Prepared self-growing supported nickel catalyst by recovering Ni (Ⅱ) from metal wastewater using geopolymer microspheres.

Here, new and effective microsphere adsorbents were synthesized by NaOH activating slag based geopolymer (Na-SGS). These microsphere adsorbents upset the adsorption equilibrium with the maximum Ni adsorption capacity of 414.38 mg/g which is much larger than that of other geopolymer materials. After Ni adsorption from simulated nickel electroplating wastewater, more active positions for the adsorption Ni ions on Na-SGS were provided as shifts from the average pore diameter of 22.00-7.44 nm, the pore volume of 0.06 to 0.25 cm/g, the Brunauer-Emmett-Teller (BET) surface area of 10.46-125.35 m/g and the apparent change of new morphology. Moreover, the adsorbed Ni species were distributed uniformly on Na-SGS. Thermodynamic performance reflected an exothermic, spontaneous and molecular disorder adsorption process, which can be easily controlled by the pH, dosage, initial concentration, contact time and temperature. Through the controllable adsorption, Na-SGS after Ni adsorption (Na-SGS-Ni) was recycled and then reduced to be directly supported nickel catalysts (red-Na-SGS-Ni), which showed superior catalytic activity for CO methanation. Although the highest percent of CO conversation (XCO =99.54%) and methane selectivity (SCH =99.5%) are both at 300 °C, red-Na-SGS-Ni performed good XCO (99.48%) and SCH (98.2%) at low temperatures (100 °C).