Abstract: A pH sensor device, intended to be inserted into the ground in order to be in contact with a region containing a fluid from the ground, for which fluid the pH is desired to be known, comprising: a pH sensor comprising a surface covered in a polymer material configured to be in contact with the region containing a fluid when the device is inserted into the ground, a metal element having a surface configured to be in contact with the region containing the fluid when the device is inserted into the ground, electrical connection means connected at least to the metal element and configured to receive a cathodic-protection electrical potential for the metal element. The invention also relates to a method for measuring pH that can be used for cathodic protection.

Abstract: A method for preparing a solution including monochloramine includes the steps of: a) in an electrolyzer including an anode area and a cathode area separated by a membrane limiting the migration of hypochlorite ions, forming hypochlorite ions in the anode area by means of the oxidation of chloride ions in an aqueous solution, and forming ammonium ions in the cathode area by means of the reduction of nitrate and/or nitrite ions in an aqueous solution; and b) reacting the ammonium ions with at least one portion of the hypochlorite ions, with a molar ratio of hypochlorite ions to ammonium ions no lower than 1, resulting in the formation of monochloramine.