Sustainable mechanochemical synthesis of zeolite/periwinkle shell nanocomposites for lead adsorption and antimicrobial activity

Zeolite/periwinkle shell ash (Ze/PSA) nanocomposite was prepared via the mechanochemical technique and characterized by SEM/EDX, TEM, AFM, XRD, FTIR, and BET to determine its morphological, structural, and surface characteristics for Pb 2 + adsorption and antimicrobial treatment. The minimum inhibitory concentration was determined to vary from 2.5 to 12.5 mg/mL for Pseudomonas aeruginosa , Streptococcus spp , Escherichia coli, and Staphylococcus aureus . The nanocomposite was hierarchically porous, polydisperse nanoparticle (1.55–22.25 nm) and possesses a large surface area (396.2 m 2 /g), good for adsorption and trapping of microbes. The optimum pH of 6.0 yielded ∼92 % removal of Pb 2+ in 90 min. The adsorption data were equally well-described by both the Langmuir (qe = 102.04 mg/g) and Freundlich (K F ∼ = 9.85 mg/g)(L//mg)1/n) isotherm models, with similar high correlation coefficients (R² = 0.999). Kinetic data were best described by the pseudo-second-order model (qe = 107.70 mg/g), indicating a chemisorption mechanism. Thermodynamic data; ΔH° = + 28.15 kJ/mol, ΔS° = + 114.83 J/mol revealed a spontaneous, endothermic, and entropy-favored adsorption. Hence, Ze/PSA emerges as a promising, cost-effective adsorbent with robust mechanistic properties, making it an attractive option for metal-selective adsorption of Pb 2+ over Cu (II), Cd (II), Zn (II) , and for antimicrobial applications. Future work should include validation of the binding mechanisms and testing with real wastewater to confirm practical applicability and cost-effectiveness, utilizing advanced spectroscopic techniques. • A novel zeolite/periwinkle shell nanocomposite was crafted via eco-friendly, solvent-free mechano-chemistry. • Boasts a high surface area (396 m²/g) and hierarchical pores for superior contaminant capture. • Achieved rapid Pb²⁺ adsorption (102 mg/g) driven by chemisorption at pH 6.0 in 90 mins. • Exhibits potent, broad-spectrum antibacterial action via a dual physical and chemical mechanism. • Adsorption is inherently favorable and entropy-driven, firmly confirming a chemisorption mechanism.