Preparation and application of thiol wheat straw as sorbent for removing mercury ion from aqueous solution

In this paper, thiol wheat straw (TWS) was prepared by esterifying mercaptoacetic acid onto cellulose in wheat straw. The potential feasibility of TWS as sorbent for removing mercury ion from aqueous solution was investigated in a batch system. The Hg2+ removal was found to be dependent on initial pH, sorbent dose, Hg2+ concentration, contact time, and temperature. The maximum value of Hg2+ removal appeared in the range of pH 4 to 7. The isothermal data of Hg2+ sorption conformed well to the Langmuir model and the maximum sorption capacity (Qm) of TWS for Hg2+ was 72.46 mg/g. The equilibrium of Hg2+ removal was reached within 100 min. The Hg2+ removal process could be described by the pseudo-first-order kinetic model. The thermodynamic study indicated that the Hg2+ removal process was spontaneous and exothermic.