Study of the risks of the graphene oxide preparation process by reaction calorimetry

The improved Hummers method uses graphite powder as the raw material to produce graphene oxide, whose preparation releases a large amount of heat. This heat release increases the risks associated with the process as it contributes to combustion and explosion accidents. Based on reaction calorimetry, differential scanning calorimetry, scanning electron microscopy, and energy-dispersive spectrometry, the mechanisms underlying such heat release and related hazards are discussed. According to the conditions influencing the heat release, an orthogonal experimental design was applied to quantify the amount of heat released and the oxidation degree during the preparation process. The optimum working conditions were determined in terms of the stirring speed (250 rpm), feeding time (60 min), feeding temperature (0 °C), and temperature of the intermediate-temperature stage (20 °C). These conditions effectively reduce the risks of the overall manufacturing process.