Preparation And Properties Of Zeolite/Slag Based Porous Geopolymer Microspheres

With the development of modernization,the search for new green and environmentally friendly materials to treat industrial wastewater is becoming more and more urgent.Geopolymers are inexpensive and environmentally friendly silica-aluminates that can be used as construction materials and adsorbent materials for practical engineering applications.Porous geopolymer microspheres are one of the most promising adsorbent materials.However,there are few studies on adsorbents for porous geopolymer microspheres,mostly focusing on powder adsorbents,and since powder adsorbents are not conducive to recycling,there is an urgent need to investigate the preparation methods of microspheres.At present,the common methods for preparing microspheres are mainly template method,stirring method,reverse template method,ice template method and dispersion suspension solidification method.In this thesis,we prepare porous geopolymer composite microspheres by suspension solidification method.Slag(a by-product of the blast furnace iron making process)was selected as the matrix.The slag is polymerized with alkali exciter to obtain slag-based foam material,which has better corrosion resistance,low energy consumption,wide range of sources,low carbon and environmental protection compared with silicate cement.Zeolite is selected as the reinforcing agent.Zeolite can adsorb small organic molecules and can separate from large organic molecules,so zeolite is also called molecular sieve.Zeolite with its own unique pore structure provides a large specific surface area,which can adsorb substances very well.In addition,chemical reactions often occur on the surface of zeolite,which all make zeolite one of the most promising adsorbent materials.In this thesis,different shapes of porous geopolymers were firstly prepared and tested for the adsorption performance of methylene blue,and the results showed that the spherical porous geopolymers were more effective.Then,the composite microspheres of zeolite/slagbased porous geopolymer with different zeolite contents were prepared and analyzed for XRD,FTIR,porosity,open porosity,density,strength,etc.The adsorption performance of the composite microspheres on methylene blue dye was also investigated.In this thesis,different shapes of porous geopolymers were firstly prepared and tested for the adsorption performance of methylene blue,and the results showed that the spherical porous geopolymers had better adsorption effect.Then we prepared porous geopolymer composite microspheres with different zeolite contents and analyzed XRD,FTIR,porosity,open pore rate,density,strength,etc.We also investigated the adsorption performance of the composite microspheres on methylene blue dye.In the next step,the circulation adsorption ability of the composite microspheres was investigated.In this thesis,the adsorption of methylene blue was cycled ten times and the results were analyzed.The performance of the composite microspheres after adsorption was tested with the help of XRD,FTIR,BET,and intensity,and the adsorption results were analyzed.The results showed that the composition of the composite microspheres did not change after ten times adsorption,the mass of the composite microspheres changed significantly,and the intensity slightly decayed,but the adsorption amount and removal rate of the composite microspheres did not change significantly,and the removal rate could still reach 69.51%,which proved that the composite microspheres had good circulation adsorption ability.Finally,the adsorption mechanism of the composite microspheres was investigated,and this thesis focused on the adsorption kinetics,including the first-order kinetic equation,the second-order kinetic equation,and the intraparticle diffusion model.The final fitted results show that the adsorption process of methylene blue in this thesis is in accordance with the first-order kinetic equation,the second-order kinetic equation and the intraparticle diffusion model.In summary,this thesis successfully prepared porous geopolymer composite microspheres with connected multi-level pores,high strength and low cost environment friendly by suspension solidification method with slag as the matrix and zeolite as the reinforcing phase.