Spontaneous Combustion Characteristics of Activated Carbon Modified via Liquid Phase Impregnation during Drying

Spontaneous combustion characteristics are important issues for the safe operation of the wet-modified activated carbon drying process. The spontaneous combustion characteristics of activated carbon modified via liquid phase impregnation were fully investigated in this study. The modified activated carbon was prepared using columnar activated carbon and 4-amino-1,2-butanediol solution. Physical properties and surface functional group analyses were performed for activated carbon before and after modification. The ignition temperature of activated carbon before and after modification was then characterized using the methods of GB/T20450-2006, thermogravimetry-derivative thermogravimetry (TG-DTG), and TG-mass spectrometry (TG-MS). At the same time, the activation energy of activated carbon before and after modification was calculated by using thermodynamic analysis. Furthermore, a new self-designed test platform was introduced to investigate the spontaneous combustion characteristics of wet-modified activated carbon under the drying temperatures of 150, 175, 180, and 210 °C. The results show that the specific surface area of Brunauer, Emmett, and Teller (BET) is decreased by 368 m²·g^-1, the total volume of pore size is decreased by 0.17 cm³·g^-1, and the content of oxygen-containing functional groups is decreased by 0.071 mmol/g compared with row activated carbon. The ignition temperatures of the sample before modification characterized by the three methods are 483, 596, and 599 °C, respectively. The ignition temperatures of the sample after modification are 489, 607, and 611 °C, respectively. The activation energy of the modified activated carbon is increased by 35 kJ/mol compared to the original activated carbon. It is concluded that the temperature that triggers the modified activated carbon combustion during the drying process is between 175 and 180 °C, and the heat is mainly gathered at the longitudinal center of the combustion chamber through the investigation of spontaneous combustion experiments. The results in this study can contribute to safe production to prevent combustion in the process of modifying activated carbon during the drying process.