Equilibrium and kinetic studies for removal of antiviral sofosbuvir from aqueous solution by adsorption on expanded perlite: Experimental, modelling and optimization

Removal of new antiviral drug sofosbuvir from aqueous solution by non-modified expanded perlite (E-perlite) using adsorption process was investigated. Perlite is high-grade stone rich on silica utilized as inexpensive natural adsorbent. An experimental combination of Response Surface Methodology (RSM) with Central Composite Design (CCD) was applied to optimize the process parameters effecting the adsorption efficiency where the three used major independent variables are pH, adsorbent mass, and initial concentration of sofosbuvir. The results showed that maximum adsorption was attained at solution pH 6.8, sofosbuvir initial concentration 0.1 mM and E-perlite mass 20 g/L. Adsorption data were exploited by applying the kinetic models pseudo first-order, pseudo second-order, and intra-particle diffusion. The adsorption process corresponded to the Langmuir model while the adsorption kinetics correlated appropriately to the pseudo second-order equation. The morphology and composition of E-perlite were characterized by scanning electron microscopy (SEM/EDS).