Simulation studies on corrosion of stone coated roofing sheets sold in Nigeria

Abstract

ABSTRACT. Acid rain condition were simulated on three selected stone-coated roofing sheets sold in Nigeria to assess the rate of metallic dissolution using (0.25, 0.50, 0.75, and 1.00 M) concentration of sulfuric acid, simulated acid rain (0.5 M  of HCl, HNO₃ and H₂SO₄) for 30 days in a controlled environment. Six metals (Pb, Fe, Zn, Al, Si, and Cd) concentration were determined using same concentration of sulfuric acid and distilled water for three hours at elevated temperature of 55 ºC. The results showed that as concentration increases across the three samples, the corrosion rate of stone-coated roofing sheets increases. The analysis of variance (ANOVA) showed that the weight loss of the samples were significant by all input variables. The fourth order polynomial model conducted for weight loss and corrosion showed best fit with regression (R²) which ranged from 0.95 and 0.99 across three samples except for 1.00 M of sulfuric acid at 0.8953, 0.8862, and 0.8933 for Sample 1, 2 and 3, respectively. Metal dissolution conducted for three hours showed that zinc had highest dissolution across different concentration, followed by iron respectively, aluminum dissolved at 0.75 M sulfuric acid; lead dissolved at 0.25 M, 1 M and distilled water while silicon and cadmium had relatively low dissolution accordingly. Acid rain has negative impact on corrosion stone-coated roofing sheets thus influencing its lifespan and durability.

KEY WORDS: Simulation, Acid rain, Metal dissolution, Corrosion, Stone-coated roof, Nigeria

Bull. Chem. Soc. Ethiop. 2021, 35(2), 461-470.

DOI: https://dx.doi.org/10.4314/bcse.v35i2.18