MINERAL-BASED MAGNETIC NANOCOMPOSITE SORBENTS

Abstract

The article is devoted to the synthesis of mineral-based magnetic nanocomposite sorbents and the study of the influence of modification by magnetite and molybdenum disulfide on the structural-sorption and surface properties of native saponite clay. Modification of native saponite clay with nanoscale magnetite increases the specific surface area and changes pore’s distribution of the original clay from monomodal to bimodal. Next modification of magnetic saponite by micro-sized and nano-sized molybdenum disulfide results in blocking of the secondary porous structure (bimodality disappears of magnetic saponite), but it is increasing the specific surface area. It was found that the sorption activity of modified and unmodified saponite in the region of low concentrations of cationic and anionic dyes (Methyl blue and Congo red) is almost the same. The study of Congo red dye adsorption from highly concentrated solutions showed significant differences in the sorption activities of modified and unmodified saponite samples: the largest sorption capacity characteristic of ternary composites (saponite modified by magnetite and by nano-sized molybdenum disulfide). These ternary composites had in 62 times more activity than native saponite clay and 10 times more than magnetic saponite. It is established that all the samples are characterized by basic properties, but the sample of native saponite modified by magnetite and nano-sized molybdenum disulfide has the largest number of active centers (both acidic and basic character). Thus, it is shown that the modification of the native saponite clay significantly affects not only the texture-sorption but also the surface properties of the native saponite clay.