检索结果-南通市图书馆

Rare Metals 2019年第1期38卷 87-94页

作者： Xiang Li Jian-Kang Wen Xiao-Lan Mo Wu Biao Dian-Zuo Wang Hong-Ying Yang National Engineering Laboratory of Biohydrometallurgy General Research Institute for Nonferrous Metals School of Metallurgy Northeastern University

Accumulation of toxic ions in leachate is one factor limiting bioleaching applications. The effect of fluoride ions on the growth of bioleaching microorganisms has been extensively emphasized. In this study, HF is found to be the toxic form of fluoride that affects the bacterial activity under acidic conditions. The added aluminum could compete with H^+ to complex with F-, thus significantly decrease the concentration of HF and finally reduce the toxicity of fluoride to bacteria. When F^-/Al^(3+)concentration ratio is 0.5:1.0, Fe^(2+) oxidation rate could reach 0.167 g·L^(-1)·h^(-1), close to that of the biotic control group(0.195 g·L^(-1)·h^(-1)). The competitive complexation mechanism of fluoride by AlF_n^(3-n) results in stability constants of AlF_n^(3-n) complex(7.00) that are larger than those of HF(3.18). The F^-/Al^(3+) concentration ratio in the medium could affect the speciation of AlF_n^(3-n) *** the decrease in F^-/Al^(3+) concentration ratio, the coordination numbers of AlF_n^(3-n) decrease. Finally, the feasibility of fluoride detoxification by aluminum ion is verified. This work has meaningful implications for fluoride-containing bacterial bioleaching systems.

关键词： Competitive complexation Detoxification Fluoride Aluminum Bioleaching

Concentration of linoleic acid from cottonseed oil by starch complexation

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2019年第4期27卷 845-849页

作者： Dan Liang Yufeng Hu Weiting Ma Zhengtang Zhao Siqi Jiang Yichuan Wang Xianming Zhang State Key Laboratory of Heavy Oil Processing China University of Petroleum

The extraction of linoleic acid from fatty acids(FA) of the cottonseed oil using starch–FA complexes was developed for the first time. We showed that starch can form inclusion complexes of different strengths with FA and that the different strengths stem from the differences in chain length, degree of unsaturation, and position of double bonds of FA. The optimal separation conditions were determined as follows: The inclusion temperature is 69 °C, the inclusion time is 30 min, the starch/FA mass ratio is 10:1, and the ratio of the volume of methanol–water solution and the mass of FA is 18:1. Compared to urea inclusion complexation, starch complexation has milder reaction temperature and shorter reaction time. Under these conditions, linoleic acid can be concentrated from 38.9% to 70.04% by one-off extraction. Moreover, the experimental results demonstrate the almost perfect reusability of starch. These results show that starch complexation is a promising method that can be used to obtain highly concentrated linoleic acid from cottonseed oil.

关键词： Starch Linoleic acid Starch complexation Starch–FA complex Cottonseed oil

Recent developments of surface complexation models applied to environmental aquatic chemistry

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2001年第4期13卷 422-434页

作者： Liu, W.-X. Tang, H.-X. SKLEAC Res. Cntr. Eco-Environmental Sci. Chinese Academy of Sciences Beijing 100085 China

Based on numerous latest references, the current developments in surface complexation, surface precipitation and the corresponding models (SCMs and SPMs), were reviewed. The contents involved comparison on surface charge composition and layer-structure of solid-solution interface for the classical 1-pK and 2-pK models. In addition, the fundamental concept and relations of the new models, i. e., multi-site complexation (MUSIC) and charge- distribution (CD) MUSIC models were described as well. To avoid misuse or abuse, it must be emphasized that the applicability and limitation for each model should be considered carefully when selecting the concerned model(s). In addition, some new powerful techniques for surface characterization and analysis applied to model establishment and modification were also briefly introduced.

