EDTA络合滴定法间接测定水泥中SO3

ＥＤＴＡ络合滴定法间接测定水泥中ＳＯ_３郑礼胜，王士龙，张虹山东建材工业学院（２５００２２）基于形成ＢａＳＯ４沉淀而建立的ＥＤＴＡ络合滴定法间接测定硫酸根，是采用加入过量的ＢａＣｌ２将其沉淀为ＢａＳＯ４，再用ＥＤＴＡ滴定剩余的Ｂ２２［１－３］，或者是?..     

表面活性剂和四烷基溴化铵的复配：Ⅱ.四乙基溴化铵对离子型表面活性剂 …

用表面张力法研究了有机电解质四乙基溴化铵（（Ｅｔ）４ＮＢｒ）对离子型表面活性剂十二烷基硫酸钠（ＳＤＳ）和十二烷基三甲基溴化铵（ＤＴＡＢ）在气／液表面吸附行为的影响。表明（Ｅｔ）４ＮＢｒ提高了ＳＤＳ和ＤＴＡＢ降低水溶液表面张力的效率。但（Ｅｔ）４ＮＢｒ仅提高ＤＴＡＢ降低水溶液表面张力的能力,却反而削弱了ＳＤＳ降低水溶液表面张力的能力。通常电解质对离子表面活性剂表面吸附层的影响主要来自与表面活性离子电     

表面活性剂增容PVC／SBR共混体系相容性研究

本文通过ＤＳＣ、振簧仪研究了聚氧化乙烯类表面活性剂作为增容剂对ＰＶＣ／ＳＢＲ共混物相容性的影响，并用扫描电镜（ＳＥＭ）观察了ＰＶＣ／ＳＢＲ共混物中橡胶分散相的形态结构和尺寸变化。结果表明，在ＰＶＣ／ＳＢＲ共混物中加入适量的表面活性剂可明显改善两相的相容性，橡胶分散相尺寸随表面活性剂用量、液体石蜡用量的变化而变化。     

表面活性剂和四烷基溴化铵的复配 Ⅱ.四乙基溴化铵对离子型表面活性剂在气/液表面吸附行为的影响

用表面张力法研究了有机电解质四乙基溴化铵（（Ｅｔ）４ＮＢｒ）对离子型表面活性剂十二烷基硫酸钠（ＳＤＳ）和十二烷基三甲基溴化铵（ＤＴＡＢ）在气／液表面吸附行为的影响。表明（Ｅｔ）４ＮＢｒ提高了ＳＤＳ和ＤＴＡＢ降低水溶液表面张力的效率。但（Ｅｔ）４ＮＢｒ仅提高ＤＴＡＢ降低水溶液表面张力的能力,却反而削弱了ＳＤＳ降低水溶液表面张力的能力。通常电解质对离子表面活性剂表面吸附层的影响主要来自与表面活性离子电性相反的反离子,它们屏蔽了表面活性剂离子头基间的电荷,致使表面活性剂在气／液表面层排列紧密。有机电解质离子（Ｅｔ）４Ｎ＋作为反离子时,除了具有电解质离子的通常性能外,其乙基和表面活性剂碳氢链间还有一定程度的弱疏水相互作用,使部分（Ｅｔ）４Ｎ＋离子嵌入ＳＤＳ吸附层的离子头基区中,较大（Ｅｔ）４Ｎ＋离子的嵌入使周围的ＳＤＳ碳氢链排列疏松,改变了朝向空气面的表面碳氢链覆盖层结构,从而削弱了其降低表面张力的能力。     

5－Br－TAR的合成及其在反相HPLC分离测定Co（Ⅱ）、Cr（Ⅵ）、Rh（Ⅲ）中的应用

以合成的新试剂５－Ｂｒ－ＴＡＲ为往前衍生试剂，首次用阴离子表面活性剂Ｓ，Ｄ．Ｓ．为对离子试剂。以含１×１０（－２）ｍｏｌ·Ｌ（－１）的ｐＨ５．８的乙酸－乙酸钠缓冲溶液和３．５×１０（－４）ｍｏｌ·Ｌ（－１）的Ｓ．Ｄ．Ｓ．的甲醇－水（６８：３２，Ｖ／Ｖ）为流动相，在Ｃ（１８）柱上，１５ｍｉｎ内分离测定了Ｃｏ（Ⅱ）、Ｒｈ（Ⅲ）、Ｃｒ（Ⅵ）的５－Ｂｒ－ＴＡＲ配合物。当ＳＮＲ＝２时，检出限分别为０．４９、０．３２、０．４４ｐｐｂ。用于废水及电镀液中Ｃｏ（Ⅱ）、Ｃｒ（Ⅵ）的测定，效果较好。     

