# Slow pyrolysis of Terminalia catappa L. municipal solid waste and the use of the aqueous fraction produced for bovine mastitis control

## TL;DR

This paper explores using Terminalia catappa waste for pyrolysis to create products that can help control bovine mastitis.

## Contribution

The study introduces a novel use of Terminalia catappa municipal waste through pyrolysis for producing antimicrobial aqueous fractions.

## Key findings

- The pyrolysis process yielded an aqueous fraction with significant bactericidal activity against mastitis-causing bacteria.
- The aqueous fraction showed low cytotoxicity against mouse cell lines, indicating potential safety for use.
- The aqueous fraction was found to contain phenols and other compounds that may contribute to its antimicrobial properties.

## Abstract

The Terminalia catappa L. tree is an ornamental and shade tree producter of a large amount of biological waste sent to landfills. Therefore, this plant constitutes so-called municipal solid wood waste (MSWW), which causes undesirable impacts on the environment, such as the generation of methane through the action of microorganisms. Sustainable solutions for the proper use and disposal of MSWW are a topic that has assumed great relevance at present due to the high quantities of MSWW generated worldwide. Pyrolysis constitutes an attractive alternative for the sustainable use of MSWW to produce higher value-added products. This study investigated the slow pyrolysis of Terminalia catappa L. fruit and the use of the aqueous fraction produced for bovine mastitis control. We obtained four fractions from the pyrolysis process, with average yields of the aqueous phase (36.22 ± 2.0 %), bio-oil (5.52 ± 0.4 %), biochar (37.55 ± 2.8 %) and gas (20.71 ± 2.0 %). The aqueous fraction was extracted with organic solvents and analyzed by gas chromatography coupled to mass spectrometry (GC‒MS). The extracts were composed mainly of phenols (50 %), furan derivatives, cyclic ketones, and others with lower contents, such as alcohols and esters. The aqueous fraction had bactericidal activity against Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa and Escherichia coli, which are responsible for bovine mastitis. In addition, the fraction showed low cytotoxicity against a murine melanoma cell line from a C57BL/6J mouse, B16F10 cells and mouse peritoneal cells.