Ca~(2+),Th~(4+)和抗磁稀土离子与2,3-二羟基-对-二甲苯胺四乙酸的成络作用

本文用~1H NMR和UV VIS光谱技术研究了DPTA与Ca~(+2)、Th~(4+)和抗磁稀土离子Ia~(3+)、Lu~(3+)、Y~(3+)、Sc~(3+)的成络作用,发现配体与抗磁稀土离子为慢交换体系,而与Ca~(2+)为快交换体系。确定了络合物的组成,Th~(4+)与试剂生成1:2络合物,Ca~(2+)、La~(3+)、Lu~(3+)、Y~(3+)、Sc~(3+)主要生成1:1络合物。络合物组成与溶液pH有关。 比较了抗磁稀土离子络合物Δδ和Δλ变化,发现二者随离子半径的变化有相同的规律: Sc~(3+)相似文献   

CPP杨梅型树脂的交换性能

本文研究了Zn~(2+)、Cd~(2+)、Hg~(2+)、Ca~(2+)、Mg~(2+)、Pb~(2+),Co~(2+)、Ni~(2+)、Cu~(2+)等二价金属离子在CPP杨梅型树脂上的交换过程。CPP—Na/Me~(2+)的交换容量一般在3meq/g-R以上;动态交换20分钟以后,除Hg~(2+)离子外,可达2.3—3.2meq/g—R。(CPP)_2—Me的稳定性顺序测得为:Cu~(2+)>Zn~(2+)>Co~(2+)>Ni~(2+)>Cd~(2+)>Hg~(2+)>Mg~(2+)>Ca~(2+)。在不同pH溶液中,二价全属离子在溶液相和树脂相之间的分配系数表明,pH<2.5时(CPP)_2—Me容易被酸再生,并且当两种或两种以上的金属离子在给定的pH溶液中分配系数差足够大时,有希望获得淋洗分离。     

铁基料中全铁量的测定

往硝酸溶液加入稍过量硫氰酸盐与铁生成稳定的红色络合物,以次甲基蓝作指示剂,用EDTA络合滴定,其终点为草绿色。方法操作简便,终点清晰。在pH1—3滴定铁时,Ca~(2+)、Mg~(2+)、Mn~(2+)、Co~(2+)、Zn~(2+)、Cd~(2+)、Cr~(2+)、Al~(3+)及少量Cu~(2+)、Ni~(2+)均不干扰测定。     

大麦根细胞质膜存在H~+/Ca~(2+)反向传递系统

在发现大麦根细胞质膜上存在不需Mg~(2+)和需Mg~(2+)两个Ca~(2+)转运过程的基础上,进一步研究了这两个过程的转运机制,发现需Mg~(2+)的Ca~(2+)转运过程依赖于跨膜H~+梯度。无论以ATP为能源的、还是人为造成的跨膜H~+梯度,都可驱动跨膜Ca~(2+)转运;跨膜Ca~(2+)转运过程伴随着H~+梯度的消减。不需Mg~(2+)的转运过程则与跨膜H~+梯度无关。这些结果指出,大麦根细胞质膜上除了Ca~(2+)-ATP酶这一初级Ca~(2+)转运系统外,还存在一个以跨膜H~+梯度为能源的次级Ca~(2+)转运系统,即H~+/Ca~(2+)反向传递系统。     

两亲性阴离子HBPN与阳离子表面活性剂CTAB络合机理的研究

用动态光散射研究了两亲性阴离子HBPN(高度枝化的聚酯纳米微粒)和阳离子表面活性剂CTAB(十六烷基三甲基溴化铵)在缓冲液中的相互作用及HBPN/CTAB络合物的形成.结果表明:在静电作用下,于碱性溶剂中,HBPN与由CTAB分子所构成的胶束形成了核壳结构络合物HBPN/CTAB.络合物粒径的大小和稳定性可以通过溶液的pH值和CTAB浓度来控制.     

