Results and discussion
3.1. MgO dissolution
Fig. 1 shows pH and the concentration of Mg2 þ ions over time. The concentration increases after the addition of magnesia in deionized water, due to the dissolution of MgO. Since the Mg2 þ concentration was obtained ex situ by means of IC analysis of the sample’s liquid phase, it was possible to determine a first con- centration value of 38.65 mg L1 at 1 min after the introduction of deionized water. The Mg2 þ concentration profile shows a subse- quent decrease within the following 3 h, which is related to the formation of magnesium hydroxide, which is discussed in detail later. Moreover, the Mg2 þ concentration in equilibrium with MgO and Mg(OH)2 is low, and the decrease is a consequence of the system reaching the equilibrium state.