Caracterização de cascas de espécies florestais brasileiras e uso de seus taninos na clarificação da água

Abstract

The general objective of this work was to characterize chemically and anatomically barks from of Myracrodruon urundeuva and Stryphnodendron rotundifolium, and formulate tannin-based coagulants of these species to be used in water clarification. Anatomy and thickness of the periderm and secondary phloem, and also the bark histochemistry were analyzed. Ash, extractives, lignin, and holocellulose content were determined as well as Stiasny index and condensed tannins content. Two types of cationization were performed, one following Mannich reaction and an alternative to formaldehyde was the use of dimethyl carbonate. Barks species presented rhytidome frequently anastomosing periderm layers, forming a reticulate pattern. M. urundeuva was marked by the presence of secretory ducts and dead phloem between the periderms. Dilation phenomena was observed in S. rotundifolium in nonconducting phloem, and in M. urundeuva after innermost periderm. Amount extractives in S. rotundifolium was much higher than in barks of several species. For M. urundeuva tannins the Stiasny index was 66.7%, whereas for S. rotundifolium tannins was 95.1%. The yield of condensed tannins was 11.1% for M. urundeuva bark, and 25.2% for S. rotundifolium bark. FTIR analysis indicated that both cationization processes occurred. Cationized tannins with dimethyl carbonate had low turbidity removal efficiency, however, can be tested as a secondary coagulant agent. No tanninbased coagulant changed the pH of the water. Both barks presented more phenolic content in outer bark than inner bark, in which it is indicated the accomplishment of studies directed to the elaboration of management plan that aim at the sustainable exploitation of these barks. Tannin-derived coagulants produced by Mannich reaction presented satisfactory results for use clarification water.