title: Removal of organic polyelectrolytes and their metal complexes by adsorption onto xonotlite.
abstract: Natural organic polyelectrolytes (humic and fulvic acids) and their metal complexes were removed by adsorption onto xonotlite. The removal percentages of humic and fulvic acids by xonotlite were approximately 80% and 30%, respectively. Humic acid removal from solution by adsorption onto xonotlite took place more readily than fulvic acid removal. The molecular weight distributions of the humic substances remaining in solution after adsorption with the xonotlite were measured with size exclusion chromatography. A comparison of molecular weight distributions demonstrated conclusively that large molecular weight components were adsorbed preferentially, indicating that adsorption efficiency depends on the number of functional groups of humic substances. Furthermore, the surface topography of the adsorbent was observed before and after adsorption by scanning electron microscopy. The calculated heat of adsorption was of 330 kJ mol(-1) which was evaluated from the Clapeyron-Clausius equation. Therefore, the adsorption type can be considered chemical. Since xonotlite can be easily synthesized and obtained at low cost, the adsorption method of humic and fulvic acids is superior to their precipitation.
authors.affiliation: Department of Chemistry for Materials, Faculty of Engineering, Mie University, Tsu, Mie 514-8507, Japan. hidek@chem.mie-u.ac.jp
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Katsumata
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kaneco
authors.forename: Rika
authors.initials: R
authors.lastname: Matsuno
authors.forename: Kumiko
authors.initials: K
authors.lastname: Itoh
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Masuyama
authors.forename: Tohru
authors.initials: T
authors.lastname: Suzuki
authors.forename: Kunihiro
authors.initials: K
authors.lastname: Funasaka
authors.forename: Kiyohisa
authors.initials: K
authors.lastname: Ohta
mesh_terms: D000327:Adsorption; D000535:Aluminum / Q000737:chemistry*; D001578:Benzopyrans / Q000737:chemistry*; D017610:Calcium Compounds / Q000737:chemistry*; D002850:Chromatography, Gel; D003300:Copper / Q000737:chemistry*; D006812:Humic Substances / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008855:Microscopy, Electron, Scanning; D008970:Molecular Weight; D017640:Silicates / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis; D013499:Surface Properties; D013816:Thermodynamics
chemical_list: D001578:Benzopyrans; D017610:Calcium Compounds; D006812:Humic Substances; D017640:Silicates; D012989:Soil Pollutants; D003300:Copper; D000535:Aluminum; C031293:calcium silicate; C005023:fulvic acid