关键词： complexation Precipitation (chemical)

Effects of Anions and Cations on π-complexation Between Olefin and Metal Halide

在线全文

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2005年第2期21卷 217-219页

作者： ZHOUJin-xia ZHANGYong-chun GUOXin-wen StateKeyLaboratoryofFineChemical DalianUniversityofTechnologyDalian116012P.R.China

An ab initio molecular orbital study was performed to determine the effects of anions and cations on the π-complexation of C_2H_4 on MX(M=Ag, Cu; X=F, Cl). The calculated results show the following order of adsorption strength: F ->Cl - for anions; Cu +>Ag + for cations. The results can be explained by the detailed analysis of atomic charge, orbital energy and orbital population by using the natural bond orbital(NBO) theory: (1) anions with stronger electronegativity can attract more electrons from the s orbital of M, while at the same time it does not obviously weaken the d orbital occupation of M, thus the nearly vacant s orbital and the sufficiently filled d orbitals of M help with forming σ-donation and d-π * backdonation with the π orbital and the π * orbital of olefin, respectively; (2) a smaller energy gap of symmetry-adapted orbitals between olefin and a cation can favor the electron transfer, that is why Cu + forms stronger adsorption with olefin than Ag + does.

关键词： complexation ab initio Calculation Olefin Anion Cation

Theoretical studies on the complexation of uranyl with typical carboxylate and amidoximate ligands

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2013年第11期56卷 1525-1532页

作者： XU ChaoFei SU Jing XU Xiang LI Jun Department of Chemistry & Key Laboratory of Organic Optoelectronics and Molecular Engineering of the Ministry of Education Tsinghua University Division of Nuclear Materials Science and Engineering Shanghai Institute of Applied PhysicsChinese Academy of Sciences Key Laboratory of Nuclear Radiation and Nuclear Energy Technology Chinese Academy of Sciences College of Chemistry and Pharmaceutical Sciences Qingdao Agricultural University

Understanding of the bonding nature of uranyl and various ligands is the key for designing robust sequestering agents for uranium extraction from seawater. In this paper thermodynamic properties related to the complexation reaction of uranyl（VI） in aqueous solution （i.e. existing in the form of UO2（H20）52＋） by several typical ligands （L） including acetate （CH3CO2）, bicar- bonate （HOCO2-）, carbonate （CO32-）, CH3（NH2）CNO- （acetamidoximate, AO-） and glutarimidedioximate （denoted as GDO2-） have been investigated by using relativistic density functional theory （DFT）. The geometries, vibrational frequencies, natural net charges, and bond orders of the formed uranyl-L complexes in aqueous solution are studied. Based on the DFT analysis we show that the binding interaction between uranyl and amidoximate ligand is the strongest among the selected complexes. The thermodynamics of the complexation reaction are examined, and the calculated results show that complexation of uranyl with amidoximate ligands is most preferred thermodynamically. Besides, reaction paths of the substitution complexation of solvated uranyl by acetate and AO have been studied, respectively. We have obtained two minima along the reaction path of solvated uranyl with acetate, the monodentate-acetate complex and the bidentate-acetate one, while only one minimum involving monodentate-AO complex has been located for AO- ligand. Comparing the energy barriers of the two reaction paths, we find that complexation of uranyl with AO is more difficult in kinetics, though it is more preferable in thermodynamics. These results show that theoretical studies can help to select efficient ligands with fine-tuned thermodynamic and kinetic properties for binding uranyl in seawater.

关键词： uranyl seawater carboxylate amidoximate complexation thermodynamics density functional theory

Synthesis, complexation properties and crystal structure of 4',5'-dibromo-oxylyl-17-crown-5 ether

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 1996年第5期14卷 447-453页

作者： XIONG,Guo-Xiang ZHOU,Qing-Fu XU,Hui-JunInstitute of Photographic Chemistry,Chinese Academy of Sciences,Beijing 100101,China Institute of Photographic Chemistry Chinese Academy of Sciences Beijing 100101 China

4',5'-Dibromo-o-xylyl-17-crown-5 ether (2BrB17C5) was synthesized,starting from 1,2-dibromo-4,5-bis(bromomethyl)-benzene and tetraethylene glycol,and was characterized by 1H NMR,MS and elemental *** yellow prismatic single crystal obtained from anhydrous ethanol was investigated by X-ray structural *** complexation properties toward alkali metal ions were examined using the solvent extraction method and UV absorption *** crown ether was found to be conformationally deformed and oblate-like and is highly selective for lithium ion.

