Bentonitas modificadas com biopolímeros, óxido de grafeno e óxido de zinco como adsorventes para fármacos e materiais antimicrobianos

Abstract

Clay minerals, such as montmorillonite (Mt), have been applied in the synthesis of functionalized materials and are used in several fields, particularly in environmental remediation and biological applications. In this work sodium bentonite was modified with chitosan (CS), sodium alginate, graphene oxide (GO) and ZnO for use as new adsorbents for tetracycline (TC) and omeprazole (OZM) and/or also as antimicrobial materials. The materials were characterized by long and short range structural, morphological and thermal techniques. Sodium bentonite (Na-Bent) reacted with CS at 100%, 200% and 300% of the Na-Bent CEC, and then eith sodium alginate in a mass ratio of 1:1 at 50 °C in 24 h, and under heating by microwave (MW) at 50 °C for 30 min. The materials were applied for removal of TC from aqueous solution. The best performance in the TC removal was observed for the material obtained with CS at 100% of CEC, in which removal reached 97.7% in 30 min. The presence of the second biopolymer did not improve TC removal under the evaluated conditions. Solids with better adsorptive capacity and Na-Bent were loaded with TC at 100; 200; 400 mg L-1, whose antimicrobial activity was evaluated by the direct contact method. Inhibition percentages varied between 69.1-100.0% for S. aureus and 88.7-100.0% for E. coli, with ~100% inhibition for both bacteria for solids loaded with TC at 400 mg L-1. New adsorbents for OMZ based on GO/Bent-Na were obtained in proportions of 5 and 10% under the same conditions. The GO/Bent-Na solids were reacted with 200% CTC Na-Bent CS. All materials presented high adsorptive potential for OMZ, whose removals were 96.3-99.0% in 40 mg gʻ1 of OMZ by GO/Bent-Na solids. The CS incorporation reduced the OMX adsorption to 50.9%. New antimicrobial materials were produced by reaction Na-Bent, ZnO (10, 20, 30% mass/mass proportions) and CS at 200% of Bent's CEC. Characterizations indicated the presence of ZnO and CS in the clay mineral. Solids with ZnO showed antimicrobial activity of 44% for S. aureus, and 33.1% for E. Coli, whose activities increased after CS incorporation to 51.9% and 44.6%, respectively. Nanomaterials have shown promise for use in environmental remediation in water treatment and development of antimicrobial materials.