Preparation and characterization of a metal-rich activated carbon from CCA-treated wood for CO2 capture

Abstract

The disposal of eucalyptus poles used in the electricity network distribution is considered a potential contamination to the environment due to the chromated copper arsenate (CCA) used as a wood preservative. The thermochemical process can be an alternative to this toxic waste disposal. In this work, the slow pyrolysis of CCA-treated wood followed by the production and application of activated carbon was proposed. Metal retention (ICP-OES), concentration of non-condensable gases produced in the pyrolysis process (via GC), as well as the capacity of activated carbon on CO2 adsorption (via TGA) were investigated. The highest formation rate of non-condensable gases was observed at 500°C, while the maximum H2 concentration was at 700°C. The char obtained in the pyrolysis was chemically treated with H3PO4 and activated in CO2 flow. The pore size distribution of activated carbons showed pore sizes lower than 1nm. The activated carbons showed a CO2 adsorption capacity of 70–83mg/g. The presence of chromium and copper may have influenced the CO2 adsorption. The fast adsorption and desorption showed by the activated carbon produced from CCA-treated wood is interesting to systems that operate in short-time cycles, as pressure swing adsorption (PSA). The reuse of CCA-treated wood for activated carbon production and its application in the CO2 adsorption could be a solution to minimize the environmental damage caused by this waste.