title: Adsorption of humic acid from aqueous solution onto irradiation-crosslinked carboxymethylchitosan.
abstract: This paper presents the adsorption of humic acid from aqueous solution onto crosslinked chitosan derivative (carboxymethylchitosan), formed by additionless irradiation technique. The surface charge and swelling properties of crosslinked samples were investigated. The adsorption of humic acid onto crosslinked carboxymethylchitosan was carried out by the batch method at room temperature, and it was found to be strongly pH-dependent. Maximum amount of humic acid was adsorbed under acidic conditions at the optimum pH value of 3.5. Adsorption kinetic studies indicated the adsorption process was transport-limited at the same pH. The adsorption isotherm analysis data under various initial humic acid concentrations confirms that experimental data fitted well into the Langmuir equation. X-ray photoelectron spectroscopy (XPS) revealed that the amino groups of carboxymethylated chitosan were protonated, suggesting the formation of organic complex between the protonated amino groups and humic acid. From these preliminary evaluations, it was concluded that crosslinked carboxymethylated chitosan derivatives have a great potential in water treatment for the removal of humic acid and other polarized or electrically charged species.
authors.affiliation: Department of Biological and Chemical Engineering, Gunma University, Kiryu, Gunma, Japan. Zhao_Long@nissin.co.jp
authors.forename: Long
authors.initials: L
authors.lastname: Zhao
authors.forename: Fang
authors.initials: F
authors.lastname: Luo
authors.forename: Jaroslaw M
authors.initials: JM
authors.lastname: Wasikiewicz
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Mitomo
authors.forename: Naotsugu
authors.initials: N
authors.lastname: Nagasawa
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Yagi
authors.forename: Masao
authors.initials: M
authors.lastname: Tamada
authors.forename: Fumio
authors.initials: F
authors.lastname: Yoshii
mesh_terms: D000327:Adsorption; D001709:Biotechnology / Q000379:methods*; D048271:Chitosan / Q000031:analogs & derivatives* / Q000737:chemistry*; D003432:Cross-Linking Reagents / Q000737:chemistry*; D004307:Dose-Response Relationship, Radiation; D006812:Humic Substances; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D015233:Models, Statistical; D011522:Protons; D013052:Spectrometry, X-Ray Emission; D014867:Water / Q000737:chemistry; D018508:Water Purification
chemical_list: D003432:Cross-Linking Reagents; D006812:Humic Substances; D011522:Protons; C514968:carboxymethyl-chitosan; D014867:Water; D048271:Chitosan