Travail de fin d'études: "Purification of stilbenes excreted by plant cells using the adsorption technology"

Abstract

The present study investigated the adsorption of five stilbene molecules (E-resveratrol, labruscol, laechinol, ε-viniferin, and δ-viniferin) from the fermentation broth of grapevine cells on polymeric macroporous resins. Firstly, five different resins (Amberlite XAD-7, XAD-4, XAD-6, XAD-1180, and FPX66) were tested for the adsorption of stilbenes. XAD-7 was chosen as the optimum adsorbent because it displayed the highest adsorption and desorption capacities of total stilbenes (86.94 ± 4.90 mg/g and 74.28 ± 0.38 mg/g, respectively). Then, the adsorption kinetics were investigated using the XAD-7 resin and it was concluded that the process follows a pseudo-second order kinetic model, and that the intraparticle diffusion of the stilbenes within the adsorbent’s pores limits the adsorption of approximately 10% of total stilbenes. Following this, the adsorption isotherm curves were well fitted to a multicomponent Langmuir model with competition. The isotherm model showed that the maximum adsorption capacity could be at qmax = 0.302 mmol/g, which is quite close to the real adsorption capacity of qeq = 0.271 mmol/g (79.98 ± 4.81 mg/g). ε-Viniferin presents the highest affinity for XAD-7, followed by labruscol, δ-viniferin, E-resveratrol, and laechinol. Next, the dynamic operation mode was studied using fixed-bed column adsorption. The dynamic experiments showed the process to be significantly influenced by bed height. For a constant flowrate of 0.3 mL/min, higher bed lengths were more efficient, and the breakthrough point was delayed. Finally, a maximum desorption capacity of the five stilbenes was observed at 70% (v/v) ethanol solution (59.74 ± 0.14 mg/g) and in a ratio of 160:1 (desorption solution:mass of adsorbent). Using XAD-7 resin to adsorb the targeted compounds coupled with an optimized washing step of the resin beads, increased the weight content (purity) of stilbenes by 4.6 times (from 5 ± 0.05 % to 23.19 ± 0.31 w/w %).