Affiliation:
1. Chemistry Department, Faculty of Science, King Abdulaziz University, P.O. Box 80200, Jeddah 21589, Saudi Arabia
2. Department of Chemistry, College of Science, Qassim University, P.O. Box 1162, Buraidah 51452, Saudi Arabia
3. Environmental Science and Engineering (BESE) Division, King Abdullah University of Science and Technology (KAUST), P.O. Box 4700, Thuwal 23955, Saudi Arabia
Abstract
Metal–organic frameworks (MOFs) have attained significant usage as adsorbents for antiviral medicines in contemporary times. This study focused on synthesizing a UiO-67 metal–organic framework using the hydrothermal method. The synthesized framework was then characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analyses (TGA), and zeta potential measurements. The UiO-67 was then employed for the purpose of assessing the efficiency of various adsorption factors in the removal of antiviral medicines from aqueous solutions, including drugs such as ritonavir (RTV) and lopinavir (LPV), which were extensively used for the treatment of coronavirus (COVID-19) during the pandemic. The variables examined were the quantity of adsorbent used, different pH of the solution, temperature, and contact duration. The experimental findings indicate that the highest level of RTV elimination was 91.2% and of experimental adsorption capacity (qe,exp) was 9.7 mg/g and for LPV this was 85.9%, and (qe,exp) 8.9 mg/g, using 50 mg of UiO-67 at a pH 8, temperature of 298 K, and for 120 min. The impact of contact duration and temperature on the kinetics of adsorption was examined by employing pseudo-first-order and pseudo-second-order kinetic models. The experimental results showed a good match with the pseudo-second-order kinetic model with value of R2 0.99 and the qe,calc was 9.7 RTV and 8.9 mg/g LPV, which is a good match with qe,exp. Also, based on diffusion kinetic studies, the adsorption was confirmed to be catalytic in nature on the surface of the UiO-67 MOFs. A thermodynamic analysis of adsorption was conducted, whereby calculations for the Gibbs free energy change (∆G), enthalpy change (∆H), and entropy change (∆S) were performed. The positive ∆H values confirm the endothermic nature of the adsorption of RTV and LPV by UiO-67. The ΔG values exhibited negativity across all temperatures, suggesting the spontaneous nature of the adsorption process of RTV and LPV by UiO-67 from an aqueous solution. UiO-67 was shown to be highly effective in extracting RTV and LPV from real environmental samples.