title: Effects of Ni(2+) on aluminum hydroxide scale formation and transformation on a simulated drinking water distribution system.
abstract: Observations of aluminum containing sediments/scales formed within the distribution pipes have been reported for several decades. In this study, the effect of Ni(2+) on the formation and transformation processes of aluminum hydroxide sediment in a simulated drinking water distribution system were investigated using X-ray diffraction spectrum (XRD), Fourier transform infrared spectrum (FT-IR), scanning electron microscope (SEM), and thermodynamic calculation methods. It was determined that the existence of Ni(2+) had notable effects on the formation of bayerite. In the system without Ni(2+) addition, there was no X-ray diffraction signal observed after 400 d of aging. The presence of Ni(2+), however, even when present in small amounts (Ni/Al=1:100) the formation of bayerite would occur in as little as 3d at pH 8.5. As the molar ratio of Ni/Al increase from 1:100 to 1:10, the amount of bayerite formed on the pipeline increased further; meanwhile, the specific area of the pipe scale decreased from 160 to 122 m(2)g(-1). In the system with Ni/Al molar ratio at 1:3, the diffraction spectrum strength of bayerite became weaker, and disappeared when Ni/Al molar ratios increased above 1:1. At these highs Ni/Al molar ratios, Ni5Al4O11⋅18H2O was determined to be the major component of the pipe scale. Further study indicated that the presence of Ni(2+) promoted the formation of bayerite and Ni5Al4O11⋅18H2O under basic conditions. At lower pH (6.5) however, the existence of Ni(2+) had little effect on the formation of bayerite and Ni5Al4O11⋅18H2O, rather the adsorption of amorphous Al(OH)3 for Ni(2+) promoted the formation of crystal Ni(OH)2.
authors.affiliation: Department of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China; Department of Environmental Technology and Ecology, Yangtze Delta Region Institute of Tsinghua University, Zhejiang, Jiaxing 314006, China. Electronic address: wwd@xauat.edu.cn.
authors.forename: Wendong
authors.initials: W
authors.lastname: Wang
authors.affiliation: Department of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China.
authors.forename: Shan
authors.initials: S
authors.lastname: Song
authors.affiliation: Department of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China.
authors.forename: Xiaoni
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Environmental Engineering, The Pennsylvania State University-Harrisburg, Middletown, PA 17057, USA.
authors.forename: J
authors.initials: J
authors.lastname: Mitchell Spear
authors.affiliation: Department of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China.
authors.forename: Xiaochang
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China.
authors.forename: Wen
authors.initials: W
authors.lastname: Wang
authors.affiliation: School of Environmental Science and Engineering, Chang'an University, Xi'an 710064, China.
authors.forename: Zhenzhen
authors.initials: Z
authors.lastname: Ding
authors.affiliation: Department of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China.
authors.forename: Zixia
authors.initials: Z
authors.lastname: Qiao
mesh_terms: D000536:Aluminum Hydroxide / Q000737:chemistry* / Q000302:isolation & purification; D060766:Drinking Water / Q000737:chemistry*; D019015:Geologic Sediments / Q000737:chemistry; D009532:Nickel / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013816:Thermodynamics; D013997:Time Factors; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000302:isolation & purification; D014881:Water Supply
chemical_list: D060766:Drinking Water; D014874:Water Pollutants, Chemical; D000536:Aluminum Hydroxide; D009532:Nickel
keywords: Aluminum hydroxide; Drinking water; Pipe scale; Water quality