Mass transfer study on noncovalent adsorption and desorption of soluble phenolics by plant cell wall materials for green purification

This study originated from the observation that plant cell walls can bind soluble phenolics through noncovalent interactions. Celery and blueberry cell wall materials obtained from waste sources were selected as effective adsorbents for purifying phenolics. First, the impact of environmental ionic strength on the adsorption of phenolics by plant cell walls was investigated, indicating that ionic interactions play a more important role in adsorption than hydrophobic interactions. Second, numerical simulation results found that the increments of diffusivities of phenolics both within the liquids in the pores of plant cell wall materials and the skeleton of cell wall adsorbents accelerated the adsorption. The abundance of adsorption sites within plant cell wall adsorbents determined their adsorption capacity, and the penetration of phenolics across the adsorbent/liquid interface was unrelated to the adsorption behavior. Third, due to the porous structure of celery cell wall adsorbents, the pore volume diffusion of phenolics impacted intraparticle diffusion within celery cell wall materials more than blueberry cell wall materials. Fourth, after plant cell wall adsorption and desorption, the obtained phenolics achieved a purity of 60%, comparable to the purification achieved by macroporous resin adsorption/desorption. Moreover, purification using plant cell wall adsorption/desorption was more efficient. These findings contribute to the theoretical understanding of interactions between plant cell walls and polyphenols and provide valuable insights for designing natural plant cell wall adsorbents and developing environmentally friendly polyphenol purification techniques.