Vitrification of petrochemical sludge for rapid, facile, and sustainable fixation of heavy metals

Abstract

Highly effective re-utilization of hazardous petrochemical wastes plays important roles in the fields of energy science, environmental remediation, and chemical engineering. To overcome the problems caused by high temperature and long-term molten ablation to the refractory material in the furnace during the vitrification of petrochemical residual sludge, here we present a facile strategy to promote the quick vitrification of petrochemical residual sludge through the temperature-stage disposal of raw sludge, followed by the addition of other doping materials such as SiO2, B2O3, and CaO to form binary SiO2/B2O3- and trinary SiO2/B2O3/CaO-doped slag materials. The obtained results indicate that the sintered slag exhibited quicker vitrification (15 min) against that of the raw sludge (more than 110 min). In addition, the slag reveals higher fixation efficiency towards every heavy metal than sludge, and it is found that the slag exhibited more than 80% enhancement towards the fixation of Zn and As than raw sludge. Based on the obtained results, we propose potential mechanisms on the vitrification and metal fixation of petrochemical sludge and slag. The sustainability of the temperature-stage disposal of sludge is further evaluated using the Sustainability Footprint method (an evaluation method based on sustainability). It is expected that the methods and findings shown in this work are helpful for readers to develop facile techniques to promote the re-utilization of hazardous wastes in the fields of materials science, chemical engineering, as well as energy and environmental science.