化学修饰在生物吸附中的应用

化学修饰技术可以掩蔽细胞壁上一些基团,从而使吸附量改变,利用该技术可以探讨生物吸附法去除金属离子的机理。化学修饰在环境污染治理方面有广阔的应用前景。     

Sb2O5/TiO2催化超声降解甲基橙溶液

采用实验室合成的Sb2O5掺杂TiO2作为催化剂,研究各种因素对甲基橙的超声催化降解反应的影响.结果表明,在Sb2O5掺杂TiO2催化剂作用下,甲基橙的超声催化降解效果明显优于单独使用TiO2的情况.1.5%掺杂量的催化剂,用量在1.0～1.5 g/L之间,超声波频率25 kHz,输出功率1.0 W/cm2,pH为1.0～3.0时,初始浓度为20 mg/L的甲基橙水溶液,100 min左右基本可全部降解,COD去除率达到99.0%以上.Sb2O5掺杂TiO2催化超声降解有机污染物的方法具有很好的应用前景.     

改性粉煤灰的制备及其对分散蓝的吸附

以聚二甲基二烯丙基氯化铵(PDMDAAC)为改性剂,制备PDMDAAC改性粉煤灰。采用正交实验考察了制备条件对PDMDAAC在粉煤灰上的负载量的影响。实验结果表明:在反应温度为70℃、反应时间为3 h、PDMDAAC质量浓度为50 g/L、溶液pH为10的最佳条件下,PDMDAAC在粉煤灰上的负载量为0.98 mg/g;在吸附温度为30℃、初始分散蓝质量浓度为50 mg/L、PDMDAAC改性粉煤灰加入量为4 g/L的条件下,PDMDAAC改性粉煤灰对分散蓝的去除率可达98%。PDMDAAC改性粉煤灰对分散蓝的吸附符合Langmuir吸附模型。     

煤矸石的改性及其对稀土生产废水中氨氮的吸附

采用热改性、盐酸改性、硫酸改性、碱改性的方法分别制备了4种改性煤矸石吸附剂,研究了吸附工艺条件对4种改性煤矸石吸附剂对稀土生产废水中氨氮去除效果的影响以及吸附机理.实验结果表明:4种改性煤矸石吸附剂吸附氨氮的最佳工艺条件为:吸附剂加入量0.02 g/mL,振荡时间2.5 h,废水pH 7～8;4种吸附剂氨氮去除率大小顺序为:碱改性煤矸石＞硫酸改性煤矸石＞盐酸改性煤矸石＞热改性煤矸石;碱改性煤矸石的氨氮去除率最高,为59.19％;碱改性煤矸石吸附剂对含氨废水中氨氮的吸附较好地符合Langmuir方程和Freundlich方程,在一定程度上符合Temkin方程.     

稀土改性NaY型分子筛催化热解废轮胎

采用稀土氧化物改性NaY型分子筛（Ⅰ型催化剂）,100 gⅠ型催化剂中添加0.5 g CeO₂得到Ⅱ型催化剂,100 gⅠ型催化剂中添加0.5 g La₂O₃和0.5 g CeO₂得到Ⅲ型催化剂。分别采用Ⅰ型、Ⅱ型和Ⅲ型催化剂催化热解废轮胎（粒径0.2 mm）,Ⅱ型和Ⅲ型催化剂的产油起始温度和终止温度均低于Ⅰ型催化剂。在催化剂加入量为2.5 g、废轮胎加入量为100 g 的条件下,Ⅲ型催化剂催化热解反应的产油率和油气总产率均高于Ⅰ型和Ⅱ型催化剂。Ⅱ型和Ⅲ型催化剂催化热解主要产生轻组分气体,Ⅱ型催化剂C₄选择性最高,Ⅲ型催化剂C₃选择性最高。     

氧化改性活性炭吸附脱除游离态汞

煤是一种主要化石能源，燃煤烟气中汞排放引起的污染现已达到严重危害人类健康的程度，主要原因是其中的游离态汞（Hg^0）由于低熔点、高平衡蒸气压以及低水溶性而难以由传统的烟气净化装置中去除。燃煤烟气中汞的治理势在必行。本文在研究国内外含汞废气治理技术的基础上，对活性炭分别进行了浓HNO3和H2O2氧化改性，研究其对游离态汞的吸附效率和吸附等温线。结果表明，改性后的活性炭对汞的吸附能力明显增强。     

