Behavior of Zinc Sacrificial Anodes in Produced Water Environments Containing CO2 and H2S

Abstract This study investigates the anodic behavior of zinc anodes in artificial seawater environments simulating produced water from gas fields, which often contains corrosive components such as CO2 and H2S. In gas processing facilities, zinc anodes are commonly used for cathodic protection due to safety concerns with other anode types. However, their performance can be affected by environmental conditions. Electrochemical tests revealed that in CO2-only environments, ZnCO3 precipitates on the anode surface, suppressing anodic performance and causing a gradual increase in electrode potential. In contrast, in CO2–H2S mixed environments, ZnS forms instead, resulting in a constant less noble potential. Thermodynamic simulations confirmed the high stability and low solubility of ZnS, even at trace H2S concentrations. These findings demonstrate that the presence of H2S significantly alters the precipitation behavior of zinc, inhibiting ZnCO3 formation and affecting anodic performance. The study highlights the importance of understanding environmental composition in the case of applying zinc sacrificial anodes for corrosion control in systems exposed to CO2 and H2S, contributing to safer and more cost-effective material selection in gas processing operations.