The Content of Benzoic Acid in Podzolic Soil and Its Sorption on Montmorillonite
2022
Kotelnikov, N. A. | Sokolova, T. A. | Tolpeshta, I. I. | Karavanova, E. I. | Izosimova, Yu. G. | Zavgorodnyaya, Yu. A.
The content of benzoic acid in water extract from podzolic soil is 3.27 and 1.83 mg/kg in the L and F organic horizons, respectively, and decreases to hundredths of mg/kg in mineral horizons. The experiment shows that with an increase in the equilibrium concentration of benzoic acid from 0.02 to 1.45 mmol/L, its sorption on Ca-montmorillonite rises from 5.61 to 15.34 mmol/kg. Taking into account the content and mineralogical composition of the clay fraction, expandable clays in the upper mineral horizons of podzolic soil are capable to retain from 0.06 to 0.15 mmol of benzoic acid per 1 kg of soil within the same range of equilibrium concentrations. The linear equation and the Freundlich model describe best the measured data. It is assumed that the main mechanisms of benzoic acid sorption under the experimental conditions were represented by cation bridging or water bridging and by the electrostatic interaction of benzoate with positively charged silanol and aluminol groups on edges of montmorillonite particles. The absorption of benzoic acid in the interlayer space of the mineral was not observed.
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