Water vapor sorption on surfactant-templated porous silica xerogels

Porous silica xerogels are prepared by sol–gel syntheses templated with Brij56 or F127 surfactants. The porous properties of the obtained silica xerogels are characterized by N2 sorption measurements. The F127 surfactant-templated silica xerogel exhibits a pore size distribution peaking at 4.2 nm in the mesopore region, a pore surface are of 510 m2 g−1, and a pore volume of 0.545 mL g−1, while the Brij56 surfactant-templated silica xerogel has a bimodal pore size distribution with maxima at 0.65 nm and near 2 nm in the micropore region, a pore surface area of 739 m2 g−1, and a pore volume of 0.354 mL g−1. Their water vapor sorption properties are evaluated under various relative humidity at 25 and 35 °C using gravimetric technique. The results show that the F127 surfactant-templated xerogel with larger pore size and higher volume could absorb a large amount of water molecules at high humidity and efficiently release it at low humidity, such that it has a large water adsorption–desorption capacity, whilst the Brij56 surfactant-templated xerogel with smaller pore size and larger pore surface area could maintain a high water content even at low humidity levels.

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► Porous silica xerogels have been prepared by sol-gel synthesis templated with oligomeric Brij56 and triblock copolymer F127 non-ionic surfactants.
► The F127-templated silica xerogel has a preponderant mesoporosity, while the Brij56-templated silica xerogel has a high fraction of microporosity.
► The F127 surfactant-templated xerogel could absorb a large amount of water molecules at high humidity, and efficiently release it at low humidity.
► The Brij56 surfactant-templated xerogel could maintain a high water content level even at a low humidity.