Dual functionality of an Ag-Fe₃O₄-carbon nanotube composite material: Catalytic reduction and antibacterial activity

Carbon-based nanomaterials have remarkable chemical and biological features. The introduction of supporting magnetic materials onto carbon-based nanoparticles has gained interest owing to their easy separation from heterogeneous systems. Herein, we report the synthesis of a novel composite comprised of single-walled carbon nanotubes, Fe₃O₄ and Ag nanoparticles with an aim to develop a bifunctional composite for water purification that maintains both high catalytic and antibacterial activities. The composite facilitated decomposition of nitrophenols and methyl orange in the presence of NaBH₄ as the reducing agent - maintaining high activity (>90%) following three regeneration cycles. The composite's catalytic activity was unaffected by the presence of dissolved organic matter (DOM) at an environmentally relevant concentration of 5mgCL^-1. DOM concentration of 50mgCL^-1 slightly decreased the reduction of p-nitrophenol, 2-methyl-p-nitrophenol, and methyl orange (by ∼14%, ∼11%, and ∼10% respectively) but significantly decreased that of o-nitrophenol (by 38%). The composite exhibited high antibacterial activity towards gram-negative and gram-positive bacteria even in the presence of DOM at an environmentally relevant concentration. However, the composite's efficiency decreased with increase in DOM concentration. This study demonstrates dual catalytic and antibacterial activity of a novel Ag-Fe₃O₄-single walled carbon nanotube composite material in the absence and presence of DOM, and considers its potential implementation in water/wastewater treatment applications.