Sustainable green conversion of coal gangue waste into cost-effective porous multimetallic silicate adsorbent enables superefficient removal of Cd(II) and dye

Converting solid wastes into new materials for wastewater decontamination is a feasible "one stone, three birds" strategy to achieve sustainable value-added utilization of resources and minimize waste emissions, but significant challenges remain. In response to this, we proposed an efficient "mineral gene reconstruction" method to syn-chronously transform coal gangue (CG) into a green porous silicate adsorbent without using any harmful chemicals (i.e., surfactants, organic solvents). The one of the synthesized adsorbents with a high specific surface area (582.28 m2/g) and multimetallic active centres shows outstanding adsorption performance (adsorption capacities: 168.92 mg/g for Cd(II), 234.19 mg/g for methylene blue (MB); removal rate: 99.04% for Cd(II) and 99.9% for MB). The adsorbent can also reach a high removal rate of 99.05%-99.46% and 89.23%-99.32% for MB and Cd(II) in real water samples (i.e., Yangtze River, Yellow River, seawater and tap water), respectively. After 5 adsorption-desorption cycles, the adsorption efficiency remained above 90%. The adsorbents mainly adsorbed Cd(II) by electrostatic attraction, surface complexation and partial ion exchange and MB by electro-static and hydrogen bonding interactions. This study provides a sustainable and promising platform for devel-oping a new-generation cost-efficient adsorbent from waste for clean water production.