Computation-Guided\nRemoval of 6PPD from End-of-Life\nWaste Tires

The increasing rate of fish morbidity and grave concerns\nregarding\nthe long-term implications on human health with exposure to <i>N</i>-(1,3-dimethylbutyl)-<i>N</i>′-phenyl-<i>p</i>-phenylenediamine (6PPD) from waste tires have brought\nto light the urgency to isolate this compound in the environment.\nToward this end, we focus on removing 6PPD from waste tires by using\nsolvent-based extraction. However, a major challenge in solvent-based\nextraction is identifying a conducive solvent that is nontoxic, efficient,\nand economically and environmentally feasible. Thus, we developed\na physics-informed computational methodology for identifying conducive\nsolvents to extract 6PPD from waste tires. The methodology spans various\nscales from quantum mechanical calculations to process development\nand environmental impact. Starting with a database of 2000+ solvents,\nwe sequentially screened the database to identify 7 candidates. This\nwas followed by a detailed investigation of these candidates from\n economic and environmental perspectives. We subsequently performed\nexperimental verification of these solvents for the extraction of\n6PPD from crumb rubber using batch microwave-assisted extraction.\nThe developed physics-based methodology could be applied to solvent\nselection in other applications as well.