钛合金表面铁氧化物膜层类Fenton催化剂制备及降解苯酚性能

采用微弧氧化法在硅酸盐电解液体系中于钛合金表面成功制备了铁氧化物膜层类Fenton催化剂。采用SEM、XRD以及XPS对所得膜层的表面形貌、晶体结构及物相组成进行表征,发现膜层中含有金红石相TiO₂（R-TiO₂）,和非晶态的铁氧化物Fe₃O₄;对膜层的表面形貌分析发现电解液中加入铁氰化钾后表面粗糙度及平均孔尺寸增大。以苯酚作为目标降解物,研究了膜层类Fenton催化活性,同时研究了铁源含量、苯酚浓度、H₂O₂投料量以及pH值对膜层降解苯酚效率的影响,优化了降解条件,研究发现在pH 3.0、温度30℃、H₂O₂ 6.0 mmol·L^-1、苯酚35 mg·L^-1及铁氰化钾含量10 g·L^-1的条件下降解90 min,苯酚降解效率可达90%。通过对不同温度下降解苯酚的反应动力学研究,利用阿伦尼乌斯方程得到了该膜层类Fenton降解苯酚的反应活化能E_a为96.9 kJ·mol^-1。最后,评价了膜层的稳定性并分析了稳定性衰减的原因。     

过氧化氢-钴-纳米银体系共振散射法测定痕量过氧化氢

基于纳米银与Co~(2+)的络合反应及H_2O_2与Co~(2+)的类Fenton反应,建立了一种测定H_2O_2的共振散射方法。在pH=5.2的柠檬酸-磷酸氢二钠缓冲液中,530nm处,H_2O_2浓度在0.02~0.4μmol·L~(-1)范围内与共振散射强度降低值△I呈良好的线性关系,相关系数r为0.9966,检出限为1.07×10~(-8)mol·L~(-1)。该法用于池塘水和雨水中过氧化氢的测定,回收率分别为104.26%和97.63%,同时探讨了反应机理。     

基于水滑石的Zn-Cr-Cu复合金属氧化物的制备及其对罗丹明B的光催化降解性能

采用共沉淀法一步组装获得席夫碱铜(Ⅱ)插层的Zn-Cr水滑石(ZnCr-SBCu-LDHs),再经500℃高温焙烧制得新颖的Zn-CrCu复合金属氧化物(ZnCr-SBCu-LDO)光催化材料。通过X射线粉末衍射(XRD)、紫外-可见漫反射图谱(UV-Vis DRS)、扫描电子显微镜(SEM)、电感耦合等离子体原子发射光谱(ICP-AES)对催化材料的结构和性质进行分析表征。以较难被水滑石吸附的阳离子型染料罗丹明B(RhB)作为模型,研究材料的光催化活性,考察材料用量、RhB溶液的初始pH值、温度以及H_2O_2初始浓度等对光催化活性的影响。结果发现:ZnCr-SBCu-LDO具有优异的光催化活性,在初始pH值为7.40、温度为25℃以及H_2O_2初始浓度10 mmol·L~(-1)的条件下,光照4 h后,1 g·L~(-1)的催化材料对5 mg·L~(-1)的RhB溶液的降解效率可达98.68%。此外,进一步对催化剂的再生能力进行了研究,并初步探讨了光催化降解的机理。     

酶功能化聚多巴胺包覆纳米普鲁士蓝的制备及电化学分析应用

在纳米金表面原位沉积普鲁士蓝,然后在核壳结构纳米金-普鲁士蓝的表面包覆一层易氧化聚合的多巴胺保护膜,利用多巴胺聚合表面残留的大量氨基和羟基进一步将纳米铂粒子修饰于聚多巴胺膜表面制得普鲁士蓝-聚多巴胺-纳米铂多层纳米复合材料。将此复合材料修饰于金电极表面,协同使用辣根过氧化物酶用于H_2O_2浓度的检测。结果表明:聚多巴胺的引入有效增加了普鲁士蓝的稳定性,增大了纳米铂的负载量以及辣根过氧化物酶的生物活性;由于普鲁士蓝、纳米铂和辣根过氧化物酶的多重信号放大作用,酶功能化纳米复合材料修饰电极对H_2O_2表现出良好的电还原活性。优化条件下,对H_2O_2的检测范围为2.0×10~(-7)~1.0×10~(-3)mol·L~(-1),检出限(S/N=3)为1.2×10~(-7)mol·L~(-1)。     

H_2O_2处理H_3PW_6Mo_6O_(40)/ZrO_2-SiO_2光催化降解甲基橙

采用浸渍法制备了H_3PW_6Mo_6O_(40)/ZrO_2-SiO_2催化剂,用H_2O_2进行敏化处理,并通过FT-IR、XRD对其进行了表征。探讨了该催化剂对甲基橙溶液的催化降解活性,较系统地研究了溶液的初始浓度、溶液的pH、催化剂用量对光催化降解甲基橙的影响。研究发现:H_3PW_6Mo_6O_(40)/ZrO_2-SiO_2对甲基橙有良好的降解效果。在甲基橙溶液初始浓度为10mg·L~(-1),溶液pH为2.5,催化剂用量为溶液总质量0.5%的条件下光照2.5h,甲基橙的降解率达到91.1%。H_3PW_6Mo_6O_(40)/ZrO_2-SiO_2催化剂光催化降解甲基橙溶液为一级动力学反应。     

