title: New physicochemical interpretations for the adsorption of food dyes on chitosan films using statistical physics treatment.
abstract: In this work, statistical physics treatment was employed to study the adsorption of food dyes onto chitosan films, in order to obtain new physicochemical interpretations at molecular level. Experimental equilibrium curves were obtained for the adsorption of four dyes (FD&C red 2, FD&C yellow 5, FD&C blue 2, Acid Red 51) at different temperatures (298, 313 and 328 K). A statistical physics formula was used to interpret these curves, and the parameters such as, number of adsorbed dye molecules per site (n), anchorage number (n'), receptor sites density (NM), adsorbed quantity at saturation (N asat), steric hindrance (τ), concentration at half saturation (c1/2) and molar adsorption energy (ΔE(a)) were estimated. The relation of the above mentioned parameters with the chemical structure of the dyes and temperature was evaluated and interpreted.
authors.affiliation: Chemical Engineering Department, Federal University of Santa Maria - UFSM, 1000 Roraima Avenue, 97105-900 Santa Maria, RS, Brazil. Electronic address: guilherme_dotto@yahoo.com.br.
authors.forename: G L
authors.initials: GL
authors.lastname: Dotto
authors.affiliation: Unit Operation Laboratory, School of Chemistry and Food, Federal University of Rio Grande, FURG, Engenheiro Alfredo Huch Street, 475, 96203-900 Rio Grande, RS, Brazil. Electronic address: dqmpinto@furg.br.
authors.forename: L A A
authors.initials: LA
authors.lastname: Pinto
authors.affiliation: Unité de Recherche de Physique Quantique, Faculté des Sciences de Monastir, Tunisia. Electronic address: abdenna@yahoo.fr.
authors.forename: M A
authors.initials: MA
authors.lastname: Hachicha
authors.affiliation: Unité de Recherche de Physique Quantique, Faculté des Sciences de Monastir, Tunisia. Electronic address: knanisalah@yahoo.fr.
authors.forename: S
authors.initials: S
authors.lastname: Knani
mesh_terms: D000327:Adsorption; D048271:Chitosan / Q000737:chemistry*; D005505:Food Coloring Agents / Q000737:chemistry*; D005524:Food Technology / Q000379:methods*; D008962:Models, Theoretical; D013696:Temperature
chemical_list: D005505:Food Coloring Agents; D048271:Chitosan
keywords: Chitosan films; Food dyes; Grand canonical ensemble; Statistical physics