纳米、微米一水草酸钙和二水草酸钙对非离子表面活性剂NP-40的吸附差异

为探究CaO_x结石的形成机理,测定了不同浓度NP-40(c_NP-40)存在下各尺寸COM或COD晶体的吸附量;采用X射线衍射和红外光谱研究吸附前后晶体是否发生晶相改变;采用ζ电位仪测定吸附后晶体表面的ζ电位随c_NP-40的变化。结果表明:不同尺寸COM、COD对NP-40的吸附能力大小顺序为:50 nm > 100 nm > 1μm > > 3μm > 10μm;相同尺寸的晶体,COM的吸附量大于COD。随着c_NP-40增加,3μm和10μm的COM、COD晶体的吸附曲线为S型,而50 nm、100 nm、1μm的COM、COD晶体的吸附曲线为直线型。加入NP-40后,ζ电位绝对值与各晶体的吸附密度成正相关。提出了草酸钙晶体吸附NP-40的分子模型。晶体尺寸越小,对NP-40的吸附量越大。非离子表面活性剂虽然自身不带电荷,但吸附到COM、COD晶体表面后可以通过位阻斥力来增加晶体悬浮液的稳定性,有利于抑制草酸钙结石的形成。     

阴离子、阳离子和非离子表面活性剂在纳/微米草酸钙晶体上的吸附差异

目的：研究尺寸分别为50 nm和3 μm的一水草酸钙（COM）和二水草酸钙（COD）晶体对不同电荷表面活性剂的吸附差异,包括阴离子型表面活性剂磺基琥珀酸钠二辛酯（AOT）、阳离子型表面活性剂十六烷基三甲基溴化铵（CTAB）和非离子型表面活性剂壬基酚聚氧乙烯醚（NP-40）,探究尿液中带不同电荷的分子对纳米、微米尿微晶的影响。方法：测定不同表面活性剂在纳/微米COM、COD晶体上的吸附量;采用ζ电位仪测定吸附不同表面活性剂后晶体表面的ζ电位;检测加入不同表面活性剂后悬浮液的沉降系数。结果：表面活性剂的吸附量大小为AOT > CTAB > NP-40,即阴离子型表面活性剂的吸附量最大,非离子型表面活性剂的吸附量最小;晶体尺寸相同时,COM的吸附能力稍大于COD;吸附表面活性剂后,晶体的ζ电位绝对值都增大,有利于抑制晶体的团聚和沉降。提出了晶体吸附不同表面活性剂的分子模型。结论：不同电荷表面活性剂与纳/微米COM、COD晶体之间存在不同的相互作用。表面活性剂吸附量越大,沉降越慢,对晶体悬浮液的稳定效果越明显。     

阴离子、阳离子和非离子表面活性剂在纳/微米草酸钙晶体上的吸附差异

研究了尺寸分别为50 nm和3μm的一水草酸钙(COM)和二水草酸钙(COD)晶体对不同电荷表面活性剂的吸附差异,包括阴离子型表面活性剂磺基琥珀酸钠二辛酯(AOT)、阳离子型表面活性剂十六烷基三甲基溴化铵(CTAB)和非离子型表面活性剂壬基酚聚氧乙烯醚(NP-40),探究了尿液中带不同电荷的分子对纳米、微米尿微晶的影响。结果表明,表面活性剂的吸附量大小为AOTCTABNP-40,即阴离子型表面活性剂的吸附量最大,非离子型表面活性剂的吸附量最小;晶体尺寸相同时,COM的吸附能力稍大于COD;吸附表面活性剂后,晶体表面的ζ电位绝对值都增大,有利于抑制晶体的团聚和沉降。提出了晶体吸附不同表面活性剂的分子模型。不同电荷表面活性剂与纳/微米COM、COD晶体之间存在不同的相互作用。表面活性剂吸附量越大,沉降越慢,对晶体悬浮液的稳定效果越明显。     

