*3.2. Stability of AAMs*

The stability of as-prepared AAMs was examined by measuring the possible leaching of the main elements of samples (i.e., Al, Ca, Mg, Na, and Si) to the water phase. Before the test, samples were crushed using a jaw crusher, sieved to a particle size of 1–2 mm, washed with deionized water, and dried. Stability tests were performed in a pressurized reactor at 150 ◦C and under a nitrogen atmosphere of 2 MPa. The crushed AAMs at a concentration of 4 g/dm<sup>3</sup> were continuously stirred for 4 h with 0.16 dm<sup>3</sup> of deionized water. The ready leaching of elements was detected by conductivity measurement during and after the test, while the possible dissolution of Al, Ca, Mg, Na, and Si was analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES, Thermo Electron iCAP 6500 Duo, Thermo Fisher Scientific, Waltham, MA, USA).
