Aplicación de biochar obtenido por pirólisis de las cáscaras de camarón para la remoción de cromo contenido en soluciones acuosas

Abstract

Water pollution caused by hexavalent chromium, originating from effluents generated by chemical industries like tanneries, is a significant concern in our country. On the other hand, Ecuador stands out as one of the leading shrimp-exporting countries, producing large quantities of shrimp shells. It is estimated that this waste amounts to 11 million tons annually, generating an environmental problem. Both issues can be addressed simultaneously by utilizing shrimp shells to create an adsorbent that enables the removal of Cr (VI) from aqueous solutions. In this study, shrimp shells were employed to prepare three types of adsorbents: biochar at pyrolysis temperatures of 350, 500, and 600 °C, designated as BC350, BC500, and BC600 respectively. They underwent characterization through sieving analysis, BET, and infrared spectroscopy. For comparison in the adsorption process, Lolab activated carbon (CA), palm shell activated carbon (CAP), and untreated shrimp shells (CC) were used. The adsorption process was examined in both batch and fixed-bed column experiments. A chromium removal of 100% (within 100 minutes) was achieved when using BC600 during the batch adsorption tests. The BC600-Cr adsorption process correlated (correlation coefficient of 0.97) with pseudo first-order and pseudo second-order kinetic models, indicating that a complex adsorption process took place. As for equilibrium, the Langmuir model demonstrated a better fit, suggesting monolayer adsorption. Finally, it was found that fixed-bed tests (bed height of 20 cm) using BC600 biochar as adsorbents adjusted to the Wang model with a correlation coefficient of 0.95