Preparation of a novel porous adsorption material from coal slag and its adsorption properties of phenol from aqueous solution

摘要

A new porous adsorption material (PAM) was successfully prepared from raw coal slag and characterized by several techniques, including N_2 adsorption-desorption isotherm, thermogravimetric analysis (TGA), flourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), Transmission electron microscope (TEM) and X-ray diffraction (XRD) measurement. The preparation procedure of PAM involved two steps: (1) SiO_3~(2-) chemical leaching from coal slag, and (2) preparation of the PAM. The optimum SiO_3~(2-) leaching condition was confirmed at 30 mL HCl for the pretreated processes, 200 mesh particle size of coal slag, leaching temperature of 100 ℃, reaction time of 2 h, NaOH initial concentration of 30 wt.%, and the ratio of alkaline to slag of 2:1. Under this condition, SiO_3~(2-) leaching yield arrived at 39.42 wt.%, which accounted for 80.78 wt.% of the total content of SiO_3~2 in coal slag. The PAM was then easily prepared with the yield of 99.20 wt.% at 90 ℃ for 4 h with Ca/ Si mole ratio of 0.75:1. According to Langmuir model, the adsorption capability of phenol on the PAM with a maximum uptake was 63.78 mg/g. According to adsorption thermodynamic results, the process was exothermic, thermodynamically feasible, spontaneous and chemically controlled.