Adsorption behavior and mechanism of methyl green on synthesized MoS2 nanosheets

Ramos-Guivar J.A.; Mejía-Barraza M.-A.; Canchanya-Huaman Y.; del Pilar Marcos-Carrillo M.; Rueda-Vellasmin R.; Moreno-Tarazona J.; Checca-Huaman N.-R.; dos Santos B.L.D.; Macedo W.A.A.; Passamani E.C.; Rodríguez-Ocanto N.; Gómez M.A.R. · Discover Nano (2026) · DOI: 10.1186/s11671-026-04859-1

Resumen

Two-dimensional molybdenum disulfide (MoS2) is a promising adsorbent for wastewater treatment because of its layered structure, tunable surface chemistry, and accessible edge sites. Here, commercial MoS₂ (MoS₂-C) and hydrothermally synthesized MoS₂ nanosheet assemblies (MoS₂-S) were comparatively evaluated for methyl green (MG) adsorption. MoS₂-S exhibited improved colloidal stability, near-complete MG removal (> 98%) across pH 2–12, and an operational equilibrium time of approximately 15 min. The kinetic data were best described by the pseudo-first-order model for MoS₂-C and by the pseudo-second-order model for MoS₂-S; these fits were treated as empirical descriptions rather than direct mechanistic evidence. The MoS₂-S equilibrium data were most parsimoniously described by the Langmuir model, with a maximum adsorption capacity of 7.1 × 102 mg g−1. Charge-corrected XPS revealed preservation of the dominant Mo4+ component after adsorption, together with the appearance of Mo5+, an increased Mo6+ fraction, modest changes in oxygen- and sulfur-related components, and MG-derived C–N signals. These results support a mixed adsorption mechanism, with predominantly non-covalent uptake on MoS₂-C and a stronger defect-associated, site-specific contribution on MoS₂-S. Box–Behnken optimization produced a significant model (R2 = 0.925; adjusted R2 = 0.884) with non-significant lack of fit and identified adsorbent dose as the principal operational factor. © The Author(s) 2026.

Instituciones: Universidad Nacional Mayor de San Marcos