A novel cellulose/lignin/montmorillonite ternary hybrid aerogel for efficiently adsorptive removal of antibiotics from water

Abstract

A novel fully environmental-friendly organic–inorganic ternary hybrid aerogel (LN/MMT@cellulose), composed of lignin (LN), montmorillonite (MMT), and cellulose, was designed and simply fabricated. LN/MMT@cellulose was employed for the adsorptive removal of typical antibiotic ciprofloxacin (CIP) in water. The combined MMT and LN reinforce the mechanical properties of the cellulose aerogel and notably enhance the selective adsorption capacity toward CIP in the presence of various inorganic and organic matters. LN/MMT@cellulose still presents good adsorption ability toward CIP even at the CIP concentration as low as 0.002 mmol/L in various actual water sources. With the combination of the adsorption kinetics, isotherms, and thermodynamic study as well as the various spectroscopic characterizations before and after adsorption, the mechanisms of LN/MMT@cellulose in CIP adsorption were investigated in detail. Various interactions were involved in CIP adsorption by this composite aerogel under different pH levels, causing the evident pH dependence of its adsorption capacity, specifically, the cation exchange and electrostatic attractions associated with the chelation, π-π electron donor–acceptor interaction, and the ordinary hydrogen bondings were dominant at pH < 6.0, but the complexation and negatively charged assisted hydrogen bondings played the key roles under neutral and alkaline conditions. LN/MMT@cellulose had a slight loss in adsorption ability toward CIP and sustained physicochemical structural stabilities, even after seven adsorption–deadsorption cycles. In addition to CIP, LN/MMT@cellulose could be efficiently used for the adsorptive removal of two other popular antibiotics, namely, tetracycline, and trimethoprim. The said vital characteristics of LN/MMT@cellulose confirmed it is a promising material for the adsorptive removal of antibiotics in practical water treatment.