Extraction of rare earth elements from monazite leach liquor using functionalized chitosan sorbents derived from shrimp waste

Glycopolymer-Mediated Selective Separation of Middle Rare Earth Elements

The selective separation of rare earth elements (REEs) remains a formidable challenge due to limitations of current methodologies, which struggle to achieve the separation efficiency required for their critical industrial applications. Middle REEs (MREEs), characterized by their intermediate ionic radii, are particularly challenging to separate without size-specific trapping mechanisms. In this study, we report a novel approach that synergistically combines heavy metal sequestration with size-selective separation, utilizing negatively charged glycopolymers to achieve the targeted separation of MREEs. We systematically investigated the binding affinities of these glycopolymers for various REEs, focusing on the selective isolation of MREEs through a controlled variation of glycopolymer properties, including degree of polymerization (DP) and charge density. Our findings reveal a distinctive U-shaped selectivity profile, with a marked preference for Samarium (Sm) and Europium (Eu) over other REEs such as Cerium (Ce), Gadolinium (Gd), and Holmium (Ho). This selectivity underscores the potential for designing tailored separation processes optimized for specific MREEs. Moreover, enrichment experiments demonstrated the practical viability of our methodology, achieving over 10 % selectivity for Sm in a Ce/Sm mixture with a 10 : 1 Ce/Sm ratio, a trend that held for Sm in a Ho/Sm Mixture with a 10 : 1 Ho/Sm ratio, indicating significant selectivity over both light and heavy REEs. A subsequent separation experiment using a 1 : 1 Ce/Sm mixture yielded a 15 % enrichment after only five passes through a filter containing minimal amounts of glycopolymer, highlighting the promise of further refinement for enhanced separation efficiency.

Eco-friendly and cost-effective adsorbent derived from blast furnace slag with black liquor waste for hazardous remediation

The current investigation concerns with preparation eco-friendly and cost-effective adsorbent (mesoporous silica nanoparticles (SBL)) based on black liquor (BL) containing lignin derived from sugarcane bagasse and combining it with sodium silicate derived from blast furnace slag (BFS) for thorium adsorption. Thorium ions were adsorbed from an aqueous solution using the synthesized bio-sorbent (SBL), which was then assessed by X-ray diffraction, BET surface area analysis, scanning electron microscopy with energy dispersive X-ray spectroscopy (EDX), and Fourier transforms infrared spectroscopy (FTIR). Th(IV) sorption properties, including the pH effect, uptake rate, and sorption isotherms across various temperatures were investigated. The maximum sorption capacity of Th(IV) on SBL is 158.88 mg/L at pH value of 4328 K, and 60 min contact time. We demonstrated that the adsorption processes comport well with pseudo-second-order and Langmuir adsorption models considering the kinetics and equilibrium data. According to thermodynamic inspections results, the Th(IV) adsorption process exhibited endothermic and random behavior suggested by positive ΔH° and ΔS° values, while the negative ΔG° values indicated a spontaneous sorption process. The maximum Th(IV) desorption from the loaded SBL (Th/SBL) was carried out at 0.25 M of NaHCO3 and 60 min of contact. Sorption/desorption processes have five successive cycles. Finally, this study suggests that the recycling of BFS and BL can be exploited for the procurement of a promising Th(IV) adsorbents.