T. Frenţiu, M. Ponta, A. Mihălţan, E. Cordoş, M. Frenţiu, G. Lăzăroiu, L. Traistă, R. Indrieş, Qualitative Assessment of Heavy Metals Sources in Pitcola/Biomass Briquettes Combustion Using Multivariate Statistical Analysis, J. Optoelectr. Adv. Mater., 11 (2009) 697 – 710

Title: Qualitative Assessment of Heavy Metals Sources in Pitcola/Biomass Briquettes Combustion Using Multivariate Statistical Analysis

Abstract: The study based on multivariate statistical approach revealed new information about source of elements during the combustion of pitcoal/biomass(sawdust) briquettes. The Principal Components Analysis showed that the pattern of total element contents was defined by four latent factors explaining more than 92 % of the total variance of the system. According to their source these factors were associated to species coming from: sedimentary minerals from pitcoal (33.9%); biomass (37.8%); silicates from pitcoal (11.5%); reducible species from pitcoal (9.2 %). Four latent factors with variance over 85 % explained the sources of water available species: free metal ions (32.5 %); adsorbed on secondary Al minerals (24.4 %); reducible species retained on oxides (14.5%); biomass (14.2 %). The contribution of variance to element pattern was higher from pitcoal than biomass, since the latent factors attributed to pitcoal explained 54.6% of the variance for the total and 71.4% for the water leachable content, respectively. Results were confirmed by the cluster analysis that highlighted three groups of elements according to their affinities as well as samples clustering according to their nature. The Pearson’s positive correlations among Fe and Al and most of trace elements attested their natural origin in both pitcoal and biomass, free from anthropogenic input.

Key words: Pitcoal/biomass briquettes, Principal components analysis, Cluster analysis, Pearson’s correlation