The fluoride content in groundwater varies depending on geological configuration. Fluoride problems tend to occur in places where these minerals are most abundant in rocks. The objective of the present work was to synthesize four biopolymers based on chitosan-polyvinyl alcohol (Ch-PVA) cross-linked with sodium tripolyphosphate pentabasic (TPP) and ethylene glycol diglycidyl ether (EGDE) and determine their ability to remove fluoride from water. The characterization of the Ch-PVA beads was performed by way of Scanning Electron Microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). The percentage of humidity and the point of zero charge were determined. The Ch-PVA beads showed a surface area of 63.87 m2 g−1, a pore size of 7.6 nm, a point of zero charge of 7.4, and 98.6% humidity. The kinetic adsorption study was adjusted to the pseudo-second-order model and the adsorption equilibrium data were adjusted to the Freundlich adsorption isotherm, showing a maximum fluoride adsorption capacity of 12.64 mg g−1 at pH 7 and 30 °C, for the beads of Ch-PVA-NaOH-TPP. According to the thermodynamic parameters: −∆G°, +∆H° and −∆S°, fluoride adsorption is spontaneous, endothermic in nature and there is no random energy change in the solid/liquid interface during the adsorption process.
Aim: The objective of this work was to determine the behavior of the trajectories of the air plots in two sites (San Mateo Atenco-(SM) and San Lorenzo Tepaltitlán-(SL)), in the atmosphere of the Metropolitan Zone of the Toluca Valley (MZTV). Methodology: In the atmosphere of the MZTV, using HYSPLIT a Backward trajectory direction analysis was performed from June 29 to July 8, 2021, considering for each day the summertime schedules of the center, indicating its Coordinated Universal Time (UTC). An ANOVA analysis (with a significance level of α=0.05) was performed for the concentrations of SM and SL obtained with PIXE, with the objective of seeing the equality of their behavior. Results: The behavior of the direction of the trajectories of the air plots in both sites is similar and the trajectories for the same day are the same in both sites but different on another day; It was determined that during night-day (19 to 12 h of the following day) the behavior is similar and changes during the remaining time, being variable. In general, the origin of the trajectories of the air plots for both sites of the MZTV is predominantly from the southeast, a situation that was confirmed with Wind Roses. Of the ANOVA analysis, the p-value was in all cases greater than the significance level of 0.05, the null hypothesis was accept, and it is possible to conclude that the elemental chemical composition of PM2.5 have equal means in both sites. Conclusion: Among other, it is possible to consider the behavior of meteorological parameters and thus take them into account for sampling studies of criteria pollutants such as PM2.5.
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