Green chemistry approach for the removal of delafloxacin from aqueous solutions using calcinated layered double hydroxide: Adsorption mechanism and material characterization

The efficacy of calcinated Layered Double Hydroxide (LDH) was explored as an effective adsorbent for delafloxacin (DLX), which has been identified as one of the most persistent pharmaceuticals found in wastewater because of the increased use of antibiotic drugs in recent decades. The synthesized LDH was characterized via various techniques, including IR spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), surface analysis via BET, and transmittance electron microscope (TEM) and scanning electron microscopy (SEM). Adsorption investigations revealed that the maximum removal capacity was achieved at pH 7, with an adsorbent dosage of 0.2 g and an optimum temperature of 40 °C. Eight nonlinear equilibrium isotherm models were assessed to fit the experimental equilibrium data. The adsorption of DLX conformed well to the Langmuir‒Freundlich model, with a high regression value (R²) of 0.99. Additionally, the adsorption process of DLX followed pseudo-second-order kinetics, with an R² value of approximately 0.99. The maximum adsorption capacity (q_max) for DLX was determined to be 957.82 mg/g. This study investigated the cytotoxic effects of LDH nanoparticles on WI-38 cells, a widely used human lung fibroblast line. The cells were exposed to various concentrations of LDH nanoparticles, and their viability was assessed via the MTT assay. The results indicate concentration-dependent cytotoxicity, suggesting careful consideration of LDH nanoparticle dosage in biomedical applications. Two green metrics were applied: the Analytical Eco-scale and the Analytical GREENness Calculator (AGREE).