Sulaiman, Nur Izzana
(2016)
Trigona sp. And Apis sp. Honey As Natural Corrosion Inhibitor For Aluminium Alloy In 1 M Phosphoric Acid.
Masters thesis, Universiti Sains Malaysia.
Abstract
Dua jenis sampel madu, madu kelulut (Trigona sp.) dan madu lebah (Apis sp.) telah dipilih dan dikaji sebagai perencat kakisan bagi aloi aluminium dalam larutan 1 M asid fosforik (H3PO4). Kajian pencirian telah dijalankan untuk menentukan kumpulan fungsi dalam madu yang bertanggungjawab dalam proses perencatan. Keputusan spektroskopi inframerah Fourier transformasi (FTIR) menunjukkkan kewujudan kumpulan fungsi utama yang boleh memenuhi ciri keperluan sebagai perencat kakisan organik yang baik. Analisis kedua-dua madu dengan menggunakan spektroskopi jisim kromatografi cecair dengan menggunakan kolum C18 fasa berbalik menunjukkan kehadiran asid p-kumarik di dalam madu yang merupakan salah satu daripada sebatian fenolik yang mempunyai kapasiti antioksida tertinggi. Kandungan fenolik dan kapasiti antioksida madu kelulut didapati lebih tinggi daripada madu lebah. Peratusan keberkesanan perencatan (IE %) kedua-dua madu telah disiasat dalam 1 M H3PO4 menggunakan kaedah penentuan kehilangan berat, pengukuran potensiodinamik, dan pengukuran spektroskopi impedans elektrokimia (EIS). Kajian mendapati bahawa IE % kedua-dua madu tersebut bertambah dengan pertambahan kepekatan madu yang digunakan.
Two types of honey samples, stingless bee honey (Trigona sp.) and natural honey (Apis sp.) were selected and studied as aluminium alloy corrosion inhibitor in 1 M phosphoric acid (H3PO4). The characterization studies have been conducted to determine the heteroatoms in honey that are responsible for inhibition process. Fourier transform infrared (FTIR) spectroscopy results suggest the presence of important functional groups that fulfilled the requirement as a potent organic corrosion inhibitor. The analysis of both honeys by liquid chromatography mass spectrometry with a reversed phase C18 column was done and the analysis showed evidence on the presence of p-coumaric acid, one of the phenolic compounds that has the highest antioxidant capacity. The phenolic content and antioxidant capacity showed stingless bee honey have the highest content compared to natural honey. The percentage inhibition efficiency (IE %) of the honeys were investigated in 1 M H3PO4 by means of weight loss method, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurement. These analysis showed IE % for both honeys increased with the increasing of the concentration of honeys.
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