Biosorption isotherms of Pb (II) and Zn (II) on Pestan, an extracellular polysaccharide, of Pestalotiopsis sp. KCTC 8637P

To assess the potential applicability of Pestan, a fungal extracellular polysaccharide, to wastewater treatment as a biosorbent, sorption of Pb (II) and Zn (II) on Pestan was examined using the Freundlich, Langmuir, and Tein and Huang's isotherms. The equilibrium isotherms were shown to be 120 mg Pb (II)/g and 60 mg Zn (II)/g Pestan, respectively. The metal sorption of Pestan fit better to Freundlich model than Langmuir model; the adsorption capacity (ln K) and adsorption intensity (1/n) of Pb (II) were higher than those of Zn (II). From the plot of reaction time against adsorption density, the adsorption constants for Pb (II) and Zn (II) were determined to be 3.57 × 105 and 5.63 × 103, respectively, and the Ka of Pb (II) was 63.4 times higher than that of Zn (II).