Silica monolith synthesis

“Monolith M1 was prepared using tetraethoxysilane (TEOS) as a silica source and the cetyltrimethylammonium bromide (CTAB) as surfactant. The methodology for the preparation of this sample was based on the literature 37. The experimental procedure consisted of adding ethyl alcohol to the aqueous nitric acid solution. Then, the polyethylene glycol (PEG) was dissolved in that solution and when a homogeneous solution was obtained, the TEOS was added. Thereafter, the sol formed was stirred until a clear solution was obtained. The CTAB was added and stirring continued until the surfactant was completely dissolved. The final sol molar composition was 1 TEOS: 0.19 CTAB: 0.25 HNO3: 0.26 PEG: 2 C2H5OH: 14.69 H20. The sample was placed in the oven at 60 ºC. The gelling time was also observed and the sample remained in the oven for another 48 h. The removal of the surfactant was performed through a thermal treatment. The material was heated up to 550 °C at 1° C/min, and kept at this temperature for 6 h. Cooling was carried out at a rate of 10 °C/min to room temperature. The steps involved in the preparation of material M1 can be seen in Fig. 1.”

“The adsorbent material was impregnated to obtain loading of 25 wt% of PEHA. Samples loaded with the amine were identified as: Al/M1-P, Ti/M1-P and Zr/M1-P. The procedure for the impregnation of amines in the porous support consisted in initially dissolving PEHA in ethanol under stirring. Soon after the complete dissolution, the calcined material was enveloped on filter paper and added to the amine solution with ethanol and stirred for about 24 hours. Thereafter, the solvent on the adsorbent was evaporated in the oven at a temperature of 60 °C.”

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