十二烷基苯磺酸钠氧化降解的研究

随着工农业的发展,表面活性剂已广泛应用于各个领域,表面活性剂废水的大量排放成为水体CODCr的重要来源.目前对此类废水的降解研究主要集中于生物法和光催化法[1].高铁酸盐具有强氧化性,在水处理方面可用于杀灭藻类和细菌[2],氧化降解水中的污染物[3,4]等,本研究以十二烷基苯磺酸钠(SDBS)水溶液作为表面活性剂模拟废水,研究高铁酸盐(FeO42-)对其处理效果和降解机理.实验结果表明,新型水处理剂高铁酸盐可以有效降解SDRS.     

草酸在Ti/IrO2-Ta2O5阳极圆柱形电解槽中的电催化氧化降解动力学

从电催化氧化降解有机污染物的机理出发,研究了草酸在Ti/IrO2-Ta2O5阳极圆柱形电解槽中的电催化氧化过程,建立了描述整个降解过程的瞬时电流效率与溶液本体有机物浓度的关系式. 通过实验对模型进行了验证,实验结果与模型计算结果基本一致,并讨论了误差产生的原因.     

有机涂层环境适应性研究进展

综述了有机涂层自然环境试验方法和实验室加速试验方法。自然环境试验方法主要有大气环境试验和海水环境试验;实验室加速试验方法不但包括模拟太阳光、热、湿热、盐雾等环境的实验室试验,还有综合模拟试验。还介绍了检测有机涂层老化的宏观分析方法、微观分析方法和电化学分析方法。其中宏观分析方法主要介绍了涂层附着力试验方法,微观分析方法则主要介绍了扫描电镜(SEM)、X射线光电子能谱仪(XPS)、傅里叶红外光谱(FTIR)及电化学交流阻抗谱法(EIS)。讨论了近年发展起来的有机涂层老化的各种机理,例如自由基降解的光老化降解机理,亲水性基团的水降解机理,热氧机理,臭氧及污染物影响的老化机理等。     

水相中POPs光化学降解研究进展

综述了近年来12种持久性有机污染物(POPs)在水体中光化学降解行为,从水体中POPs的光解途径、光解机理和定量结构-性质关系(QSPR)三个方面探讨了POPs在水体中的光化学行为,展望了水体中POPs光化学行为的研究前景.     

BiVO4光催化去除废水中的四环素和环丙沙星

利用微波水热法制备单斜白钨矿型BiVO4为光催化剂,探讨其对抗生素类污染物的去除效果.同时利用X射线衍射(XRD)、傅里叶红外(FT-IR)和场发射扫描电镜(FE-SEM)等测试手段对样品结构和性能进行了表征.以四环素(TC)和环丙沙星(CIP)为目标污染物,研究光照时间、pH及Cu(Ⅱ)共存对BiVO4光催化降解抗生素性能的影响.结果表明:BiVO4对TC和CIP的光催化具有较为宽泛的pH适用范围,其中TC在pH为5~12之间具有良好的效果,pH=8时,降解效率达到74%;CIP在pH为4~9之间适用范围最好,降解率由26%升高到37%.此外,对TC和CIP光催化降解机理和可能的降解途径进行探讨,光催化降解主要机理是有效光生电子-空穴与OH-和O2结合,将TC和CIP分解为中间产物CO2和H2O.总之,单斜白钨矿型BiVO4用于模拟抗生素废水的研究,取得一定效果,可为实际抗生素废水的处理提供参考.     

有毒难降解有机污染物的光催化降解

有毒难降解有机污染物的光催化降解在原理、过程和效率等方面仍然存在着巨大的挑战,特别是光催化剂的构效关系、可见光的利用、分子氧的活化和污染物分子矿化分解的机理仍然是今后的研究热点.本文就近年来在半导体光催化和负载型铁离子光催化降解有毒有机污染物的两个重要方面的研究进展进行了评述.     

漆酶催化氧化水中有机污染物*

漆酶是一种含铜的多酚氧化酶, 属于铜蓝氧化酶蛋白, 能催化氧化多种难降解的有机污染物。漆酶催化氧化水中有机污染物具有底物广泛、能耗低、易操作、环境友好等优点,是一项前景广阔的生物处理技术。本文综述了漆酶对水中有机污染物的催化降解,主要从漆酶的化学组成、结构、催化降解机理、漆酶的固定化、影响因素（溶液pH值、温度、金属离子、营养因子、有机溶剂、漆酶的浓度、底物的初始浓度等）、降解的动力学以及漆酶在处理水中有机污染物的应用等五个方面介绍了相关的研究进展。漆酶催化氧化有机物的机理主要表现在底物自由基中间体的产生和氧气还原成水两个方面。本文提出了目前漆酶催化氧化水中有机污染物存在的主要问题,并展望了漆酶降解水体中有机污染物的发展方向。     

环境中有机磷污染物碱性的理论研究

有机膦化合物的碱度对深入了解有机膦类污染物的降解有着重要的意义. 发展基于第一性原理的理论方法精确计算有机膦化合物的pKa值有重要意义. 本研究工作发展了精确计算有机膦阳离子化合物pKa值的方法: 用B3LYP/6- 31＋G(d)优化气相结构, PBEPBE计算单点能量, IEFPCM/Bondi (f＝1.0)计算溶剂化能. 理论值与实验值比较, 其平均偏差和均方根差分别为－0.6 pKa单位和0.7 pKa单位. 基于此方法, 我们研究了常见有机膦污染物阳离子的碱性, 定量计算其pKa值. 并进一步讨论了这类化合物的α取代效应和远程取代效应对其碱性的影响, 总结了影响杂环有机膦化合物阳离子酸性的因素.     

TiO2/AC光催化剂上气体污染物降解的反应动力学模型

 利用二氧化钛与活性炭(AC)共水热处理的方法制备了TiO2/AC复合催化剂,采用空气净化评价装置对其催化降解低浓度气体污染物丁醛的性能进行了模拟评价实验. 基于Langmuir-Hindshelwood方程和一些假设,推导了循环反应系统气体污染物降解的瞬态模型. 结果表明,该动力学模型所得数据与丁醛的模拟评价实验结果基本相符,预示着该模型能够很好地预测污染物的降解行为.     

双配体仿酶催化剂的制备及其光催化降解水中对苯二酚

以天然氯化血红素和咪唑为原料,制备了咪唑轴向五配位型的双配体配合物,并将其负载于羟基功能化的纤维素磁微球表面。 通过紫外-可见分光光度、傅里叶变换红外光谱、透射电子显微镜、热重分析和振动样品磁强（VSM）对催化剂进行表征。 在模拟太阳光照射下,以水中溶解氧为氧化剂,考察了该催化剂降解模拟废水中有机污染物对苯二酚（HQ）的性能。 结果表明,在300 W氙灯照射下,当催化剂用量0.2 g/L、HQ初始浓度20 mg/L及pH值为6的条件下,6 h后HQ的降解率达到96.97%,催化剂重复使用5次后,降解率仍可达92%以上。同时对该催化剂光催化降解对苯二酚的机理进行了初步研究。     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

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.     

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%).     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.     

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.     

Synthesis of substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.