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Fenitrothion adsorption – desorption on organo – minerals

Kovacević, Dragana / Lemić, Jovan / Damjanović, Milan / Petronijević, Radivoj / Janaćković, Đorđe / Stanić, Tanja

Abstract The adsorption–desorption of the pesticide fenitrothion on organo-montmorillonite, organo-clinoptilolite and organo-sepiolite was studied at different loadings of stearyl- dimethylbenzylammonium cations (SDBA). The SDBA retained by ion exchange mostly remained on the surface of the minerals after washing with an ethanol/water solution. The hydrophobic character of the organo-minerals with monolayer coverage of the surface was confirmed by adsorption of water vapor. The adsorption of organo-montmorillonite, organo-sepiolite and organo-clinoptilolite for fenitrothion increased with the surfactant loading up to the value of the cation exchange capacity (CEC) for montmorillonite and sepiolite and of the external cation exchange capacity (ECEC) for clinoptilolite. The adsorption of the most hydrophobic samples (M80, C7.5 and S15), at a concentration of the pesticide of 10mg/dm³ in solution, was 99%, 89% and 95%, respectively. The maximal amounts of pesticide adsorbed on the organo-montmorillonite, organo-clinoptilolite and organo-sepiolite were 300μmol/g, 150μmol/g and 130μmol/g. The amounts of fenitrothion, released from organo-montmorillonite, organo-clinoptilolite and organo-sepiolite pesticide complexes into 0.005M diethylenediamine-pentacetic acid, 0.1M CaCl2 and 0.1M triethanolamine solution after ten cycles were 20%, 40% and 50%, respectively.

Research highlights ► Organo-minerals can be used as carriers for the controlled release of pesticides. ► Hydrophobic interactions are responsible for the adsorption of the fenitrothion. ► The adsorption of fenitrothion was largely irreversible.