Ion Association of Cadmium Acetate from Conductivity Measurements

Conductivity of cadmium acetate over the concentration range of 10^?4 to 10^?3M was measured at 25°C. The approximate dissociation constant of CdAc₂ in dilute aqueous solution was estimated from the relation, α=[Λ?36.5+39√C(1+2α)]/[57.9?93√C(1+2α)]. The limiting value of log₁₀K for the association constant of CdAc⁺ ion was evaluated to be 1.75 at 25°C.     

芥子气模拟剂2-氯乙基乙基硫醚的光催化降解

利用连续流动微反、原位红外和GC/MS等手段考察了芥子气模拟剂2-氯乙基乙基硫醚（2-CEES）在P25 TiO2上的光催化降解反应,证实CO2和H2O是这个反应的最终产物.详细的跟踪分析表明,除了CO2和H2O外,在反应的气相混合物中可检测到C2H4、CH3CHO、CH4、CO、HCl和H2S；少量小分子的羧酸、醚和砜；微量C2H5SC2H5、C2H5S2C2H5、C2H5SC2H4Cl和CH2ClCH2Cl等中间产物;在反应后的催化剂表面可检测到C2H5S2C2H5、C2H5SC2H4OH、C4H9S2C2H5和C2H5S2C2H4OH、等物.根据这些结果提出了2-CEES光催化降解的反应机理,推断2-CEES的光催化降解涉及脱氯、C－S键断裂、有机硫化物光聚合和裂解等复杂过程最终转化为CO2和H2O.认为各种硫物种在表面的积聚引起了催化剂的缓慢失活.     

Synthesis of a transition metal-dithionite complex, (η5-C5H5)(CO)2FeS(O)2S(O)2Fe(CO)2(η5-C5H5)

The reaction of Na[η⁵-C₅H₅Fe(CO)₂] with large excess of SO₂ in THF at ?78°C followed by warming to room temperature affords an iron—dithionite complex, (η⁵-C₅H₅)(CO)₂FeS(O)₂S(O)₂Fe(CO)₂(η⁵-C₅H₅).     

Catalytic phenomena in the electrochemical reduction of triphenylphosphine and triphenylphosphine oxide in non-aqueous solvents with tetraalkylammonium supporting electrolytes

Polarography, cyclic voltammetry and coulometry reveal that a catalytic reduction of the tetraalkylammonium cation, R₄N⁺, of the supporting electrolyte is involved in the electrochemical reduction of triphenylphosphine (TPP) and its oxide (TPPO) in aprotic solvents such as acetonitrile, dimethylformamide and hexamethylphosphoramide. There is however progressive consumption of TPP and TPPO resulting in the final formation of phenyl substitution products (RPØ₂ and ROPØ₂). Comparison with the reduction of the BuPØ₃⁺ cation allows to propose the following mechanism which involves a chemical type catalytic process:

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Redox type catalytic mechanisms are discussed and shown to be unlikely. Values of the alkylation rate constant are derived from the polarographic or the coulometric data or from cyclic voltammetry according to its magnitude which varies with the solvent. TPP anion radical appears as more readily alkylable than TPPO anion radical.     

β—环糊精交联聚合物与有机显色剂客体包结反应研究

β－环糊精与环氧氯丙烷交联共聚物是一种具有三维网状结构的聚合树脂，它保留了β－环糊精所原有的与有机疏水基团形成包结物的特性，与一系列含有芳得环的有机显色剂配体（如吡啶偶氮染料，变色酸双偶氮试剂，三苯甲烷类碱性与酸性染料以及杂氧蒽酮类试剂等）均可形成相应的包结配合物，着重研究了有关包结配合物的稳定性及影响稳定性的各种因素，为进一步研究包结物分离富集痕量金属提供必要的理论依据。     

Exciton interactions in CdS nanocrystal aggregates in reverse micelle

Here we report the formation and spectroscopic properties of cadmium sulfide (CdS) nanocrystal systems: individual nanocrystal and CdS aggregates. The optical absorption and luminescence spectra of the aggregated CdS nanocrystals and individual nanocrystal show exciton aggregate and individual exciton characteristics. Although it is not Bose-Einstein condensation, such aggregated quantum dots (QDs) seem to supply us opportunity to study the interactions and condensation of excitons in multi-QDs system, not in the separated QDs system.     

