Environmental and toxicological assessment of nanodiamond-like materials derived from carbonaceous aerosols

Carbonaceous aerosols (CAs) are ubiquitous and among the most significant environmental materials found in ambient air, mainly derived from anthropogenic sources (biomass burning, industrial activity, vehicle emissions, etc.). Elemental carbon (black carbon) and organic carbons are the major constituents of CAs. Due to their toxic effects, they are considered as high-risk compounds for human health. The key objective of the present work is to conduct a feasibility study for the conversion of CAs (TSP and PM₁₀) into a value-added carbon nanostructured product by using a chemical method. High resolution-transmission electron microscopy (HR-TEM), X-ray diffraction (XRD), Raman spectroscopy, Fourier transforms infrared spectroscopy (FT-IR), X-ray photoelectron spectrometer (XPS), ultraviolet-visible spectroscopy (UV-visible), fluorescence spectroscopy (FL), and Zeta potential analyses indicated the formation of carbon nanomaterials with crystalline phases, which exhibit the characteristics of nanodiamonds (NDs). The HR-TEM image analysis showed that the nominal size of the CAs-derived NDs ranged from 4 to 17 nm composed of mainly carbon and oxygen. The FT-IR and XPS analysis indicated that the NDs are highly functionalized with an oxygen-containing functional group. The CAs-derived NDs showed the property of blue-fluorescence with excitation dependent. In the cytotoxicity and genotoxicity study, the NDs obtained was observed to be biocompatible and suitable for bioimaging applications. This result provides a new avenue for the conversion of CAs to high-value products leading to the mitigation of atmospheric pollution.