TiO2纳米粒子气固相光催化降解乙烯初探

该文对TiO₂纳米粒子气固光催化降解果蔬贮藏环境乙烯技术进行了初步研究。采用溶胶-凝胶法制备的纳米TiO₂薄膜作光催化剂，利用自行设计的气固光催化实验系统，研究了乙烯浓度、紫外光作用时间对光催化降解反应的影响，探讨了乙烯的光催化降解的动力学。结果显示：该研究所制备的TiO₂锐钛矿型含量为48.766%，比表面积为47.186 m²/g，具有良好的光催化性能；光催化降解乙烯比直接紫外线光降解效果显著，光照10 min时光催化乙烯降解率比直接紫外线光降解提高23.76%；乙烯的降解率随着其浓度的增加而降低；乙烯的光催化降解的动力学可以用Langmuir-Hinshelwood动力学方程加以描述。     

60Co-g辐照改性银掺杂纳米TiO2及光催化降解乙烯

为了解60Co-射线辐照且以活性炭纤维(ACF)为载体所负载TiO2的半导体材料(TiO2/ACF)对光催化降解冷藏环境中乙烯的影响,该文拟采用60Co-辐照制备纳米Ag沉积的TiO2/ACF(Ag-TiO2/ACF)光催化材料,在模拟园艺产品的冷藏环境中,进行了3种不同膜的光催化降解乙烯效果的研究,并利用场发射扫描电镜(FESEM)、透射电子显微镜(TEM)、X射线衍射仪(XRD)对所制备的光催化材料进行相关的表征分析。结果表明:在加入分散剂聚乙烯吡咯烷酮后,60Co-辐照能使Ag颗粒较好地负载在TiO2上,TiO2均匀分散在ACF膜上而不发生团聚,且TiO2颗粒晶相改变、尺寸变小,有助于提高Ag-TiO2/ACF的催化效率。Ag-TiO2/ACF光催化降解乙烯的效果用一级动力学速率方程描述;经辐照制备的Ag-TiO2/ACF薄膜比未辐照的TiO2/ACF和辐照的TiO2/ACF薄膜光催化降解乙烯的反应速率常数分别提高了44%和37%。研究结果为TiO2光催化技术的进一步的应用提供了参考。     

60Co-γ辐照改性银掺杂纳米TiO2及光催化降解乙烯

为了解60Co-γ射线辐照且以活性炭纤维(ACF)为载体所负载TiO2的半导体材料(TiO2/ACF)对光催化降解冷藏环境中乙烯的影响,该文拟采用60Co-γ辐照制备纳米Ag沉积的TiO2/ACF (Ag-TiO2/ACF)光催化材料,在模拟园艺产品的冷藏环境中,进行了3种不同膜的光催化降解乙烯效果的研究,并利用场发射扫描电镜(FESEM)、透射电子显微镜(TEM)、X射线衍射仪(XRD)对所制备的光催化材料进行相关的表征分析.结果表明:在加入分散剂聚乙烯吡咯烷酮后,60C0-γ辐照能使Ag颗粒较好地负载在TiO2上,TiO2均匀分散在ACF膜上而不发生团聚,且TiO2颗粒晶相改变、尺寸变小,有助于提高Ag-TiO2/ACF的催化效率.Ag-TiO2/ACF光催化降解乙烯的效果用一级动力学速率方程描述;经辐照制备的Ag-TiO2/ACF薄膜比未辐照的TiO2/ACF和辐照的TiO2/ACF薄膜光催化降解乙烯的反应速率常数分别提高了44％和37％.研究结果为TiO2光催化技术的进一步的应用提供了参考.     

