Mesoporous MCM-41 supported amorphous MnLa oxides for selective removal of As(V), Cd(II) and Pb(II)

The coexistence of oxyanion-type and cationic heavy metals in complex aqueous systems poses a significant challenge for adsorption-based remediation. Herein, mesoporous silica-supported manganese‑lanthanum mixed oxides (Mn x La 1-x @MCM-41) were synthesized via an oxidation-coprecipitation strategy. The mesoporous silica framework effectively confined amorphous Mn/La oxides, suppressing oxide aggregation and manganese leaching. The as-prepared Mn x La 1-x @MCM-41 materials exhibited efficient removal of heavy metals, with maximum adsorption capacities of 57.3 mg g −1 for As(V), 141.6 mg g −1 for Cd(II), and 333.0 mg g −1 for Pb(II). By adjusting the Mn/La molar ratio, the adsorption behavior toward different metal species could be systematically regulated, with La-enriched compositions favoring As(V) uptake and Mn-rich materials exhibiting enhanced affinity toward Cd(II) and Pb(II). High removal efficiencies for all three heavy metals were maintained under multicomponent coexisting conditions. The composition-dependent adsorption behavior reflects a functional differentiation of Mn- and La-associated surface sites, enabling the simultaneous immobilization of oxyanion and cationic contaminants. Overall, this work demonstrates that integrating mesoporous confinement with compositional regulation provides an effective strategy for constructing stable and multifunctional adsorbents for multicomponent heavy-metal remediation.