Adsorption of diethyl phthalate ester to clay minerals. (January 2015)

• Record Type: Journal Article
• Authors: Wu, Yanhua; Si, Youbin; Zhou, Dongmei; Gao, Juan
• Is Part Of: Chemosphere. Volume 119(2015)
• Page Start: 690
• Page End: 696
• Publication Date: 2015-01
• Subjects: Phthalate ester -- Clay mineral -- Montmorillonite -- Adsorption -- Interlayer -- Thermodynamic; DEP diethyl phthalate ester -- DnBP di-n-butyl phthalate ester -- HA humic acid -- ΔHobs observed adsorption enthalpy -- mont montmorillonite -- X-RD X-ray diffraction -- FTIR Fourier transform infrared spectroscopy; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2014.07.063
• Languages: English
• ISSNs: 0045-6535

Abstract

Highlights: Montmorillonite interlayer was important for DEP adsorption. Cation K + and lower temperature facilitated more adsorption of DEP. pH and ionic strength had limited effect on DEP adsorption to K + /Ca 2+ saturated montmorillonite. The interaction between DEP and montmorillonite was weak adsorption. Abstract: Phthalate esters are a group of plasticizers, which have been widely detected in China's agricultural and industrial soils. In this study, batch adsorption experiments were conducted to investigate the environmental effects on the adsorption of diethyl phthalate ester (DEP) to clay minerals. The results showed that DEP adsorption isotherms were well fitted with the Freundlich model; the interlayer spacing of K + saturated montmorillonite (K-mont) was the most important adsorption area for DEP, and di-n-butyl ester (DnBP) was limited to intercalate into the interlayer of K-mont due to the bigger molecular size; there was no significant effect of pH and ionic strength on DEP adsorption to K-mont/Ca-mont, but to Na-mont clay. The adsorption to kaolinite was very limited. Data of X-ray diffraction and FTIR spectra further proved that DEP molecules could intercalate into K-/Ca-mont interlayer, and might interact with clay through H-bonding between carbonyl groups and clay adsorbed water. Coated humic acid on clay surface would enhance DEP adsorption at low concentration, but not at high concentration (eg. C e > 0.26 mM). The calculated adsorption enthalpy (Δ H obs ) and adsorption isotherms at varied temperatures showed that DEP could be adsorbed easier as more adsorbed. This study implied that clay type, compound structure, exchangeable cation, soil organic matter and temperature played important roles in phthalate ester's transport in soil.