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Poly(ethylene oxides), PEO, end-capped with hexadecyl dimethylammonium, HDDMA+, and trimethylammonium hexyldimethylammonium, THA2+, changed distinctly the sol–gel transition of sodium montmorillonite dispersions. In the presence of HDDMA+-PEO 1,500 and 4,000, domains of sol with increased salt tolerance (ck=550–1,000 mmol NaCl/l) were found at high polymer and low montmorillonite contents. The corresponding PEO of higher molar mass (20,000 and 35,000) led to extended fields of flocs. THA2+-PEO 1,500 formed attractive gels at polymer concentrations >2–5 g/l and montmorillonite contents >0.5%. These gels showed very high yield values. THA2+-PEO of higher molar mass acted as stabilizing agents. The salt tolerance was highest (300–750 mmol/l) in the presence of THA2+-PEO 20,000. The observed sol–gel diagrams reveal the interplay between polymer end-group fixation on the clay mineral particles, polymer conformation, and colloidal stabilization and destabilization mechanisms.Poly(ethylene oxides), PEO, end-capped with hexadecyl dimethylammonium, HDDMA+, and trimethylammonium hexyldimethylammonium, THA2+, changed distinctly the sol–gel transition of sodium montmorillonite dispersions. In the presence of HDDMA+-PEO 1,500 and 4,000, domains of sol with increased salt tolerance (ck=550–1,000 mmol NaCl/l) were found at high polymer and low montmorillonite contents. The corresponding PEO of higher molar mass (20,000 and 35,000) led to extended fields of flocs. THA2+-PEO 1,500 formed attractive gels at polymer concentrations >2–5 g/l and montmorillonite contents >0.5%. These gels showed very high yield values. THA2+-PEO of higher molar mass acted as stabilizing agents. The salt tolerance was highest (300–750 mmol/l) in the presence of THA2+-PEO 20,000. The observed sol–gel diagrams reveal the interplay between polymer end-group fixation on the clay mineral particles, polymer conformation, and colloidal stabilization and destabilization mechanisms.

Abstract. Cationic surfactants are strongly coagulating agents for clay mineral dispersions. The critical coagulation concentration of cetyltrimethylammonium chloride (CTMAC) is 0.09 mEql^-1 for a 0.025% sodium montmorillonite dispersion and increases to 0.35 mEql^-1 for a 0.5% dispersion. The very low concentrations are caused by the strong adsorption of the organic cations on the clay mineral surface. The particles aggregate in different ways. Phase diagrams in relation to the mass content of CTMAC and bentonite reveal four domains of different states of the dispersions. As long as the amount of CTMAC added is below the cation exchange capacity, ξ, the dispersion consists of fine flocs and separates into a two-phase system of large volume and a clear supernatant (domain I). At CTMAC amounts near ξ, the fine flocs rearrange into voluminous flocs (domain II) and at CTMAC amounts of about 2ξ into compact fine flocs (domain II) as a consequence of recharging of the particles. Unlike type-I dispersions, the type-III dispersions exhibit Newtonian flow, even at relatively high bentonite concentrations (2.5% w/w and above), and the flocs settle to sediments of distinctly smaller volumes.

Abstract: Magnesium aluminum hydroxide, the most important member of layered double hydroxides, was peptized by intense washing. The particle diameter, 70–130 nm, depended on the temperature of aging the parent material. The electrophoretic mobility of the particles decreased with increasing pH, from 3.7 × 10−8 m2/Vs at pH 5 to 0.5 × 10−8 m2/Vs at pH 12.3. An isoelectric point at pH∼7 was reached with the addition of 87 mmol/l NaSCN, 3 mmol/l Na2SO4 and Na2CO3, and 0.7 mmol/l Na2HPO4. The critical coagulation concentration for the 2% (w/w) dispersion was 88 mmol/l NaCl, 1.8 mmol/l Na2CO3, 1.4 mmol/l Na2SO4, and 1.2 mmol/l Na2HPO4 at pH∼7. The 2% dispersion at pH∼7 showed an almost Newtonian flow behavior. Yield values were developed after salt addition. The 2% dispersion reached a yield value of 2 Pa at 100 mmol/l NaCl, 3 Pa at 100 mmol/l Na2SO4, and 5 Pa at 100 mmol/l Na2CO3. Sodium phosphate in comparison with the other salts showed a liquefying effect. The yield value increased to 3 Pa at 1–10 mmol/l Na2HPO4 and decreased to 0.5 Pa at 100 mmol/l Na2HPO4.

Abstract: Montmorillonite dispersions were completely coagulated ¶by magnesium aluminum hydroxide when the hydroxide mass fraction, χ, was 0.2 or greater. The hydroxide dispersion required only a montmorillonite mass fraction of 0.06 for total coagulation. Thus, heterocoagulates were formed for 0.2<χ>0.5, both properties decreased steeply, indicating the reduced mechanical stability of the network. Divalent anions at concentrations above 1 mmol/l acted as liquefying agents for the dispersed heterocoagulates. The specific surface area of the freeze-dried dispersions increased to a maximum value at χ = 0.65. The pore size distributions revealed that montmorillonite lamellae and hydroxide particles were not homogeneously distributed.

