A chitosan-thiomer polymer for highly efficacious adsorption of mercury

Thiomers have recently attracted attention as effective adsorbents for Hg2+. In the present study a chitosan-thiobarbituric acid based thiomer(CTG) was investigated as a potential adsorbent for elemental mercury (Hg degrees), inorganic mercury (Hg2+) and methyl mercury (CH3Hg+). CTG was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). Adsorption experiments were performed to optimize the parameters for maximum removal of Hg degrees, Hg2+ and CH3Hg+. The experimental data fitted well to Freundlich isotherm and pseudo second order kinetic models with high R-2 and minimal error function values. The maximum adsorption capacities were determined to be 1367 +/- 96.9, 2493 +/- 174.6 and 2531 +/- 178.4 mg/g for Hg degrees, Hg2+ and CH3Hg+ respectively. Quantitative desorption of Hg degrees, Hg2+ and CH3Hg+ from CTG could be performed using 0.01 N thiourea, 0.01 N HClO4 and 0.2 N NaCl respectively.