Synthesis and Characterisation of PVA - Capped CuS/Bentonite Nanocomposites

This study reports the synthesis and characterisation of polymer-capped CuS/bentonite nanocomposites prepared as multifunctional adsorbent materials for wastewater treatment. A thiourea-based pyrrolidone ligand was used as the sulphur-donating precursor during homogeneous precipitation of CuS nanoparticles, while PVA were introduced as capping agents to control particle growth, improve colloidal stability and minimize agglomeration. The capped nanoparticles were immobilized onto bentonite clay to enhance dispersion and provide additional surface-active and ion- exchange sites. FTIR analysis showed metal-Sulphur vibrations at 515–638 cm⁻¹, together with shifts in –OH, C=O and C–O bands, confirming interaction between the polymers, metal sulphides and bentonite clay. XRD patterns confirmed the formation of crystalline monoclinic covellite CuS phases, with an estimated crystallite size of 17.8–24.6 nm. SEM-EDS and HR-TEM analyses revealed quasi-spherical nanoparticles uniformly anchored on bentonite platelets, with an average particle size of 21.3 ± 4.7 nm and homogeneous Ag, Cu and S distribution. BET analysis showed a surface area of 156.4 m²/g, pore volume of 0.36 cm³/g and average pore diameter of 8.9 nm. TGA indicated improved thermal stability, with 61.8% residual mass at 800 °C. DRS and PL results suggested enhanced visible-light absorption and reduced electron-hole recombination. These findings confirm successful formation of a stable, porous and well-dispersed Ag₂S-CuS/bentonite nanocomposite for water treatement applications.