巯基棉分离富集甲酚红光度法测定垃圾渗滤液中的镉

1引言 垃圾渗滤液中含有的重金属可能造成土壤中重金属污染,故对镉的分析方法进行研究具有一定意义.目前,对镉的光度法测定已有较多报道,但均未对垃圾渗滤液中镉的测定进行研究.本实验在对渗滤液进行除臭、除污及色度处理后,采用巯基棉分离富集-甲酚红(CRR)显色光度法测定Cd2 的含量,灵敏度较高,选择性较好,方法相对简便快速.     

食品包装材料上油墨中残留烷基苯成分分析及其迁移性的GC-MS研究

建立了一种食品包装材料上多色油墨中残留烷基苯成分的提取和气相色谱-质谱联用(GC-MS)分析方法. 采用选择离子检测(SIM)模式, 以内标定量法对某些食品包装材料上多色油墨中烷基苯残留量进行了准确定量分析. 对油墨中残留烷基苯向食品中迁移的初步研究结果表明, 包装材料上油墨中的苯及苯系物等有害物质可能透过薄膜进入食品而造成污染.     

FCC催化剂氢气还原活化脱镍研究

我国的FCC催化剂在使用中镍污染较为严重, 镍不仅会破坏催化剂的结构, 而且还会影响反应产物的分布, 增加企业的生产成本. 本研究提出了氢气还原活化＋稀硝酸洗涤的脱镍新方法, 具有良好的效果. 镍在FCC催化剂上以NiAl₂O₄和Ni₂SiO₄的形式存在, 这些物种在700 ℃以下就可以被氢气还原, 并且随着温度的升高, 不仅催化剂表面的镍能够被还原, 而且催化剂体相中的镍也可以迁移到表面从而被还原, 但这种迁移受到平衡的限制. 还原后生成的金属镍可以溶于稀硝酸, 因而可以洗涤除去. 在适宜的条件下, 经过一次还原＋酸洗处理, 脱镍率可达到50%以上; 经过两次处理, 脱镍率可达75%以上. 脱镍后催化剂的微反活性可以得到大幅度提高.     

蓝藻水华衍生的微囊藻毒素污染及其对水生生物的生态毒理学研究

富营养化导致的蓝藻水华频发,引发各种衍生物污染,严重时造成重大生态灾害事件,甚至危及人类健康。其中微囊藻毒素以其毒性大、分布广和结构稳定的特点,成为水环境中常见的潜在危害物质,它主要由微囊藻产生,是一类具有多种异构体的环状七肽物质。本文根据微囊藻毒素污染现状及其水生生态毒理学研究的最新研究进展,介绍了微囊藻毒素的理化性质及其产生、迁移和转化,在我国天然水体、水库源水和饮用水中的污染现状以及部分水产品中的微囊藻毒素累积情况,较全面地评述了微囊藻毒素的分子致毒机理以及对水生生态系统的重要组成成分--常见水生植物和鱼类的生态毒理学效应,并提出了该领域未来研究的主要方向。     

激光工艺雕刻双色板挥发性物质气相色谱-质谱分析

激光工艺雕刻过程中,聚合物材料会产生难闻的气味,释放出有毒有害的挥发性物质,严重污染了周边空气质量,损害了附近居民的身体健康。目前,该行业排放废气的主要污染物成分和含量,以及如何监控等问题国内外均未见文献报道。本文开展对激光工艺雕刻产生挥发性物质的分析,对于确定     

焦炭-NO异相还原的密度泛函理论研究进展

燃煤电站中煤炭高温燃烧时产生的氮氧化物(NOx)对环境产生严重污染,控制NOx污染物排放成为全世界的共同行动.焦炭-NO异相还原反应在燃煤过程中普遍存在,但由于焦炭复杂的化学结构和成分以及燃烧反应中气固成分,焦炭-NO异相还原反应的机理尚不明晰.本研究通过总结焦炭-NO异相还原反应机理的密度泛函理论方面的研究,从焦炭模...     

