Effect of ionic surfactants on the electrophoretic mobility of hydroxyapatite

Recent literature on solubility and interfacial properties of hydroxyapatite is reviewed. Representation of thermodynamic equilibrium between the solid and the solution is discussed for the system containing calcium, phosphate and hydrogen ions and their complexes.The origin of surface charge and the conditions for zero charge on hydroxyapatite are discussed, and adsorption mechanisms for fluoride and organic ions are critically reviewed. The literature review reveals that complex interfacial and dissolution interactions occur in this system.

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“…Specific adsorption of dodecylammonium and dodecyltrimethylammonium ions on hydroxyapatite was observed by Mishra et al ( 45).…”

Section: Adsorption Of Organic Ionsmentioning

confidence: 84%

“…These ions act as potentialdetermining ions as well as specifically adsorbed ions, as demonstrated by Mishra et al (45) and Somasundaran (48).…”

Section: Hydroxyapatite S Chander and D W Fuerstenaumentioning

confidence: 90%

Solubility and Interfacial Properties of Hydroxyapatite: A Review

Chander

Fuerstenau

1984

Adsorption on and Surface Chemistry of Hydroxyapatite

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“…The patches of associated ions were termed "hemi-micelles." Dodecylammonium chloride also exhibits this phenomenon at the hydroxyapatite surface (Mishra et aL, 1980). Structuring effects at the solid/liquid interface has also been shown by the phase transitions of 1-octanol/heptane mixtures on a graphitized carbon black (Brown et al, 1975).…”

Section: Enthalpy Of Solution In the Interlamellar Phasementioning

confidence: 78%

Adsorption of n-Aliphatic Alcohols from Dilute Aqueous Solutions on RNH₃-Montmorillonites. III. Interlamellar Aggregation of the Adsorbate

Stul

1985

Clays and clay miner.

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Abstract--The large amount of water in the interlamellar space of alkylammonium montmorillonites in aqueous solutions is not fixed by intercalated hexanol or octanol. The hydration of the NH3+-group and the filling of the empty spaces between the carbon chains are responsible for this phenomenon. Hydrogen bonds between the alcohols and the ammonium groups reduce the enthalpy of solution of hexanol and octanol in the interlamellar region at infinite dilution to + 17.6 and + 12.7 kJ/mole, respectively. Selfassociation of the alcohols further diminishes the enthalpy of solution at higher alcohol concentration. The interlamellar fixation of the RNH3 cations prevents a micellization as has been obtained in bulk solutions. At a given alcohol concentration smectic type aggregates, i.e., double layers of alcohol molecules, appear as shown by an increase of the basal spacing of the organo-clay complexes. The aggregate formation is favored by a longer chain length of both the cation and the alcohol. Key Words--Adsorption, Alcohol, Alkylammonium cations, Intercalation, Micellization, Montmorillonire. Samenvatting--Het hoge watergehalte van de interlamellaire faze van alkylammonium-montmorillonieten in waterige oplossing is niet gefixeerd door de binnenkomende hexanol of oktanol. De hydratatie van de NH3+-groep en het opvullen van de ruimtes tussen de koolwaterstofketens zijn er verantwoordelijk voor. Bij oneindige verdunning reduceren waterstotbruggen tussen alkoholen en ammoniumgroepen de oplossings-enthalpie van respektievelijk hexanol en oktanol in de interlamellaire raze tot + 17,6 en 12,7 kJ/mol. Bij hogere alkoholkoncentratie vermindert deze oplossings-enthalpie verder door associatie van de alkoholen. De interlamellaire fixatie van RNH3 kationen verhindert her miceUisatiefenomeen zoals het zich in bulk oplossingen voordoet. Bij een bepaalde alkoholkoncentratie duidt een verhoging van de basisafstand van de organo-kleikompleksen het optreden aan van aggregaten van het smektiet type, d.i. een dubbellaag van alkohol molekulen. Deze aggregaat vorming wordt bevorderd door een langere keten van zowel het kation als van de alkohol.

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“…According to the manufacturer, Zonyl FSC is compatible with most anions in an aqueous solution, but it may be pre cipitated by phosphates. From the analogy with hydrocarbon quaternaries, adsorp tion of the surfactant to the negatively charged apatitic surface is likely [Levinskij, 1968;Mishra et al, 1980;Iwasaki, per sonal communication, 1986]. If Zonyl FSC attaches to the enamel, displacement of Ca2+ from the Stern layer into the bulk of the solution would follow.…”

Section: Discussionmentioning

confidence: 99%

The Caries Inhibitory Effect of Repeated Topical Applications of NaF or NH₄F in Rodents

Grøn¹,

Čáslavská²,

Tamura³

et al. 1987

Caries Res

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The caries inhibitory effect of topical applications of 200 ppm fluoride from neutral sodium and ammonium fluoride solutions was tested in the hamster. Similarly, 1,000 ppm fluoride from sodium and ammonium fluoride solutions with and without orthophosphate at pH 5 and 7 was tested in the rat. Also tested in the hamster study was the combination of neutral sodium or ammonium fluoride with Zonyl FSC (DuPont de Nemours, Wilmington, Del., USA). This positively charged surfactant accelerates the formation of apatitically bound fluoride during fluoride enamel interactions. Findings in the hamster study show that repeated fluoride treatments (4 per week) depressed caries in (M₁ + M₂), but not in M₃. Considering individual groups, only the animals treated with the sodium fluoride with Zonyl FSC experienced significantly less caries than the control group (M₁ + M₂). The findings in the rat showed all the fluoride-treated animals to experience less caries than the control group. Although the greatest caries inhibition resulted from repeated applications of ammonium fluoride with phosphate at pH 5, there was no statistically significant superiority of ammonium fluoride over sodium fluoride, irrespective of the presence of orthophosphate. On the other hand, solutions with orthophosphate were more effective than those without at pH 5, irrespective of whether the cation was sodium or ammonium. Finally, in the presence of orthophosphate, the sodium and ammonium fluoride solutions were more effective at pH 5 than at pH 7. A hypothesis is proposed explaining the differences in reactivity between NH₄- and Na-fluoride solutions with enamel on the basis of the structure of the solutions and access of the ions to the solid-liquid interface.

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Effect of ionic surfactants on the electrophoretic mobility of hydroxyapatite

Cited by 56 publications

References 16 publications

Solubility and Interfacial Properties of Hydroxyapatite: A Review

Solubility and Interfacial Properties of Hydroxyapatite: A Review

Adsorption of n-Aliphatic Alcohols from Dilute Aqueous Solutions on RNH₃-Montmorillonites. III. Interlamellar Aggregation of the Adsorbate

The Caries Inhibitory Effect of Repeated Topical Applications of NaF or NH₄F in Rodents

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Effect of ionic surfactants on the electrophoretic mobility of hydroxyapatite

Cited by 56 publications

References 16 publications

Solubility and Interfacial Properties of Hydroxyapatite: A Review

Solubility and Interfacial Properties of Hydroxyapatite: A Review

Adsorption of n-Aliphatic Alcohols from Dilute Aqueous Solutions on RNH3-Montmorillonites. III. Interlamellar Aggregation of the Adsorbate

The Caries Inhibitory Effect of Repeated Topical Applications of NaF or NH4F in Rodents

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Adsorption of n-Aliphatic Alcohols from Dilute Aqueous Solutions on RNH₃-Montmorillonites. III. Interlamellar Aggregation of the Adsorbate

The Caries Inhibitory Effect of Repeated Topical Applications of NaF or NH₄F in Rodents