RESORCINOL-FORMALDEHYDE (RF) AEROGEL MICROBEADS VIA DROPPING METHOD

Abstract

RF aerogels have received much attention due to their properties include high porosity ( 80%), high surface area ( 400 m2/g), low thermal conductivity (0.012 W/mK) and low density (0.03 g/cm3). The pyrolysis of RF gels resulted in the development of nanostructured carbon aerogels. They find applications in various field such as adsorption, catalysis, electrochemical storage, foundries, etc. Most of the researchers focussed on the development of monolithic RF and carbon aerogels, which are liable to defects and required long and costly processing. Hence, an alternative method to produce RF aerogel microbead is of current interest. A common way to produce RF aerogel microbeads is by an inverse emulsion approach. The beads produced are polydisperse in nature and required additional washing. To the best of our knowledge, no reports were available on the production of RF aerogel microbeads by dropping method. It is quite challenging to shape RF sol as spherical beads because of their low viscosity. Here, we aimed to improve the viscosity of the RF sol by the addition of polysaccharide-based thickener and achieved the bead formation. The production of RF microbeads by dropping of pre-gelled RF sol with thickener into an acid bath has been successfully achieved. The influence of the thickener concentration, gelation baths and initial pH of the sol have been investigated. The average sizes of the RF beads were found to be in the range of 2.18-2.56 mm. IR spectra of RF beads confirmed that additive does not influence or hinder the polycondensation of the precursors. BET surface area of the RF beads were in the range of 10-30 m2/g. SEM images revealed that RF particles grow along the fibers and are interconnected by the fibers from the thickener. The bulk production of the microbeads will be tested using Jet Cutter technology.