离子型稀土矿山浸矿土壤的氮化物迁移实验研究

赣南离子型稀土浸矿开采过程中,因大量使用(NH_4)_2SO_4作浸矿剂造成土壤氮化物累积,引发矿区土壤及水体氮化物的持续严重污染。通过模拟土柱实验,测定原矿土壤(未开采的稀土矿土壤)和一般土壤(矿山周边的普通土壤)在模拟浸矿过程中氮化物的污染含量,研究氮化物在土柱实验中的迁移特征及规律。结果表明:浸矿过程中,原矿土壤和一般土壤中氮化物主要以铵态氮形式存在,说明铵态氮是导致稀土矿区土壤污染和水环境污染的主要原因;同时由于土壤的固氮作用、淋滤过程中铵态氮向下迁移及减少的共同作用,致使试验中原矿土壤和一般土壤铵态氮含量总体随天数表现为降低、升高、再降低趋势;并且与一般土壤相比,原矿土壤中稀土离子和NH~+_4会发生交换解析作用增加原矿土壤的固氮作用,同时稀土的存在会增加土壤本身对氮化物的吸附能力。研究结论为赣南离子型稀土矿浸矿过程中氮化物的迁移规律提供基础依据。     

RbCl由H2O至混合溶剂(H2O-DMF)标准迁移熵的测定

电解质迁移热力学性质的测定,对于离子溶剂化的研究具有重要意义.迁移自由能主要反映离子与溶剂分子间的相互作用,迁移熵则主要反映不同溶剂分子间的相互作用,迁移熵随温度及溶剂组成的改变可为溶剂的原有结构推测及溶液秩序改变提供信息.我们曾运用离子选择性电极测定了部分碱金属卤化物在水及含水混合溶剂中的热力学性质[1-3].本文用离子选择性电极方法,通过测定不同温度下电池的标准电动势,根据溶液热力学原理,求得ＲｂＣｌ由Ｈ2Ｏ至混合溶剂(Ｈ2ＯＤＭＦ)的标准迁移自由能ΔＧｔ及其温度系数,计算ＲｂＣｌ的标准迁移熵ΔＳｔ.结果尚未见…     

稀土精矿冶炼过程放射性元素迁移分布规律

中国稀土资源储量巨大,但多为天然放射性核素伴生矿,放射性污染问题一直以来都是关注的焦点。随着稀土矿石的开发利用,这些放射性核素随之迁移,扩散,重新分布和富集,并随着稀土矿冶炼过程产生的三废进入到环境中,处理不当就会成为严重的环境污染问题,也会造成资源的浪费。放射性核素是核能发展中的重要元素,为了更好地利用处置放射性核素,应该清楚这些核素的迁移、分布和富集过程和规律。通过实地调研,考察和查阅大量文献,总结出几大稀土矿主流冶炼工艺过程中放射性元素的迁移分布规律和富集过程。结果表明:几大稀土矿虽然冶炼工艺不同,但其中放射性元素90%左右迁移、富集到冶炼废渣中,剩余少部分分布到废水、废气及产品中。因此,需要加大稀土矿冶炼新工艺的研究及现行工艺的技术改造,从源头解决放射性废渣的污染和堆存问题;研究开发现存的冶炼废渣中稀土、钍(铀)等有价元素回收利用工艺,实现废渣减量化、资源化和无害化。     

微波消解试样-电感耦合等离子体质谱法测定鱼体中锌、铁、铅、铬、镉和汞的含量

重金属是具有潜在危害的重要污染物,它会被湖泊或海洋中沉积物或悬浮物所吸附,并在生物体内富集,成为持久污染物,对环境造成严重的污染。水体一旦受到严重的重金属污染,生物的食用卫生质量就会受到影响。金属元素含量的测定多采用原子吸收光谱法,其灵敏度高,准确性好,但不能实     

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.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

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.     

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.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

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.