Effect of alkaline treatment of wooden sawdust for the removal of heavy metals from aquatic environments

Abstract

This paper reports a study of the removal of heavy metals from water by unconventional waste products including the wooden sawdust of poplar, cherry, spruce and hornbeam. The efficiency of Cu(II), Zn(II), and Fe(II) ion sorption under various initial concentrations from model solutions by raw and alkaline-modified sawdust was investigated. Data obtained by neutron activation analysis revealed that ion exchange is one of the mechanisms underlying metal removal by the selected sawdust from the model solutions. Analysis of the structure and morphology of natural and alkali-modified wooden sawdust by SEM/EDX did not reveal significant changes. The FT-IR spectra showed changes in functional groups due to the alkaline modification of sawdust where the intensity of hydroxyl peaks was considerably increased. It was found that the sorption capacity of the modified sawdust for the model solutions of 50 mg.L–1 of Cu(II) and Zn(II) was approximately 4.5 times higher in comparison to the untreated sawdust; however, the alkaline-modified sawdust had a negative influence on Fe(II) ion removal because of organic-metallic dye formations. The adsorption capacity of the alkaline modified wooden sawdust for the removal of heavy metals from wastewater was improved.