CQTDs/SiO₂NPs nanocomposite for Pb²⁺ and Cd²⁺ remediation and reuse applications in LFP detection and photocatalysis

Due to their propensity to bioaccumulate, lead and cadmium, two hazardous heavy metals, can seriously disrupt the ecosystem. These metals have the potential to cause major environmental and human health problems. Herein, carbon quantum dots were used to coat silica nanoparticles to create a brand-new nanocomposite called CQTDs/SiO₂NPs. Cd²⁺ and Pb²⁺ ions were effectively removed from water and preconcentrated using the produced nanocomposite. The novel nanocomposite was characterized using SEM, TEM, FT-IR, XRD, and XRF. The bending vibration of Si–O–Si/Si–O–C and Si–OH are responsible for the FT-IR bands that were detected in the nanocomposite at 1041 and 954 cm⁻¹, respectively. XRD demonstrated that the silica nanoparticles were amorphous. Additionally, SEM and TEM analysis revealed the nanocomposite's shape, which was determined to be spherical with minimal agglomeration.While XPS demonstrated the binding energy of the functional group present in the composite and further confirmed the metal loaded onto the adsorbent. On CQTDs/SiO₂NPs nanocomposite, the optimum pH and dosage were 8 and 0.2 g respectively. The highest Cd²⁺ and Pb²⁺ ion adsorption capabilities are 14.87 and 38.49 mg g ⁻¹, respectively. The use of the nanocomposite resulted in an exothermic, physical and non-spontaneous adsorption that closely resembled the Langmuir equilibrium isotherm and the second-order kinetics. The metal loaded adsorbent used as a fingerprint labelling agent displayed clear fingerprint ridges and degraded the sulfamethoxazole (SMX) for up to 90 %. The prepared composite has proven to be coherent in heavy metal removal and can thus be reused in Latent fingerprint and photocatalysis applications. The reuse of the nanocomposite in the above-mentioned applications is an alternative solution to avoid secondary pollution.