Mesoporous silica from fly ash for environmental applications : CO2 capture and rare earth metal ions recovery

초록

* Mesoporous silica foam (MSF) was prepared via hydrothermal synthesis using fly ash as a silica source. The process was optimized to increase the pore size and pore volume to promote easy accommodation of the guest molecules for subsequent environmental applications. * MSF was impregnated with polyethyleneimine (PEI/MSF), which exhibited a CO2 uptake of 4.6 mmol/g at 75 oC and 1 bar with high CO2 /N2 selectivity. * MSF was functionalized with ethylenediaminetetraacetic acid (EDTA) using (3-aminopropyl) triethoxysilane (APTES) as a spacer and tested as an adsorbent for neodymium ion (Nd 3+ ). The adsorption capacity was ca. 117 mg/g at the optimal pH of 6 with sufficiently fast kinetics, and the adsorbent showed good recyclability. * KIT-6-EDTA and KCC-1-EDTA were prepared via post-synthesis grafting and the obtained KIT-6-EDTA and KCC-1-EDTA.shows the Nd 3+ recovery amount of 110 and 97 mg/g at pH 6, respectively. And the poly(amidoamine) dendrimer (PAMAM)-grafted mesoporous silica foam (G2/PAMAM-MSF) was also prepared applied as an adsorbent for the recovery of Gd 3+ , and the adsorption capacity of G2/PAMAM-MSF toward Gd3+ was estimated to be 132 mg/g at the optimal pH of 6.5.