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The study of the interaction between graphene oxide (GO) and arsenic is of great relevance not only in the design of adsorbent materials to remove this contaminant but also in the understanding of its combined nanotoxicity. In this work, we show that As(III) adsorption, primarily H 3 AsO 3 , by graphene oxide is affected by its degree of oxidation. Three types of GO with C/O ratios between 1.35 and 1.98 were produced, resulting in important variations in the concentration of COH and COC functional groups. The less oxidized material reached a maximum As(III) adsorption capacity of 123 mg/g, whereas the GO with the highest degree of oxidation reached a value of 288 mg/g at pH 7, the highest reported in the literature. We also show that sulfates and carbonates present in water strongly inhibit As(III) adsorption. The interaction between graphene oxide and As(III) was also studied by Density Functional Theory (DFT) computer models showing that graphene oxide interacts with As(III) primarily through hydrogen bonds, having interaction energies with the hydroxyl and epoxide groups of 1508.6 and 1583.6 kJ/mol, respectively. Finally, cytotoxicity tests showed that the graphene oxide maintained cellular viability of 57% with 50 μg/ml, regardless of its degree of oxidation., (Copyright © 2019 Elsevier B.V. All rights reserved.)

In this work, we describe a methodology for developing a mathematical model based on infrared (IR) detection to determine the moisture content (M) in solid samples. For this purpose, an experimental setup was designed, developed and calibrated against the gravimetric method. The experimental arrangement allowed for the simultaneous measurement of M and the electromotive force (EMF), fitting the experimental variables as much as possible. These variables were correlated by a mathematical model, and the obtained correlation was M=1.12×exp(3.47×EMF), ±2.54%. This finding suggests that it is feasible to measure the moisture content when it has greater values than 2.54%. The proposed methodology could be used for different conditions of temperature, relative humidity and drying rates to evaluate the influence of these variables on the amount of energy received by the IR detector., (Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.)