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The application of Sb, Pt and Hg in the development of new strategic technologies has increased significantly in recent years. This study evaluates the impact of vehicular traffic on the rise in emission of Sb, Pt and Hg in the atmospheric environmen of Mexico City and their correlation to Co, Cr, Cu, Ni, Pb, V and Zn. Ficus benjamina leaves were collected as biomonitor of atmospheric metals deposited in areas exposed to heavy vehicular traffic. High enrichment factor values (metal(loid) concentration/background values) were calculated: 146 (Sb), 52.8 (Pb), 29.7 (Pt) and 25.1 (Cr). Enrichment factors of Ni, Zn, Co, V, Cu and Hg decrease in that order and are

Platinum (Pt) concentrations in PM2.5 were evaluated by means of inductively coupled plasma mass spectrometry (ICP-MS) to evaluate the spatial and temporal behavior and to assess trends. Samples we...

In this study, atmospheric mercury concentration in airborne particulate matter with an aerodynamic diameter ≤ 2.5 µm (PM2.5) was analyzed by ICP-MS. Samples were collected in the Mexico City Metropolitan Area (MCMA), during 2013, in five locations, Northwest, Northeast (NE), Central, Southwest and Southeast, along three seasons: dry warm, rainy, and dry cold (DC). It can be observed that NE shows the highest mercury concentration (p

The goal of this study was to optimize methyl parathion (O,O-dimethyl-O-4-p-nitrophenyl phosphorothioate) degradation using a strain of Escherichia coli DH5α expressing the opd gene. Our results indicate that this strain had lower enzymatic activity compared to the Flavobacterium sp. ATCC 27551 strain from which the opd gene was derived. Both strains were assessed for their ability to degrade methyl parathion (MP) in a mineral salt medium with or without the addition of glucose either as suspended cells or immobilized on tezontle, a volcanic rock. MP was degraded by both strains with similar efficiencies, but immobilized cells degraded MP more efficiently than cells in suspension. However, the viability of E. coli cells was much higher than that of the Flavobacterium sp. We confirmed the decrease in toxicity from the treated effluents through acetylcholinesterase activity tests, indicating the potential of this method for the treatment of solutions containing MP.

Nowadays, hydrogen has a preponderant position among the potentially sustainable energy sources. Due to its power density, its storage is of main concern when considering a broad use in practical applications. Carbon nanotubes constitute promising candidates for the design and construction of hydrogen storage devices. This work explores the use of some procedures involving electrochemistry, aimed to bond atomic Ti on the outer surface of MWNTs. Each titanium atom has the potential of hosting two hydrogen molecules and relinquishing them by heating. Nevertheless, nanotubes are difficult to handle due to electrostatic charge and agglomeration, and in this context, two routes were tested as procedures to spread and stick nanotubes on an electrode: (1) a functionalization capable of attaching gold was tested in two forms, as either using 4 nm particles or a flat gold electrode. The fixation of Au particles was confirmed by HRTEM. (2) A simpler route that consisted on drying a CH2Cl2/nanotubes solution previously spread on a glassy carbon flat electrode. CH2Cl2was selected as the medium and TiCl4as the precursor for attaching atomic Ti to the nanotubes. The results revealed that hydrogen adsorption, estimated from voltamperometry, was five times higher on Ti-MWNTs than on bare nanotubes.