title: Chemical removal of nitrate from water by aluminum-iron alloys.
abstract: Zero-valent iron has been intensively investigated in chemical reduction of nitrate in water, but the reduction requires acidic or weak acidic pH conditions and the product of the reduction is exclusively ammonium, an even more toxic substance. Zero-valent aluminum is a stronger reductant than iron, but its use for the reduction of aqueous nitrate requires considerably alkaline pH conditions. In this study, aluminum-iron alloys with an iron content of 10%, 20% and 58% (termed Al-Fe10, Al-Fe20 and Al-Fe58, respectively) were investigated for the reduction of aqueous nitrate. Al-Fe alloys were efficient to reduce nitrate in water in an entire pH range of 2-12 and the reduction proceeded in a pseudo-first order at near neutral pH conditions. The observed reaction rate constant (Kobs) of Al-Fe10 was 3 times higher than that of Fe and the Kobsof Al-Fe20 doubled that of Al-Fe10. The nitrogen selectivity of the reduction by Al-Fe10, Al-Fe20 and Al-Fe58 was 17.6%, 23.9% and 40.3%, respectively at pH 7 and the nitrogen selectivity by Al-Fe20 increased from 18.9% at pH 2-60.3% at pH 12. The enhanced selectivity and reactivity of Al-Fe alloys were likely due to the presence of an intermetallic Al-Fe compound (Al13Fe4).
authors.affiliation: School of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Xu
authors.affiliation: School of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029, China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Pu
authors.affiliation: School of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029, China.
authors.forename: Wei-Kang
authors.initials: WK
authors.lastname: Qi
authors.affiliation: School of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029, China. Electronic address: yangxj@mail.buct.edu.cn.
authors.forename: Xiao Jin
authors.initials: XJ
authors.lastname: Yang
authors.affiliation: Department of Applied Chemistry, Beijing University of Chemical Technology, Beijing 100029, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Tang
authors.affiliation: Department of Applied Chemistry, Beijing University of Chemical Technology, Beijing 100029, China.
authors.forename: Pingyu
authors.initials: P
authors.lastname: Wan
authors.affiliation: Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB2 1TN, United Kingdom.
authors.forename: Adrian
authors.initials: A
authors.lastname: Fisher
mesh_terms: D000497:Alloys / Q000737:chemistry; D000535:Aluminum / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000737:chemistry*; D007700:Kinetics; D009566:Nitrates / Q000737:chemistry*; D009584:Nitrogen / Q000737:chemistry; D009589:Nitrogen Oxides / Q000737:chemistry; D010084:Oxidation-Reduction; D014867:Water / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
chemical_list: D000497:Alloys; D009566:Nitrates; D009589:Nitrogen Oxides; D014874:Water Pollutants, Chemical; D014867:Water; D000535:Aluminum; D007501:Iron; D009584:Nitrogen
keywords: Aluminum-iron alloy; Iron content; Nitrate reduction; Nitrogen gas selectivity; Water treatment