十二烷基苯磺酸钠和无机阳离子之间相互作用的密度泛函理论研究（英文）

研究阴离子表面活性剂和阳离子之间的相互作用对于理解阴离子表面活性剂的沉淀和溶解现象具有十分重要的理论和实际意义,但关于两者相互作用的相关理论模型鲜有报道。本文采用密度泛函理论(DFT)方法研究了十二烷基苯磺酸根阴离子(DBS~-)与阳离子(Na~+,Mg~(2+)和Ca~(2+))在溶液内及气/液界面处的相互作用。在溶液内,在两种不同溶液环境中(水相和正十二烷)构建DBS~-/阳离子相互作用模型,并对其进行优化。结果表明,DBS~-能够与阳离子以双齿结构稳定结合。DBS~-与阳离子的结合能不仅取决于参与的无机盐离子种类,还与溶剂的性质有关。在气/液界面处,DBS~-与六个水分子相互作用形成的水合物DBS~-·6H_2O最为稳定。但是,无机盐离子的引入会严重破坏DBS~-·6H_2O水合物的水化层结构。本文定义无量纲参量def用来对水化层结构的变化程度进行评价。无机盐离子对DBS~-·6H_2O水化层结构破坏程度的顺序为:Ca~(2+)Mg~(2+)Na~+。电荷分析结果表明水化层在十二烷基苯磺酸钠(SDBS)头基与阳离子的相互作用中起了重要作用。     

ATP与Mg~(2+)、Ca~(2+)生成配合物反应的热力学研究

核苷酸类化合物与二价金属离子生成配合物的反应,在生物体内起着重要作用。许多科学工作者采用不同的手段,对这类反应进行了研究。但是由于实验方法和实验条件上的差异,所得结果亦不尽相同。Mg~(2+)和Ca~(2+)作为ATP酶的激活剂,参与ATP酶催化水解ATP的反应。一般认为该反应的机理是ATP先与Mg~(2+)、Ca~(2+)生成配合物ATPMg~(2-)与ATPCa~(2-),然后被催化水解。本文采用微量量热法,研究了这一中间过程。对于ATP-Mg~(2+)体系测定的结果,与在相似实验条件下用微量量热法得到的文献值相吻合,验证了数据的可靠性。对于ATP-Ca~(2+)体系,     

烟酰胺腺嘌呤二核苷酸在纳米α-氧化铝上的吸附作用

用紫外-可见吸收光谱、X射线衍射、荧光光谱和衰减全反射傅里叶变换红外(ATR-FTIR）光谱等方法,研究了烟酰胺腺嘌呤二核苷酸(NAD+)在纳米α-Al2O3粒子上的吸附行为。 实验结果显示,NAD+的吸附量受pH值和离子强度影响较大,说明NAD+主要通过静电作用吸附在纳米α-Al2O3粒子上。 采用ATR-FTIR光谱分析了不同pH值溶液中及被吸附的NAD+,发现吸附后的NAD+与溶液中NAD+ 的ATR-FTIR光谱相似,但磷酸根的吸收峰向高波数位移,说明磷酸根参与了表面静电作用。 吸附过程符合Langmuir和Freundlich等温式。 荧光实验结果显示,随着吸附剂α-Al2O3用量的变化,NAD+构象也发生变化。     

海水体系中黑碳吸附三丁基锡的行为与机理

在700,400℃条件下热解碳化杉木制得2种黑碳(BC700和BC400).研究了海水体系中,pH和盐度影响下2种黑碳(BC)对三丁基锡(TBT)的吸附行为与机理.实验结果表明,BC700的比表面积较大,BC400的有机质含量较高.盐度的增加(5～35 g/kg)使BC表面净电荷降低,静电作用减弱;但同时导致盐析效应增强,使TBT的有效浓度增大,综合结果导致2种BC对TBT的吸附增加了1.03～2.12倍.当溶液pH为4.00和6.25时,TBT以离子(TBT+)和中性(TBT)形态共同存在,而在pH为8.00时几乎全为中性态,分子形态的不同导致TBT与BC间的作用机理发生变化.TBT的最大吸附发生在pH=6.25时,这是静电作用、物理吸附和疏水分配等多种机制共同作用的结果.X射线光电子能谱(XPS)分析结果表明,Sn3d5/2峰结合能随着pH的降低而增加,证明TBT与BC之间存在静电作用.因此可以认为,TBT在BC700上的吸附主要为物理吸附和静电作用,而在BC400上的吸附则由疏水分配、物理吸附和静电吸引共同主导.     

