Evaluación de la capacidad adsorbente de la cáscara de maní para la eliminación de cafeína y triclosán contenidos en agua mediante ensayos batch

Abstract

Currently, several pollutants have been found in water bodies, so alternatives for their removal have been sought. Bioadsorption has been shown as an easily accessible and inexpensive process. In this work, we studied the adsorption of peanut shells used to eliminate two emerging contaminants from synthetic waters: caffeine and triclosan. For this purpose, the chemical composition of the peanut residue was determined using ASTM standards. Its morphology and functional groups before and after adsorption were studied by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR), respectively. Batch adsorption tests were carried out with 30 mg/L caffeine and triclosan solutions. Three variables were considered: peanut shell particle granulometries, doses and contact time. Optimal adsorption conditions were determined by analysis of variance (ANOVA). The best granulometry of peanut shells was 125-150 µm for removing both contaminants. The optimal doses and contact times for caffeine and triclosan removal were 10 g/L for 180 min and 0.1 g/L for 45 min, respectively. The removal percentages were 85.6% for caffeine and 89.3% for triclosan. Pseudo-second order kinetic models were fitted for both contaminants, corresponding to a chemisorption process. The best-fitting adsorption model was that of Langmuir.