表明,紫外光照120min,pH值为9时亚甲基蓝降解率最高。     

Production of bio-oil from algal biomass and its upgradation to biodiesel using CaO-based heterogeneous catalysts

The present article deals with the production of bio-oil from algal biomass as well as the preparation and characterization of noble CaO-based heterogeneous catalyst for upgradation of bio-oil to biodiesel. The bio-oil has been extracted from algal biomass using hexane as solvent in soxhlet apparatus and upgraded to biodiesel by transesterification using noble CaO-based heterogeneous catalysts. Catalyst with TiO₂:CaO molar ratio of 0.25 and calcination temperature of 700°C has been found to be most suitable among all the catalysts developed. Characterization of the catalysts has been done by using X-ray diffraction (XRD), scanning electron microscope (SEM), and thermo-gravimetric analysis (TGA). The input--output model has been developed to correlate experimental and predicted value of biodiesel yield. Optimization of process parameters has been done using response surface methodology. Various properties and elemental composition of algal bio-oil and biodiesel have been determined and compared with biodiesel.     

LiFePO4非均相Fenton法处理亚甲基蓝染料的研究

采用水热法制备出LiFePO4催化剂,通过电子显微镜(SEM)、X射线衍射(XRD)和傅立叶红外光谱(FTIR)对其进行表征,并将其作为非均相Fenton催化剂处理亚甲基蓝(MB)染料溶液。实验结果表明,在催化剂用量为4 g/L,H2O2浓度为0.04 mol/L,pH值为3,温度为50℃,反应时间为60 min的条件下,浓度为500 mg/L的亚甲基蓝脱色率达99%。根据实验结果,讨论了LiFePO4作为非均相Fenton催化剂对亚甲基蓝的降解机理。     

Ba/TiO_2/MCM-41光催化降解对硝基苯甲酸

以钛酸丁酯为钛源、MCM-41分子筛为载体,采用溶胶-凝胶法制备了掺杂与负载相结合的光催化剂Ba/TiO2/MCM-41。结果表明：Ba/TiO2/MCM-41是一种比表面积高达341.2 m2/g的介孔材料,主要晶相为锐钛矿相,比P25有更强的紫外光吸收。将Ba/TiO2/MCM-41用于光催化氧化水中的对硝基苯甲酸,当催化剂投加量为0.5 g/L,对硝基苯甲酸初始pH为4、浓度为2×10-4mol/L时,紫外光照30 min后,对硝基苯甲酸降解率达到96.0%。用紫外光谱、红外光谱和高效液相色谱分析对硝基苯甲酸降解前后的变化,发现随着光照时间延长,苯环上的硝基、羧基吸收峰逐渐减弱;对硝基苯甲酸首先被降解为一些中间小分子产物,随着反应进行,小分子物质也逐渐被降解。     

TiO2光催化处理络合铜废水的实验研究

研究了以悬浮态TiO2为催化剂,在紫外光的作用下对络合铜废水进行光催化反应,分别考察了常温下TiO2投加量、反应时间、废水初始pH值、反应气氛等因素对处理效果的影响,并探讨了反应机理。结果表明：TiO2投加量为2 g/L,废水pH=4,300 W高压汞灯照射下,载入60 mL/min的空气反应40 min,120 mg/L EDTA络合铜废水的Cu（II）与COD的去除率达到最高,分别为96.56%和57.67%。     

Fe/Ce/沸石负载型类芬顿催化剂制备及其特性

采用柠檬酸盐溶胶-凝胶法制备了Fe/Ce/沸石负载型芬顿催化剂,通过透射电镜(TEM)和X射线衍射(XRD)对其进行表征,并将其作为非均相类芬顿催化剂处理孔雀石绿染料溶液。研究表明,通过掺杂Ce,可提高催化剂颗粒分散度和催化剂表面的氧气含量,进而提高催化活性。在催化剂投加量3.0 g/L,H2O2投加量67 mg/L,pH=8.0的条件下,反应30 min后,浓度为150 mg/L的孔雀石绿溶液脱色率可达97.3%。