金属离子对不同分子量腐殖酸生成三卤甲烷的影响

通过超滤手段将腐殖酸溶液分离成分子量为10K、10K-30K、30K-100K和100K的四部分。考察了金属离子K~+、Ca~(2+)、Mg~(2+)、Al~(3+)、Fe~(3+)对各分子量组分生成三卤甲烷(THMs)的影响,结果表明五种金属离子对腐殖酸各分子量组分三卤甲烷生成的影响不同。K~+使100K分子量组分生成的CHCl_3减少,Br-THMs增加;Ca~(2+)、Mg~(2+)的加入促进了分子量10K的组分生成THMs;Fe~(3+)、Al~(3+)表现出与Ca~(2+)、Mg~(2+)类似的结果。但各金属离子的加入都使得10K的分子量组分的THMs生成量降低。     

土壤颗粒表面电场作用下固-液界面Mg2+-K+与Ca2+-K+交换动力学的比较研究

通过恒流法研究了不同表面电场作用下Mg2+、Ca2+吸附动力学. 结果发现: (1)实验初期阶段是强静电力作用下的零级动力学过程和一定反应时间后的弱静电力作用下的一级动力学过程, 且零级速率过程和一级速率过程之间存在明显的转折点; (2)不同电解质构成中Ca2+的吸附速率明显快于Mg2+的, 平衡吸附量也大于Mg2+的, 且Ca2+在土壤颗粒表面的覆盖度比Mg2+在土壤颗粒表面的覆盖度高; (3)离子的相对有效电荷系数与土壤颗粒表面电场作用的不同是各体系中Ca2+、Mg2+吸附动力学有差别的根本原因; (4)根据离子吸附的理论模型可以分别计算出速率系数、平衡吸附量、离子在土壤颗粒表面的覆盖度以及固定液的体积, 这些参数可以定量评估土壤颗粒表面电场对离子吸附动力学的影响.     

Dispersion stability of a ceramic glaze achieved through ionic surfactant adsorption

The adsorption of cetylpyridinium chloride (CPC) and sodium dodecylbenzenesulfonate (SDBS) onto a ceramic glaze mixture composed of limestone, feldspar, quartz, and kaolin has been investigated. Both adsorption isotherms and the average particle zeta potential have been studied in order to understand the suspension stability as a function of pH, ionic strength, and surfactant concentration. The adsorption of small amounts of cationic CPC onto the primarily negatively charged surfaces of the particles at pH 7 and 9 results in strong attraction and flocculation due to hydrophobic interactions. At higher surfactant concentrations a zeta potential of more than +60 mV results from the bilayered adsorbed surfactant, providing stability at salt concentrations < or = 0.01 M. At 0.1 M salt poor stability results despite substantial zeta potential values. Three mechanisms for SDBS adsorption have been identified. When anionic SDBS monomers either adsorb by electrostatic interactions with the few positive surface sites at high pH or adsorb onto like charged negative surface sites due to dispersion or hydrophobic interactions, the magnitude of the negative zeta potential increases slightly. At pH 9 this increase is enough to promote stability with an average zeta potential of more than -55 mV, whereas at pH 7 the zeta potential is lower at about -45 mV. The stability of suspensions at pH 7 is additionally due to steric repulsion caused by the adsorption of thick layers of neutrally charged Ca(DBS)2 complexes created when the surfactant interacts with dissolved calcium ions from the calcium carbonate component.     

Study of cetyltrimethylammonium and cetylpyridinium adsorption on montmorillonite

Adsorption of cetyltrimethylammonium (CTA) and cetylpyridinium (CP) onto Na-rich montmorillonite (MMT) was studied. For this purpose, the adsorption isotherms of CTA and CP, along with desorption curves of metal cations (Na+, K+, Ca2+, Mg2+), were obtained by means of capillary isotachophoresis and atomic absorption spectrometry. Infrared, X-ray diffraction pattern, specific surface area, porosity, and moisture adsorption measurements of montmorillonite revealed that CTA and CP were adsorbed in monolayer arrangements. CTA is assumed to be attached to the negatively charged MMT surface mainly by electrostatic forces. On the other hand, CP, adsorbed in higher amounts, can be additionally bound via other interactions of pyridinium rings, such as induced and pi-pi interactions. By the surfactant adsorption, the montmorillonite surface became hydrophobic and its micro- and mesopores were significantly diminished. Using scanning electron microscopy, aggregation of such organically modified MMT particles was observed.     

