The triple action of sulfuric acid on the preparation of carbon-based solid acid from waste toner and its application

Waste toner with high carbon content has the potential to become a carbon material, but its utilization is limited due to the low carbonization yield. In this work, a carbon-based solid acid was prepared by carbonization and sulfonation of waste toner with the aid of sulfuric acid. The characterization of its structure and the evaluation of its properties revealed that sulfuric acid played three roles in the process of carbon-based solid acid prepared from waste toner (WT-CSA). Specifically, this method not only solved the problem of low yield of carbon precursor (CP) obtained by carbonization of waste toner but also introduced thiophene sulfur into the aromatic carbon flakes during the carbonization process. Moreover, thiophene sulfur makes the sulfonation easier, thus increasing the density of -SO3H. In addition, the activity and cyclic stability of the catalyst were evaluated by cellulose hydrolysis. The results show that the catalyst exhibits excellent hydrolytic activity and hydrothermal stability.