Biodegradable cellulosic aerogels for rapid and efficient adsorptive removal of ciprofloxacin and methylene blue from contaminated water

Abstract

Once celebrated as milestones of scientific progress, activated pharmaceutical ingredients (APIs) now fuel a growing crisis — their unchecked release into aquatic environments accelerates antimicrobial resistance, endangering human and animal health globally. Conventional remediation strategies often suffer from inefficiency, high operational costs, and limited scalability. Here, we demonstrate cellulosic aerogels, synthesized via a sol–gel process and subsequent lyophilization, as sustainable bio-adsorbents for removing ciprofloxacin (CIP), an API, and methylene blue (MB) from contaminated water. Structural characterization via FESEM and BET analysis confirmed a hierarchical porous network with a specific surface area of ≈ 398 m2/g and large pore volume. Batch adsorption experiments demonstrated highest affinity for CIP and MB, achieving maximum adsorption capacities. The adsorption processes followed pseudo-second-order kinetics with a good correlation coefficient. Mechanistic investigation revealed that adsorption is predominantly governed by strong π-π stacking interactions between the aromatic structures of ciprofloxacin and the cellulose matrix, supplemented by hydrogen bonding and electrostatic attractions. Additionally, zeta potential measurements indicated a negatively charged surface (-25 ± 2 mV), enhancing interaction with cationic pollutants. Our findings highlight the potential of biodegradable cellulosic aerogels as efficient, low-cost alternatives to synthetic adsorbents, offering a scalable solution for antibiotic removal and broader applications in wastewater treatment technologies.