The colloidal state (stable, coagulated, or gel-like) and the rheological properties of Na-rich montmorillonite (Wyoming) dispersions are strongly influenced by organic cations. This effect is shown for homologous organic cations: alkyl trimethylammonium ions, paraquat, diquat, alkyl bispyridinium ions, and the triphenylmethane dyes crystal violet, methyl green, and tris (tri-methylammonium phenyl) methane chloride. The critical coagulation concentrations, cK, are small (often < 1 mmol/L) because the cations are enriched in the Stern layer and influence the solvent structure near the surface. The strong adsorption of the counterions at the clay-mineral surface causes cKvalues to increase with the solid content. Charge reversal (recharging) of the particles was observed with the longer chain alkyl trimethyl-ammonium ions, dodecyl bispyridinium ions, and crystal violet. Other cations reduced the electrophoretic mobility to zero but positive particle charges were not observed. The plastic viscosity increased sharply at the critical coagulation concentration and showed a minimum slightly below cK, which was caused by the electroviscous effect. Yield values were developed at concentrations above cK. In most cases, yield values reached a plateau where the amount of organic cations was ∼0.5 mmol/g, i.e., about half of the cation-exchange capacity. The cKvalues decreased with increasing hydrophobicity of homologous compounds, but the yield value showed maxima at intermediate chain lengths. The yield value of several 0.5% dispersions was high, e.g., dodecyl trimethylammonium ions, 71 Pa; paraquat, 100 Pa; diquat, 42 Pa; hexyl bispyridinium ions, 53 Pa (vs.Ca2+, 0.2 Pa; Al3+, 0.7 Pa). The storage modulus as a function of the number of organic cations changed in a similar way as the yield value, and high values were observed (e.g., dodecyl trimethylammonium ions, hexyl bispyridinium ions: 1000 Pa, paraquat: >4000 Pa). Thus, dispersions with high viscosity, yield value, and pronounced viscoelasticity are obtained by coagulating Na-rich montmorillonite dispersions with organic cations.

Abstract: For the first time, the particle distribution and aggregation in Pickering emulsions were made visible by transmission X-ray microscopy. Oil/water emulsions were stabilized by heterocoagulates of a clay mineral and magnesium aluminum hydroxide. Stability is optimum when the particles surround the oil droplets and also assemble to form a network extending through the coherent phase.

Abstract: Oil–water emulsions stabilized by solids have been imaged with sub-100 nm spatial resolution and analyzed spectroscopically using a scanning transmission X-ray microscope. The emulsions are stabilized by particle heterocoagulate cages surrounding the oil droplets. These cages form due to the interaction of negatively charged clay mineral particles (sodium montmorillonite, Wyoming) and positively charged particles of calcium/aluminum layered double hydroxide (LDH). The emulsions were studied at atmospheric pressure, without any pretreatment using carbon K and calcium L X-ray absorption edges. Oil- and calcium-rich LDH were separately mapped, and the clay mineral dispersions were also imaged. Applying X-ray absorption-edge contrast, oil could be distinguished from water in the emulsion near the carbon K absorption edge (284 eV, 4.4 nm). Spectromicroscopy near the calcium L absorption edge (346 eV, 3.6 nm) allowed the structural details of heterocoagulate formation to be revealed.

The critical coagulation concentration,cK, of sodium chloride for sodium montmorillonite dispersed in water (solid content 0.025 percent) is 8 mmol/L. It remains virtually constant (7.5–8.5 mmol/L) in water-rich alcohol mixtures (below 50% (v/v) methanol and 40% ethanol and propanol). At higher alcohol contents thecK decreases to 3.6 mmol/L (70 percent methanol), 1.2 mmol/L (70 percent ethanol), and 0.8 mmol/L (60 percent propanol). In the presence of 10-4 M sodium diphosphate thecK in water rises to 195 mmol/L. In contrast to the behavior in the absence of diphosphate, even small amounts of alcohol reduce the critical coagulation concentration. In 70% methanol thecK is 7.5 mmol/L, in 70 percent ethanol 2.5 mmol/L and in 60% propanol 5 mmol/L. The main mechanism is coagulation by contacts between negatively charged edges and faces.

The boundary region separating a latex particle from the surrounding medium has a great influence on the properties of latex dispersions. Four types of polystyrene and polystyrene/comonomer latices differing greatly in the structure of the boundary region were prepared. The first part of a series of papers reports on the preparation of the various latex dispersions. Mean particle sizes were obtained from simple turbidity measurements, quasi-elastic light scattering, and electron micrographs. The behavior of the particles in the centrifugal force field is a simple tool for detecting aggregation tendencies that are not directly related to salt stability. The BET-surface area agrees with the area calculated from the mean particle size when a sharp boundary and smooth surface is developed between the particle and the surrounding medium. In the case of particles with extended boundary regions (core/shell particles or particles with hairy envelopes), film formation reduces the specific surface area. Removal of soluble oligomers and polymers from the boundary region during subsequent treatments (purification and centrifugation before freeze-drying) can increase the surface area considerably.

