Resorcinol-formaldehyde xerogels; catalyst amount; mechanical properties;surface; adsorption; oxyreactivity

The effect of catalyst amount on properties of resorcinolformaldehydexerogels was investigated. The samples were prepared by solgelpolycondensation of resorcinol with formaldehyde at three differentlevels of catalyst (Na2CO3, molar ratios of resorcinol/catalyst R/C =1000, 2000, 3000). The influence on mechanical, thermal andthermomechanical properties of organic xerogels and on properties ofcarbon xerogels (surface, adsorption and oxyreactivity) was evaluated.The higher R/C ratio leads to increased particle size of the materials,which affects mechanical strength, residual humidity and shrinkage duringheating (all parameters decrease). The R/C ratio does not affectsignificantly pyrolysis process and microporosity of the materials, theeffect on oxyreactivity was negligible. Contrary, higher catalyst content(R/C = 1000) lead to relative high volume of ink-bottle shaped mesopores,but this pores are practically unavailable for adsorption of largemolecules of methylene blue or hydrated chromate anions, which negativelyinfluenced adsorption of both adsorbates from aqueous solution on thecarbon xerogels.