Lysine-functionalized layered double hydroxides for the antibiotics' efficient removal: Controllable fabrication via BBD model and mechanism

Lysine-functionalized layered double hydroxides (LDHs) controllable fabrication based on Box-Behnken Design (BBD) model was investigated in this study. Ly @ FeZn presented stable and efficient removal performance for Ciprofloxacin (CIP) removal. Characterizations analysis and batch tests results showed that Ly @ FeZn had significantly different adsorption performance towards CIP and Ofloxacin (OFL). The highest adsorption capacity of CIP was 193.83 mg/g, while that of OFL was 62.12 mg/g due to the bulky structure of OFL, which posed steric hindrance for its interaction with the adsorbent. Furthermore, adsorption kinetics of CIP were better simulated with the pseudo-first-order kinetic model, while that of OFL was better described by the pseudo-second-order. The adsorption thermodynamics of Ly @ FeZn for CIP indicated that the adsorption processes were exothermal, feasible and spontaneous. It was worth noting that the adsorption mechanism of Ly @ FeZn for CIP were the synergistic reaction of surface complexation and interlayer adsorption. Also, this study provided a promising adsorbent for efficient antibiotics removal in practical water remediation.