Cd²⁺ ion adsorption and re-use of spent adsorbent with N-doped carbon nanoparticles coated on cerium oxide nanorods nanocomposite for fingerprint detection

This work provides a novel approach to prepare nitrogen-doped carbon nanoparticles (CNPs) coated on a cerium oxide nanorods nanocomposite (N-CNPs/CeO₂NRsnC) for the uptake of cadmium (Cd²⁺) ions and re-using the spent adsorbent, Cd²⁺-CNPs/CeO₂NRsnC for latent fingerprint detection (LFP). N-CNPs were prepared by a thermal method with urea and cabbage powder as precursors. N-CNPs/CeO₂NRsnC was developed with N-CNPs and CeO₂NRs with a hydrothermal method and characterized by various instrument methods like UV-visible, FT-IR, XRD, BET, XPS, SEM, and TEM. The N-CNPs/CeO₂NRsnC had a greater surface area (9.96 m²/g) than N-CNPs (0.64 m²/g). The synthesized N-CNPs/CeO₂NRsnC proved to be a good sorbent material to remove Cd²⁺ from water at a maximum pH 8 and dosage 10 mg/L. The adsorption was spontaneous and endothermic at 25 ºC. In addition, Cd²⁺-N-CNPs/CeO₂NRsnC has been shown to be sensitive and selective for LFP identification on several porous substrates. It is therefore a good labeling agent for latent fingerprint identification in forensic science.