title: Characteristics and kinetics of phosphate adsorption on dewatered ferric-alum residuals.
abstract: The characteristics and kinetics of phosphate (P) adsorption on dewatered ferric-alum water treatment residuals (Fe-Al-WTRs) have been investigated. The existence of both aluminum (Al) and iron (Fe) in the residuals can result in significantly high P adsorption capacities. The P adsorption kinetics of Fe-Al-WTRs exhibited an initial rapid phase, followed by a slower phase. This could be described by three models, including a pseudo-first-order equation, a pseudo-second-order equation, and a double-constant rate equation. The latter was especially good for those runs with initial P concentrations of 500 and 1000 mg L(-1). Both the Langmuir and Freundlich isotherms fit the experimental data well, particularly the Freundlich isotherm, which had a correlation coefficient of 0.9930. The maximum measured P adsorption capacity of Fe-Al-WTRs was 45.42 mg g(-1), which is high when compared to those of most WTRs, as well as other reported adsorbents. The results also show that the P adsorption is a spontaneous endothermic process. Highest P adsorption capacities of Fe-Al-WTRs were measured at low pHs and a particle size range of 0.6 to 0.9 mm.
authors.affiliation: The Key Laboratory of Water and Sediment Sciences, Ministry of Education, School of Environment, Beijing Normal University, Beijing, PR. China.
authors.forename: Changhui
authors.initials: C
authors.lastname: Wang
authors.forename: Wei
authors.initials: W
authors.lastname: Guo
authors.forename: Binghui
authors.initials: B
authors.lastname: Tian
authors.forename: Yuansheng
authors.initials: Y
authors.lastname: Pei
authors.forename: Kejiang
authors.initials: K
authors.lastname: Zhang
mesh_terms: D000327:Adsorption; D000534:Alum Compounds / Q000737:chemistry*; D005290:Ferric Compounds / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008670:Metals / Q000032:analysis; D010316:Particle Size; D010710:Phosphates / Q000737:chemistry*; D013696:Temperature; D014866:Waste Products / Q000032:analysis; D014867:Water / Q000737:chemistry; D018508:Water Purification / Q000379:methods*
chemical_list: D000534:Alum Compounds; D005290:Ferric Compounds; D008670:Metals; D010710:Phosphates; D014866:Waste Products; D014867:Water