碱金属和碱土金属离子在反相高效液相色谱柱上的保留机理

发现以酒石酸和吡啶二甲酸等羧酸水溶液作淋洗剂时，钠，铵，钾，镁和钙等碱金属及碱土金属离子在ＯＤＳ反相高效液相色谱柱上有明显的保留，而且相互之间能达到一定程度的分离。单独用分配或疏水作用等反相高效液相色谱的保留机理难以解释其保留行为。为此，作者提出了动态包固定相机理，即认为羧酸根阴离子因其疏水性在ＯＤＳ固定相有保留，在固定相表面形成具有羧酸基阳离子交换树脂功能的动态包覆固定相。     

酯化淀粉乳化剂制备的高效氯氟氰菊酯O/W乳液的稳定机制

通过测定辛烯基琥珀酸淀粉钠的用量、盐离子、pH值和温度等因素对油滴Zeta电位及表面吸附量的影响,分析了以酯化淀粉辛烯基琥珀酸淀粉钠为乳化剂制备的5％高效氯氟氰菊酯水乳剂的稳定机制.结果表明,辛烯基琥珀酸淀粉钠质量分数为7％时,Zeta电位达到最大值,油滴表面吸附量接近饱和;Na+、Mg2+和Al3+压缩油滴表面的双电层,降低Zeta电位,削弱静电排斥作用,增加辛烯基琥珀酸淀粉钠分子柔性,提高辛烯基琥珀酸淀粉钠表面吸附量,且随着Na+、Mg2、Al3+离子强度依次增大,压缩双电层能力依次增强,Zeta 电位降低和表面吸附量增加程度依次增大;pH值影响辛烯基琥珀酸淀粉钠在水中的解离,在碱性范围内解离出较多羧酸根,静电排斥力较大,Zeta电位较高,但表面吸附量有所降低;温度升高,辛烯基琥珀酸淀粉钠在水溶液中溶解度增大,呈舒展状态,且辛烯基琥珀酸淀粉钠从油滴表面逃逸的趋势增加,油滴表面Zeta电位和表面吸附量均随着温度升高而降低,在低温区差别不大,温度越高二者变化越明显.辛烯基琥珀酸淀粉钠通过吸附于油滴表面为其提供较强的静电斥力和空间位阻作用而维持O/W乳液稳定.     

Coagulation of bitumen with kaolinite in aqueous solutions containing Ca2+, Mg2+ and Fe3+: effect of citric acid

Heterocoagulation experiments of kaolinite with solvent-diluted-bitumen were carried out to investigate the effect of hydrolyzable metal cations and citric acid on the liberation of bitumen from kaolinite. The adsorption of Ca(2+) and Mg(2+) on kaolinite, and zeta potentials of kaolinite and bitumen droplets in solutions containing 10(-3)mol/L of Ca(2+), Mg(2+) and Fe(3+) with or without citric acid were also measured. It was found that the heterocoagulation of bitumen with kaolinite was enhanced in the presence of the metal cations from pH 7 to pH 10.5, accompanied by a decrease in the magnitude of the zeta potentials and an increase in the adsorption of the metal cations on kaolinite and possibly on bitumen droplets. The addition of 5 x 10(-4)mol/L citric acid reduced the degree of coagulation from 90% to less than 40% in the presence of 10(-3)mol/L Ca(2+) and Mg(2+) cations at pH approximately 10, and at pH approximately 8 for Fe(3+). It was found that hydrolyzable metal cations enhanced bitumen-kaolinite interactions through electrical double layer compression and specific adsorption of the metal hydrolysis species on the surface of kaolinite. The effect of metal cations was removed by citric acid through formation of metal-citrate complexes and/or the adsorption of citrate anions, which restored the zeta potentials of both kaolinite and bitumen. Therefore, electrostatic attraction or repulsion was responsible for the coagulation or dispersion of kaolinite particles from bitumen droplets in the tested system.     

