Laboratory-scale study on the effect of silicate on copper pipe corrosion

Abstract

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.

Sensitive Detection of Silicon in Aqua Phase by Microwave-Assisted Laser-Induced Breakdown Spectroscopy

“…However, a high silica concentration has a negative impact because it forms a glassy layer on the internal surfaces of turbine boilers, pipes and blades, which causes thermal and steamflow deficiencies when temperatures and pressures are high inside the system [13,14]. In addition, at high concentrations and ambient temperatures, sodium silicate ceases to inhibit corrosion and instead creates corrosion [12,15]. Therefore, techniques employed to monitor silica concentrations include atomic absorption spectroscopy [16], colourimetric methods (yellow and blue silicomolybdic acid procedures) [17], inductively coupled plasma optical emission spectroscopy, inductively coupled plasma mass spectroscopy [18], flow injection [19,20] and laser-induced breakdown spectroscopy (LIBS) [21].…”

Corrosion mechanism of copper immersed in ammonium sulfate solution

“…With desirable electrical conductivity, thermal conductivity, stable chemical properties, good ductility, and plasticity, copper and its alloys are widely used in the fields of electricity, electronics, transportation, energy, marine industry, etc. However, the copper would be corroded by some polluted gases and salt particulates after exposure in the ambient atmosphere, [1][2][3][4][5][6][7][8][9][10][11][12] which can reduce its service life. One of the common salt particles within the rural and industrial atmosphere is (NH 4 ) 2 SO 4 , which would be dissolved to form a thin (NH 4 ) 2 SO 4 solution layer on copper surface when the ambient humidity gets greater than the critical relative humidity of (NH 4 ) 2 SO 4 and consequently gives rise to the corrosion of copper.…”