Argilominerais modificados com sais de amônio e quitosana por reações em micro-ondas como adsorventes para diclofenaco de sódio

Abstract

Natural and synthetic layered silicates are versatile materials with variable composition and structure, which can have their adsorption properties improved through reactions with ammonium salts and biopolymer. In this work, new adsorbents for sodium diclofenac were obtained through reactions over microwave (MW) heating between sodium bentonite (Bent-Na+) and the salts 1-dodecylpyridinium (C12pyCl) and hexadecylpyridinium (C16pyCl) chlorides; sodium vermiculite (Ver-Na+) and tetradecyl- (C14Br), hexadecyl- (C16Br) and octadecyltrimethylammonium (C18Br) bromides, as well as sodium magadiite (Mag-Na+) with C12pyCl, C16pyCl and C16Br. All systems were prepared in the 100% and 200% cationic exchange capacity (CEC) proportions for each silicate in MW at 50 oC for 5 min. Additionally, the influence of the interlayer cations in Bent sample (Na+, Mg2+, Ca2+, Sr2+ or Ba2+) in the formation of Bent/chitosan (CS) bionanocomposites prepared at 500% CEC proportion in MW was also investigated. Reactions were evaluated by X-ray diffractometry, CHN elemental analyses, Fourier transform infrared spectroscopy and thermogravimetry. The amount of intercalated ammonium salts was higher for organophilic magadiites, and the interlayer arrangement of organic moieties in the different systems was influenced by the structure of the silicate. The diclofenac removals depended of the organophilic layered silicates like the structure of the inorganic matrix, type of surfactant and degree of organophilization. Results suggested that electrostatic and nonelectrostatic interactions contributed for the adsorption mechanism. For the exchanged bentonites/CS hybrids, results showed that CS was incorporated in all solids, however their interlayer arrangements were affected by the type of exchangeable cation, and this can influence in the further application. Results confirmed the versatility of MW heating for the preparation of modified silicates and suggested the specificity of individual organophilic matrix in relation to adsorption of sodium diclofenac from aqueous solution.