Electrochemical corrosion characteristics of ductile iron used for municipal drinking water supply pipeline under different pH conditions
In order to solve the deterioration of water quality caused by water supply pipeline corrosion during early stage,the corrosion characteristics of ductile cast iron,under different pH(6,7,8)conditions were explored.The electrochemical corrosion process was monitored by polarization curve and impedance spectrum.The influence of corrosion on water quality and the composition of corrosion scale were discussed.The results showed that the TDS,conductivity and Larsen index of pH 6 treat-ment were significantly higher than those of other treatments(P＜0.05).While the Langelier index was significantly lower than that of pH 8 treatment(P＜0.05),indicating that the corrosion tendency was the highest when pH was 6.The study on the types of corrosion scale products on the metal surface showed that the types of corrosion products under different pH conditions are γ-FeOOH,β-FeOOH,Fe2O3 and Fe3O4,but the corrosion products of the deionized water control group only include y-FeOOH.Study on the corrosion process showed that the corrosion current density(2.54 to 0.13μA·cm-2)of ductile cast iron under different pH treatments increased rapidly and then decreased grad-ually.The corrosion current density was the highest(2.54 μA·cm-2)at pH 6 on the first day.It can be seen that although the municipal pipeline will be corroded in the early stage,when the pH of the water is acidic,i.e.,pH 6,the corrosion tendency will be the highest and the corrosion rate be the fastest.
municipal drinking water supplyductile iron pipescorrosionpHmicroorganismselectrochemical analysis
万方数据
维普
