Silicate in the form of basic silica is used as a copper corrosion inhibitor in drinking water distribution systems. In this work, the effect of silicate on copper pipe corrosion during stagnation was studied. In addition, the effect of silicate and phosphate on copper pipe corrosion was compared. Using a laboratory setup, copper pipe corrosion experiments were performed under controlled pH conditions. Malachite‐scaled copper pipes were used for the corrosion experiments. Each experiment was run for 8 h. The addition of silica into water of pH 6.5 and 7.5 increased the initial release of copper (II) ions into water. As the experiments progressed, small amounts of copper (II) ions were removed from solution by precipitation. Dissolved oxygen was consumed during the process. When phosphate was used as corrosion inhibitor, it initially increased copper (II) ions released in water of pH 6.5. In water of pH 7.5, phosphate reduced the leaching of copper (II) ions. When phosphate and silicate were jointly used as corrosion inhibitors, their combined effect was similar to the effect of phosphate. The silica content of water before and after the experiments did not change. Phosphate was removed from water during the process probably by adsorption on the copper pipe surface.

The application of mathematical modeling and simulation-based tools in chemical science helps to link scientific theories to real-time complex dynamic chemical processes. In this work, Modelica programming language is applied to model the general corrosion of copper pipes during stagnation of water in the pipes. The corrosion process was simulated in OpenModelica simulation environment. The simulation package is based on three general corrosion sub-processes: copper oxidation by dissolved oxygen present in water; precipitation of malachite on the pipe surface; dissolution of malachite from the pipe surface. These sub-processes also affect the physico-chemical quality of water, i.e., pH, alkalinity, ionic strength, chemical complex formation, etc. In the model setup, the chemical reactions describing the processes were first expressed as rate equations. The rate equations and other equations describing the system were then transferred to the OpenModelica software environment.The simulation package was validated by simulating two different laboratory corrosion experiments and comparing the simulation results with the results of the experiments. The developed simulation package effectively simulated generalized copper pipe corrosion during water stagnation in pipes.