Quality attributes of commercial charcoals produced in Amapá, a Brazilian state located in the Amazonia

Abstract

The charcoals of Amapa, a Brazilian state located in the Amazonia forest, have been produced from wastes of high-quality native and exotic wood species. However, there is no control to avoid mixing raw materials with different potentials for bioenergy. This work aimed to compare the quality of two brands of Amapa charcoals for domestic use, besides to analyze the variability of properties within and among packages. Charcoals of brands A and B were produced from harvesting wastes of Acacia mangium wood and sawing wastes of mixed native wood species, respectively. Five packages of each brand were acquired, from which thirteen samples were randomly selected for physical and chemical analyses. The higher heating value was estimated from the chemical composition. The brands were compared by analysis of variance or Wilcoxon–Mann–Whitney test. The variability within and between packages was investigated through box plots. The Amapa charcoals showed moisture content (≈ 7.3%) somewhat above the stipulated (5%) by the Brazilian standardization for domestic use. The proper quality of the charcoals was attested by high apparent density (≈ 0.568 g/cm3), high fixed carbon (≈ 87.2%), low volatile matter (≈ 11.7%), low ash content (≈ 1.0%) and high higher heating value (≈ 32,925.40 kJ/kg). The charcoal of the brand B showed better quality considering significant higher average apparent density, no outlier of ash content above the maximum ideal value and overall lower variability within and among packages of the properties. The apparent density greatly varied among packages, while a greater variation within packages was observed for the other properties.