Crystalline silicic acids are prepared from alkali layer silicates by exchanging protons for the alkali ions. The acid H2Si20O41 · xH2O (parent material K2Si20O41 · xH2O) exhibits some outstanding gas adsorption properties which are related to the layer structure and the interlamellar microporosity. The external surface, about 20 m2 g-1, is estimated from nitrogen adsorption data after blocking the micropores. Slit-shaped ultramicropores (with diameters similiar to that of the nitrogen molecule) between the layers are widened to supermicropores near the crystal edges. During an adsorption run the nitrogen molecules penetrate more deeply into the ultramicropores. Nitrogen molecules strongly adsorbed in the ultramicropores are not desorbed at 77 K. Additional amounts of nitrogen are adsorbed by widening of the slit-shaped micropores at the crystal edges when pressure increases. This process proceeds slowly and is reversible.

The grafting of organosilyl groups in the interlamellar space of certain crystalline silicic acids, such as H-magadiite, occurs when the interlayer spaces have been expanded previously by intercalation of some polar organic substances. The interlamellar Si-OH groups are then accessible to silylating reagents and Si-O-Si bridges form between the silicic acid surface and the organic groups.

Summary Complexes of nonionic surfactantsR-(OCH2CH2)x OH with montmorillonite have been studied (R =n-hexadecyl,n-octadecyl and oleyl ;x=2, 10 and 20).

The adsorption from methanol/water and the enthalpy of displacement of methanol by water were studied on K-60 silica gel, on graphitized PRINTEX-80, and onn-alkylammonium vermiculites. The adsorption between the hydrophobized silicate layers was followed by x-ray measurements. The excess isotherms of alkylammonium vermiculites in methanol/water exhibit two maxima corresponding to the two steps of the individual isotherm. The equilibrium constant of the exchange of water by methanol is calculated. For calculating the adsorption capacities and molar adsorption potentials, a new equation is proposed which combines the adsorption excess quantities with free energy and enthalpy functions.

Lamellar crystalline silicas (crystalline silicic acids, chemical composition SiO2·xH2O; examples: H4Si14O30·xH2O, H4Si20O42·xH2O) are distinguished from the amorphous forms by their layered structure and exceptional adsorption properties. One outstanding example is the reaction with anionic surfactants. Several types of crystalline silicas (typical H4Si20O42·xH2O) can intercalate ionic pairs consisting of surfactant anion and gegen ion into the interlayer space. The saturation value of SDS adsorption is 0.475 mmol SDS/g H4Si20O42·3H2O. The acid H4Si14O30·xH2O adsorbs anionic surfactants at the external surfaces only (saturation value 0.04 mmol/g H4Si14O30·0.8 H2O). When anionic surfactants are adsorbed in the interlayer space, the layer separation increases to such an extent that the crystals disarticulate in a fan-like manner or delaminate into thinner packets of layers or smaller aggregates. Washing-out the SDS ionic pairs or drying reconstitutes the parallel layer orientation and leads to re-aggregation of the packets and fragments.

Two groups of polymer networks (polymer resins) are investigated by selective liquid sorption fromn-propanol-water mixtures. Group 1 consists of gel polymerized polar (hydrophilic) ion exchangers which swell in the binary liquid mixture. Group 2 consists of non-polar, non-swelling, macroporous resins. The free energy isotherms accompanying the sorption processes are calculated from the excess isotherms and the bulk activities. The adsorption excess free energies reveal the differences in polarity of the polymer network.

Presently, a large variety of layered materials are synthesized that are able to intercalate neutral guest molecules or to exchange inorganic and organic ions for interlayer ions. Several of these materials are also found as minerals.

