Preparation and characterization of a mercaptan derivative of chitosan for the removal of mercury from brines

Chitosan, [(1,4)‐2‐amino‐2‐deoxy‐β‐D‐glucan], was reacted consecutively with epichlorohydrin and thiourea. Subsequent hydrolysis of the isothiouronium salt yielded the mercaptan derivative of chitosan, which scavenges mercury ions from solution in the presence of a considerably high concentration of chloride ions. Sulfur contents varied with reacting conditions and reached values up to 7.3%. The derivative is insoluble due to partial crosslinking of chitosan during the reaction with epichlorohydrin and was characterized by IR spectroscopy, solid‐state 13C NMR, thermal analysis and pyrolysis‐mass spectrometry.