Mechanism of paracetamol removal by vegetable wastes: the contribution of pi-pi interactions, hydrogen bonding and hydrophobic effect.

The aim of the present work is to investigate the potential use of some vegetable wastes (grape stalk, yohimbe bark and cork bark) for the removal of paracetamol (acetoaminophen) from water. The factors influencing adsorption like contact time, initial pH, sorbent concentration and temperature were evaluated. The most effective biosorbent resulted to be grape stalk waste. Sorption kinetic and equilibrium data of paracetamol sorption onto grape stalks were submitted to kinetics and equilibrium models in order to get the adsorption constant rate and the maximum capacity of the sorbent. According to modeling calculations, is-stacking interactions between aromatic moieties from lignin of grape stalks and paracetamol and hydrogen bonding should make the major contribution to the sorption process. Further favorable contribution is expected to come from the hydrophobic effect accompanying the association of this species in water.