Caractérisation du pouvoir entartrant des eaux dures et inhibition du tartre par voie électrochimique et chimique.

Abstract

The ground water Hamma rich in calcium and bicarbonate likely to deposit the tartar and subsequently lead to the obstruction of the pipes and the seizing of the stopping devices in addition to the financial losses resulting therefrom. It is therefore necessary to optimise an antiscaling treatment in order to avoid the risk of formation of tartar deposits in the various installations, and to protect the equipment in contact with this water. Three chemical inhibitors were tested: MgCl2, polyacrylate, and RS1600. The latter is a new green inhibitor that would allow the formation of tartar to be delayed. It is a mixture of vitamins B1 and B6 with a percentage of 50 % for each. To optimise the effective concentration of each product, we used two electrochemical methods (chronoamperometry and impedance) and three chemical methods (rapid controlled precipitation, the technique of degassing CO2 by agitation and technique of CO2 degassing by nitrogen sparge) to identify the best inhibitor and the best method for optimizing antiscaling treatment by chemical inhibition. The results obtained showed that the method of precipitation of calcium carbonate by degassing CO2 by agitation is the most effective method because the coefficient of oversaturation that is reached is closer to the real case avoiding thereafter the overestimation of inhibitors. This study also showed that it is possible to classify the chemical inhibitors according to their efficacy against the formation of calcium carbonate. All methods used revealed that RPI2000 is the most effective inhibitor. IR, RX, Raman spectroscopy, and SEM indicate that the raw waters of Hamma give precipitates in the form of calcite (the most stable form), with the presence of a small amount of magnesian calcite and aragonite. In the presence of the three inhibitors, calcium carbonate changes morphology to other forms that do not exist in the deposit obtained from the raw water (vaterite and calcium carbonate monohydrate).