Turning municipal food organic waste into activated carbon: A step towards circular economy

• First study of unsorted municipal FW as an AC source for adsorption. • MB adsorption capacity of FW-derived AC and commercial AC was comparable. • Kinetics of MB adsorption on FW-derived AC was faster than on commercial AC. • FW derived AC has potential as low-cost and environmentally friendly adsorbent. Finding a suitable way of managing the growing problem of municipal organic waste is a pressing issue worldwide. Unsorted municipal food waste (FW) was utilized for the first time as an activated carbon (AC) precursor. Varying pyrolysis conditions such as generation steps and carbonization temperature appeared to have a minor impact on AC characteristics compared to higher activation temperature, particularly 800 °C as indicated by a series of physicochemical characterizations. Selected FW-derived ACs were tested as an adsorbent under different experimental conditions to explore their efficacy in removing methylene blue (MB) from water. The adsorption of MB on FW-derived AC occurred in multilayers on heterogenous surfaces whereas the adsorption of MB on commercial AC occurred on a homogenous surface in a monolayer fashion which can be explained by chemisorption. The maximum MB adsorption by FW-derived AC was 47.72 mg/g under the conditions tested, although results indicated that the adsorption capacity had not been reached. Importantly, the kinetics of MB adsorption onto FW-derived AC was substantially faster than adsorption onto commercial AC. The findings of this study suggest that AC prepared from a diverse mixture of municipal FW is a promising, novel, and cost-effective adsorbent to eliminate MB.