Physico-chemical characteristics of humic acids obtained from urban waste (AH-CRSU) and sewage (AH-LETE) produced in the city of Rio de Janeiro, were determined through elemental analysis, total acidity, spectroscopic methods and electron scanning microscopy. The analysis of structural traits revealed some differences between the humic acids investigated. The presence of aromatic moieties was confirmed with UV-Vis spectroscopy, with more substituted systems present in the AH-LETE. IR spectroscopy showed aliphatic groups in the AH and as more complex signals due the presence of polysaccharides in AH-CRSU. Furthermore, the presence of COOH, COO-, CO2NH2, OH, was observed apart from aromatic systems. The CP/MAS 13C NMR analysis allowed to observed a higher amount of aromatic and COOH groups. showed the presence of polysaccharides, aminoacid N and OCH3 groups. The results allow to define the humic acids from urban source as of the type or like those of pedogenic origin.
Humic substances; compost of municipal wastes; sewage sludge; ultraviolet-visible; infrared; CP-MAS 13C NMR