Interaction of paracetamol and 125I-paracetamol with surface groups of activated carbon: theoretical and experimental study

Abstract

The selection of activated carbon (AC) filters for water decontamination is currently carried out empirically. The low concentrations of drugs in the environment make the radioisotope labeling a valuable tool for physical and chemical studies of the adsorption process. A theoretical study of paracetamol and 125 I-paracetamol adsorption onto AC was performed to evaluate the interactions between pollutants and surface groups (SG) of AC. Paracetamol was labeled with 125 I and adsorption isotherms were obtained using radioanalytical and spectrophotometric techniques. The radioanalytical method overestimates the paracetamol adsorption. The validity of the chosen approach for qualitative assessment of SG influence over the adsorption process was demonstrated.

Evaluation of the molecular inclusion process of β-hexachlorocyclohexane in cyclodextrins

“…38 Although the Gibbs free energy of association (DG assoc ) is the thermodynamic criterion used to dene the spontaneity of a process, here, the association energy (DE assoc ) was preferred. This criterion has been widely used in the past [39][40][41][42] because it is simpler from a computational point of view; also, it avoids the necessity of calculating the association entropies. DE assoc is dened as:…”

“…A favorable thermodynamic association implies that the supermolecule will be more stable than the isolated molecules; namely, a greater absolute value of DE assoc corresponds to more energetically favorable associations. The MMH methodology usually works with semiempirical methods [39][40][41][42][43][44] for the evaluation of the energies while using statistical mechanics to obtain thermodynamic properties related to the molecular association. 38 The main procedure of this approach constructs several random non-redundant molecular geometries, starting from the independently optimized structures of the interacting molecules, in order to explore the conguration space of the formed complexes.…”

Explaining the interactions between metaldehyde and acidic surface groups of activated carbon under different pH conditions

“…The application of computational chemistry methods allow an economization of the material resources while optimizing the work and security of the researchers and technicians [16]. The influence of surface groups (SG) content over adsorption properties has been reported and studied to some extent theoretically for porous carbons (mainly AC and soot particles) [9,[17][18][19][20][21][22][23] in the last few years employing different AC models. In 2014 Enriquez-Victorero et.…”

“…Subsequently, Hernández-Valdés et. al [21] applied this approach to evaluate the interactions of paracetamol and its iodine-labeled analogous (I-paracetamol) with AC, improving the AC model to a coronene sheet. The results obtained in this work shows that I-paracetamol does not adsorb into AC in the same extension, a fact that was experimentally proved.…”

“…More recently, Gamboa-Carballo et. al [22], while studying adsorption of chlordecone into AC, established a work flow that incorporated Quantum Theory of Atoms in Molecules [28,29] to the methods used by Hernández-Valdés et al [21] for quantitatively describing the interactions presents in the studied systems. This strategy was later used by Melchor et al [23] for describing the interactions at a basic pH of hydrated chlordecone with an AC, which, when coupled with the results by Gamboa-Carballo et.…”