title: Nitrate reduction in water by aluminum alloys particles.
abstract: Nano zero-valent iron (NZVI) particles have been extensively investigated for nitrate reduction in water. However, the reduction by NZVI requires acidic pH conditions and the final product is exclusively ammonium, leading to secondary contamination. In addition, nanomaterials have potential threats to environment and the transport and storage of nanomaterials are of safety concerns. Aluminum, the most abundant metal element in the earth's crust, is able to reduce nitrate, but the passivation of aluminum limits its application. Here we report Al alloys (85% Al) with Fe, Cu or Si for aqueous nitrate reduction. The Al alloys particles of 0.85-0.08 mm were inactivate under ambient conditions and a simple treatment with warm water (45 °C) quickly activated the alloy particles for rapid reduction of nitrate. The Al-Fe alloy particles at a dosage of 5 g/L rapidly reduced 50 mg-N/L nitrate at a reaction rate constant (k) of 3.2 ± 0.1 (mg-N/L)1.5/min between pH 5-6 and at 4.0 ± 0.1 (mg-N/L)1.5/min between pH 9-11. Dopping Cu in the Al-Fe alloy enhanced the rates of reduction whereas dopping Si reduced the reactivity of the Al-Fe alloy. The Al alloys converted nitrate to 20% nitrogen and 80% ammonium. Al in the alloy particles provided electrons for the reduction and the intermetallic compounds in the alloys were likely to catalyze nitrate reduction to nitrogen.
authors.affiliation: School of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029, China.
authors.forename: Zunsheng
authors.initials: Z
authors.lastname: Bao
authors.affiliation: South University of Science and Technology of China, Shenzhen, Guangdong 518055, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Hu
authors.affiliation: School of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029, China; Beijing Key Laboratory of Advanced Functional Polymer Composites, Beijing University of Chemical Technology, Beijing 100029, China. Electronic address: qiwk@mail.buct.edu.cn.
authors.forename: Weikang
authors.initials: W
authors.lastname: Qi
authors.affiliation: School of Science, Beijing University of Chemical Technology, Beijing 100029, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Tang
authors.affiliation: School of Science, Beijing University of Chemical Technology, Beijing 100029, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.affiliation: School of Science, Beijing University of Chemical Technology, Beijing 100029, China.
authors.forename: Pingyu
authors.initials: P
authors.lastname: Wan
authors.affiliation: Chemical Metrology and Analytical Science Division, National Institute of Metrology, Beijing 100013, China.
authors.forename: Jingbo
authors.initials: J
authors.lastname: Chao
authors.affiliation: School of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029, China; Beijing Key Laboratory of Advanced Functional Polymer Composites, 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
mesh_terms: D000497:Alloys; D000535:Aluminum; D058440:Denitrification; D007501:Iron; D009566:Nitrates; D014867:Water; D014874:Water Pollutants, Chemical; D018508:Water Purification
chemical_list: D000497:Alloys; D009566:Nitrates; D014874:Water Pollutants, Chemical; D014867:Water; D000535:Aluminum; D007501:Iron
keywords: Aluminum alloys; Nitrate reduction; Water treatment; Zero-valent metals