Theoretical Studies on the Interactions of Cations with Diazine

1 INTRODUCTION Interaction between cations and π electron systems is a kind of common and important non-covalent inter- action[1～21]. It could be observed in many systems, such as gas ion-molecule complexes and biological macromolecular proteins. Especially, in biological macromolecular systems, this interaction is signi- ficant for revealing the structures and functions of proteins or disclosing the atomic essence of protein- ligand effect. Interaction between benzene and metal ions h…     

聚合物分散剂对氟虫脲水悬浮剂分散稳定性的影响

通过测定药物颗粒界面Zeta电位和平均粒径, 研究了聚合物分散剂苯乙烯磺酸聚合物钠盐(GY-D08)用量、pH和盐离子对氟虫脲水悬浮剂分散稳定性的影响, 研究结果表明, 分散剂GY-D08的加入量与水悬浮剂分散效果密切相关, 制备质量分数为5%氟虫脲水悬浮剂的GY-D08最佳用量为2%, GY-D08用量过多或过少都会使分散效果下降; pH影响分散剂GY-D08在水中的电离能力, 当pH=9时, GY-D08分子完全电离, 能为颗粒提供较大的静电位阻, 水悬浮剂分散稳定性最好; Mg²⁺或Ca²⁺压缩颗粒界面的双电层, 降低Zeta电位, 使颗粒因带电量减少而聚结, 导致水悬浮剂分散稳定性变差, 且Mg²⁺或Ca²⁺浓度愈大, 其分散稳定性愈差; 当离子浓度相同时, Ca²⁺压缩双电层的能力比Mg²⁺强, 添加Ca²⁺后的水悬浮剂的分散稳定性更差.     

Structural transition of actin filament in a cell-sized water droplet with a phospholipid membrane

Actin filament, F-actin, is a semiflexible polymer with a negative charge, and is one of the main constituents of cell membranes. To clarify the effect of cross talk between a phospholipid membrane and actin filaments in cells, we conducted microscopic observations on the structural changes in actin filaments in a cell-sized (several tens of micrometers in diameter) water droplet coated with a phospholipid membrane such as phosphatidylserine (PS; negatively charged head group) or phosphatidylethanolamine (PE; neutral head group) as a simple model of a living cell membrane. With PS, actin filaments are distributed uniformly in the water phase without adsorption onto the membrane surface between 2 and 6 mM Mg2+, while between 6 and 12 mM Mg2+, actin filaments are adsorbed onto the inner membrane surface. With PE, the actin filaments are uniformly adsorbed onto the inner membrane surface between 2 and 12 mM Mg2+. With both PS and PE membranes, at Mg2+ concentrations higher than 12 mM, thick bundles are formed in the bulk water droplet accompanied by the dissolution of actin filaments from the membrane surface. The attraction between actin filaments and membrane is attributable to an increase in the translational entropy of counterions accompanied by the adsorption of actin filaments onto the membrane surface. These results suggest that a microscopic water droplet coated with phospholipid can serve as an easy-to-handle model of cell membranes.     

Interplay of bonding and geometry of the adsorption complexes of light alkanes within cationic faujasites. Combined spectroscopic and computational study

A FT-IR spectroscopic study of methane, ethane, and propane adsorption on magnesium and calcium forms of zeolite Y reveals different vibrational properties of the adsorbed molecules depending on the exchanged cation. This is attributed to different adsorption conformations of the hydrocarbons. Two-fold eta(2) coordination of light alkanes is realized for MgY, whereas in case of CaY zeolite quite different adsorption modes are found, involving more C-H bonds in the interaction with the cation. The topological analysis of the electron density distribution function of the adsorption complexes shows that when a hydrocarbon coordinates to the exchanged Mg(2+) ions, van der Waals bonds between H atoms of the alkane and basic zeolitic oxygens significantly contribute to the overall adsorption energy, whereas in case of CaY zeolite such interactions play only an indirect role. It is found that, due to the much smaller ionic radius of the Mg(2+) ion as compared to that of Ca(2+), the former ions are significantly shielded with the surrounding oxygens of the zeolitic cation site. This results in a small electrostatic contribution to the stabilization of the adsorbed molecules. In contrast, for CaY zeolite the stabilization of alkanes in the electrostatic field of the partially shielded Ca(2+) cation significantly contributes to the adsorption energy. This is in agreement with the experimentally observed lower overall absorption of C-H stretching vibrations of alkanes loaded to MgY as compared to those for CaY zeolite. The preferred conformation of the adsorbed alkanes is controlled by the bonding within the adsorption complexes that, in turn, strongly depends on the size and location of the cations in the zeolite cavity.