Adenosine-5-phosphates (ATP, ADP, AMP) are adsorbed by clay minerals at very low concentrations (=2 mg/liter). In contrast to quartz, the clay minerals exhibit a strong preference for ATP over AMP. The experimental data are expressed as recovery rates (adenosine-phosphate in solution to total nucleotide added). For example, the recovery rates of ATP, ADP, and AMP in the presence of sodium montmorillonite are 0,17, and 100%; in the presence of quartz 95, 100, and 99%. The recovery rate of AMP on clays is markedly decreased by the presence of ATP, that is, ATP increases the adsorption of AMP by cooperative interactions. A part of ATP not recovered in the equilibrium solution is dephosphorylated to ADP. For example, 45% of ATP not recovered in equilibrium solution with calcium montmorillonite is recovered as ADP; with sodium montmorillonite only ADP can be recovered in solution. ????????-5-?????? (???, ???, ???) ????????????? ?????????? ?????????? ??? ????? ?????? ????????????? (=2 ??/????). ? ????????????????? ??????, ????????? ???????? ????????? ??????? ???????????? ? ??? ?? ????????? ? ???. ????????????????? ?????? ?????????? ? ???? ??????? ??????????? (????????-??????? ? ???????? ? ?????? ???????????? ?? ??????????). ????????, ????????? ??????????? ???, ???, ? ??? ? ??????????? ?????????? ??????????????? ???????? 0, 17, ? 100%; ? ??????????? ?????? 95, 100, ? 99%. ??????? ??????????? ??? ?? ?????? ??????? ??????????? ? ??????????? ???, ?? ????, ??? ??????????? ????????? ??? ? ?????????? ?????????????? ??????????????. ????? ???, ?? ???????????????? ? ??????????? ????????, ??????????????? ? ???. ????????, 45% ??? ???????????????? ? ??????????? ???????? ? ???????? ???????????????? ?????????????? ??? ???; ? ??????????? ?????????? ??????????????? ?????? ??? ????? ???? ?????????????? ? ????????. [N. R.] Adenosin-5-phosphationen (ATP, ADP, AMP) werden von Tonmineralen bereits bei sehr kleinen Konzentrationen =2 mg/litre) adsorbiert. Im Gegensatz zu Quarz binden die Tonminerale ATP bevorzugt vor AMP. Die experimentellen Daten werden durch die Wiederfundraten ausgedrückt, die angeben, welcher Anteil des einer Suspension zugesetzten Nucleotids in der Gleichgewichtslösung zurückbleibt. Zum Beispiel werden in Natriummontmorillonit-Suspensionen 0,17, und 100% des zugesetzten ATP, ADP, und AMP wiedergefunden, während bei Quarz keine Adsorption erfolgt (Wiederfundraten 95, 100, und 99%). Die Wiederfundrate von AMP an Tonmineralen sinkt stark ab, wenn gleichzeitig ATP anwesend ist: die Adsorption des AMP wird durch kooperative Wechselwirkungen mit ATP begünstigt. Die Abnahme des ATP-Gehaltes der Suspension geht nicht nur auf die Adsorption des ATP zurück; ein Teil des ATP wird an der Festkörperoberfläche in ADP hydrolysiert. So finden sich z.B. in Calcium-montmorillonit-Suspensionen 45% des ATP als ADP wieder, bezogen auf die Differenz: zugesetztes ATP-ATP in der Gleichgewichtslösung. Bei Natriummontmorillonit wird sogar nur ADP in der Lösung gefunden. Les phosphates-adenosine-5 (ATP, ADP, AMP) sont adsorbés par des minéraux argileux à de très basses concentrations (=2 mg/litre). Contrairement au quartz, les minéraux argileux montrent une forte préférence pour l’ATP par rapport à l’AMP. Les données expérimentales sont exprimées en taux de récupération (l’adénosine phosphate en solution par rapport au nucléotide total ajouté). Les taux de récupération d’ATP, ADP, et AMP en présence de montmorillonite sodium par exemple, sont 0, 17, et 100%; en. présence de quartz, 95,100, et 99%. Le taux de récupération d’AMP sur les argiles est remarquablement amoindri en présence d’ATP, c’est à dire, l’ATP accroît l’adsorption d’AMP par interaction cooperative. Une partie d’ATP non récupéré dans la solution d’équilibre est déphosphorilaté en ADP. Par exemple, 45% d’ATP, non récupéré dans la solution d’équilibre avec la montmorillonite calcium sont récupérés comme ADP, avec la montmorillonite sodium, seul l’ADP peut être récupéré en solution. [D. J.]

Abstract:  Adsorption of n-butanol and water from butanol–water mixtures is studied on adsorbents of different hydrophobicity (activated carbon and hydrophobized montmorillonites). The shape of the adsorption isotherms of the hydrophobized clay minerals does not indicate preferential adsorption of butanol. Therefore, the adsorption capacity cannot be determined on the basis of the Langmuir isotherm. A new equation for determining the adsorption capacity is derived by combining the free enthalpy of adsorption with the adsorption excess amount. Both collections of data are obtained from the surface excess isotherm. The reliability of the adsorption capacity is checked by X-ray diffraction measurements.

Abstract:  Paraffin/water emulsions were stabilized by colloidal particles without surface active agents. Mixtures of two types of particles with opposite signs of charge were used: a layered double hydroxide (the hydroxide layers carry positive charges) and the clay mineral montmorillonite (the silicate layers carry negative charges). The emulsions were very stable and did not separate a coherent oil phase. The stability of the emulsion (no oil coalescence after centrifugation) was independent of the mixing ratio of both the compounds when the total solid content was >0.5%. Solid contents up to 2.0% were optimal. In contrast to stability, flow behavior of the emulsion was dependent on the mass fraction χ of the hydroxide. The maxima of viscosity and yield value were observed at χ≈0.2–0.3; the emulsion showed pronounced antithixotropic behavior. Weak thixotropic properties, smaller viscosities and yield values were observed at χ≤0.2 and ≥0.5. In the absence of the clay mineral, the double hydroxide particles stabilize by forming envelopes around the oil droplets. Addition of bentonites creates a three-dimensional network of particles with high elasticity which impedes coalescence of the oil droplets.

