Sains Malaysiana 43(7)(2014): 1083–1087

Effect of Scan Rate on Corrosion Inhibition of Carbon Steel in the Presence of

Rice Straw Extract - Potentiodynamic Studies

(Kesan Kadar Imbasan Terhadap Perencatan Kakisan Keluli Karbon

Dalam Kehadiran Ekstrak Jerami Padi - Kajian Potensiodinamik)

SOLHAN YAHYA, NORINSAN KAMIL OTHMAN*, ABD RAZAK DAUD & AZMAN JALAR

School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia

43600 Bangi, Selangor, Malaysia

Diserahkan: 15 Mac 2013/Diterima: 9 Februari 2014

ABSTRACT

The effect of scan rate on the accuracy of corrosion parameter in evaluating the efficiency of rice straw extract as corrosion inhibitor has been studied via potentiodynamic polarization measurement. Scan rate in the range of low (0.1-0.25 mV s^-1), medium (0.5-1.0 mV s^-1) and high (1.5-2.0 mV s^-1) scan were carried out on the carbon steel in 1 M HCl. The corrosion parameters such as corrosion rate, polarization resistance and corrosion current density have been analyzed through Tafel polarization curve. High scan rate gave poor accuracy of corrosion parameter compared to medium and low scan. Medium scan at 1.0 mV s^-1 has been chosen as the optimum scan rate due to the approached steady-state and small disturbance of charged current. As a result, the addition of rice straw extract in 1 M HCl has reduced the values of corrosion current density in both cathodic and anodic reactions signified the corrosion has been inhibited. The efficiency of rice straw extracts as a corrosion inhibitor offer good result as much as 86%.

Keywords: Corrosion; potentiodynamic polarization; rice straw extract; scan rate

ABSTRAK

Kesan kadar imbasan ke atas ketepatan parameter kakisan dalam menilai kecekapan perencat kakisan ekstrak jerami padi telah dikaji menerusi ukuran pengutuban potensiodinamik. Penggunaan kadar imbasan pada julat imbasan rendah (0.1-0.25 mV s^-1), sederhana (0.5-1.0 mV s^-1) dan tinggi (1.5-2.0 mV s^-1) telah dilakukan ke atas sampel keluli karbon dalam medium 1 M HCl. Parameter kakisan seperti kadar kakisan, rintangan pengutuban dan ketumpatan arus kakisan telah dianalisis menerusi keluk pengutuban Tafel. Penggunaan kadar imbasan yang tinggi memberikan keputusan parameter kakisan yang kurang tepat berbanding kadar imbasan rendah dan sederhana. Kadar imbasan sederhana pada 1.0 mV s^-1 telah dipilih sebagai kadar imbasan yang optimum berdasarkan keadaan-mantap yang telah tercapai dan gangguan kecil pada arus tercas. Keputusan menunjukkan penambahan ekstrak jerami padi di dalam 1 M HCl telah menurunkan nilai ketumpatan arus kakisan di kedua-dua tindak balas katodik dan anodik menandakan kakisan telah direncatkan. Kecekapan ekstrak jerami padi sebagai perencat kakisan memberikan keputusan yang baik sebanyak 86%.

Kata kunci: Ekstrak jerami padi; kadar imbasan; kakisan; pengutuban potensiodinamik

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*Pengarang untuk surat-menyurat; email: insan@ukm.edu.my