异辛酸亚锡中总Sn和Sn（Ⅱ）的测定

本文研究了ＫＩＯ３滴定法，ＥＤＴＡ络合滴定法和偏锡酸重量法测定异辛酸亚锡中总Ｓｎ（ＴＳｎ，ＫＩＯ３）直接滴定法和Ｋ２Ｃｒ２Ｏ７间接滴定法测定Ｓｎ。     

选择性螯合滴定法测定镍含量

选择性螯合滴定法测定镍是采用过量ＥＤＴＡ螯合镍离子及其它金属离子，然后用ＳＣＮ＾－，Ｃ５Ｈ５Ｎ选择分解Ｎｉ－ＥＤＴＡ，释放出ＥＤＴＡ，用Ｐｂ（ＮＯ３）２标准溶液滴定，从而计算镍的含量。以ＸＯ－ＭＴＢ－ＣＰＢ为混合指示剂，终点变化敏锐。本法操作简便，结果准确，可用于测定电镀液和镍基合金镀层中的镍。     

新型阴离子表面活性剂与十二烷基三甲基溴化铵的相互作用

本文研究了新型阴离子表面活性剂二氧乙基月桂醇醚羟丙基磺酸钠（Ｃ１２ＥＯＰＳ）与十二烷基三甲基溴化铵（ＤＤＴＡＢ）的复配体系，通过测定表面张力γ和ｃｍｃ计算了在这些体系中分子间的相互作用参数β＾ｍ和β＾ｓ及标准自由能ΔＧ＾０ｍｉｃ、ΔＧ＾０ａｄ。进而讨论了这些复配体系的增效作用。     

用MSA作释放剂选择性螯合滴定法测定锆

本法提出测定锆的简易、快速螯合滴定法。向含有锆（Ⅳ）和其它阳离子的溶液中，加入过量的ＥＤＴＡ，在ｐＨＳ～６时以ＸＯ（二甲酚橙）－ＣＰＢ（溴化十六烷基吡啶）为混合指示剂，用Ｚｎ（ＮＯ３）。标准溶液返滴过量的ＥＤＴＡ。然后加入巯基丁二酸（ＭＳＡ）分解Ｚｒ－ＥＤＴＡ螯合物，释放出的ＥＤＴＡ，用Ｚｎ（ＮＯ３）２标准溶液滴定．终点变化更加敏锐．研究了各种离子的干扰．此法已被用于测定锆英石矿、高温耐火涂料中的锆，结果是满意的．     

用TGA作释放剂选择性螯合滴定法测定锡

叙述了选择性螯合滴定法测定锡。在含有锡（Ⅳ）和其它阳离子的溶液中，加入过量ＥＤＴＡ，在ｐＨ５～６，以ＸＯ－ＣＰＢ为混合指示剂，用Ｐｂ（ＮＯ３）２标准溶液返滴过量的ＥＤＴＡ。然后加巯基乙酸（ＴＧＡ）分解Ｓｎ（Ⅳ）－ＥＤＴＡ螯合物，释放出的ＥＤＴＡ，用Ｐｂ（ＮＯ３）２返滴定。研究了各种阳、阴离子的干扰。此法用于测定镀铅锡合金溶液、无氰铅基合金镀层中锡的含量。     

Mechanism of micelle formation in sodium dodecyl sulfate and cetyltrimethylammonium bromide

pH changes as a function of concentration for sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB) were observed by addition of 1 N HCl and 1 N KOH. pH values increased up to the critical micellar concentration (CMC) for the SDS/HCl system and decreased for the CTAB/KOH system. In the SDS/HCl and CTAB/KOH systems, the micellar phase had a fixed composition and was homogeneous and monodisperse above the CMC. However, in the SDS/KOH and CTAB/HCl systems, pH values increased continuously and gradually below and above the CMC, and the properties of the micellar phase changed as a function of concentration, giving rise to inhomogeneity and polydispersity.     

