Resorcinol–formaldehyde aerogels (five samples, three of them with addition of nitrogen containing precursors—3-hydroxypyridine, 3-aminophenol and melamine) have been prepared by sol–gel polycondensation, subcritical drying and pyrolysis. The pyrolysis of prepared organic aerogels has been studied by non-isothermal TG at constant heating rate. The process of pyrolysis has been found to consist of three steps with the total mass loss 40.2–61.7% (room temperature—1,000 °C). The resulted carbon aerogels have been tested as sorbents of Ni(II), Pb(II) and Cu(II) ions from aqueous solutions. Various relations have been found among the results obtained from the pyrolysis experiments and properties affecting adsorption. Besides the expected correlation between the mass loss gained from TG (isothermal step at 500 °C was applied) and from heating in the laboratory oven, the relationship between the mass loss during pyrolysis and sorption capacities for all three metal ions has been found. Other relations among pyrolysis behaviour, surface area and content of nitrogen have been also examined. Batch adsorption experiments show (with an exception of one sample) that N-doped samples have higher adsorption capacity for metal ions. In addition, changing of nitrogen functionalities during the pyrolysis has been considered and pyridinic-N (N-6) functionality has been contemplated as a suitable structure for the adsorption process.
1. PekalaRW, KongFM. A synthetic route to organic aerogels—mechanism, structure, and properties. J Phys Colloq. 1989;50:33–40.
PekalaRW, KongFM. A synthetic route to organic aerogels—mechanism, structure, and properties. J Phys Colloq. 1989;50:33–40.)| false
Kim, P-H, Kwon, J-D, Kim, JS. The impregnated synthesis of polypyrrole into carbon aerogel and its applications to photovoltaic materials. Synth Met. 2004;142:153–160. 10.1016/j.synthmet.2003.08.006.)| false
Kadirvelu, K, Goel, J, Rajagopal, C. Sorption of lead, mercury and cadmium ions in multi-component system using carbon aerogel as adsorbent. J Hazard Mater. 2008;153:502–507. 10.1016/j.jhazmat.2007.08.082.)| false
Meena, AK, Mishra, GK, Rai, PK, Rajagopal, C, Nagar, PN. Removal of heavy metal ions from aqueous solutions using carbon aerogel as an adsorbent. J Hazard Mater. 2005;B122:161–170. 10.1016/j.jhazmat.2005.03.024.)| false
Pels, JR, Kapteijn, F, Moulijn, JA, Zhu, Q, Thomas, KM. Evolution of nitrogen functionalities in carbonaceous materials during pyrolysis. Carbon. 1995;33:1641–1653. 10.1016/0008-6223(95)00154-6.)| false