title: Reduction of concentrated nitrate by using in situ synthesized zero-valent copper.
abstract: Although zero-valent iron represents a promising approach for reduction of nitrate (NO(3)(-)) in water, its application in concentrated nitrate is limited by surface passivation. In this study, an alternative approach using in situ synthesized zero-valent copper (Cu(0)) produced by borohydride (NaBH(4)) was investigated. Complete reduction was observed within 55 min by reacting 677 mg-N/L of NO(3)(-) with CuO (0.312 g/L) and NaBH(4) (4.16 g/L) at 60 °C. The pseudo-first-order rate constant was 0.059 min(-1), and it increased threefold when the CuO dose was increased to 1.24 g/L. Increasing the NaBH(4) dose produced less nitrite (NO(2)(-)) throughout the experiments, indicating that it is the primary agent for reducing NO(2)(-). The initial pH exerted a significant effect on the reaction rate, and NO(3)(-) was rapidly reduced when the initial pH was less than 4. Based on the research findings, possible reaction pathways for NO(3)(-) reduction by Cu(0) are proposed in this work.
authors.affiliation: Department of Chemical Engineering, National Taiwan University of Science and Technology, 43 Keelung Road, Section 4, Taipei 106, Taiwan E-mail: liu1958@mail.ntust.edu.tw.
authors.forename: Tihitinna Asmellash
authors.initials: TA
authors.lastname: Belay
authors.affiliation: Department of Chemical Engineering, National Taiwan University of Science and Technology, 43 Keelung Road, Section 4, Taipei 106, Taiwan E-mail: liu1958@mail.ntust.edu.tw.
authors.forename: F M
authors.initials: FM
authors.lastname: Lin
authors.affiliation: Institute of Nuclear Energy Research, 1000 Wen-Hua Road, Chia-An Village, Lung-Tan District, Tao-Yuan City 32546, Taiwan.
authors.forename: C Y
authors.initials: CY
authors.lastname: Lin
authors.affiliation: Institute of Nuclear Energy Research, 1000 Wen-Hua Road, Chia-An Village, Lung-Tan District, Tao-Yuan City 32546, Taiwan.
authors.forename: H M
authors.initials: HM
authors.lastname: Hsiao
authors.affiliation: Institute of Nuclear Energy Research, 1000 Wen-Hua Road, Chia-An Village, Lung-Tan District, Tao-Yuan City 32546, Taiwan.
authors.forename: M F
authors.initials: MF
authors.lastname: Chang
authors.affiliation: Department of Chemical Engineering, National Taiwan University of Science and Technology, 43 Keelung Road, Section 4, Taipei 106, Taiwan E-mail: liu1958@mail.ntust.edu.tw.
authors.forename: J C
authors.initials: JC
authors.lastname: Liu
mesh_terms: D003300:Copper / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007501:Iron; D009566:Nitrates / Q000737:chemistry*; D009573:Nitrites; D009589:Nitrogen Oxides; D010084:Oxidation-Reduction; D014867:Water; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification
chemical_list: D009566:Nitrates; D009573:Nitrites; D009589:Nitrogen Oxides; D014874:Water Pollutants, Chemical; D014867:Water; D003300:Copper; D007501:Iron