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Effects of Ni(2+) on aluminum hydroxide scale formation and transformation on a simulated drinking water distribution system.

Chemosphere (2014-01-15)
Wendong Wang, Shan Song, Xiaoni Zhang, J Mitchell Spear, Xiaochang Wang, Wen Wang, Zhenzhen Ding, Zixia Qiao
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.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Nickel, rod, diam. 6.35 mm, ≥99.99% trace metals basis
Sigma-Aldrich
Nickel, powder, <50 μm, 99.7% trace metals basis
Sigma-Aldrich
Nickel, wire, diam. 0.5 mm, ≥99.9% trace metals basis
Sigma-Aldrich
Nickel, foil, thickness 0.1 mm, 99.98% trace metals basis
Sigma-Aldrich
Nickel, foil, thickness 0.5 mm, 99.98% trace metals basis
Nickel, foil, 50mm disks, thickness 0.01mm, 99.95%
Nickel, foil, not light tested, 300x300mm, thickness 0.0125mm, 99.9%
Nickel, foil, light tested, 150x150mm, thickness 0.025mm, annealed, 99%
Nickel, foil, light tested, 50x50mm, thickness 0.01mm, 99.95%
Nickel, foil, light tested, 100x100mm, thickness 0.075mm, annealed, 99%
Nickel, foil, not light tested, 25x25mm, thickness 0.00075mm, temporary acrylic support, 99.95%
Nickel, foil, not light tested, 100x100mm, thickness 0.008mm, 99.95%
Nickel, rod, 1000mm, diameter 12.7mm, 99.98%
Nickel, foil, 25x25mm, thickness 0.25mm, annealed, 99%
Nickel, foil, not light tested, 300x300mm, thickness 0.0125mm, annealed, 99%
Nickel, tube, 500mm, outside diameter 1.0mm, inside diameter 0.8mm, wall thickness 0.1mm, hard, 99.5%
Nickel, pellets, 20g, max. size 20mm, 99.99+%
Nickel, foil, 25mm disks, thickness 0.25mm, annealed, 99%
Nickel, foil, 0.5m coil, thickness 0.125mm, annealed, 99%
Nickel, foil, 0.5m coil, thickness 0.005mm, as rolled, 99.9%
Nickel, foil, not light tested, 98x100mm, thickness 0.005mm, as rolled, 99.9%
Nickel, mesh, 65x65mm, nominal aperture 0.34mm, thickness 0.025mm, wire diameter 0.041mm, 70 wires/inch, open area 80%, electro-formed mesh, 99.9%
Nickel, tube, 500mm, outside diameter 2.5mm, inside diameter 2mm, wall thickness 0.25mm, hard, 99.5%
Nickel, rod, 1000mm, diameter 2.0mm, 99.99+%
Nickel, mesh, 240x240mm, nominal aperture 0.43mm, thickness 0.004mm, wire diameter 0.067mm, 51 wires/inch, open area 75%, electro-formed mesh, 99.9%
Nickel, foil, 2m coil, thickness 0.5mm, annealed, 99.98%
Nickel, foil, 50x50mm, thickness 2.0mm, annealed, 99%
Nickel, foil, 50x50mm, thickness 0.25mm, as rolled, 99.99+%
Nickel, foil, 50mm disks, thickness 0.0075mm, 99.9%
Nickel, foil, 50mm disks, thickness 0.025mm, annealed, 99%