Two α-aminophosphonate anlages (methyl- and phenyl-derivatives, MeAP and PhAP, respectively) were synthesized via an in-situ reaction. Moreover, their corresponding sand nanocomposites, MeAPNC and PhAPNC, respectively, were prepared using an eco-friendly, inexpensive and facile solid-state synthetic route. These materials were extensively characterized by CHNSP/O, XRD, FTIR, SEM-EDX, TEM, and PZC. Lanthanum sorption characteristics were investigated and compared through the study of pH dependence (optimal pH: 4.5), equilibration time (achieved at 120 and 90 min for α-APs and nanocomposites, respectively), and sorption isotherms. The Sips isotherm and pseudo-second-order (PSORE) kinetics were the optimal models for fitting the experimental data. Sorption isotherms showed that methyl-derivatives (≈1.29–1.359 mmol/g) were more effective than their corresponding phenyl-derivatives (≈0.941–0.986 mmol/g) due to steric hindrance, acid-base differences, and inductive effects. Sorbents showed appreciated stability with just a 4.5–10.5 % loss in performance over six reuse cycles using HCl (0.2 M). Notably, sand incorporation slightly increased capacity with half-organic-portion in composites, as well as enhanced kinetics and regeneration efficiency. La(III) sorption is spontaneous, exothermic, and increases randomness across all sorbents. Finally, the prepared sorbents have proven effective sorption for Nd(III) beside La(III) with high selectivity from acidic complex monazite liquor.
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