Adsorptive removal of fluoroquinolone antibiotics using green synthesized and highly efficient Fe clay cellulose-acrylamide beads

Environmentally sustainable clay polymeric nanocomposite hydrogel beads based on carboxymethyl cellulose (CMC), acrylamide (AM), and Fe clay were developed by an ionotropic gelation technique and studied as an efficient adsorbent for fluoroquinolone antibiotics. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Thermo gravimetric analysis (TGA), X-ray diffraction (XRD), swelling measurement, and point of zero charge (pHPZC) were used to define the chemical structure and surface morphology of the prepared nanocomposite hydrogel beads. A series of batch adsorption experiments were used to optimize various parameters affecting the removal of Cipro and Levo. At the optimized condition of solution pH (5), initial antibiotic concentration (10 mg/mL), incubation temperature (35 °C), adsorbent dosage (1500 mg/L), and bead weight (15 g/L), the pollutant removal was more than 92% for Cipro and 93% for Levo. For determining Cipro and Levo adsorption on newly synthesized nanocomposite, isotherm, kinetic, and thermodynamic characteristics were evaluated. The Langmuir model well-represented equilibrium data from adsorption and the pseudo-second-order model clearly describes kinetics data. The maximum adsorption capacity obtained for Cipro and Levo was 57.84 mg/g, and 38.01 mg/g respectively. The reusability study revealed that the Cipro and Levo removal efficiency was above 85% for Cipro and 90% for Levo up to the fifth cycle, and validation with the real water samples confirmed above 70% Cipro and Levo removal. The residual toxicity of treated effluent against freshwater Chlorella sp. was significantly lower (>80%) compared to the untreated one, indicating that the process effectively reduced the environmental toxicity of the pollutants.