Adsorption of heavy metals on crosslinked lignocatechol: a modified lignin gel

Crosslinked lignocatechol gel was prepared by immobilizing catechol onto wood lignin followed by crosslinking. The adsorption behavior of crosslinked lignocatechol was studied batchwise by varying different parameters like pH, initial concentration of metal ions and shaking time. Based on the results obtained in batchwise experiments, breakthrough profiles were examined using a column packed with crosslinked lignocatechol gel for the separation of small concentration of Pb(II) from an excess of Zn(II) followed by elution tests. Ten consecutive adsorption–elution cycles were conducted so as to check the stability and efficiency of the gel for recycling purpose. A constant efficiency was observed that reveals the feasibility of recycling of the gel. Cation exchange mechanism is postulated as the predominant process of the adsorption.