Percorrer por autor "Mendes, Sandra S."
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- Re-utilization of sewage sludges as a precursor for activated carbon productionPublication . Gutiérrez, Maria S. C.; Rocha, Maria J.; Mendes, Sandra S.; Freitas, Maria Madalena; Silva, Paula; Beleza, VitorinoThe possibility of re-utilization of sewage sludges from wastewater treatment plants as raw-material for activated carbon production was investigated. Activated carbons were prepared from secondary sludges by physical activation with carbon dioxide. Pyrolysis was carried out in nitrogen atmosphere at 873 K during 3 h. Physical activation was performed in pure CO2 flow, for 1h, at temperatures between 1123 and 1223 K. Global yields of the process range from 30 to 4o wt %. Activated carbons have surface areas from 60 to 100 m?/g and micropore volumes up to 0,020 cm3/g. Porous structure presents about 50% microporosity. A chemically activated sample (H.SO,, 973 K, 15 min, N, flow) was also prepared for comparative purposes. Results show that activated carbons produced have potential to be used as pollutant adsorbent, but further optimization studies will be needed in order to improve its porous structure.