title: Characteristics of granular boehmite and its ability to adsorb phosphate from aqueous solution.
abstract: In this study, we investigated the surface properties of granulated boehmite with vinyl acetate (G-BE20) and measured the amount of phosphate it adsorbed and the effect of contact time and solution pH on the adsorption process. The specific surface area (144.9 m(2)/g) and the number of surface hydroxyl groups (0.88 mmol/g) of G-BE20 were smaller than those of virgin boehmite (BE), which gave a specific surface area and number of surface hydroxyl groups of 297.0 m(2)/g and 1.08 mmol/g, respectively. The amount of phosphate adsorbed increased with the temperature. The isotherm model of Langmuir was used to fit experimental adsorption equilibrium data for phosphate adsorption onto G-BE20. The calculated thermodynamic parameters show the spontaneous and endothermic nature of the adsorption process. The equilibrium adsorption onto G-BE20 was reached within 16 h and the amount of phosphate adsorbed was 8.4 mg/g. The kinetic mechanism of phosphate uptake was evaluated with two different models: the Largergren pseudo first- and pseudo second-order models. The data obtained showed a better fit to the pseudo second-order model (0.991) than to the pseudo first-order model (0.967), as indicated by the r values. The rate constants for the adsorption of phosphate onto G-BE20 were calculated as 0.481 1/h and 0.029 g/mg h. The adsorption of phosphate onto G-BE20 was the maximum in the pH range 3.0-4.0.
authors.affiliation: Faculty of Pharmacy, Kinki University, 3-4-1 Kowakae, Higashi-Osaka, Osaka 577-8502, Japan.
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Ogata
authors.forename: Hisato
authors.initials: H
authors.lastname: Tominaga
authors.forename: Moe
authors.initials: M
authors.lastname: Kangawa
authors.forename: Kenji
authors.initials: K
authors.lastname: Inoue
authors.forename: Naohito
authors.initials: N
authors.lastname: Kawasaki
mesh_terms: D000327:Adsorption; D000536:Aluminum Hydroxide / Q000737:chemistry*; D000537:Aluminum Oxide / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008855:Microscopy, Electron, Scanning; D010710:Phosphates / Q000737:chemistry*; D012996:Solutions; D013816:Thermodynamics; D014867:Water / Q000737:chemistry
chemical_list: D010710:Phosphates; D012996:Solutions; D014867:Water; D000536:Aluminum Hydroxide; C069471:aluminum oxide hydroxide; D000537:Aluminum Oxide