Preparation and characterization of a novel porous silicate material from coal gangue

Abstract A novel porous silicate material (PSM) derived from coal gangue was successfully prepared and characterized by N2 adsorption–desorption isotherms, thermogravimetric analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and X-ray diffraction measurements. The preparation procedure involved two steps: (1) SiO 3 2 − leaching from coal gangue by both activation and chemical approaches, and (2) preparation of the PSM by reaction of the leachate with Ca(OH)2. It was found that the maximum SiO 3 2 − leaching yield was achieved at calcination temperature of 1000 °C, reaction temperature of 106 °C for 2 h, NaOH concentration of 25%, and the ratio of coal gangue to alkali of 0.5:1. The PSM was then easily prepared from the SiO 3 2 − leaching at 98 °C for 2 h with a Ca/Si ratio of 1.2:1 and the pH value of 12.70. The spectroscopic results showed that the PSM was mainly composed C, Ca, O, Si and Na, in the form of Ca2+, Na+, SiO 3 2 − , and CO 3 2 − ions. Some adsorbed water and/or surface water was observed. The adsorption behavior revealed that the CO2 adsorbed amount on PSM was 36.69 mg g−1 at 293.15 k and ambient pressure with a pure CO2 flow rate of 120 mL min−1 during 90 min.