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Adsorption of cationic surfactants and their effects on the interfacial properties of quartz.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Adsorption of cationic surfactants and their effects on the interfacial properties of quartz.
作者:	Jia, Renhe.
面頁冊數:	161 p.
附註:	Chair: Douglas W. Fuerstenau.
附註:	Source: Dissertation Abstracts International, Volume: 64-09, Section: B, page: 4564.
Contained By:	Dissertation Abstracts International64-09B.
標題:	Engineering, Materials Science.
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3105255
ISBN:	049652822X

Adsorption of cationic surfactants and their effects on the interfacial properties of quartz.
Jia, Renhe.

Adsorption of cationic surfactants and their effects on the interfacial properties of quartz. [electronic resource] - 161 p.

Chair: Douglas W. Fuerstenau.

Thesis (Ph.D.)--University of California, Berkeley, 2003.

The molecular structure of surfactant ions (chain length, number of hydrocarbon chains and number of headgroups) was found to significantly affect their surface activity. Increasing the hydrocarbon chain length of the surfactant lowers the concentration of surfactant required for minimum suspension stability, as well as redispersion. The adsorption is stronger for surfactants whose structure permits hydrogen bonding with sites on the solid surface. A larger head group also results in stronger adsorption. The addition of another hydrocarbon chain increases the surface activity of the surfactant and lowers the concentration required for minimum stability and redispersion. Adding a second ionic moiety to the molecule yield divalent surfactant that exhibits strong interaction with the oppositely charged surface relative to that of a monovalent surfactant. However, the stronger headgroup-headgroup repulsion between surfactant ions prevents them from packing close together to form hemimicelles. (Abstract shortened by UMI.)

ISBN: 049652822XSubjects--Topical Terms:

226940
Engineering, Materials Science.

Adsorption of cationic surfactants and their effects on the interfacial properties of quartz.
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520 # $a The molecular structure of surfactant ions (chain length, number of hydrocarbon chains and number of headgroups) was found to significantly affect their surface activity. Increasing the hydrocarbon chain length of the surfactant lowers the concentration of surfactant required for minimum suspension stability, as well as redispersion. The adsorption is stronger for surfactants whose structure permits hydrogen bonding with sites on the solid surface. A larger head group also results in stronger adsorption. The addition of another hydrocarbon chain increases the surface activity of the surfactant and lowers the concentration required for minimum stability and redispersion. Adding a second ionic moiety to the molecule yield divalent surfactant that exhibits strong interaction with the oppositely charged surface relative to that of a monovalent surfactant. However, the stronger headgroup-headgroup repulsion between surfactant ions prevents them from packing close together to form hemimicelles. (Abstract shortened by UMI.)
520 # $a This dissertation is primarily concerned with an investigation of the interfacial behavior of natural quartz in aqueous solution where the adsorption of various cationic surfactants is involved. The broad objective of this research was to delineate the mechanisms involved in the adsorption of cationic surfactants using experimental determination of adsorption isotherms, zeta potentials, suspension turbidity, contact angles, induction times, as well as Hallimond tube flotation response.
520 # $a With dodecylpyridinium chloride as the model surfactant, four-region adsorption isotherms were observed and found to correlate well with zeta potential, suspension stability and contact angle measurements. Calculations of adsorption energy showed strong specific adsorption in Region I, probably resulting from H-bonding of the pyridinium headgroup to active sites on the silica. As a result of hemimicelle formation at the solid-liquid interface in Region II, pronounced increases in the adsorption density, zeta potential, and surface hydrophobicity were observed. The stability of quartz suspensions showed a significant drop in this region. In Region III, the zeta potential is reversed and the stability of the suspensions begins to increase again. In this region, the surface hydrophobicity of quartz decreases with further surfactant adsorption, suggesting reverse orientation of the adsorbed surfactant ions. In Region IV, the adsorption isotherm and zeta potential reach a plateau when the surfactant concentration reaches the CMC, and the surface becomes completely hydrophilic.
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