Biosorption is the uptake of metals carried out by a complete biomass, through physicochemical mechanisms such as adsorption or ion exchange. It is a technology that allows to give a treatment and added value to agricultural waste that previously had no use. In this work, the biosorption process of Cd (II) and Pb (II) in aqueous solutions was evaluated using natural guava seeds (SN) and seeds modified with a cationic surfactant. To carry out the above, guava seeds were obtained from the waste of the industrial processing of said fruit; it was cleaned and ground to a particle size of 2mm and modified with a solution of hexadecyltrimethylammonium bromide (HDTMA-Br). Subsequently, batch-type adsorption experiments were carried out with aqueous solutions of cadmium and lead and both types of biosorbents (SN and SM). The adsorption equilibrium and kinetic parameters were determined, as well as the effects of adsorbent dose and pH. The experimental data were fitted to mathematical models, which describe the adsorption kinetics and isotherms. The characterization of the biosorbent materials was done by means of scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and measurement of the potential Z (PZ), in order to determine their morphology and the functional groups present in the material. , as well as the point of zero load. The results showed that the hydroxyl and carboxyl groups are involved in the adsorption process. The cadmium adsorption kinetics indicates that the equilibrium time was reached at 120 min, while for lead the equilibrium time was reached at 280 min with a removal of. Furthermore, the regeneration of the biosorbent was evaluated using nitric acid during 4 biosorption-desorption cycles. The thermodynamic parameters (?Go, ?Ho and ?So) showed that the adsorption of both metal ions was feasible and spontaneous, in addition to being an endothermic process for the Cd-SN system and exothermic for the Pb-SN system. In the case of SM, the adsorption process of Cd (II) and Pb (II) was exothermic. Based on the results obtained in this work, it was shown that guava seeds have the adsorption capacity of Cd (II) and Pb (II) ions and when modifying them with a cationic surfactant, functional groups are incorporated that increase said adsorption capacity.
La biosorción es la captación de metales que lleva a cabo una biomasa completa, a través de mecanismos fisicoquímicos como la adsorción o el intercambio iónico. Es una tecnología que permite darle un tratamiento y valor agregado a los desechos agrícolas que antes no tenían ninguna utilidad. En este trabajo, se evaluó el proceso de biosorción de Cd(II) y Pb(II) en disoluciones acuosas mediante semillas de guayaba natural (SN) y semillas modificada con un surfactante catiónico. Para llevar a cabo lo anterior, se obtuvieron las semillas de guayaba del desecho del procesamiento industrial de dicho fruto; se limpió y se molió hasta obtener un tamaño de partícula de 2mm y se modificó con una solución de bromuro de hexadeciltrimetilamonio (HDTMA-Br). Posteriormente, se realizaron experimentos de adsorción tipo lote con soluciones acuosas de cadmio y plomo y ambos tipos de biosorbentes (SN y SM). Se determinaron los parámetros cinéticos y de equilibrio de adsorción, así como los efectos de la dosis de adsorbente y el pH. Los datos experimentales se ajustaron a modelos matemáticos, que describen las cinéticas y las isotermas de adsorción. La caracterización de los materiales biosorbentes se hizo mediante microscopía electrónica de barrido (MEB), espectroscopía infrarrojo por transformada de fourier (FTIR) y medición del potencial Z (PZ), con el fin de determinar su morfología y los grupos funcionales presentes en el material, así como el punto de carga cero. Los resultados mostraron que los grupos hidroxilo y carboxilo están involucrados en el proceso de adsorción. La cinética de adsorción de cadmio indica que el tiempo de equilibrio se alcanzó a los 120 min, mientras que para plomo se alcanzó el tiempo de equilibrio a los 280 min con una remoción de. Además, se evaluó la regeneración del biosorbente utilizando ácido nítrico durante 4 ciclos de biosorción-desorción.
