title: Adsorption and preconcentration of 2,4-dichlorophenoxyacetic acid on a chemically modified silica gel surface.
abstract: The herbicide 2,4-dichlorophenoxyacetic acid (2,4-D), chemically anchored to a silica gel surface, was used to adsorb and preconcentrate the same herbicide from aqueous solutions at room temperature. From a series of adsorption isotherms adjusted to a modified Langmuir equation, the maximum number of moles adsorbed was calculated as 4.67 x 10(-5) mol g(-1), with the highest retention capacity at pH 5. This modified silica gel was used in a column for preconcentrating trace levels of 2,4-D. The preconcentrated herbicide can be directly eluted with methanol with a recovery efficiency higher than 97%. The concentration factor was 8.33.
authors.affiliation: Instituto de Química, Universidade Estadual de Campinas, São Paulo, Brazil.
authors.forename: A G
authors.initials: AG
authors.lastname: Prado
authors.forename: C
authors.initials: C
authors.lastname: Airoldi
mesh_terms: D015084:2,4-Dichlorophenoxyacetic Acid / Q000032:analysis* / Q000737:chemistry; D000327:Adsorption; D002845:Chromatography / Q000379:methods; D004785:Environmental Pollutants / Q000032:analysis; D006540:Herbicides / Q000032:analysis* / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008956:Models, Chemical; D058428:Silica Gel; D012822:Silicon Dioxide / Q000737:chemistry; D018508:Water Purification / Q000379:methods
chemical_list: D004785:Environmental Pollutants; D006540:Herbicides; D015084:2,4-Dichlorophenoxyacetic Acid; D058428:Silica Gel; D012822:Silicon Dioxide