Dahon, Nur Hazwani
(2013)
Effects Of Gambir Extract Treatment On The
Rusted Mild Steel.
Masters thesis, Universiti Sains Malaysia.
Abstract
Uncaria gambir was extracted using six different solvents and the effects on the
extraction yield and phenolic contents were investigated. The phenolic contents,
namely, total phenolic (TPC), total flavonoid (TFC), condensed tannin (CTC) and
antioxidant activity (AA) of the gambir extracts were quantified. Ethyl acetate
solvent was found successfully extracted the highest TPC (93% catechin equivalent),
TFC (91% catechin equivalent) and CTC (96% weight). Besides, the phenolic
content shows the ability of gambir extract as antioxidant. The performance of
gambir extract as rust converter was evaluated. The effects of gambir concentration,
pH solution, contact time and the addition of phosphoric acid in rust converter were
studied. The FTIR spectra showed that the conversion of lepidocrocite (γ-FeOOH)
was the fastest, followed by magnetite (Fe3O4) and goethite (α-FeOOH) was the
slowest. The effectiveness of rust conversion coatings was studied via EIS and
potentiodynamic polarization. The Tafel and Nyquist plots analyses were in
agreement showing that increasing the gambir concentration decreased the corrosion
rate and the mixture of 10% gambir and 5% H3PO4 produced a better rust converter.
The changes in morphology of the rust were significant as viewed by SEM analysis.
The spike-shaped rust was converted into a more homogeneous and compact surface
after treatment with rust converter. XRD patterns showed a decrease of the rust
products after being treated with gambir-based rust converter.
Actions (login required)
 |
View Item |
