Pyrolysis of Colombian spent coffee grounds (SCGs), characterization of bio-oil, and study of its antioxidant properties
Dionisio Humberto Malagón Romero, Andres C. Torres-Velasquez, Lizeth Katherine Tinoco Navarro, Juan Pablo Arrubla Vélez
Abstract
Coffee is the second most consumed beverage in the world. Spent coffee grounds (SCGs) are promising raw material for pyrolysis. The Kissinger-Akahira-Sunose model (KAS) and Ozawa-Flynn Wall (OFW), determined the pyrolysis activation energy to be 142.40 and 66.08 kJ/mol, respectively. The pyrolysis products were bio-oil with a 22.5% yield and a calorific power of 28.91 MJ/kg. The bio-oil composition was 50.86% fatty acids, 31.65% linear hydrocarbons, and 11.31% aromatics, as determined by GC-MS. The total phenolic content (TPC) was 362 ± 44 mg GA g−1, with DPPH activity of 24.8 ± 2% inhibition and antioxidant activity of 108.5 ± 13.6 mg L−1 of Trolox equivalents. The results showed that bio-oil could be used as a biofuel and a source of chemical compounds.