What happens to the pH of the environment around the cathode during cathodic protection?

During cathodic protection, the environment around the cathode becomes more alkaline due to the production of hydroxyl ions. This process occurs because, at the cathode, a reduction reaction takes place, where electrons are supplied to the metal being protected, causing the reduction of hydrogen ions or other species in the solution. When hydrogen ions (H⁺) receive electrons, they can be converted to hydrogen gas (H₂) or reduced to form hydroxyl ions (OH⁻) in aqueous solutions. The increase in the concentration of hydroxyl ions raises the pH of the solution, making it more alkaline.

This fundamental electrochemical reaction is crucial in preventing corrosion on the metal surface, as a higher pH environment reduces the solubility of many corrosive species, thus providing better protection. The creation of alkaline conditions is an essential aspect of how cathodic protection effectively slows down or prevents deterioration in metals subjected to corrosive environments.