Synthesis and characterization of CDs/Al2O3 nanofibers nanocomposite for Pb2+ ions adsorption and reuse for latent fingerprint detection

This study reports a new approach of preparation of carbon dots coated on aluminum oxide nanofibers (CDs/Al(2)O(3)NFs) nanocomposite and reusing the spent adsorbent of lead (Pb2+) ions loaded adsorbent (Pb2+-CDs/Al(2)O(3)NFs) nanocomposite for latent fingerprint detection (LFP) after removing Pb2+ ions from aqueous solution. CDs/Al(2)O(3)NFs nanocomposite was prepared by using CDs and Al2O3 NFs with adsorption processes. The prepared nanocomposite was then characterized by using UV-visible spectroscopy (UV-visible), Fourier transforms infrared spectroscopy (FTIR), Fluorescence, X-ray diffraction pattern (XRD), scanning electron microscope (SEM), Transmission electron microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDS), Zeta potential, X-ray photoelectron spectroscopy (XPS). The average size of the CDs was 51.18 nm. The synthesized CDs/Al(2)O(3)NFs nanocomposite has proven to be a good adsorbent for Pb2+ ions removal from water with optimum pH 6, dosage 0. 2 g/L. The results were best described by the Freundlich Isotherm model. The adsorption capacity of CDs/Al(2)O(3)NFs nanocomposite showed the best removal of Pb2+ ions with q(m) = (177. 83 mg/g), when compared to the previous reports. This adsorption followed the pseudo-second order kinetic model. Delta G and Delta H values indicated spontaneity and the endothermic nature of the adsorption process. CDs/Al(2)O(3)NFs nanocomposite therefore showed potential as an effective adsorbent. The data were observed from adsorption-desorption after 6 cycles which showed good adsorption stability and re-usability of CDs/Al(2)O(3)NFs nanocomposite. Furthermore, the spent adsorbent of Pb2+-CDs/Al(2)O(3)NFs nanocomposite has proven to be sensitive and selective for LFP detection on various porous substrates. Hence Pb2+-CDs/Al(2)O(3)NFs nanocomposite can be reused as a good fingerprint labelling agent in LFP detection so as to avoid secondary environmental pollution by disposal of the spent adsorbent. (C) 2020 The Author(s). Published by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).