Опубликована: Янв. 1, 2024
In this dissertation, a two-step protocol for the fabrication of novel, green, and sustainable chitosan-based hydrogel adsorbent was developed recovery dysprosium (III) (Dy(III)), an important rare earth element (REE) used in manufacture magnets. The virgin chitosan's physicochemical physicomechanical properties were improved by crosslinking primary amine chitosan with glutaraldehyde 4-hydroxycoumarin via one-step three-component Mannich reaction to form modified-chitosan (Cs/MB). utilization as component justified its efficient reactivity variety amines that produced library products moderate high yields (60-90%) purity (97.8 ± 3.1%) verified Nuclear Magnetic Resonance (NMR) spectroscopy, without need catalyst or chemical purification. functionalization Cs/MB phosphate group at alcohol backbone found be imperative coordination Dy(III) achieved phosphorylation P2O5 methanesulfonic acid established method. determined sequence optimized product's physical quality first introduce P2O5/methanesulfonic method, then aqueous ethanol room temperature 12 h. PCs/MB characterized Fourier Transform-Infrared Spectroscopy (FT-IR) verifying presence key functional groups added polymer namely peaks 1319, 972, 908, 514 cm-1 peak ~754 cm-1. Elemental mapping Na PCs/MB, suggesting successful conversion Na-form. Batch adsorption studies conducted obtained maximum capacity 34 mg/g 2 h, whereas column attained saturation 22 after 3 h bed length 1.8 cm, flow rate 0.1 mL/min, feed concentration pH 13 mg/L = 5.2, respectively, temperature. lanthanide-phosphate ~630 cm-1, absence glycosidic C-O-C stretching ~1154 weakening N-H ~3400 FT-IR spectrum spent provided direct evidence tandem onto one hexose unit subsequent complexation free amino next unit. surface elemental confirmed ion exchange phenomenon between Dy(III). Kinetics thermodynamics predicted transport is limited exothermic process Gibb's energy +1.88 kJ/mol equilibrium constant 0.47 25 degree C. Competitive neodymium(III) (Nd(III)) approximately equimolar carried out both batch continuous mode, which consistently separation factor 2.2 0.2 preference Complete Nd(III) from desorption two 48-hr cycles using 2.0 g/L 0.001 M HCl per cycle total REEs 1.8x cycle. reappeared desorption, liberation desorption.
Язык: Английский