水中2，4—二氯苯酚的光催化降解研究

以高压汞灯、紫外灯、氙灯和太阳光为光源，进行ZnO,ZnS,TiO2及纳米TiO2对2，4－二氯苯酚溶液的光催化降解研究。结果表明，ZnO,ZnS,TiO2及纳米TiO2对2，4－二氯苯酚均有较强的光催化效果；在相同催化剂浓度下，以ZnO的催化效果最好，其次是TiO2；4种光源中以高压汞灯下的光解最快，太阳光次之；纳米TiO2对2，4－二氯苯酚的光催化降解属于一级动力学反应；曝气能加快2，4－二氯苯酚的光催化降解。     

纳米TiO2催化下表层土壤中BaP的紫外光降解

采用光解试验,研究了紫外照射与纳米TiO2联合作用下,土壤表层中苯并[a]芘（BaP）的降解动力学;同时考察了催化剂的浓度、土壤pH、腐植酸和光质对BaP的光催化降解的影响。结果表明,土壤中BaP的光催化降解表现为准一级动力学。催化剂TiO2可以明显地促进土壤中BaP的光降解,较少量的催化剂（0．5％）使光解的半衰期从363．22h减少到103．26h。H^＋和OH^-离子对BaP的催化光解起促进作用,在酸性和碱性土壤中BaP光催化降解高于中性土壤,酸性土壤中的降解速率最快。腐殖质吸收紫外光照射时,产生的活性氧中间产物能够攻击BaP,添加腐植酸能增加土壤表层中BaP的光催化降解。BaP的光解半衰期从无外加腐植酸的89．34h,减少到添加浓度分别为5、10、20和40mg·kg^-1的29．37、32．69、35．73和38．51h。BaP的催化降解随波长的增加而降低,在波长254、310和365nm下,BaP降解的一级动力学常数分别为0．0078h^-1、0．0061h。和0．005h^-1。     

利用60Co-?射线辐照使TiO2改性后对乙烯的催化降解效果

为了解60Co-γ射线辐照且以活性炭纤维（activated carbon fiber,ACF）为载体所负载Ag沉积的TiO2的半导体材料（Ag-TiO2/ACF）对光催化降解冷藏环境中乙烯的影响,在模拟园艺产品的冷藏环境中,研究了不同辐照剂量下的TiO2对乙烯的降解,并利用X射线衍射仪（XRD）及X-射线光电子能谱（XPS）对所制备的光催化材料进行相关的表征分析。表征结果表明：随着辐照剂量的增加,总体上锐钛矿的含量及尺寸减小,Ti3+及羟基氧含量提高,这些变化能使TiO2的催化活性增强。乙烯降解试验结果表明,当辐照剂量小于25 kGy时,乙烯降解速率随辐照剂量的提升而提高;当辐照剂量大于25 kGy时,乙烯降解速率随辐照剂量的提升而下降,可能是辐照能量过高导致TiO2粒子聚集沉淀,催化能力下降。研究结果为 TiO2光催化技术的进一步应用提供了参考。     

正电晕放电耦合Ag-TiO_2降解乙烯的动力学及参数优化

为了解直流正电晕-纳米银沉积纳米TiO2光电催化耦合反应系统降解乙烯及调控臭氧的机理及其动力学规律,该文采用多针对圆筒内壁式电晕放电反应器为对象,在模拟园艺产品的冷藏环境中,进行了纳米TiO2的掺银量、放电功率和气流量等因素对乙烯降解和臭氧控制效果的影响研究。结果表明:建立了正电晕放电耦合活性炭纤维(activated carbon fiber,ACF)负载掺银的纳米TiO2(Ag-TiO2/ACF、Ag-TiO2*/ACF)降解乙烯的动力学模型,通过龙格库塔法数值求解微分方程组和最小二乘法得到动力学模型的反应常数,通过对反应常数比较,正电晕放电耦合Ag-TiO2*/ACF催化膜对乙烯降解和控制臭氧浓度具有较优的性能。采用二次旋转组合试验和回归拟合,建立了正电晕放电耦合Ag-TiO2*/ACF催化膜的乙烯降解反应常数、臭氧浓度上限的预测值与影响因素关系的二次多项数学模型,验证了模型的有效性,并优化出反应体系参数。研究结果为正直流电晕放电耦合纳米二氧化钛技术在园艺产品贮运保鲜设备中的应用提供了依据。     