芬顿体系降解邻苯二酚和对苯二酚研究

基于石墨烯修饰电极,分别建立了对苯二酚(HQ)和邻苯二酚(CC)浓度与电化学信号的工作曲线,并通过差分脉冲伏安法(DPV)考察了Fe~(2+)与H_2O_2添加量、pH环境及降解时间对HQ、CC降解率影响。结果表明:Fe~(2+)/H_2O_2芬顿体系对HQ、CC的降解效果明显,其中羟基自由基起主导作用。处理50 mL 6×10~(-5) mol·L~(-1)的苯二酚污染物时,Fe~(2+)与H_2O_2摩尔比为5∶4,芬顿试剂添加量为9.8×10~(-5) mol,降解时间为45 min,分别在pH=4.0的条件下降解HQ和pH=5.0的条件下降解CC,降解率分别达88.8%(HQ)和96.1%(CC)。     

[Mn(salen)]2促进Fenton反应降解苯酚废水的催化特性与机理

研究了席夫碱锰配合物{[Mn(Ⅲ)(salen)(H_2O)]_2(ClO_4)_2,简写为[Mn(salen)]_2,salen=N,N'-二(亚水杨基)-1,2-乙二胺}对Fenton反应降解苯酚的催化作用。通过紫外分析、液相色谱、双倒数作图等方法对反应特性、反应机理进行分析。实验结果表明,[Mn(salen)]_2配合物加入Fenton体系后,可提高Fenton反应降解苯酚的效率。在不同pH体系和过量H_2O_2中,均保持一定降解能力。配合物中锰离子可转变成高价态锰中间体,加速有机物氧化,提高降解效率。加入配合物后,[Mn(salen)]_2-Fenton体系催化反应活化能下降了35.9%。重复利用7次后,[Mn(salen)]_2依然保持60%的催化活性。     

水环境中ZVI/氧化剂体系及其电子迁移作用机制

利用零价铁(Zero-Valent Iron,ZVI)去除水环境中的污染物成为近年来的研究热点。当O_2、H_2O_2等氧化剂存在时,ZVI、氧化剂与污染物之间的电子迁移机制非常复杂,ZVI和氧化剂之间的相互影响机制尚无定论。传统观点认为,O_2会促进ZVI钝化膜的形成并阻断电子传递从而降低ZVI的还原性能。然而O_2可在ZVI作用下通过双电子传输转化为H_2O_2,构成ZVI/O2类Fenton体系;在此基础上,利用额外加入H_2O_2、HSO_5~-、S_2O_8~(2-)等氧化剂,发展出了基于·OH或SO_4~(·-)的ZVI/氧化剂高级氧化体系(ZVI-AOPs),从而氧化降解有机污染物。有学者认为H_2O_2、KMnO_4、S_2O_8~(2-)等强氧化剂的加入反而可以加快ZVI腐蚀和失电子的速率,从而提高ZVI去除重金属等污染物的还原性能,该研究结论对钝化膜机制提出了挑战。ZVI与氧化剂的联合作用还可以实现同时还原去除重金属和氧化降解有机物,也可以对卤代有机物等抗氧化污染物实现先还原后氧化去除。本文综述了基于ZVI/氧化剂的高级氧化或还原体系及其电子迁移机制,同时对ZVI与氧化剂的联合作用体系作一总结,并就值得深入研究的问题进行了展望。     

水系混合离子全电池LiMn2O4//NaTi2(PO4)3

分别以LiMn_2O_4,NaTi_2(PO_4)_3为正负极,1 mol·L~(-1) Li_2SO_4和0.5 mol·L~(-1) Na_2SO_4的混合水溶液为电解液组装成一种水系混合离子全电池。分别将正负极材料在3种不同水相电解液(1 mol·L~(-1) Li_2SO_4、0.5 mol·L~(-1)Na_2SO_4以及1 mol·L~(-1) Li_2SO_4+0.5 mol·L~(-1)Na_2SO_4混合电解液)中进行循环伏安和恒流充放电测试,结果发现,LiMn_2O_4在上述电解液中仅有Li~+的脱出/嵌入而Na~+由于半径较大而不参与该过程,NaTi_2(PO_4)_3在3种电解液中Li+、Na+均参与嵌入/脱嵌过程,且Li~+和Na~+的嵌入/脱出峰电位相差不大,分别为-0.82和-0.64 V,-0.95和-0.75 V;全电池在265 mA·g~(-1)电流密度下平均放电电压为1.55 V,充放电比容量分别为100.1和74.9 m Ah·g~(-1)。     

苯酚和氯苯酚的Pt／TiO2催化光解

在TiO_2和Pt/TiO_2催化作用下水溶液中苯酚、对氯苯酚、2,4-二氯苯酚和2,4,6-三氯苯酚均能发生光致降解(λ≥345nm)。在固定于反应器内壁的薄层Pt/TiO_2催化作用下,这些化合物的光致降解均呈现一级反应动力学;表观反应速率常数K_(ob)的相对大小为:苯酚<对氯苯酚<2,4-氯苯酚<2,4,6-三氯苯酚。少量H_2O_2(1.9×10~(-2)mol·L~(-1))能提高这些化合物的光解速率。光照1.0～5.0h后这些化合物的降解率大于97％,COD去除率大于95％。     

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%.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

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.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

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.