Synthesis and application studies of chitosan acryloylthiourea derivative for the separation of rare earth elements

ABSTRACT

The adsorption behaviors of lanthanum (III) from an aqueous chloride medium, using Chitosan acryloylthiourea (CATU) derivative, were studied using an equilibrium batch technique. Here, the chemical modification of chitosan is of interest because the modification would not change the fundamental skeleton of chitosan, would keep the original physicochemical and biochemical properties, and finally would bring new or improved properties. The optimum pH value was defined to be 5.0 at a temperature of 298 K. Kinetic and isotherm experiments were carried out at the optimum pH. It was enough to reach the adsorption equilibrium at 4 hours and the maximum uptake capacity was 2.1 mmol g⁻¹ at 25°C. Complexion, ion exchange, and electrostatic interaction were all believed to play a role in lanthanum adsorption on CATU derivative. The equilibrium adsorption data were fitted to a second-order kinetic equation. The Langmuir adsorption isotherm models were used to describe the adsorption process. The proposed method was validated and successfully applied for the determination of lanthanum in certified reference samples and ore sample with satisfactory results. The elution experiment was carried out by 0.05 mol/L CaCl₂ as an eluent.

GRAPHICAL ABSTRACT

KEYWORDS:

• Adsorption
• chitosan
• kinetics
• lanthanum
• regeneration