ON THE EVALUATION OF OPERATIONAL CLOUD SEEDING PROJECTS1

ABSTRACT Operational cloud seeding projects, those designed to produce a desired change in the weather and that are nonexperimental in nature, continue to be pursued widely in the United States. A recurring question by scientists, project sponsors, and cloud seeders has been, “was the weather altered and if so, by how much?” Evaluation of such projects is now recognized as having scientific benefits, and a four-year study has addressed various techniques and statistical methods to perform evaluations and to learn more about how to modify the weather. Most such evaluations hinge on some type of space-time comparisons, but valid comparisons can be obtained only avoiding biases in the project design and operation. Through simulated changes in weather conditions, it was determined that the principal component regression techniques were used to evaluate selected rain and hail modification projects, revealing modification in certain projects and none in others. Various relevant issues have been examined such as use of other weather variables (covariates) to increase detection power, the validity of using historical data as controls for discrete operational periods, possible randomization options during cloud seeding operations, and analyses of individual rain events versus that based on monthly or seasonal units.     

STORM CHARACTERISTICS OF CONVECTIVE-SCALE PRECIPITATION1

A classification scheme for convective precipitation, having applications in both analysis and modeling of meteorological and hydrological events, is presented. The method is based upon observations of rainfall at the ground, radar scans of storm events, and visible and infrared satellite imagery of larger storm systems. Empirical and theoretical frequency distributions are derived for total storm rainfall, rainfall duration and time between storms for each of the convective categories. This stratification is directly applicable to the experimental design and evaluation of weather modification projects and may be useful for the development and interpretation of meteorological and hydrological models. When atmospheric conditions limit storm development to cells, rainfall was seldom observed. Small clusters also produce small amounts of rainfall but have a longer lifetime than cells and are likely candidates for cloud seeding attempts to encourage their growth to large clusters. Large and nested clusters usually produce large amounts of natural precipitation. A few large storms account for most of a season's rainfall.     

PAA改性纳米铁强化还原降解水中亚甲基蓝

利用纳米零价铁去除水中各类污染物是近年来的研究热点,但纳米零价铁颗粒在水中的团聚会导致反应活性降低,研究通过在纳米铁颗粒制备过程中添加分散剂聚丙烯酸(PAA),提高其分散性,强化其在水中反应活性,合成改性纳米零价铁颗粒(PAA-Fe),并首次用于降解水中的亚甲基蓝.对其SEM、TEM、XRD和比表面积表征结果表明,与未改性原始纳米零价铁颗粒相比,PAA-Fe颗粒表面较光滑,团聚减少、颗粒粒径减小,比表面积增大.改性剂PAA添加浓度为0.1 g·L-1时,经过60 min降解反应,PAA改性纳米铁颗粒对亚甲基蓝的脱色率为98.84%,较未改性颗粒脱色率提高了27.32%.改性纳米铁颗粒对亚甲基蓝的脱色效果受初始溶液的p H值、初始溶液的浓度、PAA-Fe投加量和反应温度影响.PAA-Fe与亚甲基蓝的脱色反应符合假一级反应动力学规律.     

不同类型LDHs对垂直流人工湿地无烟煤基质的覆膜改性及其脱氮效果研究

选取垂直流人工湿地无烟煤基质,采用不同类型金属化合物(CaCl2、ZnCl2、MgCl2、FeCl3、AlCl3、CoCl3)两两组合方式,在碱性环境下共沉淀生成9种不同类型的层状双金属氢氧化物LDHs并覆膜于基质表面;构建基质试验柱,分别对未改性及9种LDHs覆膜改性无烟煤基质进行模拟垂直流人工湿地脱氮效果研究.结果表明,9种不同组合方式生成的LDHs均能有效地进行无烟煤基质覆膜改性;Mg2+参与合成的改性基质对TN和氨氮均有很好的去除效果,其中MgCo-LDHs改性基质对TN的平均去除率超过80%,对氨氮的平均去除率达到了85%;Mg2+和Fe3+参与合成的改性基质对氨氮的去除效果优良,其中CaFe-LDHs和MgFe-LDHs改性基质的平均去除率达到了85%以上.