磁性多壁碳纳米管吸附水中双氯芬酸的热力学与动力学

研究了磁化多壁碳纳米管(MWCNTs)对于水中非甾体抗炎药双氯芬酸的吸附过程.结果表明,双氯芬酸的吸附量随磁性MWCNTs投加量的增加而增大,而且吸附剂量增加到一定阶段后,双氯芬酸的吸附量达到平衡.在磁性MWCNTs的量为0.7g·L-1时,水溶液中双氯芬酸被磁性MWCNTs吸附的量达到最大,为33.37mg·g-1,对应的双氯芬酸去除率为98.1%.双氯芬酸的去除率随溶液pH的增加先增大后下降,随温度的升高而下降.用准一级、准二级模型进行了动力学分析.回归结果表明,准二级模型更准确地反映了吸附动力学.通过实验确定了Langmuir和Freundlich等温线的线性相关系数与标准偏差,结果揭示出Langmuir等温线与实验数据有很好的拟合度.对热力学参数的计算表明,ΔG00,意味着磁性MWCNTs对双氯芬酸的吸附是自发的;ΔH00,指明吸附是一个放热的物理吸附过程,温度低对吸附有利;ΔS00,代表该吸附是熵增过程.     

螯合吸附材料ASA-PGMA/SiO2对稀土离子的吸附性能研究

采用静态吸附法研究了ASA-PGMA/SiO2对稀土离子的螯合吸附性能、吸附动力学和热力学。实验结果表明,其对稀土离子的吸附能力分别为:La3+:38.6 mg.g-1,Pr3+:39.6 mg.g-1,Nd3+:41.8 mg.g-1,Sm3+:42.8 mg.g-1,Tb3+:46.2 mg.g-1。吸附等温模型符合Lang-muir型单分子层吸附。介质pH值对材料的吸附能力有很大影响,pH值为6时吸附量最大。以盐酸为洗脱剂,当酸度为0.1 mol.L-1时,洗脱率为99.8%。连续吸附-脱附实验表明,ASA-PGMA/SiO2重复使用10次后,吸附能力变化很小。     

杨梅单宁为模板制备介孔氧化铝及其对水体中氟的吸附特性研究

以杨梅单宁为模板,Al(NO3)3.9H2O为铝源制备了介孔Al2O3吸附材料,研究了介孔Al2O3对水体中氟的吸附特性。X-射线衍射分析表明,所制备的Al2O3的晶形为γ-Al2O3。N2-吸附/脱附分析表明,γ-Al2O3存在明显的介孔结构。吸附实验发现,在酸性条件下介孔γ-Al2O3对氟的吸附量较高;介孔γ-Al2O3对水体中氟的吸附量随温度的升高而增大,当初始氟离子浓度为95mg·L-1、温度为303K时的平衡吸附量达到58.28mg·g-1,而温度为323K时的平衡吸附量达到68.27mg·g-1,而且吸附等温线符合Langmuir方程。介孔γ-Al2O3对氟的吸附在前2h吸附较快,8h基本达平衡,吸附动力学符合拟二级速度方程。介孔γ-Al2O3吸附氟达平衡后经5mmol·L-1的NaOH溶液解吸,能将吸附的氟全部解吸,解吸后的介孔γ-Al2O3对氟的吸附能力基本不变,表现出良好的重复使用性能。     

ZrO2负载碳纳米管吸附去除水中氟的研究

以ZrO2负载多壁碳纳米管(ZrO2-MWCT)为吸附剂,系统研究了其对水中F-的吸附、脱附性能。结果表明,F-在ZrO2-MWCT吸附剂上的吸附等温线可以用Freundlich方程模拟,吸附动力学符合拟二级动力学方程,吸附速率随着F-初始浓度的提高而减低。当pH为4~5时,F-在ZrO2-MWCT吸附剂上的吸附量最大。水中阴离子的存在降低ZrO2-MWCT对F-的吸附量,不同阴离子对F-影响的大小顺序为:CO32->SO42->Cl->NO3-。吸附饱和的ZrO2-MWCT可用0.1mol/L的NaOH脱附再生,经4次再生后,其吸附量仍为14.55mg/g。     

