The Inhibitive Action of Ocimum gratissimum leaf Extract on Mild Steel Corrosion using the Ultra Violet Light

Abstract

This study investigated on the use of Ultra violet rays to determine its effect on mildsteel coated with Ocimum gratissimum leaf extract.  It was an experimental research that was carried out using two media (the acid and the base), where the HCl served as the acidic medium while NaCl served as the basic medium respectively. Two containers containing 1200mg/l concentration of each corrodent, that is, 1200mg/l of HCl and NaCl respectively were used. Four well-polished coupons having mirror image were weighed and suspended over the corrodents HCl and NaCl respectively and placed in a dark cupboard over a UV light for one week. After one week two coupons were removed weighed, snapped and discarded. The remaining two were sprayed for another one week and kept under the UV light, they were blow dried and snapped for comparism. The results obtained showed that addition of Ocimum gratissimum leaf extract synergistically increased the efficiency of the inhibitor and that the HCl corroded more than the NaCl. The result shows that there was a reduction in the weight of the coupons, indicating that the UV light had an effect on the coupons by reducing the corrosive effect. It is observed that the two coupons in the acidic medium (HCl) weighed 5.0403 before brushing and 4.7697 after brushing and after one week under the UV light, it was observed that they weighed 5.0938 and 4.6082 before and after brushing respectively. The same thing was done for the basic medium(NaCl) and the result showed the weight of the two coupons before brushing was 4.5647 and after brushing was 4.5073 respectively.  After one week it was seen that the weight of the coupons before brushing was 4.8786 and after brushing was 4.7237 respectively. This shows that UV radiation also increased the inhibitor efficiency and that corrosion activation energy increased in presence of the inhibitor. There was a reduction in the weight of the coupons in both media.  It is therefore recommended that a mechanism of adsorption is proposed to explain inhibition behaviour.