Microwave-Assisted Extraction of Polyphenols from Eucalyptus Bark-A First Step for a Green Production of Tannin-Based Coagulants

• Type: Article in International Scientific Journal
• Date: 2023

Authors

Tomasi, IT (Author) Other; Santos, SCR (Author) Other; Boaventura, RAR (Author) Other; Cidália Botelho (Author) FEUP

Journal

Title: Water

Vol. 15

Final page: 317

ISSN: 2073-4441

Publisher: MDPI

Indexing

ISI Web of Knowledge - 0 Citations

Scopus

Other information

Authenticus ID: P-00X-V9Z

DOI: 10.3390/w15020317

Abstract (EN): Tannins are natural polyphenolic compounds widely found in plants. The production of natural coagulants for water treatment is one of their new applications. Polyphenols extraction is the first step for synthesizing tannin-based coagulants. Eucalyptus globulus bark (EGB), an abundant by-product of the pulp and paper industry, usually applied as fuel for energy production, was used in this work as a tannin source. The extraction of polyphenols from EGB was studied using water as a solvent. Extraction assays employing different extraction techniques were conducted. Microwave-assisted extraction showed superior performance and was further optimized. The influence of irradiation time, water-to-bark ratio, and temperature were evaluated using Response Surface Methodology. The extraction yield and the total phenolic content of the extract were modeled as function of the extraction conditions. The overall best conditions that maximize both responses were obtained through multi-response optimization. Optimized values (15% of extraction yield and a phenolic content of 354 mg of gallic acid equivalents per gram of extract) were predicted for an extraction time of 15 s, a liquid-to-solid ratio of 48.5 mL/g, and 141 degrees C. The extract generated under these conditions presented a condensed tannin content of 645 mg/g, expressed in terms of catechin equivalents. EGB presented good tannin-extractable contents to produce natural coagulants.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 14