关键词： Crown ether complexation crystal structure

Ultra-deep Removal of Metal Ions from Coal Tar by complexation:Experimental Studies and Density Functional Theory Simulations

在线全文

学校读者我要写书评

暂无评论

中国炼油与石油化工:英文版 2023年第3期25卷 127-135页

作者： Wu Hao Wei Hongyuan Li Wangliang School of Chemical Engineering and Technology Tianjin UniversityTianjin 300350China SINOPEC Research Institute of Petroleum Processing Co. Ltd.Beijing 100083China CAS Key Laboratory of Green Process and Engineering Institute of Process EngineeringChinese Academy of SciencesBeijing 100190China

As one of the important aspects of upgrading coal tar,the ultra-deep removal of metal ions via the complexation method was investigated by screening four complexing agents and performing density functional theory(DFT)*** of the compositions and contents of the metallic compounds in the coal tar revealed that the main components were iron and calcium *** filtration reduced the mechanical impurity content from 0.24%to 0.0752%,indicating that most of the large particles could be easily *** the four complexing agents,namely,acetic acid,oxalic acid,citric acid,and ethylenediaminetetraacetic acid,oxalic acid exhibited the best demetallization *** DFT simulations suggested that the high performance of oxalic acid originated from its 1:1 coordination mode,rigid dicarboxyl structure,and greater binding energy.

关键词： complexation metallic compounds coal tar upgrading density functional theory

A Novel Synthesis of 2-Amino-2-deoxy-D-gluconic Acid and Its complexation with Cu（Ⅱ） in Alkaline Medium

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 2006年第10期24卷 1458-1461页

作者：顾文秀夏文水 The School of Chemical & Material Engineering Southern Yangtze University Wuxi Jiangsu 214036 China The School of Food Southern Yangtze University Wuxi Jiangsu 214036 China

A novel synthesis of the functional carbohydrate 2-amino-2-deoxy-D-gluconic acid was introduced and its complex formation with Cu（Ⅱ） was investigated to obtain the stability constant for its further applications to the food and pharmaceutical industries. The equilibrium was investigated by spectrophotometric measurements and processed by dual-series linear regression method. Results： the yield of 2-amino-2-deoxy-D-gluconic acid is 70%. The complexation molar ratio is 1 ： 2, the molar apsorptivity of the complex is 39.906 L·mol^-1·cm^-1 at 630 nm, and the stability constant βn is 6.24 × 10^5.

关键词： 2-amino-2-deoxy-D-gluconic acid complexation synthesis copper(Ⅱ)

Synthesis and complexation Properties of Novel Biscalixarene Composed of Calix[4]arene and Thiacalix[4]arene Subunits

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2006年第8期17卷 1029-1032页

作者： Fa Fu YANG Xia ZHAO Cui Yu HUANG Hong Yu GUO Si Ning ZHENG Qi PENG College of Chemistry and Materials Fujian Normal University Fuzhou 350007 State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of Matter China Academy of Science Fuzhou 350002

The first example of biscalixarene composed of calix[4]arene and thiacalix[4]arene subunits 3 was facilely synthesized and showed good complexation properties for metal cations and zwitterionic α-amino acids.

关键词： Biscalixarene thiacalixarene complexation cation amino acid.

The　Rmodynamic　Study　on　the　Aqueous　complexation　of　Metal　CationswithN－aceticAcidSubstitutedTetraazamacrocycle

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 1996年第9期7卷 862-863页

作者： Bi, JH Xie, FX Chen, LQ Ni, SS ANHUI INST EDUC DEPT CHEMHEFEI 230061PEOPLES R CHINA ANHUI UNIV DEPT CHEMHEFEI 230039PEOPLES R CHINA

The stability constants of the 1:1 complexes of H4L (5.12-diphenyl-7.14-dimethyl-1,4,8,11-tetraazamacrocyclotetradecane-N',N',N'',N''-tetraacetic acid) with M(2-) ions (M=***,Co,Zn,Mn,***,***,Ba) were determined in 0.5 mol L KCl aqueous solution at 45℃,50℃ and 60℃ by potentiometric titration and computer fitting. The △H and △S of the coordination reaction in the solution were given.

关键词： complexation Metal Aqueous