VII Simposio Internacional de Química 2019 "SIQ 2019" -IV Simposio Internacional "Seguridad Tecnológica y Ambiental"

VII Simposio Internacional de Química 2019

SIQ 2019

ADSORPTION OF AN ORGANOCHLORINATED PESTICIDE ON A FUNCTIONALIZED ACTIVATED CARBON: EXPERIMENTAL AND THEORETICAL STUDY

Resumen [ES]

In this work, the adsorption of chlordecone (CLD) on activated carbons prepared from sugar cane bagasse is evaluated and a theoretical study is done, aiming to understand the mechanism of CLD adsorption on the acidic AC surface. First, a physic-chemical characterization of the ACs were evaluated by thermal desorption, X-ray photoelectron and Boehm studies. Adsorption isotherms of CLD show that the adsorption capacity increases with the amount of carbon and by the presence of acidic groups (SGs) at the AC surface of chemically activated carbons. These results are in agreement with theoretical findings, where for deprotonated carboxyl and hydroxyl modifications of the AC model, significant associations with CLD suggest a chemical sorption at slightly acidic and neutral pH conditions. However, under acidic conditions (pH < 5) a non-dependence of the association energy with the SGs composition is observed. At basic pH conditions the interactions between the chlordecone hydrate (CLDh) and SGs onto AC are governed by dispersive interactions of chlorine atoms of CLD with the graphitic surface and by electrostatic interactions of CLDh with COO- and O- groups and water molecules. These results are confirmed by a Temperature-Programmed Desorption study, showing that CLD molecules are associated with carboxylic groups of the AC surface. As results, the best conditions for the adsorption of the CLD on AC with SGs are in the pH range between 5 and 9, as confirmed by the theoretical and the experimental results. An increase in carboxylic SGs content is proposed to enhance CLD adsorption onto AC.

Resumen [EN]

In this work, the adsorption of chlordecone (CLD) on activated carbons prepared from sugar cane bagasse is evaluated and a theoretical study is done, aiming to understand the mechanism of CLD adsorption on the acidic AC surface. First, a physic-chemical characterization of the ACs were evaluated by thermal desorption, X-ray photoelectron and Boehm studies. Adsorption isotherms of CLD show that the adsorption capacity increases with the amount of carbon and by the presence of acidic groups (SGs) at the AC surface of chemically activated carbons. These results are in agreement with theoretical findings, where for deprotonated carboxyl and hydroxyl modifications of the AC model, significant associations with CLD suggest a chemical sorption at slightly acidic and neutral pH conditions. However, under acidic conditions (pH < 5) a non-dependence of the association energy with the SGs composition is observed. At basic pH conditions the interactions between the chlordecone hydrate (CLDh) and SGs onto AC are governed by dispersive interactions of chlorine atoms of CLD with the graphitic surface and by electrostatic interactions of CLDh with COO- and O- groups and water molecules. These results are confirmed by a Temperature-Programmed Desorption study, showing that CLD molecules are associated with carboxylic groups of the AC surface. As results, the best conditions for the adsorption of the CLD on AC with SGs are in the pH range between 5 and 9, as confirmed by the theoretical and the experimental results. An increase in carboxylic SGs content is proposed to enhance CLD adsorption onto AC.

Sobre el ponente

Kenia Melchor Rodríguez

MsC. Kenia Melchor Rodríguez

InSTEC Flag of Cuba
Información Práctica
English (US)
No definido
30 minutos
No definido
Autores
MsC. Kenia Melchor Rodríguez
Anthuan Ferino Pérez
Dr. C. Sarra Gaspard
Msc. Juan J. Gamboa Carballo
Naddy Passe Coutrin
Dr. C. Axell Durimel
Ulises J. Jáuregui Haza
Palabras clave
chlordecone
functionalized activated carbon
molecular modelling
pesticide remotion