The external and internal surface area of the calcium aluminum double hydroxide [Ca2Al(OH)6] NO3· 2H2O were hydrophobized by the anionic surfactants sodium dodecylsulfate and sodium dodecylbenzene sulfonate. The adsorption behavior towards liquid mixtures (benzene/n-heptane and n-propanol/toluene) was studied by determining the surface excess adsorption isotherms, the heats of immersion in these liquids, and the basal spacing, i.e. the expansion of the interlayer space. Both hydrophobic layered double hydroxides (LDHs) adsorbed n-heptane, benzene, toluene, and n-propanol between the layers with considerable increase of the basal spacing. Interlamellar swelling of the hydrophobizised LDHs in n-heptane was fundamentally different to the behavior of hydrophobized 2:1 clay minerals (smectites, vermiculites). The surface excess isotherms for benzene/heptane mixtures were U-shaped and indicate preferential adsorption of benzene. Dodecylbenzene sulfonate double hydroxide preferentially adsorbed propanol from n-propanol/toluene mixtures but the dodecylsulfate derivative adsorbed both compounds.

Alkylammonium ion exchange on mixed-layer minerals gives detailed information about the variation of cation density in succeeding interlayer spaces. Three mixed layer samples from Japan (supplied by Dr. H. Kodama) were investigated. Their nearly 1:1 interstratification is based on regularly alternating high- and low-charged interlayer spaces, which are caused by a regular sequence of polar layers. The cation density in the high-charged interlayer spaces is >0.8 eq/(Si, Al)4O10. The low-charged interlayer spaces have an average cation density of 0.4 eq/(Si, Al)4O10and heterogeneous charge distribution. The kind of heterogeneity of the Goto Mine sample differs from that of the Yonago Mine and the Honami Mine samples. The Goto Mine specimen has a rather regular sequence of the low- and high-charged interlayers in proportions close to 0.50:0.50. The other two samples contain interlayer spaces with pronounced unsymmetrical charge distribution. The Yonago Mine sample probably has in random distribution with the polar layers about 10% mica-like layers segregated to packets of three and more layers; the ratio of high-charged interlayers to the low-charged ones is increased to about 0.55:0.45. The Honami Mine sample probably contains isolated mica-like layers or pairs of them. The proportion of the high-charged interlayers is estimated to be about 0.53:0.47 and is lower than determined by Kodama from the glycerolated sample. The samples investigated may be considered as end-members of a series of interstratified specimens which begins with smectites with mixed-layer like charge distribution. Ионный обмен смешаннослойных минералов и алкиламмония позволяет получить детальную информацию о изменениях плотности катионов в последую-щих межслойных промежутках. Были исследованы три смешанно-слойных образца из Японии (предоставленных Др.Кодома). Их переслаивание, близкое 1:1 основано на регулярном чередовании сильно- и слабо-заряженных межслойных про-межутков, что обусловлено регулярной последовательностью полярных слоев. Плотность катионов в сильно заряженных межслойных промежутках >0, 8эк/(Si, Аl)4О10. Слабо заряженные промежутки имеют среднюю плотность катионов 0, 4эк (Si, Аl)4O10и гетерогенное распределение зарядов. Вид гетерогенности образцов Гото Майн отличается от видов гетерогенности образцов Янаго Майн и Гонами Майн. Образец Гото Майн имеет довольно регулярную последователь-ность слабо- и сильно-заряженных межслойных промежутков в пропорции, близ-кой к 0, 50:0, 50. Другие два образца содержат межслойные промежутки с явно несимметричным распределением зарядов. Образец Янаго Майн имеет около 10 процентов слюдо-подобных слоев, беспорядочно перемежающихся с полярными слоями и обособленных в пакеты из трех и более слоев; отношение сильно за-ряженных межслойных промежутков и слабо заряженных возрастает до примерно 0, 55:0, 45. Образец Гонами Майн возможно содержит изолированные слюдо-по-добные слои или их пары. Пропорция сильно заряженных межслойных промежут-ков определяется примерно как 0, 53:0, 47 и ниже, чем было определено Кодома в обработанном глицерином образце. Изученные образцы могут рассматриваться как конечные члены серии пере-слаивающихся образцов, которая начинается смектитами с подобным смешанно-слойному распределению зарядов. Der Alkylammoniumionenaustausch an 2:1 Schichtsilikaten mit Wechsellagerungsstruktur ermöglicht Aussagen über die Variationen der Kationendichte in aufeinanderfolgenden Zwischenschichträumen. Drei Proben aus Japan (zur Verfügung gestellt von Dr. H. Kodama) wurden untersucht. Ihre fast 1:1 Wechsellagerung