## 3 Results and Discussion
### Corrosion Protection Effect of GE-EP@OIMs in Various pH NaCl Solutions
#### 3.3.2 Surface Observation of L80 Steel After Immersion Test  
Figure 14 illustrates the microscopic morphology of L80 immersed in NaCl with and without GE-EP@OIMs at different temperatures over a 60-day period. As shown in the figure, L80 without the solid corrosion inhibitor underwent severe corrosion within the 60-day immersion period, with the extent of corrosion increasing as the temperature rose. At 20 \({}^{\circ}\)C, the surface of L80 was uniformly corroded, exhibiting a dimple-like morphology with relatively high surface roughness. At 50 \({}^{\circ}\)C, a few corrosion pits appeared on the surface of L80, while at 80 \({}^{\circ}\)C, the surface was covered with numerous corrosion pits, indicating the most severe corrosion. These corrosion pits are attributed to the Cl\({}^{-}\) ions present in the solution. When the solid corrosion inhibitor was added, the corrosion of the carbon steel was significantly slowed. At 20 \({}^{\circ}\)C, traces of sandpaper polishing were still visible, while at 50 \({}^{\circ}\)C, the surface became smoother and flatter, with lighter corrosion traces. At 80 \({}^{\circ}\)C, small corrosion pits began to appear, and surface roughness slightly increased. The SEM results, aligned with electrochemical and weight loss data, confirm that the GE-EP@OIMs solid corrosion inhibitor demonstrates its ability to provide corrosion protection across a wide temperature range for steel over 60 days at temperature up to 80 \({}^{\circ}\)C.  
Figure 14 clearly differentiates the microstructures of L80 steel with and without the GE-EP@OIMs inhibitor, highlighting the differences in surface morphology. The sample without the inhibitor shows severe corrosion damage with deep pits, while the inhibited sample exhibits a smoother surface with fewer corrosion defects. This indicates that GE-EP@OIMs effectively reduces localized corrosion by forming a protective barrier, minimizing metal dissolution and pit formation. Additionally, the inhibited sample shows a more uniform surface with fewer polishing scratches affected by corrosion behavior, suggesting that GE-EP@OIMs not only mitigates corrosion initiation but also slows down the propagation of corrosive attack. This protective effect is attributed to the controlled release of OIMs, which adsorbs onto the steel surface, reducing aggressive ion penetration and stabilizing the passive film.  
The GE-EP@OIMs solid corrosion inhibitor is particularly well-suited for oilfield applications where corrosion rates are influenced by temperature variations. Due to its temperature-responsive release behavior, it is ideal for downhole tubing, pipelines, and storage tanks exposed to fluctuating thermal environments (20-80 \({}^{\circ}\)C). The material's ability to release inhibitors more rapidly at higher temperatures makes it highly effective in high-temperature, high-salinity, and CO\({}_{2}\)-rich environments, where conventional inhibitors may degrade or require frequent replenishment. Additionally, its solid-state formulation eliminates the challenges associated with liquid inhibitor injection systems, making it a cost-effective and long-lasting solution for corrosion protection in offshore and onshore oil-and-gas operations.