Many adsorbent materials are now commercially available; however, studies have focused on modifying them to enhance their properties. In this study, an activated carbon (AC) and hydroxyapatite (HAp) composite was synthesized by the immersion of ACs in a simulated body fluid solution, varying the AC oxidation degree along with the addition of CaSiO₃. The resulting composites were characterized by ash %, X-ray fluorescence (XRF), Fourier-transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and point of zero charge (PZC). The characterization results indicated that the addition of CaSiO₃ and the oxygenated functional groups in the AC surface are key factors for HAp growth. The composites were tested on methylene blue (MB) adsorption as a potential application for the synthesized materials. Adsorption isotherms were modeled with Langmuir and Freundlich isotherms, and the composites were fitted to a Langmuir model with the highest q_max value of 9.82. The kinetic results indicated that for the pseudo-second-order model, the composites fitted, with a contact time of 180 min to remove a 95.61% average of the MB. The results indicate that composite materials can be an efficient adsorbent for the removal of MB from aqueous solutions at low concentrations since the material with the highest amount of HAp growth removed 99.8% of the MB in 180 min.

In this study, carbon nanostructures were synthesized utilizing a warm plasma jet at atmospheric pressure in a continuous and catalyst-free process. The procedure and apparatus were designed and constructed in our laboratory. Plasma was generated with 600 W of electrical energy, using a high-voltage, high-frequency alternating current power source. The working gas utilized was a propane/butane mixture, with a concentration ratio of 60:40, respectively. A production rate of 300 mg min⁻¹ of powdered material was achieved, with a particle size between 20 and 100 nm. The product was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, Raman spectroscopy, x-ray diffraction, and transmission electron microscopy. Results show the formation of multilayer carbon nanostructures with a low content of functional groups; the obtained material presented structural defects and amorphous carbon. This work demonstrates that, with adequate control, warm plasma jet discharges can be employed for the synthesis of carbon nanostructures. The process is scalable and can be utilized for hydrocarbon reforming and hydrogen production. However, further studies are needed to improve the quality of the nanostructures and process efficiency. The synthesized material can potentially be used in gas adsorption or in the manufacture of polymeric nanocomposites with enhanced thermal, electrical, and mechanical properties.

En este estudio se desarrollaron y caracterizaron sistemas híbridos a base de poliácido láctico (PLA), óxido de grafeno (GO) y montmorillonita (MMT) con el propósito de mejorar su estabilidad térmica y comportamiento frente a la flama. Los nanocompuestos fueron obtenidos mediante mezclado por fusión y posteriormente moldeados por compresión. La caracterización térmica mediante análisis termogravimétrico (TGA) mostró un incremento significativo en la temperatura de degradación inicial y en el rendimiento de carbón residual respecto al PLA puro, evidenciando una mayor estabilidad térmica y resistencia a la descomposición térmica. Las pruebas de calorimetría de cono revelaron una reducción notable en la tasa máxima de liberación de calor (HRR) y en la liberación total de calor (THR), indicando un efecto sinérgico entre GO y MMT en la formación de una capa carbonosa protectora. El análisis morfológico por microscopía electrónica de barrido (SEM) confirmó una dispersión homogénea de los nanorrellenos y la formación de una estructura carbonosa densa y continua tras la combustión, la cual actúa como barrera térmica y de masa. En conjunto, los resultados demuestran que la incorporación simultánea de GO y MMT en la matriz de PLA mejora sustancialmente la estabilidad térmica y la retardancia a la flama, proponiendo un enfoque sostenible para el desarrollo de biopolímeros con propiedades ignífugas avanzadas.