氨基修饰超高交联树脂对单宁酸的吸附行为及机理研究

选用单宁酸作为天然有机酸中典型中分子、高水溶性有机酸,系统研究了氨基修饰超高交联树脂对单宁酸的吸附行为和机理.吸附等温线表明氨基修饰超高交联树脂WJN-08对单宁酸有较高的吸附容量,其静态饱和吸附量比传统商业吸附剂高15%以上;吸附表面分析表明离子键、π-π共轭作用和阳离子-π键是重要吸附作用力;吸附热力学试验表明树脂WJN-08吸附单宁酸是化学吸附主导,吸附焓变在20~22 kJ mol-1;吸附动力学试验表明树脂WJN-08吸附单宁酸速率同时受控于颗粒内扩散和膜扩散过程.动态小柱吸附-脱附实验表明树脂WJN-08对单宁酸有较好的吸附-脱附性能,饱和吸附量和穿透吸附量分别为24.43 mg g-1和19.56 mg g-1,脱附率为98.6%。     

均苯四甲酸酐修饰壳聚糖微球对Pb2+和Cd2+的吸附

用交联的壳聚糖微球 (CTS) 与均苯四甲酸酐在无水条件下反应,合成均苯四甲酸酐修饰壳聚糖微球,并用FT-IR和XPS表征产物的结构。研究它对水溶液中Pb2+和Cd2+的吸附行为。考察溶液的pH,吸附时间及Pb2+和Cd2+的初始浓度对吸附金属离子的影响。吸附等温线可以用Langmuir 方程较好的描述,当pH 5.0时,该吸附剂对Pb2+和Cd2+的最大吸附量分别为296.7mg g-1和149.9mg g-1。动力学过程用二级吸附动力学模拟具有很好的线性相关性,从而确定了吸附过程为化学吸附。采用0.2mol L-1的EDTA为解析剂,Pb2+和Cd2+分别获得92.4%和85.3%的解析率。表明该吸附剂有再生性能。应用于电镀废水中铅的处理,结果满意。     

丁烯-1在MoO3.Bi2O3.P2O5/SiO2催化剂上的程序升温脱附

本文采用程序升温脱附技术,考察了MoO_3·Bi_2O_3·P_2O_5/SiO_2催化剂晶格氧的逸出和丁烯-1在催化剂上的程序升温脱附特性和表面反应。 实验结果表明:程序升温脱附峰T_M值随丁烯-1吸附量的增加而逐渐增高。从脱附物组成的色谱分析证实,在程序升温脱附过程中吸附的丁烯-1在表面晶格氧参与下发生复杂的催化反应,不单有丁烯异构物、聚合物、丁二烯,还有含氧化合物的生成。丁烯1和其产物的总包脱附活化能随丁烯-1吸附量的增加而增大。采用在不同脱附温度下切割程序升温脱附溜出物和改变程序升温脱附前的抽空条件然后进行色谱分析,初步对丁烯-1在催化剂上的表面反应活性中心进行了分类,并估算了各类反应中心的数目。当温度低于120℃时,发生异构化和双聚反应,高于120℃时有显著的氧化和氧化脱氢反应。还从吸附等温线计算了不同复盖度时丁烯的等容吸附热。并根据本文实验结果和松浦等从经典吸附法求得的丁烯吸附热值进行了讨论。     

改性固化单宁对稀土离子Pr3+,Nd3+吸附性能研究

以苎麻纤维为基础,通过甲醛交联固化杨梅单宁制备吸附材料(RF-BT),进一步经Mannich反应改性,引入-NH2,制备改性苎麻纤维接枝杨梅单宁吸附材料(RF-BTM)。通过IR和SEM等方法表征了两种材料的结构,并研究了两种材料对Pr3+,Nd3+稀土离子的吸附性能。实验结果表明:反应温度为303 K,p H为5.5,Pr3+溶液初始浓度为1127.2 mg·L-1,Nd3+溶液初始浓度为1153.6 mg·L-1时,RF-BT的最大吸附量为:Pr3+420.3 mg·g-1,Nd3+432.8 mg·g-1;RF-BTM的最大吸附量为:Pr3+461.7 mg·g-1,Nd3+477.8 mg·g-1;表现出优良的吸附性能,其吸附热力学符合Freundlich方程,动力学可用拟二级速率方程描述。     

