Pyrolysis of the food waste collected from catering and households under different temperatures: Assessing the evolution of char structure and bio-oil composition

The accumulation of food waste brings several challenges to the economy and environment, its pyrolysis technology has received extensive attention. The present investigation mainly focused on the evolution of char structure and bio-oil composition during the pyrolysis process of the typical food waste, which was characterized by FT-IR, Raman, UV, and GC/MS. The experimental results show that the bio-oil has the highest yield at 400-600 degrees C and remains basically unchanged (around 40%), and decreases apparently at 700 degrees C due to the secondary thermal cracking and reforming. With the increase of temperature, the cracking of macromolecular organic matter in the food waste becomes more intense, resulting in the yield of bio-char gradually decreasing from 34.90% to 23.54% in the range of 400-700 degrees C. The ratio of small aromatic ring systems to large aromatic systems (I(VR+VL+GR)/ID) in the bio-chars increases apparently with temperature, and the amounts of aromatic rings in bio-oil also increase gradually. The content and relative percentage of N-compounds are the largest in bio-oil, and the content of it reaches the maximum value at 500 degrees C, while the changes in its relative percentage are slightly different, which decreases from 33.57% to 24.15% at 400-600 degrees C, and then increases apparent to 40.63% at 700 degrees C. Hydrocarbons are also one of the main components in bio-oil, their relative percentage decreases from 17.70% to 2.40% in the range of 400-700 degrees C. In addition, Carboxylic acid, alcohols, esters, ketones, saccharides, phenols, and other substances are also contained in bio-oil, and its content has different changing trends with temperature.

Automated summary

The pyrolysis process of food waste results in a decrease in bio-char yield and an increase in bio-oil yield with temperature. The bio-oil composition shows an increase in aromatic rings and N-compounds at higher temperatures. Hydrocarbons are the main components in bio-oil, but their relative percentage decreases with increasing temperature.