Nature gives us a large number of compounds with interesting biological properties, within them we have essential oils, which are an important source of new bioactive molecules, which can replace synthetic chemicals, since they are friendly to the environment and they are less toxic. Currently there are more than 20.000 publications in which essential oils are related to some biological activity, according to the search made in different databases until January 2018. This confirms the wide utility of essential oils as the main source of bioactive metabolites, which can be used in different areas of our life.

Chromium (Cr(VI)) presents carcinogenic and mutagenic effects in living beings. Biosorption is an alternative to conventional technologies for the treatment of waste water. The aim of this study was to assess the use of corncob and orange peels modified with citric acid and calcium chloride, respectively, for the removal of Cr(VI) using a batch system taking into account pH and particle size. Biomaterial were characterized using an elemental and chemical analysis, and FTIR, in which was evidenced the presence of hydroxyl, carbonyl and carboxyl groups, belonging to the cellulose and lignin that are attributed for the presence of active centers which intervene in the adsorption process. Adsorption experiments through batch system were performed using a solution of potassium dichromate at 100 ppm, 150 rpm, varying pH (2, 3, 4 and 6) and particle size (0.355, 0.5 and 1 mm). From de results was found that maximum removal percentage was obtained at pH 2 and particle size of 0.355 using corncob and orange peels. Final concentration of Cr(VI) was determined by using the standard method ASTM D1687-02 with 1,5-diphenylcarbazide at 540 nm. Adsorption kinetics and isotherms were assessed with the best conditions found, in which the experimental data was adjusted to the Pseudo-second order and Freundlich models, respectively. R2 value greater than 0.95 suggests that the process is controlled by a chemical reaction leading the formation of multilayers. The performance of the biomass in terms of q0 was found to be: corncob>orange peels>corncob modified>orange peels modified.

In this work was studied the effect of sulfonation of styrene-acrylic ester and of titanium dioxide nanoparticles on the proton exchange membranes. It was evaluated the physicochemical characterization of membranes, such as, the water uptake capacity, ion exchange capacity, the mechanic properties of stress/strain, and the chemical functional groups present in the membrane structure by FTIR analysis. Water uptake increases with increasing the time of sulfonation reaction, reaching 60.9% after 8 hours of sulfonation; while, ion exchange capacity of loaded-sulfonated membrane increases with increasing the time of sulfonation reaction and with increasing the TiO 2 load, reaching 0.39 meq/g for 8 hours and 4% TiO 2. It was observed that the elasticity of the synthesized membranes increases with increasing the time of sulfonation reaction, and it decreases with the addition of the TiO 2 load. This physicochemical property set allows to consider the membrane with high potential of application in the fuel cells area.

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