“…With the increase in the temperature to 750°C, the weight loss increases to 6.6, 5.4 and 4.66 % (for K-OMS-2RS, K-OMS-2RC and K-OMS-2RA, respectively), which is due to the release of the water molecules inside the tunnels, besides the desorption of the structural oxygen close to the surface (related with the formation of lattice vacancies without decomposition of the material). A weight loss of *1.0, 3.0 and 2.3 % at 750-950°C, and 2.6, 3.1 and 2.5 % at up to 950°C occurred on using K-OMS-2RS, K-OMS-2RC and K-OMS-2RA, respectively, which implies the transformation of cryptomelane to bixbyite (Mn 2 O 3 ) and then to hausmannite (Mn 3 O 4 ) species [23,24], with total weight loss 15.20, 16.40 and 13.06 %. The total weight loss for acetate material (Fig.…”