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This article reports on the preparation of iron nanoparticles (FeNPs) supported in chitosan beads (Chi-EDGE-Fe) for removing aldrin from aqueous solutions. The FeNPs and Chi-EDGE-Fe beads were characterized by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), and the Mössbauer spectroscopy (MS) techniques. TEM, XRD, and MS showed that the FeNPs had core-shell structures consisting of a core of either Fe0 or Fe2B and a shell of magnetite. Furthermore, SEM images showed that Chi-EDGE-Fe beads were spherical with irregular surfaces and certain degrees of roughness and porosity, whilst the sorbent mean pore size was 204 nm, and the occluded iron nanoparticles in the chitosan material had diameters of 70 nm and formed agglomerates. The sorbent beads consisted of carbon, oxygen, chlorine, aluminum, silicon, and iron according to the SEM-EDS analysis. Functional groups such as O-H, C-H, -CH2, N-H, C-O, C-OH, and Fe-OH were detected in the FTIR spectra. In addition, a characteristic band appeared at about 1700 cm−1 after the sorption process involving aldrin. MS also showed that the iron nanoparticles in the beads probably oxidized into NPs of α-Fe2O3 as a result of the supporting process. The isotherm of the aldrin removal followed the Langmuir–Freundlich model and presented a maximum adsorption capacity of 74.84 mg/g, demonstrating that chitosan-Fe beads are promising sorbents for the removal of toxic pollutants in aqueous solutions.

This research presents a study of environmental monitoring at different sampling sites from the Metropolitan Area of the Valley of Toluca (MAVT), Mexico, using mosses (Leskea angustata (Tayl.) and Fabronia ciliaris (Brid.)) and soil samples. The epiphytic mosses and soils were sampled in two campaigns within two periods of the year, a rainy and dry-cold season. The selected sampling sites included urban regions (UR), transitional regions (TR), and protected natural areas (PA). The samples were analyzed by the Instrumental Neutron Activation Analysis (INAA) to determine As, Cr, Hg, and Se principally. However, due to the versatility of the analytic technique used, other elements including Cs, Co, Sc, Sb, Rb, Ce, La, Eu, and Yb were also detected. Statistical analysis (As, Cr, Hg, and Se) was carried out with principal components and cluster analysis methods; this revealed that a good correlation exists between metal content in mosses and the degree of pollution in the areas sampled. The obtained results in mosses showed that the concentrations of As, Cr, Co, Cs, Rb, Ce, La, and Yb increased with respect to the concentrations obtained during the first sampling, whereas Se, Sc, Sb and Eu, concentrations were decreased. For As and Hg, the concentrations were similar in both sampling periods. The soil samples present the most significant concentration.