title: Theoretical study of chlordecone and surface groups interaction in an activated carbon model under acidic and neutral conditions.
abstract: Activated carbons (ACs) are widely used in the purification of drinking water without almost any knowledge about the adsorption mechanisms of the persistent organic pollutants. Chlordecone (CLD, Kepone) is an organochlorinated synthetic compound that has been used mainly as agricultural insecticide. CLD has been identified and listed as a persistent organic pollutant by the Stockholm Convention. The selection of the best suited AC for this type of contaminants is mainly an empirical and costly process. A theoretical study of the influence of AC surface groups (SGs) on CLD adsorption is done in order to help understanding the process. This may provide a first selection criteria for the preparation of AC with suitable surface properties. A model of AC consisting of a seven membered ring graphene sheet (coronene) with a functional group on the edge was used to evaluate the influence of the SGs over the adsorption. Multiple Minima Hypersurface methodology (MMH) coupled with PM7 semiempirical Hamiltonian was employed in order to study the interactions of the chlordecone with SGs (hydroxyl and carboxyl) at acidic and neutral pH and different hydration conditions. Selected structures were re-optimized using CAM-B3LYP to achieve a well-defined electron density to characterize the interactions by the Quantum Theory of Atoms in Molecules approach. The deprotonated form of surface carboxyl and hydroxyl groups of AC models show the strongest interactions, suggesting a chemical adsorption. An increase in carboxylic SGs content is proposed to enhance CLD adsorption onto AC at neutral pH conditions.
authors.affiliation: Instituto Superior de Tecnologías y Ciencias Aplicadas, A.P. 6163, La Habana, Cuba. Electronic address: rqjjg@instec.cu.
authors.forename: Juan José
authors.initials: JJ
authors.lastname: Gamboa-Carballo
authors.affiliation: Instituto Superior de Tecnologías y Ciencias Aplicadas, A.P. 6163, La Habana, Cuba. Electronic address: keniamr@instec.cu.
authors.forename: Kenia
authors.initials: K
authors.lastname: Melchor-Rodríguez
authors.affiliation: Instituto Superior de Tecnologías y Ciencias Aplicadas, A.P. 6163, La Habana, Cuba. Electronic address: danielhv@instec.cu.
authors.forename: Daniel
authors.initials: D
authors.lastname: Hernández-Valdés
authors.affiliation: Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4 Canada. Electronic address: carlos.enriquezvicto@ucalgary.ca.
authors.forename: Carlos
authors.initials: C
authors.lastname: Enriquez-Victorero
authors.affiliation: Laboratorio de Química Computacional y Teórica, Facultad de Química, Universidad de La Habana, 10400 La Habana, Cuba; Departamento de Física, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, 780-0003 Ñuñoa, Santiago, Chile. Electronic address: analilian.montero@gmail.com.
authors.forename: Ana Lilian
authors.initials: AL
authors.lastname: Montero-Alejo
authors.affiliation: Laboratoire COVACHIM M2E, EA 3592, Université des Antilles et de la Guyane, BP 250, 97157 Pointe à Pitre Cedex, Guadeloupe. Electronic address: sgaspard@univ-ag.fr.
authors.forename: Sarra
authors.initials: S
authors.lastname: Gaspard
authors.affiliation: Instituto Superior de Tecnologías y Ciencias Aplicadas, A.P. 6163, La Habana, Cuba. Electronic address: ulises.jauregui@infomed.sld.cu.
authors.forename: Ulises Javier
authors.initials: UJ
authors.lastname: Jáuregui-Haza
mesh_terms: D000327:Adsorption; D002606:Charcoal / Q000737:chemistry*; D007631:Chlordecone / Q000302:isolation & purification*; D004583:Electrons; D005618:Fresh Water / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D011083:Polycyclic Compounds / Q000737:chemistry*; D011789:Quantum Theory; D013499:Surface Properties; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*; D018508:Water Purification / Q000379:methods
chemical_list: D011083:Polycyclic Compounds; D014874:Water Pollutants, Chemical; D002606:Charcoal; C012256:coronene; D007631:Chlordecone
keywords: Activated carbon; Chlordecone; DFT; MMH; QTAIM; Surface groups