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[Display omitted] • Phosphorylated porous phenolic resins (PO-PPRs) were prepared with POCl 3 post-modification. • PO-PPRs with hierarchical pore structures demonstrated a broad pH working range (3.0–7.0). • PO-PPRs exhibited excellent adsorption capacities of light and heavy REEs (63.9–118 mg/g). • The Nd3+/Al3+ separation factor of PO-PPR-1 reached 24. • PO-PPRs can efficiently extract and recycle low-concentration REEs from tailing wastewater. Efficient extraction and recycling of rare earth elements (REEs) from low-concentration complex tailing wastewater is critical to meeting the growing industrial demands and optimizing resource utilization. In this work, three phosphorylated porous phenolic resins (PO-PPRs) were prepared via the phosphorylation of phenolic hydroxyl groups with POCl 3 , and employed to extract REE3+ from both simulated and practical low-concentration REE3+-containing aqueous solution. The PO-PPRs, characterized by hierarchical pore structures, exhibit high adsorption capacities for both light and heavy REE3+ ions over a broad pH working range from 3.0 to 7.0, along with fast adsorption kinetics (<30 min). And the maximum adsorption capacities of PO-PPRs for Nd3+, Dy3+ and Y3+ were found to be 104.1, 118.0 and 63.9 mg/g, respectively. Furthermore, the introduction of phosphonic groups significantly improves the REE3+ adsorption selectivity against various interfering metal ions such as Na+, K+, Ca2+, Mg2+, and Al3+. For instance, the Nd3+/Al3+ separation factor (S.F.) of 24 exceeded that of most commercial resins and reported materials. In a simulated mixed multi-element aqueous solution system containing Nd3+, Dy3+, Y3+, Al3+, Ca2+, Mg2+, Mn2+, K+ and Na+, PO-PPR-1 extracted 82.5% of total REE3+ while maintaining Al3+ adsorption efficiency of less than 13%. Moreover, the extraction efficiency of total REE3+ for PO-PPR-1 in pretreated practical wastewater from ion-adsorbed ores tailing reached 99.6%. Additionally, PO-PPRs demonstrated easy regeneration and excellent recycling performance after 5 consecutive adsorption–desorption cycles, confirming their promising application potential in low-concentration REEs extraction. [ABSTRACT FROM AUTHOR]

[Display omitted] • 2D multilayered Ti 3 C 2 T x MXene adsorbents were fabricated via selective Al element etching. • Li+-intercalation increased the interlayer spacing and surface area. • TCF-2 exhibited broad working pH range and excellent Nd3+ adsorption capacity (517.8 mg/g). • The Nd3+/Fe3+ selectivity of TCF-2 reached 221. • The adsorption mechanism was elucidated using different characterizations. Recovering rare earth elements (REEs) from low-concentration REE-bearing waste streams has been deemed as a sustainable approach to diversity REE supply and reduce environmental burden. However, highly selective separation of trivalent Fe3+ and Al3+ impurities during low-concentration REE processing still remains a critical challenge. In this study, two-dimensional multilayered MXene adsorbents TCFs were successfully prepared and utilized for Nd3+ adsorption via selective etching of Al element in Ti 3 AlC 2. It was found that LiF/HCl-etched TCF-2 can simultaneously realize effective Al etching, interlayer spacing expansion and in-situ Li+ intercalation. The intercalated Li+ amount was up to 4.44 wt% (6.40 mmol/g). Compared with HF-etched TCF-1, TCF-2 demonstrated boosted adsorption kinetics (2 h), large adsorption capacity (517.79 mg/g), impressively high selectivity (Nd3+/Fe3+ SF = 221, Nd3+/Ca2+ SF = 858, Nd3+/Mg2+ SF = 3545), and broad working pH range (2–7). Various experimental characterizations reveal that selective Nd3+ recovery is owing to the ion-exchange and surface complexation induced by interlayer Ti-O/Ti-OH of TCF-2. Specifically, the extended X-ray sorption fine structure (EXAFS) results, in combination with density functional theory (DFT) calculations, further confirm the Nd3+ is selectively adsorbed by forming surfaced complexes structure in the interlayer. And this is also evidenced by the decrease of Nd-O distances and high coordination number. The present results illustrate that alkaline metal ion-intercalated MXene could serve as a promising candidate to efficiently remove trivalent Fe3+ impurities for REEs recovery. [ABSTRACT FROM AUTHOR]