纳米/微米一水草酸钙、二水草酸钙对牛血清白蛋白的吸附性能

研究了牛血清白蛋白(BSA)在尺寸分别为100 nm、3μm的一水草酸钙(COM)和二水草酸钙(COD)晶体上的吸附等温线及晶体ζ电位随BSA浓度(cBSA)的变化。结果表明,4种晶体对BSA的最大吸附量顺序为COD-100 nmCOM-100 nm≥COD-3μmCOM-3μm,即吸附量与晶体的比表面积成正相关。而比表面积归一化后,吸附量顺序为COD-3μmCOM-3μmCOM-100 nmCOD-100 nm,说明COM和COD晶体的结晶水数量和晶面电荷密度影响了BSA的吸附。吸附等温线都很好地拟合了Langmuir模型,表明BSA在纳米/微米COM、COD晶体上的吸附属于单分子层吸附。COM和COD等电点大小顺序为COM-100 nm(7.2)COD-100 nm(6.7)≥COM-3μm(4.7)COD-3μm(4.3),因此在病生理条件下(p H≈6.3)纳米级晶体的团聚比微米级晶体的更严重。纳米级和微米级晶体对BSA的最大吸附量都在BSA等电点附近(p H=4.8)。BSA在纳米/微米COM和COD晶体上的吸附与晶体的比表面积、晶面电荷、团聚、结晶水数量和pH值有关。本文结果有助于阐明尿液中不同性质微晶与尿蛋白质对草酸钙结石形成的影响。     

带正电荷蛋白在纳米/微米草酸钙晶体上的吸附特性及其与带负电荷蛋白吸附的比较

研究尺寸分别为100 nm和3 μm的一水草酸钙（COM）和二水草酸钙（COD）晶体对带正电荷的蛋白溶菌酶（LSZ）的吸附差异,并与带负电荷的蛋白牛血清白蛋白（BSA）的吸附进行了比较。LSZ在纳米/微米COM和COD晶体上的吸附都很好的拟合了Langmuir模型,属于单分子层吸附。纳米/微米COM和COD对LSZ的最大吸附量顺序为COD-100 nm >COM-100 nm >COD-3 μm >COM-3 μm;晶体的比表面积越大,曲率越小,晶体表面所带电荷越负,晶体结晶水越多,均导致LSZ吸附量越大。体系离子强度和pH值亦影响LSZ的吸附。随着NaCl浓度增加,LSZ的吸附量减小,说明Na⁺离子能与带正电荷的蛋白LSZ竞争晶体表面的吸附位点,导致晶体表面吸附LSZ的位点减少。晶体对LSZ的最大吸附量都出现在LSZ的等电点附近（pH=10.7）;在pH=5~8（生理条件）时,LSZ的吸附量随pH值的增大而增大。本文结果提示,通过减小尿液的pH值或者适当增大尿液的离子强度,可以减小LSZ在尿微晶上的吸附量,有可能达到抑制草酸钙结石的效果。     

缺陷LB膜诱导特异形貌草酸钙堆积图形

A special pattern of calcium oxalate monohydrate (COM) crystals was induced by DPPC Langmuir-Blodgett films with defects. The pattern was that a large hexagonal COM crystal located in the middle of a ring-shaped pattern of needle-liked crystals. The number of such special patterns with a diameter between 10 μm and 40 μm accounted for about 5% of the whole crystal patterns. It is due to the “islands” composed of aggregated film-forming molecules in the middle of the liquid-condensed domains. The effects of the concentration of potassium oxalate and the growth time on the crystal patterns were studied. When the concentration of potassium oxalate(c_K2C2O4) was 0.6 mmol·L^-1, the needle-liked COM crystals on the rings grew towards inside part of the patterns as the induced-time increased from 1 h to 4 h. After 2 h, the solid circle patterns were formed. On the other hand, the size of the hexagonal COM crystal in the middle of the pattern increased. The size of the COM crystals on the rings were about 3 μm × 2 μm, and that of three-dimensional COM crystals in the middle of the patterns were about 16 μm × 7 μm × 6 μm after 4 h. However, when c_K2C2O4 was increased to 5.0 mmol·L^-1, there was only a large COM crystal grown in the middle of the circular COM crystallites no matter 1 h or 4 h of crystal growth, and the ratio of these special COM patterns increased. It can be explained that the interaction between oxalate and DPPC molecules is enhanced as the increase of c_K2C2O4, so more and more DPPC molecules fled away from the substrate surface, resulting in decrease of the nucleating sites in the circle.     

