A Study on the Possibility of Utilizing Coffee Waste as a Recycled Resource Material using Ultrasonic Extraction Method. London Journal of Engineering Research, [S. l.], v. 23, n. 5, p. 33–40, 2023. Disponível em: https://journalspress.uk/index.php/LJER/article/view/600. Acesso em: 2 feb. 2026.