Preparation of geopolymer based on tail coal by thermal activation alkali activation and its adsorption on Pb (Ⅱ)

Based on the problem of rational utilization of coal based solid waste tailings with huge emissions,tail coal based geopolymer (TGP) was prepared from flotation tailings by thermal activation alkali excitation. The effect of thermal activation temperature on the adsorption capacity of TGP for Pb (Ⅱ) was investigated. The physicochemical properties of TGP were characterized by SEM,XRD,FTIR and bet,and the adsorption behavior of TGP for Pb (Ⅱ) was discussed. The results showed that the adsorption capacity of TGP after thermal activation at 800 ℃ was 228.57 mg/g,which was much higher than that of raw coal (64.48 mg/g,6 times of that of raw coal);after the sixth use,the adsorption capacity of all TGP reached more than 80% of the highest adsorption capacity;when the activation temperature was below 600 ℃,the utilization rate of silicon and aluminum in the tailing coal was low;when the activation temperature was above 600 ℃,the adsorption capacity of TGP was higher than that of raw coal all of them were transformed into amorphous materials,and the silicon and aluminum elements were fully utilized;the flotation tailings were mainly composed of irregular particles with dispersed size,and the surface of the tailings was adhered to many powder particles;after the thermal activation alkali stimulation method was used,the structure of the original tailings disappeared,showing a coarse and loose gel shape;when the temperature was 800 degrees,the hydroxyl groups were broken off and the crystal structure was destroyed;the absorption peak at 1 104 cm-1 is Al-O/Si-O asymmetric stretching vibration. The absorption peak at 683 cm-1 and below is due to the symmetric stretching and bending vibration of TO (T=Si or Al) bond in tetrahedron structure,which indicates the formation of geopolymer gel;the specific surface area of TGP is 9 times higher than that of raw coal;TGP adsorption on Pb (Ⅱ) accords with the quasi two level kinetic model.the adsorption of Pb (Ⅱ) by TGP is endothermic and spontaneous. In conclusion,the preparation of TGP from flotation tailings has the advantages of high utilization rate of raw materials,developed pore structure and good adsorption performance,which has good potential industrial application value.