Exploring the favorable ion-exchange ability of phthalylated cellulose biopolymer using thermodynamic data.
A phthalylated ion-exchange biopolymer was obtained by adding cellulose to molten phthalic anhydride in a quasi solvent-free procedure. Through this route 2.99+/-0.07 mmolg(-1) of pendant groups containing ester and carboxylic acid moieties were incorporated into the polymeric structure that was characterized by elemental analysis, solid-state carbon nuclear magnetic resonance (CP/MAS), infrared spectroscopy, X-ray diffraction, and thermogravimetry. The chemically modified polysaccharide is able to exchange cations from aqueous solution as demonstrated by batchwise methodology. The data were adjusted to a modified Langmuir equation to give 2.43+/-0.12 and 2.26+/-0.11 mmolg(-1) for divalent cobalt and nickel cations, respectively. The net thermal effects obtained from calorimetric titration measurements were also adjusted to a modified Langmuir equation, and the enthalpy of the interaction was calculated to give endothermic values of 2.11+/-0.28 and 2.50+/-0.31kJmol(-1) for these cations, respectively. The spontaneity of this ion-exchange process is reflected in negative Gibbs energy and with a contribution of positive entropic values. This set of thermodynamic data at the solid-liquid interface suggests a favorable ion-exchange process for this anchored biopolymer for cation exchange from the environment.
de Melo
Júlio C P
JC
Institute of Chemistry, University of Campinas, Campinas, SP, Brazil.
da Silva Filho
Edson C
EC
Santana
Sirlane A A
SA
Airoldi
Claudio
C
D002151:Calorimetry; D002482:Cellulose / Q000737:chemistry*; D007474:Ion Exchange; D010795:Phthalic Acids / Q000737:chemistry*; D013816:Thermodynamics; D014961:X-Ray Diffraction
D010795:Phthalic Acids; D002482:Cellulose