Cellulosic composite adsorbent prepared via high-speed shear induced regeneration and chemical modification for ciprofloxacin removal

Utilizing environmentally friendly bio-adsorbents with ultra-high adsorption capacities to remove antibiotics from aqueous environments is a potential strategy in addressing global water pollution. Herein, a novel carboxyl-functionalised nanocellulose adsorbent (H-BTCA-RC) was successfully prepared from agricultural waste-derived regenerated cellulose (H-RC) and 1,2,3,4-butanetetracarboxylic acid (BTCA). The prepared H-BTCA-RC was used to evaluate its adsorptive performance for removing typical antibiotic ciprofloxacin (CIP) from water. Its efficiency was optimized based on factors such as pH, contact time, initial antibiotic concentration, temperature, and adsorbent dosage. Notably, the dispersion of H-RC chains among a matrix of encasing urea molecules with high-speed shear induced facilitates the development of well-ordered micro- and nanostructures inside H-RC, letting to a relatively high compressive strength of 200.5 kPa at 80 % strain. Results suggested that the intricate network composed with micro- and nanoscale H-RC architecture of the fibers functions as a scaffold for adsorbent, enhancing the availability of reactive –OH and increasing the accessibility for pollutants contact. Furthermore, the incorporation of BTCA facilitated the formation of adequate covalent bonds and hydrogen bonding interactions among H-RC fibers, culminating in a denser structural network within the cryogel. The adsorbent exhibited excellent adsorption characteristics of CIP with a removal efficiency of 95.63 % and an adsorption capacity of 300.01 mg/g. Additionally, the adsorbent showed high recyclability, retaining efficacy exceeding 91 % throughout more than ten cycles. This work demonstrates that cellulosic antibiotic adsorbent materials have potential in the utilization of agricultural waste for the efficient extraction of antibiotics from aquatic environments.