Preparation and properties of tea polyphenol nanofoamed gel for preventing coal spontaneous combustion

The current technologies employed to prevent the spontaneous combustion of coal, such as grouting, inert gas, retardants, gels and foams have the disadvantages of high pollution, easy failure at high temperature, and high cost. In this study, in order to develop an environmentally friendly, efficient and low-cost composite gel material to inhibit coal spontaneous combustion, tea polyphenols were added to the gel for grafting, while nanomaterial halloysite nanotubes were introduced for intercalation reaction. Finally, sodium bicarbonate and acetic acid were used as foaming agents to produce tea polyphenol nanofoaming gels. The microscopic characterization of the composite gel was studied using X-ray diffraction experiments and scanning electron microscopy. Experiments on physical properties such as fluidity, thermal stability and adhesion were also carried out. In addition, fire performance studies such as thermogravimetric experiments, oxidation kinetic analysis, infrared spectroscopy of gas products, analysis of the change law of active functional groups and crossing-point temperature analysis were completed. The results show that composite gel renders the activity of active functional groups inert, which inhibits coal spontaneous combustion, while it can cover the surface of coal and plug the fissures efficiently. Therefore, it is an ideal material to inhibit the spontaneous combustion of coal.