Competitive Adsorption of La3+/Ce3+/Nd3+ Ions on Poly (Methyl Methacrylate)-co-Diacrylate/Single-Walled Carbon Nanotube Nanocomposites

Recovery of rare earth elements (REEs) is one of the important processes in high-end industries using critical raw materials. In this study, we developed a new microencapsulated nanocomposite adsorbent consisting of poly(methyl methacrylate) copolymerized with liquid crystal diacrylate (RM 257) and single-walled carbon nanotube (SWCNT). The adsorbent was synthesized by oil-in-water (O/W) emulsion polymerization with the ratio 1:7 and aimed to recover La3+, Ce3+, and Nd3+ ions in an aqueous solution. The FTIR and Raman spectroscopy results confirm the components that formulate this microencapsulation. Besides that, FTIR, BET, and SEM-EDS have characterized the microencapsulated adsorbents before and after adsorption. The morphology and element mapping using SEM-EDS showed that Ce3+ and Nd3+ ions are distributed well on the surface of the adsorbent, whereas La3+ diffused into the pores of the adsorbent. The kinetics and isotherm models have been fitted to evaluate the competitive adsorption of La/Ce/Nd ions at low concentrations (0.5–6 mg/L). The study found that the adsorption of La3+, Ce3+, and Nd3+ ions in an aqueous solution followed pseudo-second-order kinetics and the Freundlich isotherm model. The maximum adsorption capacity was 0.1538, 0.1352, and 0.1217 mg/g for La3+, Nd3+, and Ce3+ ions.