Mechanism of sorption of phenols from aqueous solutions onto surfactant-modified montmorillonite

Equilibrium and kinetic studies on the sorption of phenol, m-nitrophenol (m-NP), and o-cresol from water onto montmorillonite modified with cetyltrimethylammounium bromide (CTAB) were conducted. Experiments were carried out as a function of solution pH, sorbate concentration, and temperature (25-55 degrees C). It was shown that the sorption capacity decreased in the order phenol>o-cresol>m-NP. The Langmuir, dual-mode sorption, and Redlich-Peterson models were tested to fit the sorption isotherms of single-solute systems, whereas the Langmuir competitive model was used to describe bisolute sorption equilibria. Thermodynamic parameters (DeltaH degrees and DeltaS degrees ) and the mean free energy (E) for the sorption of phenols were determined from the temperature dependence of the distribution constant and the Dubinin-Radushkevick equation, respectively. A simplified kinetic model was proposed to confirm the sorption mechanism.     

Adsorption separation of terpene lactones from Ginkgo biloba L. extract using glass fiber membranes modified with octadecyltrichlorosilane

In this study porous glass fiber membranes were modified by reaction with octadecyl-trichlorosilane to form C18 hydrophobic membranes. The contact angle and the CH2 vibration bands at 2855 and 2920 cm(-1) found by FTIR measurements verified the successful immobilization of C18 groups on the glass fiber membranes. The resulting C18 hydrophobic membranes were used to adsorb terpene lactones from crude Ginkgo biloba L. extracts. In batch adsorption processes, the modified C18 membranes exhibited a better adsorption performance than commercial C18 solid phase extraction adsorbents. Different desorption solvents were tested and ethyl acetate was found to preferentially desorb terpene lactones from the modified C18 membranes. In flow adsorption experiments at 1 mL/min, terpene lactone contents higher than 6 wt% (the standardized content) could be achieved in the elution step using ethyl acetate.     

Preparation and characterization O-lauroyl chitosan/poly (L-lactic acid) blend membranes by solution-casting approach

O-Lauroyl chitosan/poly(L-lactide) (OCS/PLLA) blend membranes with different compositions were prepared by solution-casting approach using chloroform as common solvent. The experimental results of FT-IR, DSC and WAXD indicated that inter-association hydrogen-bond interactions existed between OCS and PLLA in the blend membranes. And SEM observation confirmed that the blend membranes with suitable compositions were compatible.     

12-钼磷酸—聚乙烯醇的光电子转移反应

12-钼磷酸—聚乙烯醇体系具有不可逆光致变色的特性。根据X射线光电子能谱、电子自旋共振谱、紫外及可见光谱的测试结果,笔者认为:在PMo_(12)-PVA的光电子转移反应中,PMo_(12)既是氧化剂也是光敏剂。PMo_(12)分子中氧可分成O_p、O_b和O_t三种情况.其中O_t可成为光化学的活性位置,它和PVA羟基上的氧均较易被紫外光激活。激活的0_t边使周围的一个电荷向金属原子(Mo~(Ⅵ))转移,边与PVA羟基上被激活的氧作用,电子就由此羟基上的氧向O_t转移,致使体系中部分PMo_(12)与PVA发生二电子或四电子氧化还原反应,形成Mo(Ⅵ、Ⅴ)配合物而变色,同时,PVA分子的部分羟基及该羟基位的碳上脱氢形成羰基而具有酮结构。此外,从Mo(V)的ESR特征信号随时间变化而减弱,但其吸收光谱的吸光度未变,于是推断该光化学反应过程中尚有Mo(Ⅳ)生成,已由XPS谱证实。