Tuning the wettability of alginate-based nanocomposite beads for efficient removal of pharmaceuticals from water

Abstract

Long-term exposure to pharmaceuticals, such as diclofenac (DCF) and tetracycline (TC), poses various risks to human health, including antibiotic resistance and endocrine disruption. In this work, we investigated the removal of DCF and TC from water and probed the removal performance of contaminants in a complex matrix consisting of DCF and TC mixtures using alginate (AL)-based nanocomposite beads with tunable wettability. We improved the selectivity of the beads towards hydrophobic contaminants by reducing graphene oxide (GO) to rGO in the presence of AL using a mild and green reducing agent (Vitamin C). Thein-situchemical reduction of GO in AL matrix resulted in amphiphilic rGO-containing beads,as confirmed by several characterization techniques.Thein-situreduction, apart from restoring the sp2hybridized carbon, greatly improved the mechanical properties and stability of the nanocomposite, ensuring reusability beyond 10 adsorption/desorption cycles.Compared to neat AL beads, the addition of only 3.5% rGO (AL:3.5rGO) improved the beads adsorption capacity for TC and DCF by 660% and 747%, respectively. The beads exhibited remarkable performance in the simultaneous removal of TC and DCF from contaminant mixtures. The superior performance of AL:3.5rGO beads is attributed to the enhanced π-π interactions between the aromatic rings of the contaminants and the sp2domains of rGO-containing adsorbents.