Equilibrium studies of sorption of lead(II) ions by different pectin compounds

The adsorption of Pb(II) ions from aqueous solution by different pectin compounds was studied in a batch sorption system. Water-soluble low- and high-esterified pectins and insoluble calcium pectate beads were investigated. The lead-binding capacity of all pectin compounds was highest within the pH range from 7 to 8. The binding capacities and rates of Pb(II) ions by pectin compounds were evaluated. The Langmuir, Freundlich and BET sorption models were applied to describe the isotherms and isotherm constants. Sorption isothermal data could be well interpreted by the Langmuir model. These results obtained through the study suggest that pectin compounds are favorable sorbers. The largest amount of Pb(II) ions were bound by pectin with the low degree of esterfication. Therefore, pectin substances may be considered as perspective for sorption and removal of Pb(II) ions from wastewaters. (c) 2007 Elsevier B.V. All rights reserved.