beruht auf regelmäßig abwechselnden hoch und niedrig geladenen Zwischenschichträumen, welche durch eine regelmäßige Anordnung polarer Schichten verursacht wird. Die Kationendichte in den hoch geladenen Zwischenschichträumen ist >0,8 Äquivalente/(Si,Al)4O10. Die niedrig geladenen Zwischenschichträume haben eine mittlere Kationendichte von 0,4 Äquivalenten/(Si,Al)4O10und die Ladungsverteilung ist heterogen. Die Proben von Goto Mine, Yonaga Mine und Honami Mine besitzen alle eine verschiedene Heterogenität. Die Goto Mine Probe hat eine recht regelmäßige Anordnung der hoch und niedrig geladenen Zwischenschichten im Verhältnis 0,50:0,50. Die anderen zwei Proben enthalten Zwischenschichträume mit ausgesprochen unsymmetrischer Ladungsverteilung. Wahrscheinlich enthält die Probe von Yonaga Mine zusätzlich Pakete aus mehreren Glimmerschichten. Das Verhältnis der hoch geladenen Schichten zu den niedrig geladenen nimmt bis etwa 0,55:0,45 zu. Die Honami-Probe enthält wahrscheinlich isolierte Glimmerschichten oder Paare davon. Der Anteil der hoch geladenen Zwischenschichten wird auf 0,53:0,47 geschätzt und ist niedriger als Kodamas Werte aus der Glycerinaufweitung. Die untersuchten Proben können als Entglieder einer Entwicklungsreihe von Wechsellagerungsverbindungen angesehen werden, an deren Anfang die Smektite mit wechsellagerungsartiger Ladungsverteilung stehen. L’échange d’ions alkylammonium sur des argiles interstratifiées donne une information détailée concernant la variation de densité de cations dans la succession d’espaces interfeuillets. Trois exemples du Japon (procurés par Dr.H.Kodama) ont été étudiés. Leur rapport d’interstratification, quasi 1:1, se base sur des espaces interfeuillets alternants régulièrement entre des charges hautes et basses, qui sont causés par une suite régulière de feuillets polaires. La densité de cations dans les espaces interfeuillets à haute charge est > 0,8 eq/(Si,Al)4O10. Les espaces interfeuillets à basses charges ont une densité de cation moyenne de 0,4 eq/(Si,Al)4O10et une distribution de charge hétérogène. Le genre d’hétérogénéité des échantillons des mines de Goto est différant de celui des échantillons des mines de Yonago et de Honami. L’échantillon de la mine de Goto a une séquence assez régulière d’espaces interfeuillets à haute et basse charge dans des proportions proches de 0,50:0,50. Les deux autres échantillons contiennent des espaces interfeuillets dont la distribution de charge est d’une assymétrie prononcée. L’échantillon de la mine de Yonago a probablement, en distribution fortuite avec des feuillets polaires, à peu près 10 pourcent de feuillets semblables au mica, rassemblés en paquets de trois feuillets ou plus; le rapport entre les espaces interfeuillets à haute charge et ceux de basse charge est augmenté à prés de 0,55:0,45. L’échantillon de la mine de Honami contient probablement des feuillets isolés semblables au mica, ou des paires de tels feuillets. La proportion des espaces interfeuillets à haute charge est estimée à prés de 0,53:0,47 et est plus basse que celle déterminée par Kodama de l’échantillon glycérolé. Les échantillons étudiés peuvent être considérés comme étant les termes extrêmes d’une série d’échantillons interstratifés qui commence avec les smectites à distribution de charge semblable à celle des argiles interstratifiées.

Complexes of n-tetradecylammonium-beidellite with n-alkanols $${\rm{(n - }}{{\rm{C}}_{{\rm{14}}}}{{\rm{H}}_{{\rm{29}}}}{\rm{N}}{{\rm{H}}_{\rm{3}}}^{\rm{+}}{\rm{)_{{\rm{0,44}}}(n - C_{{\rm{x}}}}}{{\rm{H}}_{{\rm{2x}}}}{\rm{+}}{}_{\rm{1}}{\rm{OH) }}{}_{{\rm{1,56}}}{{\rm{\{ M}}{{\rm{g}}_{{\rm{0,28}}}}{\rm{A}}{{\rm{l}}_{{\rm{1,81}}}}{{\rm{(OH)}}_{\rm{2}}}{\rm{S}}{{\rm{i}}_{{\rm{3,56}}}}{\rm{Al}}{}_{{\rm{0,44}}}{\rm{O_{{10\}} }}}^{{\rm{0,44 - }}}}$$(x= 8–22) have been prepared and characterized by their basal spacings and by measurements of the specific heat cp. The compounds undergo a series of reversible phase transitions $${\beta _1} \rightleftharpoons...\rightleftharpoons{\beta_i}\rightleftharpoons...\rightleftharpoons{\beta_\omega}\rightleftharpoons{\alpha_1}...\rightleftharpoons{\alpha_j}$$with rising temperature. The maximum number ω of β-phases depends upon the chain lengths and increases from 1 with decanol to 6 with docosanol. Due to the evaporation of alkanol the number of χ-phases is not yet established in all details. The β-transitions correspond to conformational changes of the alkyl chains via rotational isomerisation, especially kink formation. The β-phases become unstable if the kink concentration exceeds 0,14 kinks/-CH2-. The β/α-transition is probably caused by a rearrangement into special gauche-block structures.

