Synthesis of mesoporous silica foams from power plant fly ash and its application: CO2 capture and Nd3+ adsorption

초록

Improper disposal of power plant fly ash is a serious burden to the environment, and its recycle and conversion into a porous silica product can be a useful alternative to bypass the problem. In this work, we prepared a mesoporous silica foam using the sodium silicate extracted from fly ash after acid washing and NaOH fusion. The structure directing agent Pluronic P123 was dissolved in the mixture of hydrochloric acid, trimethylbenzene, NH4F, and de-ionized water at 40 °C for 2 h. Then a solution of extracted sodium silicate was added and the mixture was kept at 40 °C for 24 h, followed by aging at 70 °C for 12h, and calcination at 560 oC for 6 h. The obtained mesosilica foam was examined for two different applications: 1) polyethyleneimine (PEI) was introduced into the pores of the silica foam by wet impregnation and the composite was tested for CO2 capture gravimetrically, and 2) Nd3+ adsorption in water was carried out as a function of the contact time, ion concentration, and pH of the solution using the EDTA-functionalized mesosilica foam.