title: Removal of anionic dyes from aqueous solutions by an ion-exchanger based on pullulan microspheres.
abstract: Pullulan-graft-poly(3-acrylamidopropyl trimethylammonium chloride) (P-g-pAPTAC) microspheres were prepared by suspension cross-linking of the pullulan previously grafted with cationic moieties. Adsorption of Azocarmine B by the P-g-pAPTAC microspheres was used as a model to demonstrate the removal of anionic dyes from aqueous solutions. Batch adsorption studies concerning the effect of the contact time, pH, initial dye concentration, temperature, grafting, and the nature of sulfonated anionic dyes on the adsorption kinetics were investigated. Adsorption was shown to be independent of pH. The experimental data best fitted to the pseudo-second order model which provided values of the rate constant k(2) of 1.4×10(-4) g mg(-1) min(-1) for 100 mg L(-1) solution and of 3.7×10(-4) g mg(-1) min(-1) for 500 mg L(-1) solution. From the Langmuir isotherm linear equation, the maximum adsorption capacity determined was 113.63 mg of Azocarmine B per gram of adsorbent; the negative value of the free energy change indicated the spontaneous nature of the adsorption process.
authors.affiliation: Petru Poni Institute of Macromolecular Chemistry, Department of Natural Polymers, Bioactive and Biocompatible Materials, Gr. Ghica Voda Alley 41A, 700487 Iasi, Romania. marieta@icmpp.ro
authors.forename: Marieta
authors.initials: M
authors.lastname: Constantin
authors.forename: Ionela
authors.initials: I
authors.lastname: Asmarandei
authors.forename: Valeria
authors.initials: V
authors.lastname: Harabagiu
authors.forename: Luminita
authors.initials: L
authors.lastname: Ghimici
authors.forename: Paolo
authors.initials: P
authors.lastname: Ascenzi
authors.forename: Gheorghe
authors.initials: G
authors.lastname: Fundueanu
mesh_terms: D000327:Adsorption; D004396:Coloring Agents / Q000737:chemistry* / Q000302:isolation & purification*; D005936:Glucans / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007474:Ion Exchange; D007700:Kinetics; D008863:Microspheres; D012996:Solutions; D013451:Sulfonic Acids / Q000737:chemistry; D013696:Temperature; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000302:isolation & purification*
chemical_list: D004396:Coloring Agents; D005936:Glucans; D012996:Solutions; D013451:Sulfonic Acids; D014874:Water Pollutants, Chemical; D014867:Water; C009109:pullulan