title: Microwave irradiation-assisted synthesis of a novel crown ether crosslinked chitosan as a chelating agent for heavy metal ions (M(+n)).
abstract: Microwave irradiation was used to obtain a di-Schiff base type crosslinked chitosan dibenzocrown ether (CCdBE) via the reaction between the -NH(2) and -CHO groups in chitosan and 4,4'-diformyldibenzo-18-c-6, respectively. The structure of the synthesized compound was characterized by elemental analysis, solid state 13C-NMR and FT-IR spectra analysis. The results showed that the mass fraction of nitrogen in the CCdBE derivative was much lower than those of chitosan. The FT-IR spectra of CCdBE revealed the expected chitosan-crown ether structure, as evidenced by the presence of the characteristic C=N and Ar peaks. The adsorption properties of CCdBE for Pd2+ and Hg2+ were investigated and the results demonstrated that the adsorbent has both desirable adsorption properties with a high particular adsorption selectivity for Hg2+ when in the presence of Pb2+ as well as selectivity coefficients for metal ions of K(Hg(2+)/Pb(2+)) = 8.00 and K(Hg(2+)/Pb(2+)) = 10.62 at pH values of 4 and 6, respectively. The reusability tests for CCdBE for Pb2+ adsorption showed that complete recovery of the ion was possible with CCdBE after 10-multiple reuses while CTS had no reusability at acidic solution because of its higher dissolution. The studied features of CCdBE suggested that the material could be considered as a new adsorbent. It is envisaged that the crosslinking of CTS into CCdBE would enhance practicality and effectiveness of adsorption in ion separation and removal procedures.
authors.affiliation: College of Pharmacy, King Saud University, Riyadh, Saudi Arabia.
authors.forename: Awwad A
authors.initials: AA
authors.lastname: Radwan
authors.forename: Fars K
authors.initials: FK
authors.lastname: Alanazi
authors.forename: Ibrahim A
authors.initials: IA
authors.lastname: Alsarra
mesh_terms: D000327:Adsorption; D002614:Chelating Agents / Q000138:chemical synthesis*; D048271:Chitosan / Q000138:chemical synthesis* / Q000737:chemistry; D043844:Crown Ethers / Q000737:chemistry*; D008628:Mercury; D019216:Metals, Heavy / Q000737:chemistry / Q000302:isolation & purification*; D008872:Microwaves; D015394:Molecular Structure; D010165:Palladium
chemical_list: D002614:Chelating Agents; D043844:Crown Ethers; D019216:Metals, Heavy; D010165:Palladium; D048271:Chitosan; D008628:Mercury