STUDIES ON THE UPTAKE OF LEAD AND ZINC BY LIGNIN OBTAINED FROM BLACK LIQUOR - A PAPER-INDUSTRY WASTE MATERIAL

Lignin extracted from black liquor - a paper industry waste material, has been characterized and used for the removal of lead and zinc metals. The uptake of lead is found to be greater than the uptake of zinc, and the sorption capacity increases with increasing pH. Adsorption on lignin follows the Freundlich and Langmuir models. Isotherms have been used to obtain the thermodynamic parameters of the process. Several polyhydric phenols and other substituted analogues may be involved in the uptake of metal ions. In comparison to other low-cost adsorbents, the sorption capacity of the material, under investigation is found to be significantly high for the two metal ions.