Formation of enhanced gelatum using ethanol/water binary medium for fabricating chitosan aerogels with high specific surface area

Abstract

Acquiring high specific surface area (SSA) is a crucial reason why aerogels possess diverse unusual functionalities both in nanoscale structures and macroscopic properties. Although biomass aerogels can remedy the mechanical brittleness in contrast to conventional silica aerogels, regrettably causing a major decrease in SSA aspect. Here we present a generalizable synthetic means towards a family of chitosan aerogels (CAs) with large internal surface area, originating from chitosan sols in ethanol/water binary medium. The as-prepared CAs show high SSA of 973m2g−1, appropriate texture homogeneity and thermal stability, attributing to uniformly inter-associated structures. We found an emergent phenomenon that free-standing wet chitosan gel could be still produced despite greatly lowering its substance concentration, attesting the remarkable role of ethanol for promoting gelatum formation. This enhancement to gelation is due to the introduction of micro-dispersed active phases upon ethanol/water excitation, easily forming fine interconnected skeletons of CAs. The adsorption tests of CAs for abatement of methyl orange (MO) verify that dye-treated water almost recovers into pure one, well in line with the evidence of high SSA CAs. A convincing explanation for gelling and cross-linking is also analyzed. Our work facilitates to explain the generation mechanism of gels in binary solvents for the creation of CAs with high SSA.