过饱和度、钙/草酸化学计量比对草酸钙晶体形成的影响及降解茯苓多糖的调控作用

为研究草酸钙(CaC₂O₄)晶体成核、生长和聚集,探讨降解茯苓多糖(PCP)的抑制作用,采用X射线衍射、FT-IR、扫描电镜、拉曼光谱、ζ电位仪和紫外分光光度计等方法对不同条件下形成的 CaC₂O₄晶体进行表征。结果表明,在低过饱和度(RS≤26.6)时,主要生成一水草酸钙(COM)晶体;至RS为37.6和46.0时分别生成了11.6%和38.3%的二水草酸钙(COD)晶体,且高RS时晶体的聚集程度增加。在RS相同时,随着Ca²⁺/Ox^2-(Ox^2-=C₂O₄^2-)化学计量比(n_Ca²⁺/n_Ox^2-)增大,晶体中COD比例增加。降解PCP的加入可增加体系中可溶性Ca²⁺浓度,减少生成的CaC₂O₄晶体质量,增加晶体表面ζ电位绝对值,这些均有利于抑制CaC₂O₄结石的形成。因此,高Ox^2-浓度对肾结石形成的风险远大于高Ca²⁺浓度,提示草酸的摄入对CaC₂O₄结石的风险远远大于钙的摄入,降解PCP能同时抑制CaC₂O₄晶体的成核、生长和聚集。     

聚合羟基铁改性蒙脱石的制备、表征及吸附Se（Ⅵ）的特性

采用共沉淀法制备了3种聚合羟基铁改性蒙脱石（Mt-Fe_x,x=1,2,3）,对比研究了纯蒙脱石（Mt）和Mt-Fe_x（x=1,2,3）的表面性质及吸附Se（Ⅵ）的特性。结果表明,Mt样品的d_（001）层间距为1.296nm,在Mt-Fe_x中升高至1.430nm以上;与Mt样品比较,Mt-Fe_x的孔体积、表面积、表面分形度均随含铁量的增加而升高,其中微孔体积和微孔表面积的变化尤为明显;Mt样品的等电点（IEP）低于3,而Mt-Fe₃的IEP升高至6.8;初始pH=5.0时,Mt和Mt-Fe_x（x=1,2,3）的表面ζ电位分别为-33.5,-11.7,9.9和33.2mV。单吸附位Langmuir模型能够很好地拟合Mt样品对Se（Ⅵ）的等温吸附数据（R²=0.993）,4种样品吸附数据的单吸附位Langmuir拟合判断系数（R²）随样品含铁量的增加而降低;3种Mt-Fe_x样品的吸附数据更适合用双吸附位Langmuir模型拟合（R²=0.993~0.997）;Freundlich模型对4种样品的吸附数据拟合度较低（R²=0.849~0.970）,其判断系数（R²）随样品含铁量的增加而升高。初始pH=5.0时,Mt和Mt-Fe_x（x=1,2,3）对Se（Ⅵ）的吸附容量分别为4.23,7.83,10.38和14.34mg·g^-1。可见,聚合羟基铁含量较高的Mt-Fe_x样品对土-水体系中Se（Ⅵ）的固定能力明显高于Mt。     

