Facile preparation of activated carbon foam via pyrolysis of waste bread under CO2 atmosphere

Activated carbon foam was prepared via direct pyrolysis of waste bread (WB) under CO2 atmosphere. The product was characterized by N2 adsorption/desorption and Fourier transform infrared spectroscopy (FTIR). The preparation process was investigated online by a thermogravimetric analyzer coupled with FTIR (TG-FTIR). The adsorption isotherms of methylene blue (MB) by the product were investigated. The experimental data demonstrated that the product had a high surface area of 1575 m2 g−1 and a total pore volume of 0.883 cm3 g−1. Thermal decomposition of polymers in WB mainly occurred between 200 and 500 °C, leading to the release of carbonyl compounds, aliphatic hydrocarbons, alcohols, and furans. The dominant CO2 activation process started at above 800 °C. The MB adsorption equilibrium data followed Langmuir model with a monolayer adsorption capacity of 403 mg g−1. This study provides a reference for the utilization of WB as a promising precursor of activated carbon foam adsorbent, which has highly porous structure and excellent floatability in water.