Effect of Layer Charge on Adsorption Properties of Octadecyl Trimethyl Ammonium Chloride by Montmorillonite

摘要

In this paper, the adsorption properties of octadecyl trimethyl ammonium chloride in two kinds of montmorillonite with different layer charges were studied at a constant temperature of 353 K. The result showed both montmorillonites could efficiently adsorb octadecyl trimethyl ammonium chloride with an adsorption efficiency over 97%, when the concentration of octadecyl trimethyl ammonium chloride was low (M-1-Na was less than 1.62 mmol/g, M-2-Na was less than 1.53 mmol/g), However, when the concentration of octadecyl trimethyl ammonium chloride increased (M-1-Na was more than 1.62 mmol/g, and M-2-Na was more than 1.53 mmol/g), the adsorption efficiency of octadecyl trimethyl ammonium chloride in montmorillonite began to decrease significantly. The saturated adsorption amount of octadecyl trimethyl ammonium chloride in the M-1-Na was larger than that in the M-2-Na with a higher layer charge; the values were 1.684 mmol/g and 1.490 mmol/g, respectively. The isothermal adsorption experimental data of octadecyl trimethyl ammonium chloride in both montmorillonites were in well accordance with the Langmuir, Redlich-Peterson, and Modified Langmuir models. The saturated adsorption amount of octadecyl trimethyl ammonium chloride in two montmorillonites fitted by the modified Langmuir model were 1.672 mmol/g and 1.576 mmol/g, and the aggregation numbers n of the corresponding surface-active agent were 1.086 and 1.068, respectively.