The separation of rare earth ions (RE
3+) from aqueous solutions poses a significant challenge due to their similar chemical and physical characteristics. This study presents a method for synthesizing hematite nanoparticles (Fe
2O
3 NPs) through the high-temperature phase transition
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The separation of rare earth ions (RE
3+) from aqueous solutions poses a significant challenge due to their similar chemical and physical characteristics. This study presents a method for synthesizing hematite nanoparticles (Fe
2O
3 NPs) through the high-temperature phase transition of natural pyrite for adsorbing RE
3+ from mine wastewater. The characteristics of Fe
2O
3 NPs were studied using XRD, SEM, BET, XPS, FTIR, and Zeta potential. The optimal condition for RE
3+ adsorption by Fe
2O
3 NPs was determined to be at pH 6.0 with an adsorption time of 60 min. The maximum adsorption capacities of Fe
2O
3 NPs for La
3+, Ce
3+, Pr
3+, Nd
3+, Sm
3+, Gd
3+, Dy
3+, and Y
3+ were 12.80, 14.02, 14.67, 15.52, 17.66, 19.16, 19.94, and 11.82 mg·g
−1, respectively. The experimental data fitted well with the Langmuir isotherm and pseudo-second-order models, suggesting that the adsorption process was dominated by monolayer chemisorption. Thermodynamic analysis revealed the endothermic nature of the adsorption process. At room temperature, the adsorption of RE
3+ in most cases (La
3+, Ce
3+, Pr
3+, Nd
3+, Sm
3+, and Y
3+) onto Fe
2O
3 NPs was non-spontaneous, except for the adsorption of Gd
3+ and Dy
3+, which was spontaneous. The higher separation selectivity of Fe
2O
3 NPs for Gd
3+ and Dy
3+ was confirmed by the separation factor. Moreover, Fe
2O
3 NPs exhibited excellent stability, with an RE
3+ removal efficiency exceeding 94.70% after five adsorption–desorption cycles, demonstrating its potential for the recovery of RE
3+ from mine wastewater.
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