氧化铁改性蛭石的制备、表征及吸附氟的特性

采用共沉淀法制备了3种不同含铁量的氧化铁改性蛭石(Verm-Fe_x,x=5,10,20),研究了纯蛭石(Verm)和Verm-Fe_x的表面性质及吸附氟的特性。与样品Verm比较,3种Verm-Fe_x中Verm的d₍₀₀₂₎层间距略有升高;Verm-Fe_x的孔体积、表面积、表面分形度均随含铁量的增加而升高,其中微孔体积和外表面积的增加幅度更明显。4种样品的等电点(IEP)也随含铁量的增加而明显升高;初始pH＝5.0时,它们的表面ζ电位分别为-16.4,-6.1,10.5和28.4 mV。4种样品对氟的等温吸附数据用单吸附位Langmuir模型拟合(R²=0.973~0.995)时,Verm的R²最高;双吸附位Langmuir模型可很好地描述3种Verm-Fe_x样品的等温吸附过程(R²=0.991~0.998);Freundlich模型对4种样品吸附数据的拟合度较差(R²=0.835~0.937),但R²随样品含铁量的增加而略微升高。初始pH=5.0时,Verm和Verm-Fe_x(x=5,10,20)对氟的最大吸附容量(q_max)分别为3.18,6.76,9.27和12.43 mg·g^-1。可见,Verm-Fe_x(尤其含铁量较高的产物)对表生环境中氟的吸附固定性能明显高于Verm。     

氧化铁改性蛭石的制备、表征及吸附氟的特性

采用共沉淀法制备了3种不同含铁量的氧化铁改性蛭石（Verm-Fe_x,x=5,10,20）,研究了纯蛭石（Verm）和Verm-Fe_x的表面性质及吸附氟的特性。与样品Verm比较,3种Verm-Fe_x中Verm的d_（002）层间距略有升高;Verm-Fe_x的孔体积、表面积、表面分形度均随含铁量的增加而升高,其中微孔体积和外表面积的增加幅度更明显。4种样品的等电点（IEP）也随含铁量的增加而明显升高;初始pH＝5.0时,它们的表面ζ电位分别为-16.4,-6.1,10.5和28.4 mV。4种样品对氟的等温吸附数据用单吸附位Langmuir模型拟合（R²=0.973~0.995）时,Verm的R²最高;双吸附位Langmuir模型可很好地描述3种Verm-Fe_x样品的等温吸附过程（R²=0.991~0.998）;Freundlich模型对4种样品吸附数据的拟合度较差（R²=0.835~0.937）,但R²随样品含铁量的增加而略微升高。初始pH=5.0时,Verm和Verm-Fe_x（x=5,10,20）对氟的最大吸附容量（q_max）分别为3.18,6.76,9.27和12.43 mg·g^-1。可见,Verm-Fe_x（尤其含铁量较高的产物）对表生环境中氟的吸附固定性能明显高于Verm。     

New method for the determination of adsorption space volume for sorbents with an arbitrary porous structure from excess gas adsorption isotherm measurements

A new method for the determination of adsorption space volume has been proposed, which is applicable to adsorbents with an arbitrary porous structure, including nonporous adsorbents with open surfaces. The method is based on the use of an experimental excess adsorption isotherm measured over a wide range of pressures in the equilibrium gaseous phase (as a rule up to 100–150 MPa) and the absolute adsorption isotherm equation with unspecified parameters in the most general form, given by statistical physics. The method has been tested for a number of adsorption systems, and it has been found that the result was always unambiguous, correct, and stable in the sense of input data.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2381–2385, December, 1995.     

Thermal-Adsorptive Concentration

Methods for concentrating dilute fluids using adsorption followed by partial thermal regeneration were studied using the simulation package ADSIM. The systems studied were NaCl in liquid water on Amberlite XD-2 resin and benzene vapor in nitrogen on activated carbon. Cycles studied included counter-current regeneration with pure hot fluid, co-current regeneration with pure hot fluid, a new process called Hot Feed Addition (HFA) consisting of co-current regeneration with pure hot fluid followed by hot feed, and cycling zone adsorption (co-current alternating hot and cold feeds with no pure regeneration fluid). The optimum system depends upon the conditions of the system and the value function chosen to evaluate the systems. For example, for benzene in nitrogen with hot regeneration gas at 467.4 K, cycling zone adsorption used no carrier gas, had the most concentrated benzene stream and a very pure nitrogen product, but the energy use was greater than the other processes. For liquid systems counter-current operation could produce the purest product, but regenerant requirements were high. With slightly lower purity requirements HFA reduced solvent usage and increased the concentration of the concentrated waste stream. For the liquid system all processes used approximately 3% or less of the energy that would be required for evaporation.     

