title: Synthesis of ethylenediamine modified chitosan and evaluation for removal of divalent metal ions.
abstract: Selective modification of chitosan has been achieved by incorporating ethylene-1,2-diamine molecule in a regioselective manner using N-phthaloylchitosan and chloro-6-deoxy N-phthaloylchitosan as precursors. The present modification results in additional nitrogen centres which function as potential binding sites during adsorption of metal ions. The derivative ethylene-1,2-diamine-6-deoxy-chitosan and its pthaloylated precursor have been evaluated for divalent metal ion removal. The former is found to have higher capacity for adsorption due to the presence of additional NH₂ group. The samples exhibited highest affinity for Cu and least for Zn. About 80% of the adsorbed metal ions could be stripped in a solution of pH 1.2. The interaction between acidic metal centres and basic nitrogen centres on surface of the adsorbent appears to govern adsorption. Intrachain and interchain co-ordinate bonding involving NH and NH₂ groups is proposed to be the mechanism of formation of metal-adsorbent complex. The adsorption process is described by Langmuir model.
authors.affiliation: Department of Post-Graduate Studies & Research in Chemistry, Mangalore University, Mangalagangothri (DK), 574199, Karnataka, India.
authors.forename: P D
authors.initials: PD
authors.lastname: Chethan
authors.forename: B
authors.initials: B
authors.lastname: Vishalakshi
mesh_terms: D000327:Adsorption; D002413:Cations, Divalent / Q000302:isolation & purification*; D002686:Chitin / Q000031:analogs & derivatives / Q000138:chemical synthesis / Q000737:chemistry; D048271:Chitosan / Q000138:chemical synthesis* / Q000737:chemistry; D005029:Ethylenediamines / Q000138:chemical synthesis* / Q000737:chemistry; D007700:Kinetics; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D013818:Thermogravimetry
chemical_list: D002413:Cations, Divalent; D005029:Ethylenediamines; C483239:N-phthaloylchitosan; D002686:Chitin; C031234:ethylenediamine; D048271:Chitosan
keywords: Competitive adsorption; Desorption; Ethylene-1,2-diamine-6-deoxychitosan; Langmuir adsorption; Metal ion removal