Preparation of controlled porosity resorcinol formaldehyde xerogels for adsorption applications

Abstract

The synthesis of resorcinol formaldehyde xerogels was investigated by controlling its porosity for potential use as adsorbents for heavy metals removal from industrial wastewater. Resorcinol formaldehyde carbon xerogels were synthesised by sol-gel polymerization of resorcinol (R) with formaldehyde (F) in the presence of sodium carbonate (C) and then vacuum dried. Resorcinol formaldehyde (RF) gels were synthesised at same temperature conditions with varying resorcinol / catalyst (R/C) and resorcinol / water (R/W) ratios. The influence of R/C and R/W ratios on the pore structure of the xerogels was investigated. Surface area and porosity of the resorcinol formaldehyde gels were analysed by physical adsorption (physiosorption) of nitrogen (N2) at 77 K. The result(s) showed an increase in mesoporosity and pore size as R/C ratio increases. At resorcinol / catalyst (R/C) of 200, the pore size and pore volume increased with increase in R/W ratio. From the result, it can be concluded that the resorcinol / catalyst (R/C) and resorcinol / water (R/W) ratios are two contributing factors to determining the pore structure of the xerogels.