Environmental analytical evaluation of polyvinylpyrrolidone-stabilized ZnS nanoparticles for the determination and removal of malachite green dye

Zinc sulphide (ZnS) nanoparticles stabilized with polyvinylpyrrolidone (PVP) were synthesized via a facile chemical precipitation method and applied as an efficient adsorbent for the removal of Malachite Green (MG) dye from aqueous media. The synthesized nanomaterial was comprehensively characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV–Vis spectrophotometry, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and Brunauer–Emmett–Teller (BET) analysis, confirming the formation of mesoporous ZnS nanoparticles with a cubic phase and an optical band gap of 3.77 eV. An analytical method based on UV–Vis spectrophotometry was developed for MG determination, exhibiting excellent linearity over the concentration range of 2–10 mg L⁻¹ (R² ≥ 0.99). The method demonstrated satisfactory sensitivity, with low detection limits (LOD = 0.15 mg L⁻¹) and quantification limits (LOQ = 0.50 mg L⁻¹), along with acceptable precision (RSD < 5%). Adsorption parameters were systematically optimized, revealing that the maximum removal efficiency of 90.1% was achieved at pH 10, an adsorbent dosage of 0.02 g, and a contact time of 40 min. The enhanced adsorption performance is attributed to the high surface area, mesoporous structure, and strong electrostatic interactions between ZnS nanoparticles and MG molecules. The proposed method demonstrates good analytical reliability and environmental applicability, offering a simple, cost-effective, and sensitive approach for monitoring and removing dye pollutants from water samples.