Assessment of chemically modified vegetable tannins as coagulants for water treatment

  • Bruna Ferreira dos Anjos Programa de Pós-Graduação em Ciências Florestais. Escola Agrícola de Jundiaí. Universidade Federal do Rio Grande do Norte (EAJ/UFRN), Rodovia RN 160, s/n, CEP: 59280-000, Macaíba, RN, Brazil.
  • Tatiane Kelly Barbosa de Azevêdo Programa de Pós-Graduação em Ciências Florestais. Escola Agrícola de Jundiaí. Universidade Federal do Rio Grande do Norte (EAJ/UFRN), Rodovia RN 160, s/n, CEP: 59280-000, Macaíba, RN, Brazil.
  • Elaine Cristina Alves da Silva Programa de Pós-Graduação em Ciências Florestais. Escola Agrícola de Jundiaí. Universidade Federal do Rio Grande do Norte (EAJ/UFRN), Rodovia RN 160, s/n, CEP: 59280-000, Macaíba, RN, Brazil.
  • Paula Evanyn Pessoa do Nascimento Programa de Pós-Graduação em Ciências Florestais. Escola Agrícola de Jundiaí. Universidade Federal do Rio Grande do Norte (EAJ/UFRN), Rodovia RN 160, s/n, CEP: 59280-000, Macaíba, RN, Brazil.
  • Kayo Lucas Batista de Paiva Programa de Pós-Graduação em Ciências Florestais. Escola Agrícola de Jundiaí. Universidade Federal do Rio Grande do Norte (EAJ/UFRN), Rodovia RN 160, s/n, CEP: 59280-000, Macaíba, RN, Brazil.
  • Luan Cavalcanti da Silva Programa de Pós-Graduação em Ciências Florestais. Escola Agrícola de Jundiaí. Universidade Federal do Rio Grande do Norte (EAJ/UFRN), Rodovia RN 160, s/n, CEP: 59280-000, Macaíba, RN, Brazil.
  • Alexandre Santos Pimenta Programa de Pós-Graduação em Ciências Florestais. Escola Agrícola de Jundiaí. Universidade Federal do Rio Grande do Norte (EAJ/UFRN), Rodovia RN 160, s/n, CEP: 59280-000, Macaíba, RN, Brazil.
DOI: https://doi.org/10.4136/ambi-agua.2985

Abstract

This research assessed the efficiency of chemically modified tannins as coagulants for water treatment. Tannins from Anacardium occidentale (cashew tree) and Mimosa caesalpiniifolia (‘sabiá’) barks and seedless fruits of Anadenanthera colubrina (‘angico’) and Pityrocarpa moniliformis (‘angico de bezerro’) were evaluated after cationization to remove turbidity from water. After extraction, the total solids content (TSC), Stiasny index (SI), and total condensed tannins content (TCC) of the tannins extracts were determined. Extracted tannins were converted into powders and cationized. Then, the cationized tannins' effectiveness on water turbidity removal, sedimentation time, and effect on pH were assessed. Three concentrations of each type of tannin were used to evaluate flocculant efficiency: 50, 100, and 150 mg L-1. Although the P. moniliformis extract had a higher TSC value (56.06%), it presented the lowest SI (0.42%) and TTC (0.23%) values. M. caesalpiniifolia had the lowest TSC (9.18%) and the highest SI (91.27%), while Ac occidentale stood out with the highest TCC (19.83%). All species have shown potential for tannin production and efficiently removed turbidity at all concentrations. However, only A. occidentale, at a concentration of 100 mg L-1, presented a nephelometric turbidity unit of 2.4, reaching the potability standards required by international specifications and, therefore, being indicated for water treatment.

Keywords: condensed tannins, forest species, natural flocculants, turbidity removal.


Published
02/07/2024
Issue
Vol. 19 (2024)
Section
Papers

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