A multifunctional bio-agent for extraction of aged bitumen from siliceous surfaces

This paper reveals the working mechanisms of a hybrid bio-oil (HY) which plays as a multifunctional agent by desorbing bitumen molecules from siliceous surfaces and peptizing them within the bitumen colloidal structure. This in turn counteracts some of the negative effects of bitumen's aging. Recently, it was found that aging increases associated interfacial bonds at the bitumen-stone interface and promotes self-association of bitumen molecules. These negatively affects bitumen extraction from siliceous substrates, such as shale, and bitumen recycling from aged roads, airports, bridge decks, and roofs to name a few. Abovementioned extraction and recycling involve detachment of molecules of aged bitumen from stone aggregates and adequately peptizing them within the bitumen matrix. Here, we used molecular modeling and laboratory experiments to elucidate how HY facilitates the detachment and subsequent peptizing of bitumen molecules while ensures the durability. Our modeling showed that HY has two important properties: HY is a strong peptizing agent due to its interactions with molecules in aged bitumen; and HY supersedes molecules of bitumen for adsorption to siliceous surface due to HY's higher affinity toward silica active sites. According to our results, heterocyclic HY molecules (1-butyl-Piperidine and N-methyl-2-Pyrrolidone) lead by neutralizing the polar interactions between oxidized bitumen and silica, thus providing an opportunity for other HY molecules to intercalate into the interface and replace the oxidized bitumen on silica. Thus, HY makes a promising rejuvenator, which can revitalize aged bitumen by simultaneously desorbing and peptizing aged bitumen molecules. HY's preferential adsorption to silica combined with its high resistance to be replaced by water further helps improve the resistance of revitalized bitumen to moisture-induced damages, evidenced in our experiment. Therefore, HY can be a promising multifunctional bio-agent for extraction and recycling of bitumen to promote environmental sustainability and resource conservation.