Oxidation of nickel and titanium for the Fabrication of porous or tubular oxides
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Date
2019-05
Authors
Mohamad Afif Bin Mohamad Fauzi
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Abstract
This project were focus on environment aspect. The purpose of this project are
to fabricate nanoporous NiO and TiO2 nanotubes by anodization, to compare anodic
oxide formation on Ti and Ni and to assess on Cr(VI) removal via photocatalytic process
on the fabricated oxides. The industry like metal processing, chromate production,
stainless steel welding, ferrochrome and chrome pigment production disposed the
waste product consists of heavy metal to the sea and river. This heavy metal give harmful
effect to human body such as allergy, asthma, cancer, renal damage and etc. This
heavy metal like chromium will be used to investigate for its reduction from Cr(VI) to
Cr(III) by using photoreduction. The metal foil that will be used are nickel and titanium
for photoreduction reaction. For methodology consists of 5 stage. Firstly, sample preparation
which the metal foils will cut into 1cm × 0.5cm and washed with acetone,
ethanol and distilled water each 5 minutes. Then, oxidation process is the second stage
where the positive terminal is metal foil while negative terminal is platinum electrode
and immersed into the electrolyte. Then, annealing the metal foils at different temperature
(stage 3). The anneal metal foil were undergo photoreduction process to observe
the reduction of heavy metal under uv-rays for 3 hours (stage 4). Each hour, 3 mL of
chromium solution were taken for characterization. Lastly, characterization of metal
foils were done (stage 5). For the results, different parameter were used to observe the surface morphology of nickel foils and titanium foils. Firstly, the effect of time. The nickel foils produce dense layer oxide. With increasing of time, nickel foils produce a cracks and
crater on the surface of oxide layer. This is occurred due to the interaction of Ni metal with O2- by the aid of high electric field. A barrier layer has formed. As the potential
across the oxide is high enough, possibility for the Ni-O bonding is broken can occur.
This can localise mechanical breakdown of the NiO which can lead to the formation
of pits on the surface of NiO. For titanium foils, the diameter of the nanotubes for the
60 minutes sample is 76.056 nm while for 120 minutes is 92.453 nm. It shown that the
increasing time of oxidation will increase the diameter of nanotubes. Other parameter
that had been observed effect of electrolyte, effect on the addition of hydrogen peroxide
into electrolyte, effect of temperature on oxidation, photoreduction result and etc.
As a conclusion, both nickel foils and titanium foils can reduce the heavy metal from
Cr(VI) to Cr(III). For surface morphology, mostly the nickel foils produce
macroporous size while titanium foils produce nanotubes in size. For X-Ray Diffraction
(XRD), it prove that the present of nickel oxide (NiO) on the surface of metal
foils.