Direct reduction of blood serum cholesterol using Thymus vulgaris L.: Preliminary biosorption study

In-vitro batch adsorption of cholesterol from human blood serum was investigated using Thymus vulgaris L. (Thyme) as a biocompatible adsorbent. X-Ray Diffraction technique (XRD), Scanning Electron Microscopy (SEM), and Fourier Transform Infrared spectroscopy (FTIR) were selected to characterize the biosorbent. The pseudo-first-order, pseudo-second-order, Elovich and intraparticle diffusion models were employed to study the adsorption kinetic with the intraparticle diffusion and pseudo-second order models providing superior fits. Kinetic results also showed that the time required for the equilibrium was around 2 h. The Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherms were also applied to investigate the adsorption equilibria at ambient temperature. The Langmuir model provided superior agreement with the equilibrium data and the adsorption capacity was around 84.74 mg/g. The results showed that the cholesterol removal increased from 30% to 50% with increased adsorbent mass from 0.01 to 0.1 g; meanwhile, removal did not noticeably vary (similar to 7%) with further adsorbent dose increase from 0.1 to 0.2 g. The coarse Thyme powder indicated higher cholesterol removal (46%) compared to the milled (38%), due to aggregation of the latter in the serum environment. Based on the results, Thymus is an effective biosorbent for application in extracorporeal serum perfusion.