Ratiometric Interactions of Anionic Surfactants with Calf Thymus DNA Bound Cationic Surfactants: Study II

Cationic surfactant cetyltrimethylammonium bromide (CTAB) and cetylpyridinium bromide (CPB) bind to the calf thymus DNA (ct‐DNA) like anionic biopolymers electrostatically, and establish equilibrium in aqueous medium at pH 7. At low concentration, ct‐DNA does not interact with anionic surfactants, sodium dodecylsulfate (SDS) and sodium dodecylbenzylsulfonate (SDBS). However, in the ground state, anionic surfactant is found to clearly establish equilibrium with ct‐DNA‐bound cationic surfactant whereby the same surfactant–DNA isosbestic point reappears. We herein report a detail ratiometric binding of CPB with ct‐DNA, and interaction of anionic SDBS with DNA‐bound CPB in comparison with the combined ct‐DNA–CTAB–SDS system. Compaction of ct‐DNA in presence of CPB and its decompaction using anionic SDBS is also studied in comparison with CTAB–SDS combination. The techniques used are tensiometry, spectrophotometry, viscometry, cyclic voltammetry, circular dichroism, isothermal titration calorimetry, and density functional theory (DFT)‐based computational calculations. The size and surface charge density of the surfactant headgroups and the phosphate group in DNA have a contributing role in the DNA compaction–decompaction phenomenon.     

Effect of cefoperazone sodium on the physicochemical properties of surfactants

The effects of cefoperazone sodium (CS), a pharmaceutical compound, on the critical micelle concentration (CMC) of surfactants with different charges [cetyl trimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), and Triton X-100], the cloud point of Triton X-100, and the Krafft temperatures of SDS and CTAB were studied. The interaction of CS with differently charged surfactants was determined by ultraviolet and fluorescence spectrophotometry. The results show that with increasing CS concentration, the Krafft temperature increases and the CMC decreases in the SDS/H₂O system, whereas the opposite results are obtained in the CTAB/H₂O system. Both the cloud point and the CMC of Triton X-100 increase with the addition of CS. The above results are attributed to the different micellar interactions between CS and surfactants with different charges.     

Rheo-kinetics of bovine serum albumin in catanionic surfactant systems

The effects of catanionic surfactant systems consisting of mixtures of cationic cetyltrimethylamonium bromide (CTAB) and anionic sodium dodecyl sulfate (SDS) on the rheological properties and kinetics of bovine serum albumin (BSA) were investigated. The ionic strength of the solution was varied by using different mixing ratio of SDS and CTAB. Gelation curves observed in dynamic viscoelastic measurements were fitted with gelation kinetics models to describe the gelation under isothermal and non-isothermal conditions. Overall, the gelation of BSA in cationic-rich solutions was found to be more energetically favorable when compared with BSA solvated in anionic-rich solutions. Consequently, highest gel temperature (T_gel) and time (t_gel) were observed for anionic-rich solutions with SDS/CTAB molar ratio of 4.0 (i.e., SDS/CTAB=4.0), while lowest gel temperature and time were found for cationic-rich solutions with SDS/CTAB molar ratio of 0.25 (SDS/CTAB=0.25). BSA in equal molar ratio of the mixed surfactants (SDS/CTAB=1.0) showed a gel temperature and time in the halfway between the anionic and cationic-rich regions. Interestingly, under isothermal and non-isothermal conditions, BSA in equimolarly mixed and anionic-rich solutions showed a heat-dependent protective effect against thermal denaturation and gelation. The protective effect on BSA gelation in equimolar and anionic-rich solutions was diminished by increasing the catanionic concentration under non-isothermal conditions, while under isothermal conditions, protective effect on BSA gelation increased with catanionic concentration. On the other hand, cationic-rich solutions did not protect BSA from thermal denaturation and gelation, and therefore the gelation rate increased with catanionic concentration in all heating conditions examined.     

A Comparative Study on the Aggregation and Thermodynamic Properties of Anionic Sodium Dodecylsulphate and Cationic Cetyltrimethylammonium Bromide in Aqueous Medium: Effect of the Co-solvent N-Methylacetamide

The effect of co‐solvent N‐methylacetamide (NMA) (0.035, 0.046, 0.127, and 0.258 mol kg^?1) on the micellization behaviour of anionic surfactant sodium dodecylsulphate (SDS) (3.21–10.35 mmol kg^?1) and cationic surfactant cetyltrimethylammonium bromide (CTAB) (0.19–3.72 mmol kg^?1) in aqueous solution was explored by employing conductivity measurements at different temperatures (298.15–313.15 K). The critical micelle concentration (CMC) values for SDS and CTAB in aqueous solutions of NMA were determined from the conductivity versus surfactant concentration plots. The variations in the CMC values of SDS with NMA concentration are in striking contrast to those observed in the case of CTAB. The various relevant thermodynamic parameters of micellization, viz. standard enthalpy change, ΔH_m^o, standard entropy change, ΔS_m^o, and standard Gibbs free energy change, ΔG_m^o, were determined using the temperature variation of the CMC values and counterion binding. The results not only relate these thermodynamic parameters to the consequences of intermolecular interactions but are also able to differentiate between SDS–water–NMA and CTAB–water–NMA systems in terms of contributions from head groups as well as alkyl chains of surfactants.     