Die Aufnahme von Codeinkationen in die Schichtzwischenräume innerkristallin quellungsfähiger (glimmerartiger) Tonminerale (Bentonit, Veegum, Laponit) wird von Ladungsverteilung und Teilchengröße der Tonmineralkristalle und den Milieubedingungen —pH-Wert, Salzgehalt der wäßrigen Suspensionen —bestimmt. Die Zwischenschichtkationen (Na+, K+, NH 4+ , Ca++) haben keinen differenzierten Einfluß auf die Austauschisothermen im Sättigungsbereich. Röntgenographisch konnte nachgewiesen werden, daß als Folge der besonderen Konfiguration und Lage der funktionellen Gruppen die Codeinkationen in allen untersuchten Tonmineralen in gleicher Weise an den inneren Oberflächen der Schichtsilikate in den Schichtzwischenräumen angeordnet sind.

The structure and the sorption properties of partially hydrophobized silicates (dodecylammonium and dodecyldiammonium vermiculites) have been investigated in aqueous solutions of 1-butanol. The alcohol is preferentially adsorbed on the surface. The interlayer composition is calculated from adsorption and x-ray diffraction data. In air-dried state the organic cations lie flat on the interlamellar surface. In aqueous butanol solutions, the basal spacing of dodecylammonium vermiculite gradually increases with the extent of butanol adsorption because the chains increasingly point away from the surface. The basal spacing of dodecyldiammonium vermiculite is virtually independent on the interlayer composition because the expansion of the interlayer space is sterically restricted and a relatively rigid structure is formed. The enthalpy of the displacement of water by 1-butanol has been determined by flow sorption microcalorimetry. The displacement process is endothermic.

Selective adsorption of 1-propanol-water mixtures was investigated on adsorbents of various surface character. The enthalpy of displacement of 1-propanol by water was studied on graphitized PRINTEX-80, K-60 silicagel, and n-alkylammonium vermiculites. The free enthalpy and entropy isotherms of displacement were derived. The adsorption between the silicate layers of hydrophobic vermiculites was followed by x-ray measurements, and thermodynamic functions were calculated for the structural changes in the adsorption layers. Formation of alcohol-water clusters on the surfaces plays an important role.

The location, environment and availability of the interlamellar species in modified layered silicates have been investigated using two montmorillonites selected with different charge deficit distributions. A structural study has revealed release of protons and further migration to the lattice as thermal treatments are performed. The proton availability has been examined through a catalytic reaction, all the modified samples showing similar activities in this test. A possible explanation for this levelling effect has been suggested.

Zusammenfassung In der vorliegenden Arbeit wird am Beispiel der Na-Montmorillonite die Struktur zwischen plättchenförmigen Kolloidteilchen im peptisierten und geflockten Zustand untersucht. Im peptisierten Zustand mit Abständen > 30 Å zwischen den Schichten werden diffuse Ionendoppelschichten ausgebildet. Bei kleinen Schichtabständen geht diese Anordnung dagegen in eine quasikristalline Struktur mit zwei oder vier Wasserschichten zwischen den Silicatschichten über, die durch eine höhere Ordnung der Kationen und Wassermoleküle gekennzeichnet ist („Schichtsolvate“). Mit diesem Übergang ist eine Änderung in der elektrostatischen Wechselwirkungsenergie verbunden. Bei diffusen Ionendoppelschichten ist sie positiv (Abstoßung), im quasikristallinen Bereich dagegen negativ (Anziehung).

Zusammenfassung Nach der DLVO-Theorie wird die Energiebarriere zwischen großen und kleinen?d- Werten mehr oder weniger stark erniedrigt, wenn das Oberflächenpotential der beiden in Wechselwirkung tretenden Kolloidteilchen unterschiedlich ist. Als Beispiel für den Einfluß dieser unsymmetrischen Ladungsverteilung wird die reversible Peptisation und Flockung von quellungsfähigen glimmerartigen Schichtsilicaten, wie z. B. Montmorilloniten (Bentoniten) diskutiert.

Zusammenfassung Die Schichtabstände der n-Alkanolkomplexe von n-Alkylammonium-Schichtsilicaten nehmen in der Tief- und Hochtemperaturform in Stufen von 1,0 bis 1,3 Å ab. Diese Stufen werden durch Bildung von Kinken in den Alkylketten der n-Alkanole und n-Alkylammoniumionen des „bimolekularen Films“ gedeutet. Für die Struktur in der Hochtemperaturform wird ein Modell mit jog-Blöcken vorgeschlagen.

