Zirconium oxide nanoparticles (ZrO2 NPs) were synthesized via a plant-assisted route using Cycas revoluta leaf extract as a natural reducing and stabilizing agent. The synthesis and properties of the NPs were confirmed using UV–Vis, FTIR, XRD, SEM-EDS, HR-TEM/SAED, DLS, and zeta potential measurements. The adsorption performance of ZrO2 NPs toward doxycycline from water was investigated by varying pH, adsorbent dose, initial concentration, temperature, and contact time. Under the optimum conditions (pH 7, 50 mg adsorbent in 50 mL, 10 mg L−1 doxycycline, 60 °C, 180 min), a maximum removal efficiency of 60.81% was achieved. The equilibrium data were fitted using the Langmuir model, giving an estimated qmax of 11.276 mg g−1; however, this value should be interpreted cautiously because of the limited number of isotherm data points. The time-dependent adsorption data were empirically described using both pseudo-first-order and pseudo-second-order kinetic models without assigning strict superiority to either model. These results indicate that green-synthesized ZrO2 NPs can serve as a low-impact adsorbent for removal of pharmaceutical contaminants in water.
Sharma et al. (Sat,) studied this question.