The adsorption of benzotriazole (BTA) on copper surfaces in 0.001, 0.005 and 0.01 M concentrations of sulphuric acid was investigated using gravimetric measurements. BTA was tested in concentrations from 1x10 to 1x10 M at temperatures from 298 to 328 K. The adsorption mechanism is discussed in terms of applicability of the conventional Frumkin, Bockris-Swinkels and Kastening-Holleck isotherms, among others. The best fit was obtained using the Frumkin isotherm model. The projected molecular area of BTA was calculated to elucidate inhibitor orientation in the adsorption process. KeywordsCopper. Sulphuric acid. Benzotriazole. Adsorption isotherm. Objective function. Projected molecular areaPendiente de la isoterma. Un criterio para estudiar el mecanismo de adsorción del benzotriazol sobre el cobre en ácido sulfúrico ResumenEn el presente trabajo se estudia la adsorción del benzotriazol (BTA) sobre el cobre en solución de ácido sulfúrico con concentraciones de 0,001, 0,005 y 0,01 M utilizando medidas gravimétricas. La concentración de BTA ensayada varió de 1x10'^ M a 1x10'^ M y la temperatura de 298 K a 328 K. El mecanismo de adsorción se analiza en términos de la aplicabilidad de las isotermas convencionales de Frumkin, Bockris-Swinkels y KasteningHoUeck, entre otras. La mejor descripción de los resultados se obtuvo utilizando la isoterma de Frumkin. Para analizar la orientación del BTA en el proceso de adsorción sobre el cobre, se calculó la superficie de la molécula de BTA. Palabras claveCobre. Acido sulfúrico. Benzotriazol. Isoterma de adsorción. Función objetivo. Área molecular proyectada.

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The rice process generates a large amount of husk, which can become an environmental contaminant if it does not receive an adequate management. Because rice husk is a natural source of silica, in this work silica nanoparticles were obtained as an alternative use for this residue. The synthesis was carried out with the incineration, acid leaching process, and particle size reduction through high-energy mechanical ball milling. For its characterization, thermal, chemical, morphological, structural and superficial area analyses were performed with thermogravimetric analysis, X-ray fluorescence method, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Nitrogen adsorption/desorption isotherm techniques. The results indicated that between 150-450°C the organic material of the rice husk was released, and above 550°C was obtained ash rich in silica. The silica purity was effectively increased to 98.48%, through acid leaching with acid nitric. The reduction of particle size by mechanical milling at 600 rpm for 3 h was achieved up to nanometer size. Most of the nanoparticles were spherical with a diameter between 14 and 28 nm. Silicon oxide was the principal structural phase of the nanoparticles corroborated by the broad peak corresponding to the (101) plane shown by XRD pattern. A substantial increase of two magnitude orders of the specific surface area of nanoparticles was reached in comparison with particles without milling. The nanosilica particles obtained from rice husk can be used for the production of high-performance silicon or they can be also used as supplementary cementitious materials.

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