外加助剂对提高乙酰甲胺磷光催化降解效果的影响

为了进一步提高乙酰甲胺磷残留的降解效果,该文在前期乙酰甲胺磷残留纳米TiO2-紫外光催化降解工艺优化研究的基础上,重点就通入气体、外加H2O2、添加铁离子、铜离子及其与H2O2的复配效果、添加乙醇和丙酮等对乙酰甲胺磷光催化降解过程的影响进行了研究。结果表明,氧气比例相对较高的反应气氛、添加H2O2、Fe3+、Cu2+能促进乙酰甲胺磷的光催化降解;而乙醇、丙酮的添加不利于乙酰甲胺磷的光催化降解。在前期确定的乙酰甲胺磷的紫外光-纳米TiO2反应体系中(20mg/L乙酰甲胺磷溶液、0.1g/L纳米TiO2、pH值6.7、反应温度25℃),添加0.2mmol/L的Cu2+和10mmol/L的H2O2,并通入N2:O2为20:80的反应气氛时,反应20min后,光催化降解率即可达98.03%。该研究可为乙酰甲胺磷农药残留的降解提供参考。     

离子溅射Pt对光催化降解冷藏环境中乙烯的影响

为了了解纳米铂（Pt）对以活性碳纤维（ACF）为载体所负载TiO₂的复合材料（TiO₂/ACF）光催化降解冷藏环境中乙烯的影响。该文采用真空离子溅射仪制备纳米Pt沉积的TiO₂/ACF光催化材料（TiO₂/ACF-Pt）,在模拟园艺产品冷藏环境中,进行了两种不同溅射方案制备TiO₂/ACF-Pt的光催化降解乙烯反应速率影响研究,并利用环境扫描电镜（ESEM）、场发射扫描电镜（FESEM）、X射线光电子能谱仪（XPS）对制备材料进行观察与分析。结果表明：在模拟园艺产品冷藏环境中,TiO₂ /ACF-Pt光催化降解乙烯的动力学可用表观一级速率方程来描述;ACF表面先溅射沉积Pt,再进行TiO₂附着方案,能提高降解乙烯的能力,当溅射时间为60 s（Pt/Ti原子浓度比为0.112）时,表观一级速率常数是未溅射Pt的1.16倍;TiO₂/ACF-Pt的制备方法,对ACF形貌结构没有破坏,并能得到有利于对微量乙烯的吸附的多孔结构。     

纳米二氧化钛光催化修复二苯砷酸污染土壤的研究

利用纳米二氧化钛去除土壤中的二苯砷酸(diphenylarsinicacid,DPAA),研究了纳米二氧化钛对土壤吸附DPAA能力的影响,着重比较了原位直接光解法与异位泥浆处理法在去除DPAA效率上的差异,并对纳米二氧化钛催化降解的实验室条件进行了优化。结果表明:纳米二氧化钛添加可提高土壤对DPAA的吸附能力,但由于纳米颗粒的稳定性受到土壤中有机质影响,仅能提高红壤对DPAA的固定能力。直接施加纳米颗粒的原位光降解受纳米二氧化钛用量影响较小,主要受限于光在土层中的光照厚度及土壤含水量。汞灯照射10天后,DPAA的降解率最高仅为39.5%,但加水将土壤调制成泥浆、通过搅拌提高紫外照射下土壤与纳米颗粒的受辐射几率,可显著提高降解率,其中水土比变化较纳米二氧化钛用量更显著影响催化反应效率。将水土比从1︰1提升至10︰1,光照1.5 h后DPAA的降解率从34.3%上升至72.2%。泥浆搅拌下,二氧化钛光催化降解的方法在不同土壤中均表现出良好的降解效率,在有机质含量较低的红壤中DPAA的降解率最高达78.6%。     

Physical Properties of the Soils of Sibay City of the Republic of Bashkortostan

Eurasian Soil Science - The results of the study of the properties of urban soils of the city of Sibay located in the mining region of the Republic of Bashkortostan are presented. A specific...     

食用仙人掌萎蔫气象条件分析

塑料大棚内种植的食用仙人掌在土壤墒情较好时也有萎蔫现象发生，通过试验观测和对仙人掌生理习性的分析，发现阴雨过后天气突然放晴温度急剧上升易使仙人掌发生萎蔫现象，并提出了田间管理的应对措施。     

Heterogeneity of Organic Matter of Aggregates of Protocalcic Chernozems

Eurasian Soil Science - Layers were step-by-step removed from macroaggregates (2–1 mm in diameter) of Protocalcic Chernozems via successive abrasion in a revolving rotator during 5, 10, 15,...     

