Dialdehyde Chitosan/Semicarbazide Synthesis for Lanthanum, Cerium, and Neodymium Ions Recovery from Phosphate Leachate

Rare earth elements are among the world’s most crucial strategic minerals. Cell phones, lamp lights, televisions, wind turbines, and other contemporary electronics rely heavily on rare earth elements. As a result, this work aimed to prepare eco-friendly dialdehyde chitosan with semicarbazide (SC/DiACs), a promising method for recovering lanthanum, cerium, and neodymium from phosphate leach solution. Different analytical techniques were utilized to determine the physicochemical properties of SC/DiACs before and after adsorption. Sorption was conducted at pH 5 for 60 min using 50 mg SC/DiACs and 200 mg/L La, Ce, and Nd ions. The sorption capacities were 193.52 mg/g for La, 186.77 mg/g for Ce, and 171.37 mg/g for Nd. The studied ions’ sorption onto the SC/DiACs sorbent was well-fitted by the pseudo-first-order (PFO) and the isotherm produced by Langmuir. Besides, it was discovered that the sorption thermodynamic characteristics were both spontaneous and exothermic. La, Ce, and Nd ions were successfully desorbed from the SC/DiACs by imperiling it to 0.7 M/L HNO₃ and 35 min at 25 °C with a 1:40 solid/liquid (S/L) ratio. Also, the SC/DiACs sorbent was rejuvenated after seven cycles of sorption–desorption. SC/DiACs sorbent was exploited to recover RE ions from the phosphate leach solution. Ion purity levels of 90.18% were achieved by calcining the precipitate to RE oxides. Finally, the SC/DiACs sorbent was found to have excellent sorption characteristics for RE ions in their solution, as evaluated by the REEs recovery behaviors.