Zusammenfassung An den Schichteinlagerungsverbindungen vonn-Al-kylammonium-Schichtsilicaten mitn-Alkanolen wurde der Einfluß der Schichtladung und der Alkylkettenlänge auf bimolekulare Filme ausn-Alkylammoniumionen undn-Alkanolen in verschiedenen Mischungsverhältnissen untersucht.

Zusammenfassung: Die Dimethyldioctadecylammonium-Derivate der quellungsfähigen glimmerartigen Sohichtsilicate sind als stationäre Phasen für die Gasadsorptionschromatographie von aromatischen Kohlenwasserstoffen geeignet. Sie ergeben symmetrische Peaks. Die Trennwirkung ist für die einzelnen Schichtsilicate unterschiedlich, sie ist besonders gut bei den Schichtsilicaten mit hoher Schichtladung.

Zusammenfassung: In den n-Alkylammoniumderivaten der niedrig geladenen Schichtsilicate liegen die n-Alkylammoniumionen mit ihren Längsachsen parallel zu den Silicatschichten und sind je nach Schichtladung und Kettenlänge in Einfach-, Doppel- und Pseudodreifachschichten angeordnet.

Zusammenfassung: Zwischen dem Schichtabstand d und der Schichtladung (x+y) glimmerartiger Schichtsilicate

This paper deals with the preparation of sequence isomers of mica type layer silicates. These isomers differ in the succession of structurally identical but differently charged layers.

The basal spacings of long chain n-alkanol complexes of nontronite saturated with Li+, K+Mg2+, Ca2+, Sr2+and Ba2+were measured for temperatures increasing from −70°C up to 130°C. With rising temperatures the complexes rearrange from a low temperature form into a high temperature form. In the low temperature form the alkyl chains of the alkanol molecules form bilayers with their chain axes perpendicular to the silicate layers. The chains may not be in all cases in the planar all trans conformation but in special ‘kink’-conformations. The transition into the high temperature form is explained by cooperative transition from a form with a low number of ‘jogs’ to one with a high number of ‘jogs’ and ‘kinks’. Les espacements basaux des complexes formés entre des n-alcanols et la nontronite saturée par Li+, K , Mg2+, Ca2+, Sr2+et Ba+ont été mesurés aux températures allant de −70°C à 130°C. Lorsque la température s’élève, les complexes subissent un réarrangement d’une forme basse température à une forme haute température. Dans la forme basse température les chaînes alkyle des molécules d’alcanol forment des couches doubles dans lesquelles les axes des chaînes sont perpendiculaires aux feuillets du silicate. Il peut arriver que les chaînes n’adoptent pas dans tous les cas la conformation plane “all trans”, mais qu’elles aient des conformations spéciales (“kinks”). Le passage de la forme basse température à la forme haute température est expliqué par une transition coopérative d’une forme à nombre reduit de “jogs” vers une forme à nombre élevé de “jogs” und “kinks”. Die Basisebenenabstände von langkettigen n-Alkanolkomplexen mit Li+-, K+-, Mg++-, Ca++-, Sr++- und Ba++-gesättigtem Nontronit wurden im Temperaturbereich von −70°C bis 130°C gemessen. Mit ansteigender Temperatur ordnen sich die Komplexe von einer Tieftemperaturform in eine Hochtemperaturform um. In der Tieftemperaturform bilden die Alkylketten der Alkanolmoleküle bimolekulare Schichten mit senkrecht zu den Silikatschichten angeordneten Kettenachsen. Die Ketten brauchen nicht in allen Fällen in der ebenen all-trans Konformation vorzuliegen, sie können auch in speziellen Kinkenkonformationen auftreten. Der Übergang in die Hochtemperaturform wird als eine kooperative Umwandlung von einem Zustand mit einer geringen Zahl von “Jogs” in einen solchen mit einer großen Zahl von “Jogs” und “Kinken” gedeutet. Наблюдали изменения базисных параметров длинной цепи комплексов п-алканола нонтронита, насыщенного Li+, К+, Mg2+, Са2+, Sr2+и Ва2+, при повышении температуры от — 70°С до 130°С. С повышением температуры комплексы перегруппировываются из низкотемпературной формы в высокотемпературную. При низкотемпературной форме алкиловые цепи молекул алканола формуют бинарные слои при чем оси их цепей находятся перпендикулярно к слоям силиката. Не во всех случаях цепи ориентированы в планарной цельной трансконформации, иногда они ориентированы в особых «петлевых» конформациях. Переход в высокотемпературную форму объясняется объединенным переходом из формы с малым числом «спупенек» в форму с большим числом «ступенек» и «петель».

This paper deals with the cation exchange of N‐n‐alkylpyridinium ions against inorganic ions in mica type layer silicates. The arrangements of these ions in the interlayer space is derived from basal spacing measurements.