A Luminescent Tb-MOF/Pistachio Shell Bio-Composite for Rapid Adsorption and Fluorescence Detection of Methyl Parathion in Water

Methyl parathion (MP) is an organic pesticide used on crops to control pest populations. However, its indiscriminate use contaminates soil and water, necessitating the development of cost-effective solutions for its removal and detection. In this work, a novel luminescent composite (Pi@Tb-MOF) was successfully synthesized via the in situ growth of a terbium-based metal–organic framework on pistachio shell biomass. The successful formation of the Pi@Tb-MOF composite was confirmed by XRD, SEM-EDS, FTIR, and TGA analyses. The composite was evaluated for the removal and detection of MP in aqueous media. Kinetic data were best described by the second-order and Avrami models, which indicate heterogeneous surface reactions and progressive activation of adsorption sites. Isotherm analysis revealed that the Hill model provided the best fit (KH = 0.6644), suggesting cooperative adsorption and strong adsorbate–adsorbate interactions on the composite surface. Although the maximum adsorption capacity predicted by the Langmuir model was 1.47 mg/g, the material exhibited a remarkable luminescence response to MP. The Tb-MOF characteristic emission bands decreased progressively upon pesticide adsorption, enabling fluorescence-based detection with a limit of detection of 0.1 µM. The quenching process followed a linear Stern–Volmer relationship at low concentrations (R2 = 0.99), demonstrating the composite’s potential as a sensing platform. The fluorescence quenching is attributed to electron transfer interactions between the MOF ligand and the nitroaromatic group of MP combined with adsorption on the pistachio matrix. These results demonstrate that Pi@Tb-MOF is a sustainable composite capable of simultaneously removing and detecting methyl parathion, highlighting its potential as an environmentally friendly material for monitoring pesticide contamination in water. This work reports, for the first time, a novel Pi@Tb-MOF composite based on pistachio shell biomass and a luminescent Tb-MOF, which has not been previously described in the literature and enables the simultaneous adsorption and optical sensing of methyl parathion.