磁性胰蛋白酶分子印迹聚合物的制备及性能评价

以壳聚糖修饰的四氧化三铁为载体,利用壳聚糖表面的氨基与戊二醛结合,丙烯酰胺为功能单体和交联剂,胰蛋白酶为模板蛋白,制备了磁性胰蛋白酶分子印迹聚合物。通过静态平衡结合法研究了磁性分子印迹聚合物的吸附能力、选择性。结果表明,与磁性分子非印迹聚合物相比,磁性分子印迹聚合物对模板蛋白具有高选择性和高特异性吸附,最大吸附量为162.2mg·g-1;Scatchard分析表明,存在两类不同的吸附结合位点,其离解常数分别为96.5μg·mL-1(高结合位点)和2.41mg.mL-1(低结合位点)。     

纳米MnO2的制备及其电化学性能研究

加入不同浓度的十二烷基磺酸钠表面活性剂(SDS)改变微乳液溶液介质,用苯胺还原高锰酸钾,制备了不同颗粒大小的纳米片状MnO2材料.采用X射线粉末衍射、氮吸附比表面测试和扫描电镜及透射电镜表征观察合成材料.电化学测试表明,0.20 mol·L-1SDS所合成的纳米MnO2比表面约为228.2 m2·g-1,在1mol·L-1Li2SO4电解液中,该电极比电容达到237 F·g-1(0.1 A·g-1),350℃煅烧MnO2电极还可发生可逆Li+嵌脱反应增加其比电容.     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Copper catalyzed/mediated synthetic methodology for ebselen and related isoselenazolones

Scope of the copper catalyzed/mediated selenium-nitrogen coupling reaction has been studied for the synthesis of isoselenazolones. It is noticed that the 2-chloro, 2-bromo-, and 2-iodo-aryl amides substrates can be exploited in the selenium-nitrogen coupling reaction by employing 25-100 mol % of CuI/1,10-phenanthroline (L) and potassium carbonate as a base in DMF. Furthermore, electron rich 2-chloro-arylamides also underwent selenium-nitrogen coupling reaction to give biologically important selenium-nitrogen heterocycles. Also, copper-catalyzed selenium-nitrogen coupling reaction has been meticulously applied for the synthesis of diaryl diselenides having methoxy, amine, and amide functionality from respective aryl iodides in the presence of stoichiometric amount of succinimide as an external Se-N coupling partner.     

Knoevenagel condensation catalyzed by novel Nmm-based ionic liquids in water

A series of novel N-methyl morpholine (Nmm) based ionic liquids with 1,2-propanediol group were synthesized and used as catalysts for Knoevenagel condensation at room temperature in water. Under the effect of the catalyst, various aldehydes or aliphatic ketones could react with a wide range of activated methylene compounds well, including malononitrile, alkyl cyanoacetate, cyanoacetamide, β-diketone, barbituric acid, 2-arylacetonitrile and thiazolidinedione. Furthermore, most of the products could be separated just by filtrating and washing with water. Additionally, the catalyst is recyclable and applicable for the large-scale synthesis.     

Construction of polyheterocyclic spirotetrahydrothiophene derivatives via sulfa-Michael/aldol cascade reaction

A series of polyheterocyclic spirotetrahydrothiophene derivatives were obtained in moderate to excellent yields via a catalyst-free sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 under mild conditions. We also present the first asymmetric sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 with moderate to good enantioselectivities catalyzed by readily available chiral phase-transfer catalysts (PTCs).     

Suzuki-Miyaura reactions of the soluble guanylate cyclase inhibitor NS2028: a non-product specific route to C-8 substituted analogues

Both soluble guanylate cyclase (sGC) inhibitors ODQ 1 and NS2028 2 are synthesized via improved protocols. In the former case treating 3,4-dihydroquinoxalin-2(1H)-one oxime 8, which can be prepared in two steps from 1,2-benzenediamine, with 1,1′-carbonyldiimidazole (CDI) gives the dihydro-ODQ 10 that in the presence of KMnO₄ oxidises to give ODQ 1 in an overall yield of 46% starting from 1,2-benzenediamine. In the latter case, the synthesis affords NS2028 2 from 2-amino-4-bromophenol 3 in three steps with an overall yield of 85% and avoids the need for chromatography. Furthermore, Suzuki-Miyaura reaction conditions are described that enable the preparation of 8-aryl and 8-heteroaryl derivatives of NS2028 directly from NS2028 2. Finally, demethylation of the 8-(methoxyphenyl) substituted analogues afforded the 8-(hydroxyphenyl) derivatives 40-42. All new products are fully characterised.