Study On Preparation And Adsorption Properties Of Fly Ash-Based Porous Geopolymer

Along with the speeding up of the industrialization,the pollution of solid waste and the discharge of effluent containing heavy metals have become one of the main problems restricting social development.Based on the characteristics of local industry,the conception of“using waste treat waste”was proposed to make use of fly ash as raw material to prepare cheap and safe porous geopolymer.By discussing the relationship between a series of single factors in the preparation process and the properties of the materials,the optimized formulation of the materials was analyzed and successfully used in the adsorption of effluent containing heavy metal ions Cu²⁺and Cr⁶⁺,the best preparation technology and adsorption characteristics were obtained by ion concentration test and fitting with classical adsorption model.The influence of temperature,p H value and concentration of heavy metal ions on the adsorption effect was analyzed,and the harmonious coexistence of resources and environment was realized.1)By means of XRF,XRD,FTIR,BET specific surface area and other basic testing methods,the effects of single factors such as the use level of silica fume and foaming agent,the modulus of water glass and curing conditions on the properties of fly ash-based porous geopolymers were analyzed.After comprehensive consideration,the dosage of fly ash is 35g,the amount of silica fume is 9wt%,the modulus of sodium silicate is 1.9 and the amount of hydrogen peroxide is 9wt%in the optimized formulation.At this point,the mole ratio of each oxide in the slurry is Na₂O/Al₂O₃=0.27,Si O₂/Al₂O₃=4.66,H₂O/Na₂O=5.56.2)The computations of ICP-MS/AES analysis indicate that the porous geopolymer based on fly ash has excellent adsorption properties.By comparing the adsorption effect of three kinds of optimized preparation technology materials,and combining the properties of the materials such as crystallinity,porosity and specific surface area,the optimum curing condition of porous geopolymer was determined as NT-1d+80°C.The porosity of the material is 75.54%and the specific surface area is more than 11 times that of the fly ash,which is 38.080m²/g.The removal rates of Cu²⁺and Cr⁶⁺were 95.5%and96.1%respectively,meanwhile the equilibrium adsorption amounts were 151.8mg/g and0.24mg/g severally.In addition,the results show that the adsorption of Cu²⁺and Cr⁶⁺on fly ash-based porous geopolymer accords with the Pseudo-second-order adsorption kinetic model,chemical adsorption is the main process,which accords with the Langmuir monolayer adsorption and the material has a wealth of active sites.Figure 37;Table 23;Reference 59...