Study On The Corrosion Mechanism And Residual Chorine Decay In Reclaimed Water

Lack of water is more and more obvious, reclaimed water is widely used in order to solve the problem. But the quality of reclaimed water restrict this, and the corrosion problems are concerned about more and more. This paper research the rule of residual chlorine decay and mechanism of iron corrosion. The author would like to provide a reference for improve the stability of water quality.On the basis of the experience of network water supply, the paper consider the decay of reclaimed water conform to first-order reaction kinetics equation. Though static test and dynamic test, simulate the pipe wall corrosion on chlorine decay on different temperature and chlorine concentration and confirm the attenuation constant. The result find a positive correlation between temperature and the two attenuation constants, a negative correlation between chlorine concentration and the two attenuation constants. Aarrive at results by fitting the attenuation constant. Paper find temperature and the attenuation constants of residual chorine decay are exponentially-correlated, while they the are lower exponentially-correlated to the attenuation constant of pipe wall corrosion on chorine decay. On the side, the chlorine concentration and the attenuation constants of residual chorine decay are inearly dependent, but we didn’t find any correlations between the chlorine concentration and pipe wall corrosion on chorine decay. So, it need more reseachers do more. In the end, this paper consider the first-order reaction kinetics equation is more applicative to residual chorine decay than it to pipe wall corrosion on chlorine decay. Also, we can try the second-order reaction or the mix of the first-order and second-order reaction to fit the pipe wall corrosion on chlorine decay.This paper measure the corrosion rate of carbon steel in the reclaimed water by weight loss method, and find the trend is increased and decreased after a period of time, then leveled off finally. Characterized the morphologies and structures of corrosion products by scanning electron microscopy, transmission electron microscopy. The results are more stronger passivation coating were taked when the chorine concentration is lower than 7mg/L, passivation coating wouldn’t be taked when there dindn’t have disinfector, too more disinfector can destroy the passivation coating. Aslo, the paper verify the results though the electrochemical method. Qualitative and quantitative analysis the corrosion products by X-ray diffraction. Come forward a corrosion model based on all above.