The adsorption of the cationic dyes rhodamine B (RhB) and methylene blue (MB) was investigated on natural montmorillonite (MM) and its mechanoactivated form (MAMM). Mechanical modification of MM was carried out in a planetary mill using zirconia grinding media (MM-to-media mass ratio 7.5:1) at a rotor speed of 1500 rpm for 3 minutes. The adsorption efficiency increased significantly for both dyes when using MAMM compared to MM: by 26.9% for RhB and 29.8% for MB. A comparison of the physicochemical properties of the adsorbents was performed using small- and wide-angle X-ray diffraction, solid-state NMR (Si, Al, Na), scanning electron microscopy, IR spectroscopy, TG-DSC thermal analysis, low-temperature nitrogen adsorption/desorption, and static laser light scattering. The improved adsorption properties of MAMM are attributed to structural and textural changes caused by mechanoactivation, which leads to delamination of aluminosilicate layers, enhanced pore characteristics, and a reduction in clay particle size in aqueous dispersions. Additionally, MAMM retains a high degree of crystallinity of aluminosilicate layers, exhibits partial dehydroxylation, and shows a slight shift of the ζ-potential toward less negative values.
M.F. Butman (Wed,) studied this question.