Spatial distribution, environmental risks, and sources of potentially toxic elements in soils from a typical abandoned antimony smelting site.

The rapid development of the smelting industry increases the release of antimony (Sb) into the soil environment, which threatens human health and ecosystems. A total of 87 samples were collected from an abandoned Sb smelting site to evaluate pollution characteristics and environmental risks of the potentially toxic elements (PTEs). The contents of As, Cu, Ni, Pb, Sb, and Zn in the fresh soils determined by P-XRF were 131, 120, 60, 145, 240, and 154 mg/kg, respectively, whilst following drying, grinding, and sieving pretreatments, the corresponding contents increased to 367, 179, 145, 295, 479, and 276 mg/kg, respectively. There was a significant correlation between the data obtained by P-XRF and ICP-OES in the treated samples, which showed the application feasibility of P-XRF. The average contents of Sb and As were 440.6 and 411.6 mg/kg, respectively, which exceeded the control values of the development land in GB 36600-2018. The ecological risk levels of the six PTEs decreased in the following order: As > Sb > Pb > Zn > Ni > Cu. Non-carcinogenic risk revealed that As, Pb, and Sb posed health risks for children, whilst for carcinogenic risk, the risk values for As and Ni were higher than the limit values for both children and adults. Anthropogenic sources accounted for more than 70.0% of As, Pb, and Sb concentrations in soils, indicating a significant influence on PTEs accumulation. The findings provide a basis for quick determination of the contamination characteristics and risk control of PTEs at Sb smelting sites.

The difference in the adsorption mechanisms of magnetic ferrites modified carbon nanotubes.

Various ferrites modified carbon nanotubes (MFe2O4/CNTs; M = Co, Cu, Mn) were synthesized and characterized using TEM-EDS, FTIR, BET, TG-DTA, VSM, and XRD. MFe2O4/CNTs were used as adsorbents for removing ciprofloxacin (CIP), and the adsorption mechanism was revealed in a comparative manner based on the experimental results and density functional theory calculations. The adsorption capacities of CIP on MFe2O4/CNTs were 63.32 (Co), 61.60 (Cu), and 46.35 (Mn) mg/g, respectively. Different M components of MFe2O4 affected the adsorption behavior of CIP on them, while the specific surface area and total pore volume showed no significant impact. The investigation on the adsorption energy and the bond formation indicated that CIP was more favorably captured by CoFe2O4/CuFe2O4 than MnFe2O4. The local density of states of metal atoms and O atoms (from the ketone or carboxyl groups of CIP) showed that the d-band centers of Co and Cu atoms were above the Fermi level, while that of Mn was below the Fermi level, providing the fundamental understanding of the promoted O adsorption on CoFe2O4 and CuFe2O4 and restrained adsorption on MnFe2O4. This observation was supported by the electron localization function in terms of the stronger charge density overlap between Co-O/Cu-O than that of Mn-O.