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Ultrasound energy is a green and economically viable alternative to conventional techniques for surface modification of materials. The main benefits of this technique are the decrease of processing time and the amount of energy used. In this work, graphene nanoplatelets were treated with organic acids under ultrasonic radiation of 350 W at different times (30 and 60 min) aiming to modify their surface with functional acid groups and to improve the adsorption of uremic toxins. The modified graphene nanoplatelets were characterized by Fourier transform infrared spectroscopy (FT–IR), thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS). The optimum time for modification with organic acids was 30 min. The modified nanoplatelets were tested as adsorbent material for uremic toxins using the equilibrium isotherms where the adsorption isotherm of urea was adjusted for the Langmuir model. From the solution, 75% of uremic toxins were removed and absorbed by the modified nanoplatelets.

In the present work, multiple-wall carbon nanotubes (MWCNTs) were surface modified in an environmentally friendly way, using low-frequency ultrasonic energy. This type of modification was carried-out using two different types of organic acids, citric acid (CA) and oxalic acid (OA). The modification of the MWCNTs was confirmed by Fourier-transform infrared spectroscopy (FTIR), where functional groups such as OH, C=O, O–C=O and COOH were detected. By means of Raman spectroscopy, an increase in carbon surface defects was found. On the other hand, using X-ray photoelectron spectroscopy (XPS), oxidation was evidenced on the surface of the modified MWCNT. In both Raman spectroscopy and XPS, the results indicate a greater modification when CA is used, possibly due to the fact that CA has a larger number of functional groups. MWCNT-CA showed good dispersion in methanol, while MWCNT-OA showed good stability in methanol and ethanol. Finally, a 20% removal of creatinine efficiency improvement was found with respect to the unmodified MWCNTs, while no improvement was found in the case of urea and uric acid.

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Entre los diferentes materiales cerámicos, el dióxido de zirconio (ZrO2) se destaca, debido a sus aplicaciones en el área médica, química y farmacéutica. Esto es posible al ser un material de carácter anfótero, con tres fases cristalinas: monoclínica, tetragonal y cúbica, las cuales presentan distintas propiedades. El objetivo de este trabajo fue analizar los fundamentos de los diferentes métodos utilizados para la síntesis del ZrO2 y sus aplicaciones biomédicas. Las principales metodologías empleadas son los procesos hidrotérmico, precipitación, solvotérmica y sol-gel. La energía de ultrasonido y la radiación de microondas permiten reducir los tiempos de reacción y proporcionar mayor eficiencia energética a los procesos. El método de síntesis modifica las propiedades del ZrO2, lo cual es aprovechado para desarrollar diferentes aplicaciones, entre ellas destacan reemplazos óseos, prótesis dentales y liberación de fármacos.