INFLUENCE OF EPS ON ORTHOPHOSPHATE CORROSION INHIBITION FOR COPPER PIPE IN SOFT WATER

The effects of sodium alginate on orthophosphate corrosion inhibition for copper pipe in simulated soft water were investigated. The results showed that more soluble copper release was occurred in low levels for so- dium alginate. The 2-week aged copper pipe released more soluble copper than the 6, 12-month and 10-year aged copper pipe. The sequence of concentration of soluble copper release was C newC 6mC 12mC 10y. When the initial pH value was low, compared to the system of no sodium alginate, the soluble copper release distinctly increased in the presence of sodium alginate. The amount of soluble copper released from new copper pipe is lower than that from 6, 12-month and 10-year aged copper pipe, which due to the different components of copper corrosion by-products on the surface of different aged copper pipes and the different solubility of different corrosion by-products. The effects of different stagnation times on the concentration of soluble copper release were highly variable which due to the absorption of sodium alginate on the surface of copper surface and the complex between sodium alginate and copper ions.