青海省耕地资源开发利用分析及对策研究

分析论述了青海省耕地资源开发利用的现状、特点和问题。在此基础上,提出了对青海省耕地资源进行研究的框架体系和思路,同时基于GIS/RS技术设计了相关的技术路线。最后依据所做设计对青海省耕地资源开发利用做了初步分析,并进行了相关的对策研究分析。     

Characterization of physical and chemical properties of Varzea soils of Goias State of Brazil

Abstract

Brazil has approximately 30 million hectares of lowland areas, known locally as “Varzea,”; distributed throughout the country. Soils in these areas have the potential to support agricultural production, but very little is known about their fertility. The current experiment was undertaken to characterize the chemical and physical properties of representative “Varzea”; soils collected at 0–20, 20–40, 40–60, and 60–80 cm depth intervals from 23 sites in Goias State of Brazil. Organic matter contents averaged 42 g/kg in the surface 20 cm of soil and should make a significant contribution to overall nutrient availability. Soil pH increased slightly with depth from a mean value of 5.2 in the surface 20 cm of soil to a mean value of 5.4 in the 60–80 cm depth interval. Several soils had exchangeable Al values ≥ 1.0 cmol Al/kg, but soil Al saturation was generally less than the 60% level frequently associated with Al toxicity. However, cereal and legume production could benefit from lime addition in many of these soils. Although base saturation was fairly low in some soils, exchangeable Ca and Mg levels were, in general, adequate throughout the profile. Extractable P levels were adequate in most surface soil samples. Extractable K levels in these soils were generally low, and the application of K fertilizers should be beneficial, especially in conjunction with lime addition. The high clay content “Varzea”; soils of the Brazilian lowlands have some drainage problems but generally exhibit favorable chemical properties for crop production when compared to soils of the well‐drained Cerrados.     

Estimation of potential nitrogen-fixing activity of agrophytocenoses soils of the subtropical zone of Russia

An estimation of potential nitrogen-fixing activity of various soil types under agrophytocenoses of tea, filbert, peach, and pawpaw which grow in the area of Greater Sochi is given. High indicators of nitrogen fixation activity in the soil in the course of vegetation were characteristic of agrocenoses of pawpaw, peach, and filbert. The lowest level of nitrogen fixation was noted in the soil of a tea plantation. A negative correlation dependence of potential nitrogen-fixing activity on the acidity of the soil solution was established. A study of the seasonal dynamics of the activity of nitrogen fixation of soils of agrocenoses of the subtropical zone of Russia made it possible to distinguish a less active winter and more active spring-summer-autumn periods.     

物联网安全及解决措施

物联网是一个集信息通信、数据交换、传感器技术与软件工程于一体的综合性产业,探讨和分析了物联网的结构体系与发展中遇到的安全问题。     

荔枝种子结构的扫描电镜观察

荔枝种子从果实中剥离出来后, 即使在室内条件下, 也极易失水干缩, 潮湿环境中又易发霉而腐烂。扫描电镜观察表明: 种皮上布满纹孔, 水分散失面积很大; 种脐部为疏松的海绵组织, 且营养丰富。据此, 生产上应对种子彻底清洗, 并保存于适当湿度的环境中, 以提高其发芽率。     

Kinetics of Popping of Popcorn

The rate of popping of popcorn was measured in oil and in air. Kinetic data for lifetimes of individual kernels from a large population were obtained in oil at six constant temperatures (180–250°C) and also in an air‐popper at 202°C. The data are characterized by an induction period, which is, significantly, followed by a first‐order decrease in the number of unpopped kernels versus time. The activation energy for the first order process is 166.7 kJ/mol between 180 and 210°C, and 53.8 kJ/mol between 210 and 250°C. These data are consistent with a model that assumes 1) that the rate of heat transfer into a kernel follows Newton's law of cooling; 2) that in a sample of kernels there exists a distribution of critical pressures; 3) that for an individual kernel, the probability of popping is directly proportional to the difference between the internal aqueous vapor pressure and the kernel's critical pressure; and 4) that the measured rate constant at any temperature is an average overall of the kernels in the sample with critical pressures equal to or less than the internal aqueous vapor pressure. Minimum popping temperatures predicted by the model are 181 ± 2°C (oil) and 187 ± 2°C (air), in good agreement with previously reported direct measurements.