Abstract:

The phase-separation theory was used to prepare the porous silica from silicic gel derived from fly ash. Namely the polyvinyl polymer was added into the silicic sol prepared from high-alumina fly ash, and in the gel process of the silicic sol, the polymer phase separation from the siliceous phase occurred. Then the polyvinyl polymer was removed by calcination, and the porous silica formed. Using this method, the porous silica product prepared in this research has three-class pores. SEM observation shows that the pore diameters of the prepared porous silica are around 1 to 2 μm, with the BET surface area of 12.03 m²/g, corresponding to the diatomite product. The determination of the stability of the prepared porous silica in the Yanjing beer indicated that no ion such as Ca²⁺, Fe³⁺ entered the beer, meanwhile, the pH value of the beer almost kept constant. It is therefore hopeful that the prepared porous silica product, as an equivalence of the diatomite filter, is used in the beer industry.

Key words: high-alumina fly ash, phase separation, porous silica, filter