“…At the end of the experiment, the adsorption efficiency reached 62 ± 3%. It is worth mentioning that other publications in which equivalent copper adsorption efficiencies have been obtained (60–80%), under similar experimental conditions, refer to activation of the starting material by more concentrated alkaline solutions (Na 2 SiO 3 5M − NaOH 10 M) Šuránek, 2023, Baykara, 2022 [ [30] , [31] , [32] ]. In addition, the curing time used in the synthesis of the porous materials was at least 20 °C higher than the temperature used in this work (40 °C).…”