ENHANCEMENT OF THE ADSORPTIVE PROPERTIES OF BIOMATERIALS BY CHEMICAL MODIFICATION FOR THE ELIMINATION OF ANTIBIOTICS

Abstract

Antibiotics and pharmaceutical products have become emergent contaminants in residual waters due to the inefficient commercialization and distribution. This study proposes the use of waste materials from tea leaves of chamomile (CM), green tea (GT) and peppermint (PM) and their chemical modifications: carboxylation, sulfonation and thiolation as adsorbents of Penicillin G. The tea samples were treated with sustainable chemical reactions in aqueous media and minimal reagent consumption. The adsorbents and their chemical modifications were characterized by instrumental techniques. All the adsorbents reported constant thermal stability and only small morphological changes on their surfaces. The adsorption tests demonstrated a strong influence of the acidity on the elimination of the antibiotic, mostly at the level of the chemistry of the added functional groups, mainly through dipole-dipole forces. The adsorption percentages indicate that thiolation and sulfonation are the most effective chemical modifications, highlighting CM adsorbents, reaching %ADS of 27%, within the pH range 7-8. The maximum adsorption tendency of Penicillin G has the sequence: CMs > PMs ≥ GTs, whereas the chemical modifications follow the trend: Sulfonation ≥ Thiolation > Carboxylation.