The influence of sodium alginate on the structural and adsorption properties of resorcinol-formaldehyde resins and their porous carbon derivatives

A series of carbon composites were synthesised by carbonisation of resorcinol-formaldehyde resin mixtures with the addition of different amounts of sodium alginate (SA) and compared with a composite prepared using Na2CO3 as a catalyst for the polymerisation reaction. The effect of operating parameters such as SA concentration and polycondensation time on the structural and morphological properties of resorcinol-formaldehyde resins (RFR) and carbon-derived composites was investigated for further use as adsorbents. The synthesised composites were characterised by FTIR, SEM, Raman spectroscopy and N-2 adsorption/desorption techniques. It was found that the morphology, specific surface area (S-BET similar to 347-559 m(2)/g), volume and particle size distribution (similar to 0.5-4 mu m) and porosity (V-por=0.178-0.348 cm(3)/g) of the composites were influenced by the concentration of SA and the synthesis technique and determined the adsorption properties of the materials. It was found that the surface of the filled chars was found to have an affinity for heavy metals and has the ability to form chemical bonds with cadmium ions. The maximum sorption capacities for Cd(II), i. e. 13.28 mg/g, were observed for the sample synthesised with the highest SA content. This confirms the statement that as-synthesised materials are promising adsorbents for environmental applications.