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- Leaching behaviour and ecotoxicity evaluation of chars from the pyrolysis of forestry biomass and polymeric materialsPublication . Bernardo, Maria; Mendes, S.; Lapa, Nuno; Gonçalves, Maria Margarida; Mendes, Benilde; Pinto, Filomena; Lopes, HelenaThe main objective of this study was to assess the environmental risk of chars derived from the pyrolysis of mixtures of pine, plastics, and scrap tires, by studying their leaching potential and ecotoxicity. Relationships between chemical composition and ecotoxicity were established to identify contaminants responsible for toxicity. Since metallic contaminants were the focus of the present study, an EDTA washing step was applied to the chars to selectively remove metals that can be responsible for the observed toxicity. The results indicated that the introduction of biomass to the pyrolysis feedstock enhanced the acidity of chars and promote the mobilisation of inorganic compounds. Chars resulting from the pyrolysis of blends of pine and plastics did not produce ecotoxic eluates. A relationship between zinc concentrations in eluates and their ecotoxicity was found for chars obtained from mixtures with tires. A significant reduction in ecotoxicity was found when the chars were treated with EDTA, which was due to a significant reduction in zinc in chars after EDTA washing.
- Sorption of lead (Pb2+) from aqueous solutions using chars obtained in the pyrolysis of forestry pine, rubber tires and plasticsPublication . Bernardo, Maria; Mendes, S.; Lapa, Nuno; Gonçalves, Maria Margarida; Mendes, Benilde; Pinto, Filomena; Fonseca, Isabel MariaCarbonaceous solid products resulting from thermochemical processes (pyrolysis, gasification), commonly known as chars, are emerging as low-cost sorbents of metallic contaminants, being their effectiveness already demonstrated in several studies (Inyang et al., 2012; Fuente-Cuesta et al., 2012; Ko³odyñska et al., 2012; Quek and Balasubramanian, 2009; Devecia and Kar, 2013). Given the fact that the commercial viability of pyrolysis and gasification plants for the treatment and valorisation of waste streams are increasingly being demonstrated, it is expected that large amounts of solid chars will be available in a near future, as by-products or as main products (pyrolysis-carbonization). Chars may possess several characteristics which turn them effective as heavy metals sorbents: aromatic carbon matrix with relatively porous structures, the presence of functional groups or inorganic inclusions in the surface providing active sites to interact with metallic species (Inyang et al., 2012; Fuente-Cuesta et al., 2012; Ko³odyñska et al., 2012; Quek and Balasubramanian, 2009; Devecia and Kar, 2013; Lu et al., 2012). Lead (Pb2+) is considered as a priority substance in the field of European water policy (EU, 2000; EU, 2008) which means that measures shall be taken by the Member States to eliminate or reduce the water pollution caused by this pollutant in order to fulfill the emission/discharge limits legislated for this compound.