This study mainly focused on exploring the influence of different processing methods on the structure, physical and chemical characteristics and adsorption ability of modified montmorillonites. The effect of three different modifiers with different chain lengths such as 12-aminododecanoic acid (ADA), 1,12diaminododecane (DDC) and octadecylamine (ODC) on the d-spacing of montmorillonite was studied in detail. FT-IR spectra and N 2 adsorption isotherms were used to confirm the formation of modified montmorillonites. XRD experiments were carried out and the influence of structural and processing parameters of the modifiers on the interlamellar spacing of modified montmorillonites was studied. It was found that the ODC modifier with a longer carbon chain comparatively enhanced the interlamellar spacing than that of other modifiers. The influence of HCl, the amount of modifiers and temperature on the interlayer structure was also discussed. Upon modification, the peak around 2q ¼ 6.8 due to [001] plan was shifted to lower 2q values and the corresponding interlamellar spacing was increased from 1.39 nm to 2.97 nm. The adsorption behavior of the modified montmorillonites for both inorganic and organic pollutants was also discussed based on structural and surface properties. The observed log K OM values for the distribution of organic pollutants onto modified montmorillonites are comparatively larger in this study indicating that these modified montmorillonites are superior to both natural soil systems as well as literature studies reported so far.

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In this study, sodium montmorillonite was functionalized with SH, S and Si functional groups using four different soil modifiers, 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane [BAT], 3,3 0tetrathiobis(propyl-triethoxysilane) [TP], thiodiglycol bis(3-aminocrotonate) [TDBA] and (3mercaptopropyl)trimethoxysilane [MPTMS], for the effective uptake of both organic and inorganic pollutants. The uptake of inorganic (Cu 2+ , Zn 2+ ) and organic [benzene, toluene, ethylbenzene and pxylene (BTEX)] pollutants was studied with individual as well as binary mixtures. Based on the experimental results, the soil modifier MPTMS best improved the sorption characteristics and, among two metal ions, Cu 2+ showed enhanced adsorption. Sorption of BTEX was not correlated with a single parameter and hence it differed for the different cases based on the organic matter content. The obtained log K OC and log K OM values of BTEX in this study for modified montmorillonite arecomparatively larger than those of unmodified montmorillonite or natural soil. Sorption carried out in the binary mixtures showed that there is no interaction between these pollutants and the presence of one did not retard the adsorption of another. The uptake phenomenon was influenced by various combined factors such as the nature, surface charge and surface area of the modified soils.