Photocatalytic degradation of disperse blue 1 using UV/TiO2/H2O2 process

The photocatalytic degradation of a dye derivative, C.I. disperse blue 1 (1), has been investigated under UV light irradiation in the presence of TiO2 and H2O2 under a variety of conditions. The degradation was studied by monitoring the change in substrate concentration employing UV spectroscopic technique as a function of irradiation time. The degradation was studied under different conditions such as different types of TiO2, reaction pH, catalyst and substrate concentration containing hydrogen peroxide (H2O2), besides molecular oxygen in the presence of TiO2. The degradation of dye was also investigated under sunlight and the efficiency of degradation was compared with that of the artificial light source. The degradation rates were found to be strongly influenced by all the above parameters. The photocatalyst Degussa P25 was found to be more efficient for the degradation of the dye.     

Effect of steam hydration on performance of lime sorbent for CO2 capture

Lime is considered a feasible sorbent for the capture of CO₂ from large stationary sources. The positive attributes of a natural source material, low cost and lack of harmful by-products are offset by rapid deterioration in performance and high regeneration temperature. Performance can be improved by hydrating the lime using steam. We investigate a steam hydration process wherein lime is hydrated for 5 min at 300 °C and atmospheric pressure in a mixture of steam and CO₂. The experiments consisted of 10 capture cycles with 60% of the lime active at the end. Extrapolation using a decay model suggests a residual carbonation level of 48%, significantly higher than the 8% achieved by dry lime cycles. The cost of replacement sorbent under these conditions is less than $1/t of CO₂ captured. The hydrated lime process also reduces the thermal load, for heating and cooling, by half as well as the inventory, and therefore solids handling, by a factor 5 over dry lime. The introduction of the hydration reaction provides another exothermic reaction for heat management.     

锶盐废渣含硫状态分析及硫含量的测定

锶盐废渣中硫的状态及含量不同其作用大不相同,有的呈现活性导致膨胀破坏,而有的则表现为惰性,因此有必要了解硫的存在状态及含量。分析表明锶盐废渣中硫主要以硫酸盐硫(SO3)和硫化物硫(S2-)两种形式存在。选择硫酸钡重量法和碘量法进行化学测定,然后用X-射线能谱仪进行元素定性分析;并将化学分析和仪器测定两种方法进行对比。结果表明,X-射线能谱法可以快捷、方便地探测锶渣所含各种元素,但不能确定元素的价态;化学分析方法可得到相对准确的元素含量;用硫酸钡重量法和碘量法联合测定锶渣中的硫含量,与X-射线能谱法相比,偏差仅为0.37%。     

Electric Swing Adsorption for CO2 removal from flue gases

One of the most important sources of CO₂ emissions are the fossil-fuel fired plants for production of electricity. Removal of CO₂ from flue gas streams for further sequestration has been proposed by the International Panel on Climate Change experts as one of the most reliable solutions to mitigate anthropogenic greenhouse emissions. When natural gas is employed as fuel, the molar fraction of CO₂ in the flue gas is lower than 5% causing serious problems for capture. The purpose of this work is to present experimental validation of an Electric Swing Adsorption (ESA) technology that may be employed for carbon capture for low molar fractions of CO₂ in the flue gas streams. To improve energy utilization, an activated carbon honeycomb monolith with low electrical resistivity was employed as selective adsorbent. A mathematical model for this honeycomb is proposed as well as different ESA cycles for CO₂ capture.     

改性TiO_2光催化降解三苯甲烷类污染物

以硫酸钛为原料采用水热法制备了掺Fe3＋TiO2晶体粉末,采用X射线衍射仪（XRD）对样品的结构进行了表征。在可见光条件下,用溴酚蓝、甲基绿、甲基蓝、孔雀石绿、甲基紫和碱性品红等6种典型三苯甲烷类化合物为目标降解物,研究了以自制的掺Fe3＋TiO2晶体粉末对它们的催化降解作用。实验结果表明,制备的掺Fe3＋TiO2晶体属于锐钛矿型。6种化合物的光催化降解反应遵循拟一级动力学规律,且可用Langmuir-Hinshelwood（L-H）动力学模型描述,其表观反应速度常数（k）的大小顺序为：溴酚蓝〈甲基绿〈甲基蓝〈孔雀石绿〈甲基紫〈碱性品红,大小变化次序与其半衰期t1/2成反比,并从分子结构上对它们的降解规律进行定性解释。     

An assessment of indoor air quality in recent Mexican immigrant housing in Commerce City, Colorado

