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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
Raney®-Nickel, W.R. Grace and Co. Raney® 2800, slurry, in H2O, active catalyst
Sigma-Aldrich
Aluminum hydroxide, reagent grade
Sigma-Aldrich
Nickel, nanopowder, <100 nm avg. part. size, ≥99% trace metals basis
Sigma-Aldrich
Nickel, foil, thickness 0.125 mm, ≥99.9%
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Nickel, powder, <150 μm, 99.99% trace metals basis
Sigma-Aldrich
Raney®-Nickel, W.R. Grace and Co. Raney® 2400, slurry, in H2O, active catalyst
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Nickel, foil, thickness 0.5 mm, 99.98% trace metals basis
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Nickel, wire, diam. 0.25 mm, ≥99.9%
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Nickel, foil, thickness 0.1 mm, 99.98% trace metals basis
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Nickel, wire, diam. 0.5 mm, ≥99.9% trace metals basis
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Nickel, wire, diam. 0.5 mm, ≥99.99% trace metals basis
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Nickel, rod, diam. 6.35 mm, ≥99.99% trace metals basis
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Nickel, foil, thickness 0.25 mm, 99.995% trace metals basis
Nickel, mesh, 100x250mm, nominal aperture 0.73mm, wire diameter 0.25mm, 26x26 wires/inch, open area 55%, plain weave mesh, 99%
Nickel, wire reel, 20m, diameter 0.025mm, as drawn, 99.98%
Nickel, wire reel, 10m, diameter 0.01mm, as drawn, 99.98%
Nickel, rod, 100mm, diameter 16mm, 99.99+%
Nickel, foil, not light tested, 100x100mm, thickness 0.01mm, 99.95%
Nickel, wire reel, 20m, diameter 0.125mm, hard, 99.98%
Nickel, rod, 100mm, diameter 3.0mm, 99%
Nickel, wire reel, 1m, diameter 1.0mm, hard, 99.98%
Nickel, broken cathode squares, 1000g, max. size 50mm, 99.8%
Nickel, tube, 1000mm, outside diameter 6.5mm, inside diameter 5.5mm, wall thickness 0.5mm, hard, 99.5%
Nickel, foil, 50mm disks, thickness 0.05mm, annealed, 99%
Nickel, wire reel, 20m, diameter 0.5mm, as drawn, 99%
Nickel, foil, 4mm disks, thickness 0.075mm, annealed, 99%
Nickel, foil, 4mm disks, thickness 0.075mm, as rolled, 99.98%
Nickel, foil, 4mm disks, thickness 0.125mm, annealed, 99%
Nickel, foil, 4mm disks, thickness 0.125mm, annealed, 99.98%
Nickel, foil, 4mm disks, thickness 0.125mm, as rolled, 100%