Evaluation of Orthophosphate Based Corrosion Inhibitors in Treated Water for El Paso Region

Corrosion is an electrochemical phenomenon that involves the deterioration of a metal by the reaction of itself with its surrounding environment. One of the greatest issues for water utilities around the country is to keep the water quality safe. Corrosion can affect the quality of the water that we use on a daily basis by adding a bad taste, increasing the concentration of heavy metals, and allowing outside contaminants to enter the distribution system. The use of phosphate based corrosion inhibitors was tested in two different metals: iron and copper. The phosphate in the inhibitors react with the calcium in the water, creating a coating over the metal, theoretically preventing it from corroding. Several tests were conducted using both metals in order to determine the effectiveness of such inhibitors. It was found that the phosphate content of the inhibitors is directly related to its effectiveness; the higher the phosphate content, the better the results for both iron and copper. Also, the inhibitors work better at higher pH, since at low pH the water is more corrosive. The corrosion indices showed that the water used was very corrosive and aggressive towards metal, but such indices don’t take into account the use of corrosion inhibitors. Therefore, further study to develop an index that considers the effect of inhibitors is recommended