Effect of dissolved organic matter from Guangzhou landfill leachate on sorption of phenanthrene by Montmorillonite

• Published in: Journal of colloid and interface science 2011-09, Vol.361 (2), p.618-627
• Main Authors: Wu, Pingxiao, Tang, Yini, Wang, Wanmu, Zhu, Nengwu, Li, Ping, Wu, Jinhua, Dang, Zhi, Wang, Xiangde
• Format: Article
• Language: English
• Subjects: adsorbents; Adsorption; Chemistry; clay; Clay liner; Colloidal state and disperse state; Complex; Desorption; dissolved organic matter; Exact sciences and technology; Fourier transform infrared spectroscopy; General and physical chemistry; heat production; hydrophobicity; Kinetics; landfill leachates; Landfills; Mathematical models; Montmorillonite; Phenanthrene; porosity; Porous materials; scanning electron microscopes; Scanning electron microscopy; Sorption; sorption isotherms; surface area; Surface chemistry; Surface physical chemistry; Surface properties; temperature; X-radiation; X-ray diffraction; X-ray photoelectron spectroscopy
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2011.06.019

The objective of this work was to compare the difference between DOM–MMT complexes and the raw MMT on sorption behavior to phenanthrene using a combination of spectroscopic, microscopic adsorption techniques and molecular modeling. [Display omitted] ► MMT combined with DOM in leachate enhance the sorption of PHE. ► DOM was bound on the surfaces of MMT via H-bondings and cation bridges. ► DOM-MMT complex possessed higher Si/O atomic ratio on silica layers. ► The characteristic of PHE sorption isotherm is linear. To investigate the effect of dissolved organic matter (DOM) on the adsorption of phenanthrene (PHE) by montmorillonite (MMT), organic clay complex was prepared by associating montmorillonite with DOM extracted from landfill leachate. Both the raw MMT, DOM, and MMT complex (DOM–MMT) were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), X-ray photo-emission spectroscopy (XPS), and scanning electron microscope (SEM). Batch adsorption studies were carried out on the adsorption of PHE as a function of contact time, temperature, and adsorbent dose. The sorption of PHE on complex was rapid, and the kinetics could be described well by the Pseudo-first-order model (R2>0.99), with an equilibrium time of 120min. The adsorption isotherm was in good agreement with the Henry equation and Freundlich equation. Also, thermodynamic studies showed that the adsorption process was exothermic and spontaneous in nature. Compared with MMT, the adsorption capacity of DOM–MMT complex for PHE was greatly enhanced. The effects of DOM on PHE sorption by MMT may be attributed to the changes in the surface structure, the specific surface area, the hydrophobic property, and the average pore size of MMT. A series of atomistic simulations were performed to capture the structural and functional qualities observed experimentally.