Comparison of tetrachloromethane sorption to an alkylammonium-clay and an alkyldiammonium-clay

Abstract

The interlamellar space of Wyoming bentonite (clay) was modified by exchanging either decyltrimethylammonium (DTMA) or decyltrimethyldiammonium (DTMDA) cations for inorganic ions, and tetrachloromethane sorption to the resulting two organoclays from water was studied at 10, 20, and 35 °C. Only one end of the 10-carbon alkyl chain of the DTMA cation is attached to the silica surface of the clay mineral, and tetrachloromethane sorption of DTMA-clay is characterized by isotherm linearity, noncompetitive sorption, weak solute uptake, and a relatively low heat of sorption. Both ends of the 10-carbon chain of the DTMDA cation are attached to the silica surface of the clay mineral, and tetrachloromethane sorption to DTMDA-clay is characterized by nonlinear isotherms, competitive sorption, strong solute uptake, and a relatively high, exothermic heat of sorption that varies as a function of the mass of tetrachloromethane sorbed. Therefore, the attachment of both ends of the alkyl chain to the interlamellar mineral surface appears to change the sorption mechanism from a partition-dominated process to an adsorption-dominated process.

Organoclay Sorption of Benzene as a Function of Total Organic Carbon Content

“…Additionally, the sorptive capacity of the two organoclays demonstrates that the uptake of nonpolar benzene by HDTMA clay is linear and relatively weak compared to the nonlinear, strong sorptive uptake by the BTEA clay. While the sorption of benzene in this study was shown to decrease as the total organic carbon content was increased, previous research has determined that the sorption of carbon tetrachloride on BTEA clay increased as the total organic carbon content of the clay increased (14). Similarly, batch sorption tests with the hydrophobic herbicide norflurazon on BTEA clay also demonstrated that the degree of sorption increased as the total organic cation content increased; however, sorption of norflurazon to BTMA clay increased as the organic carbon exchanged was increased from 25 to 63% of the clay's CEC, but the sorption of norflurazon at 100% CEC was lower than at 63% CEC (30).…”

Adsorption of humic acid onto pillared bentonite

“…Since the discovery about their unique adsorption capacity in the 1950s, modified bentonites have been a subject of a number of studies as adsorbents for the removal of pollutants from water. For the removal of organic pollutants, bentonites are often modified by quaternary ammonium cations [5][6][7][8][9]. In aqueous solution large quaternary ammonium organic cations readily replace the inorganic cations in the intermellar space of montmorillonites by ion exchange, and the bentonites are said to be intercalated.…”

Removal of phenol from water by adsorption–flocculation using organobentonite

“…When organic cations (cationic surfactants) of the form (CH 3 ) 3 NR + , where R is an alkyl hydrocarbon, occupy the exchange sites of bentonite clay, the surface properties transform from hydrophilic to hydrophobic. Recent studies have shown that the molecular structure of cationic surfactants used to modify clay affects the mechanism of NOC sorption [1][2][3][4]. Smith et al [1] demonstrated that small organic cations create a relatively rigid, nonpolar surface amenable to NOC uptake by adsorption, a surface characterized by a relatively high NOC uptake, isotherm nonlinearity, and competitive sorption.…”