An indoor air quality assessment was conducted on 100 homes of recent Mexican immigrants in Commerce City, Colorado, an urban industrial community north of Denver. Head of households were administered a family health survey, filled out an activity diary, and participated in a home inspection. Carbon monoxide (CO) and carbon dioxide (CO₂) were measured for 24 h inside the main living area and outside of the homes. Harvard Impactors were used to collect 24-h samples of PM_2.5 at the same locations for gravimetric analysis. Dust samples were collected by vacuuming carpeting and flooring at four locations within the home and analyzed by ELISA for seven allergens. Mean indoor and outdoor PM_2.5 levels were 27.2 and 8.5 μg m⁻³, respectively. Indoor PM_2.5 and CO₂ were elevated in homes for which the number of hours with door/window open was zero compared to homes in which the number of hours was high (>15 h). Indoor PM_2.5 levels did not correlate with outdoor levels and tended to increase with number of inhabitants, and results indicate that the source of indoor particles were occupants and their activities, excluding smoking and cooking. Mean indoor CO₂ and CO levels were 1170 and 2.4 ppm, respectively. Carbon monoxide was higher than the 24-h National Ambient Air Quality Standard in 3 of the homes. The predominant allergens were cat (Fel d 1) and mouse (Mus m 1) allergens, found in 20 and 34 homes, respectively.     

Quantifying local traffic contributions to NO2 and NH3 concentrations in natural habitats

NO₂ and NH₃ concentrations were measured across a Special Area for Conservation in southern England, at varying distances from the local road network. Exceedances of the critical levels for these pollutants were recorded at nearly all roadside locations, extending up to 20 m away from roads at some sites. Further, paired measurements of NH₃ and NO₂ concentrations revealed differences between ground and tree canopy levels. At “background” sites, away from the direct influence of roads, concentrations were higher within tree canopies than at ground level; the reverse pattern was, however, seen at roadside locations. Calculations of pollutant deposition rates showed that nitrogen inputs are dominated by NH₃ at roadside sites. This study demonstrates that local traffic emissions contribute substantially to the exceedance of critical levels and critical loads, and suggests that on-site monitoring is needed for sites of nature conservation value which are in close proximity to local transport routes.     

气体ClO2对室内空气的消毒研究

气体ClO2与其他常用过氧化物消毒剂和含氯消毒剂在空间消毒方面比较有诸多优势.气体ClO2对各种微生物具有很好的杀菌消毒作用,而且不会产生有毒、有害的氯化物,较之液态ClO2具有更好的扩散性、穿透性和使用均匀性,特别适用于对大面积环境微生物的杀菌消毒.     

催化裂化装置硫化氢腐蚀问题及防治对策

阐述了H2S对设备的腐蚀机理,具体分析了催化裂化装置MIP-CGP技术改造后硫分布的新情况,从选材、工艺防腐、表面防腐、焊接质量控制和检测技术等方面提出了防硫化氢腐蚀的对策措施.     

巯基改性高岭土负载CeO2-CdS光催化降解结晶紫

为获得高效催化活性的光催化材料,实现偶氮类染料的高效降解,试验以巯基乙酸钠作为硫源和高岭土改性剂合成了巯基高岭土/CeO₂-CdS催化剂,并以降解结晶紫为模板反应,优化确定了巯基高岭土/CeO₂-CdS催化剂的制备条件.采用XRD（X射线衍射）、SEM（扫描电子显微镜）、TEM（透射电子显微镜）、FTIR（傅里叶红外光谱）和UV-Vis（紫外-可见光漫反射光谱）对催化剂进行了表征.结果表明:①催化剂是由巯基高岭土、立方相结构的CdS和萤石结构的CeO₂组成;②CdS和CeO₂的负载破坏了巯基高岭土的层状结构;③最优催化剂和巯基高岭土/CeO₂的可见光的响应范围分别为550和450 nm;④当CeO₂:CdS（摩尔比,下同）为4:6,巯基高岭土:CeO₂-CdS（质量比,下同）为1:3时,催化剂具有最优的光催化活性;⑤在50 mL结晶紫浓度为10 mg/L的溶液中,添加0.1 g最优催化剂后,采用350 W氙灯对其光照150 min时,结晶紫的降解率为95.1%;⑥最优催化剂具有良好的重复使用性能,重复使用5次时,对结晶紫的降解率为90.4%.研究显示,结晶紫降解的最终产物为CO₂和H₂O,催化剂对结晶紫的降解机理是以羟基自由基氧化为主和超氧基氧化为辅的共存氧化机理.