Distinct nature of biochar and activated carbon from pyrolysis-activation of vegetable (lettuce) and staple food (noodles) in food waste

Food waste contains generally not a single component but a mixture of vegetables like lettuce and staple food like noodles. Vegetables and staple food are distinct in biological structures, and their pyrolysis or activation might generate biochar and activated carbon with varied properties. This was investigated in this study via conducting the initial pyrolysis of lettuce and noodles at 350 or 550 degrees C, and the subsequent activation of the biochar with K2C2O4 at 800 degrees C. The results showed that it was much easier to crack/gasify the organic components in lettuce, producing more gases. The aromatization reactions could take place to a higher extent in pyrolysis of noodles, producing the activated carbon with lower specific area. The activation of the biochar produced at 350 degrees C generated higher overall yields of activated carbon with more developed pore structures. Additionally, the environmental impact of pyrolysis and activation of noodles was milder than that of lettuce.