Eco-friendly and sustainable synthesis of carbon quantum dots from waste sulfuric acid of alkylation

Waste sulfuric acid of alkylation (WSAA) poses a challenge in industrial alkylation oil production due to its substantial yield and high treatment costs. This study introduces a novel hydrothermal method that ingeniously couples the treatment of WSAA with the synthesis of high-quality carbon quantum dots (CQDs), offering a cost-effective and controllable approach. Through this method, the particle size and surface functional groups of the resulting CQDs can be precisely regulated. The average particle size tunes from 17.97 nm to 2.42 nm via increasing the hydrothermal temperature, and nitrogen-containing groups can be introduced through adding nitrogen sources during hydrothermal process. The prepared CQDs exhibit notable performance in photocatalysis and heavy metal detection, such as CQDs modified graphite carbon nitride has improved photocatalytic degradation ability and Hg (II) detection ability. Additionally, the environmental impact of the proposed method is substantially minimized, demonstrating a smaller footprint on ecosystems compared to conventional industrial disposal processes. Moreover, the economic cost associated with the method is significantly reduced by approximately 48.4 %, further highlighting its efficiency. Utilizing WSAA as a raw material for CQDs not only facilitates the recycling and sustainable utilization of waste but also enables low-cost production of high-performance carbon materials, presenting a mutually beneficial approach.