木质素胺的电导滴定

分别以不同浓度的十二烷基硫酸钠对各木质素胺水溶液进行电导滴定,并根据十二烷基硫酸钠的反应量及溶液电导率的变化,可确定滴定终点,从而能够对各木质素胺样品的改性率程度进行比较.     

Phase behavior of aqueous two-phase systems of cationic and anionic surfactants and their application to theanine extraction

Phase behavior of aqueous two-phase systems (ATPS) containing cationic (SDS) and anionic (CTAB) surfactants and its application to theanine extraction was studied. Results indicated the ATPS could form under the certain SDS/CTAB molar ratio; there was a reasonable consistency between the conductivity and the formation region of ATPS, and the viscosity was higher in the formation region of ATPS. Additionally, the phase ratio increased with increase of CATB concentration, and the interfacial film between the top phase and the bottom phase was resilient. Moreover, the theanine extraction with ATPS was realized in the waste liquid of tea polyphenol production (WLTPP), and the partition coefficient of theanine decreased with increase of WLTPP concentration, whereas the extraction rate of theanine increased. The partition coefficient decreased with increasing SDS/CTAB molar ratio, and the extraction rate of theanine increased with increase of SDS/CTAB molar ratio.     

温度对等摩尔CTAB-SDS复配体系表面张力及乳化性能的影响

测定了十六烷基三甲基溴化铵(CTAB),十二烷基硫酸钠(SDS)及它们等摩尔复配体系在不同温度下的表面张力及乳化性能。复配体系的γCMC从10℃的63.67 mN/m下降到90℃的36.38 mN/m,比相应单一体系的γCMC还略低,表现出高温下较高的表面活性。相应的单一体系的CMC值变化不明显,而CTAB-SDS体系的CMC却减少近一半。这些表面活性剂形成的乳液稳定性随温度升高而下降,与表面活性无关。90℃时复配体系的乳液分出10 mL水层的时间只需0.37 m in,使中和电荷加高温有可能成为一种较好的破乳方法,高温时等摩尔CTAB-SDS的高表面活性与所形成乳液的不稳定性使其有可能较好地应用于催化一些两相反应。     

二元表面活性剂体系微乳液的相行为及热力学研究

用表面张力法研究了苯乙烯基酚聚氧乙烯聚氧丙烯醚嵌段型非离子表面活性剂(PEP)分别与十二烷基硫酸钠(SDS)、十二烷基三甲基溴化铵(CTAB)复配体系分子间的相互作用,并根据测定的临界胶束浓度(CMC)及正规溶液理论计算了复配体系分子间相互作用参数及分子交换能,考察了表面活性剂、助表面活性剂、温度等因素对复配表面活性剂体系微乳液形成过程的相行为及热力学性质的影响。结果表明,二元组分(PEP+SDS)及(PEP+CTAB)复配体系在胶束中和表面吸附层中的都存在较强的增效作用,体系的能量降低,且前者的增效作用大于后者。(PEP+SDS)/正己醇/正庚烷/水微乳液的W/O微乳区域面积最大,温度对该微乳液的相行为影响很小。在此微乳液形成的过程中,助表面活性剂醇从连续油相进入微乳液界面层的标准自由能变化ΔGs0;标准焓变-ΔHs=0,为无热效应过程,ΔGs是由醇分子的混乱度熵变ΔSs决定的。     

Simulation of dynamic behavior of surfactants on a hydrophobic surface using periodic-shell boundary molecular dynamics

The adsorption and aggregation behaviors of sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB) on a hydrophobic graphite surface were examined using a novel molecular dynamics (MD) simulation with the periodic-shell boundary condition (PSBC). Differences in the adsorption behavior of SDS and CTAB molecules were clearly shown on the hydrophobic surface. Unexpectedly, the SDS molecules approached the graphite surface with their hydrophilic head groups. This unexpected approach mode was thought to be due to the aqueous layer on the graphite surface. The hydrophobic moiety of SDS molecules repeatedly adsorbed and desorbed on the graphite surface. In addition, SDS molecules kept moving on the graphite surface; thus, they did not form a stable adsorption layer. In contrast to SDS, the hydrophobic moiety of CTAB molecules approached the graphite surface at the primary step of adsorption. The hydrophobic moieties of CTAB molecules came close to each other, whereas the hydrophilic groups separated from one another. This result suggests that the CTAB molecules form molecular assemblies with a curved structure. The simulation results were consistent with the experimental observations. A clear difference between the adsorption behavior of SDS and CTAB molecules was revealed by MD simulations with PSBC.