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A novel thiosemicarbazide modified chitosan (TSFCS) for efficiency removal of Pb (II) and methyl red from aqueous solution

Mozaffari, Maede, Emami, Mohammad Reza Sarmasti, Binaeian, Ehsan
International journal of biological macromolecules 2019 v.123 pp. 457-467
Fourier transform infrared spectroscopy, adsorbents, adsorption, aqueous solutions, chitosan, endothermy, lead, models, pH, scanning electron microscopy, sorption isotherms, temperature, thermodynamics, thermogravimetry
Thiosemicarbazide modified chitosan, TSFCS, was prepared and characterized by FTIR, SEM and TGA techniques and its application as a novel adsorbent for the removal of Pb(II) and methyl red (MR) was investigated. The effect of some adsorption parameters such as pH, TSFCS dosage and initial concentration of solutions were evaluated. The maximum removal percentage for MR and Pb(II) was found to be about 91% and 85.6% at pH 8 and 5 and TSFCS dosage of 3.33 g/l and 1.33 g/l, respectively. Langmuir, Freundlich and Temkin isotherms were evaluated and the maximum adsorption capacities for Pb(II) and MR were found to be 56.89 mg/g and 17.31 mg/g at 55 °C and 25 °C, respectively. Isotherm studies indicate that Pb (II) and MR adsorptions follow Freundlich and Langmuir models, respectively. The adsorption kinetic was more accurately fitted by the pseudo-second order model. Thermodynamic parameters including ΔG°, ΔH° and ΔS° were determined over the temperature range of 25–55 °C. The findings show that the sorption process was spontaneous (ΔG° < 0) and endothermic (ΔH° > 0).