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A chitosan-thiomer polymer for highly efficacious adsorption of mercury

Bhatt, Rahul, P, Padmaj
Carbohydrate polymers 2019 v.207 pp. 663-674
Fourier transform infrared spectroscopy, X-ray diffraction, adsorbents, adsorption, desorption, differential scanning calorimetry, energy-dispersive X-ray analysis, kinetics, mercury, methylmercury compounds, perchloric acid, polymers, scanning electron microscopy, sodium chloride, sorption isotherms, thermogravimetry, thiobarbituric acid, thiourea
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°), 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°, Hg2+ and CH3Hg+. The experimental data fitted well to Freundlich isotherm and pseudo second order kinetic models with high R2 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°, Hg2+ and CH3Hg+ respectively. Quantitative desorption of Hg°, Hg2+ and CH3Hg+ from CTG could be performed using 0.01 N thiourea, 0.01 N HClO4 and 0.2 N NaCl respectively.