Comparative study on the corrosion behavior of mild steel in effluents, sea and fresh water

Abstract

The corrosion rate of mild steel behavior exposed to effluents (EF), sea water (SW) and fresh water (FW) were study using weight loss, scanning electron spectroscopy (SEM) and x-rays diffraction (XRD). The results show that the weight loss of mild steel in different water samples increases with increasing in immersion time and temperature respectively. The corrosion rate of water was found to be higher in sea water (0.003g cm² week^-2), effluents (0.021g cm^-2 week^-2) and fresh water (0.020g cm^-2 week^-2) respectively. The corrosion rate and behaviour of mild steel in the water sample were affected by some physical and chemical parameters such as pH, turbidity, conductivity and biological oxygen demand (BOD). Effluents (EF) were found to have pH (5.20), turbidity (13.3nut), conductivity (4203µs/cm) and BOD (0.119mg/dm³). Sea water (SW) were found to have pH (7.60), turbidity (173nut), conductivity (30800µs/cm) and BOD (0.028mg/dm³). Fresh water (FW) were found to have pH (7.60), turbidity (127nut), conductivity (419µs/cm) and BOD (0.651mg/dm³). Similarly, the presences of elements such as chloride ion (Cl^-), Fe, Ba, Br, S, La, Nb and Mo from XRF confirm that the corrosion rate is higher in sea water. SEM microgram revealed that corrosion rates of EF, SW and FW were of different nature, both the samples have rough surface with various cracks after immersion. This clearly shows that the sea water has the highest corrosion products follow by effluent than fresh water sample. Both the weight loss and corrosion rate increases as the immersion time and temperature increases.

Keywords: Corrosion rate, Mild steel, Weight loss, AAS, SEM, XRF, Immersion Time, Temperature