High-value utilization of citrus peel: Efficient extraction of essential oil and preparation of activated carbon

Abstract

This paper describes the high-value utilization of citrus peel waste, in which potassium carbonate (K2CO3) was used to assist the extraction of essential oils and served as the activating agent for the further preparation of activated carbons. A common alkali metal salt, K2CO3, was confirmed to be effective in promoting the extraction of essential oils from citrus peel. Compared to the 2.4 wt% extraction rate of essential oils obtained using regular steam distillation, a 6.2 wt% extraction rate was achieved when the citrus peel was pretreated with a K2CO3 solution. Meanwhile, its chemical composition remained stable, indicating that these additional essential oils can also be directly used in areas that have already been developed in the perfume industry. The solid residue collected after essential oil extraction was further used as the precursor for activated carbons. The specific surface area of activated carbons reached up to 1846 m2/g at a carbonization temperature of 800 ºC, and it exhibited a highly developed microporous structure.