大孔吸附树脂的吸附机理

大孔吸附树脂(macroprous adsorption resin, MAR)是近几十年发展起来的一种具有多孔立体结构、人工合成的有机高分子聚合物。由于其特殊的理化性质和吸附性能,已被广泛应用于化学、医药、环保和食品等领域。本文介绍了近年来国内外对大孔吸附树脂在吸附机理研究方面的进展,重点介绍了不同温度条件下大孔吸附树脂对靶标分子的吸附热力学行为模式,靶标分子在大孔吸附树脂表面及孔内的吸附扩散行为模式。此外,大孔吸附树脂性能参数和靶标分子结构参数之间构效关系也对其吸附选择性规律具有重要的影响。因此,大孔吸附树脂与底物间构效关系的匹配程度及其对选择性的影响是大孔吸附树脂分离理论研究的核心。本文最后介绍了可以准确客观描述吸附过程并具有一定使用范围的大孔吸附树脂吸附模型的建立和评价。     

多组分气体吸附平衡理论研究进展*

关于多组分气体吸附平衡理论的研究之所以重要,一是因为其在分离技术中的应用前景,二是因为其尚不成熟。本文对临界温度以下多组分气体吸附平衡理论研究的进展、各种数学模型的特点及适用范围作了评述,并探讨了含超临界值组分的气体吸附平衡理论所面临的问题及其研究方向。     

氨基酸在固/液界面的吸附作用

本文介绍了氨基酸在固/液界面吸附等温线的特点,氨基酸液相吸附热力学和活性炭、硅胶、二氧化钛、氧化铝、蒙脱土等自水中吸附氨基酸的机制。     

A common approach to adsorption and absorption: Polymolecular adsorption

The Brunauer-Emmett-Teller (BET) and Frenkel-Halsey-Hill equations are shown to be special cases of an equation obtained earlier for interphase equilibrium.Institute of Physical Chemistry, Russian Academy of Sciences, Moscow 117915. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 4, pp. 779–785, April, 1992.     

Thermodynamic parameters of adsorption described by the logarithmic Temkin isotherm

Thermodynamic analysis of the adsorption Temkin isotherm was performed. The equations that describe the dependence of the thermodynamic functions on the amount adsorbed were obtained. A relationship between the excess differential and mean molar thermodynamic functions was found. The thermodynamic approach does not contradict the molecular statistical theory and appears to be more general.     

Expressiveness of Adsorption Measurements for Characterization of Zeolitic Materials—A Review

This critical review concerns the author's results and experience in adsorption studies on molecular sieves comprising crystalline microporous aluminosilicates and aluminophosphates as well as amorphous mesoporous aluminosilicates. The discussion is mainly based on three distinctly different standard adsorbates: nitrogen, benzene, and water. The highlights or advantages and the shortcomings or limitations are considered from the points of view of the experimental procedures and expressiveness or concluding. The results are compared to several other zeolitic materials and adsorbates. Adsorption technique is a valuable tool for characterization of the molecular sieves. Since the measurements are very sensitive to modification of the materials, the investigations require sufficiently thorough procedures and the results a careful interpretation. A comparison between the results for larger series of materials yields valuable conclusions that are much more expressive than those from a single measurement or material. Dedicated to the memory of Professor Wolfgang Schirmer.     

Adsorption of Nitrogen on Silica Gel Over a Large Range of Temperatures

To study the mechanism of physical adsorption of supercritical gases, the adsorption equilibria of N₂ on silica gel for 103–298 K using 20 K increments and pressures up to 10 MPa were measured. A transition of the adsorption mechanism was proven on crossing the critical temperature, but the transition way observed is different from that observed with activated carbon. This causes a difference in the locations of the linear section of the n- _g isotherm at the near-critical temperature. Although the isotherm type is different on silica gel and on activated carbon in the sub-critical region, all isotherms in the supercritical region can be well modeled by a single model. It leads to the argument that the adsorption mechanism of supercritical gases is identical no matter what kind of adsorbent is used.