Application of waste cotton yarn as adsorbent of heavy metal ions from single and mixed solutions.

In this study, waste cotton yarn was used for the removal of Pb (II), Cd (II), Cr (III), and As (V) from aqueous solution. Adsorption of heavy metal ions was tested from single ion solutions, while competitive studies were performed using two- and four-ion mixtures. In order to change the structure of the material, cotton yarn was modified by sodium hydroxide solution. The surface of raw and modified cotton yarn were characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, and streaming potential method for determination of an isoelectric point. Sorption studies were performed on the basis of pH, kinetics, isotherms, and desorption results. It has been shown that waste cotton yarn modification, typically, does not improve the sorption capacity of the material and that the unmodified material could be used for the removal of examined heavy metal ions. Selectivity was in order Pb > Cd > Cr > As. Desorption studies have indicated to the possible reusability of the sorbent only in the case of Pb removal. A potential application of spent waste sorbent for the soil quality improvement has been considered.