Design of multifunctional composite materials based on acrylic ion exchangers and CaCO3 as sorbents for small organic molecules

Abstract

This study was focused on the synthesis and characterization of some ion exchange resins based on acrylic copolymers, and the composite formation by CaCO3 by carbonate diffusion protocol. The resins were deeply investigated in terms of chemical composition (anionic, cationic, amphoteric) and crosslinker content, by: swelling degree, ion-exchange capacity, volume variation, charge density, size. FTIR-ATR spectroscopy demonstrated the presence of the functional group in the acrylic copolymers, with the formation of functionalized acrylic ion exchange resins. The materials surface morphology was evidenced using scanning electron microscopy. X-ray diffraction showed that CaCO3 polymorphism depends on the chemical structure of the used ionic exchange resins. Some of the obtained resins and their composites with CaCO3 were tested as sorbents for small organic molecules, such as dyes (neutral red, NR and bromocresol green, BCG) and antibiotics (tetracycline hydrochloride, TCH). While the maximum sorption capacity for BCG and NR dyes is similar (2.247 mg/g and 2.288 mg/g, respectively), but depends on the sorbent's functional groups, all the investigated samples showed a significantly higher sorption capacity for TCH, up to 50.25 mg/g. The maximum TCH release profile was improved by CaCO3 crystallization, suggesting that the composite samples could efficiently be used as drug delivering systems.