Cu2S-ZnS PANI nanocomposite adsorbent for the removal of lead ion from water samples

In this study, copper(I) sulfide‑zinc(II) sulfide (Cu₂S-ZnS) nanoparticles were synthesized via a one-step hydrothermal method using zinc acetate, copper sulfate, and thiourea as precursors, and subsequently chemically modified with polyaniline (PANI) to produce the Cu 2 S-ZnS PANI nanocomposite. Thiourea served a dual function: it acted as a reducing agent, converting Cu 2+ to Cu + , and under hydrothermal conditions, provided sulfur for the formation of Cu 2 S-ZnS nanoparticles. The resulting Cu 2 S -ZnS PANI nanocomposite was characterized using Field Emission Scanning Electron Microscopy (FESEM), Energy-dispersive X-ray spectroscopy (EDX), Fourier Transform Infrared (FT-IR) spectrophotometry, and X-Ray Diffraction (XRD) techniques. The nanocomposite was subsequently applied for the removal of lead ion (Pb 2+ ) from water samples. Key factors affecting Pb 2+ removal were systematically investigated, with the maximum removal percentage (∼93% for 20 mg/L Pb 2+ ) achieved at pH 6.0, using 1000 mg/L of adsorbent and a 25-min contact time. Isotherm analysis indicated that Pb 2+ adsorption follows a multilayer mechanism with a maximum adsorption capacity of 169.5 mg/g. Kinetic studies revealed that the pseudo-first-order model accurately describes the adsorption process. The reusability test demonstrated that the Cu 2 S-ZnS PANI adsorbent could be used for at least six adsorption/desorption cycles without a significant loss in performance. Overall, its high efficiency, rapid adsorption, low cost, and demonstrated reusability make the Cu 2 S-ZnS PANI nanocomposite as a highly effective adsorbent for Pb 2+ removal from wastewater.