Ethylene sulfide can used in the chemical modification of biopolymer chitosan.· Ethylene sulfide is generally used in the preparation of organosulfur compounds, especially for mercaptoethylation of primary and secondary amines to obtain aminothiols. · It is used in the synthesis of dendritic thioether ligands to stabilize gold nanoparticles (Au NPs). · Chitosan can be chemically modified by treating ethylene sulfide to obtain a biopolymer for the removal of divalent cations from aqueous solutions. Ethylene sulfide can used in the chemical modification of biopolymer chitosan. A sulfur compound which was used in the chemical modification of chitosan.