Investigation of Balanced Feedstocks of Lipids and Proteins to Synthesize Highly Effective Rejuvenators for Oxidized Asphalt

This paper examines the merits of coliquefying high-protein algae with high-lipid swine manure to form a bio-oil containing a high concentration of nitrogen-containing fused aromatics to intercalate into oxidized asphaltene nanoaggregates. Such bio-oils can rejuvenate the aged asphalt found in the reclaimed asphalt pavement by restoring the aged asphalt binder's original chemical balance and molecular conformation. In this study, several combinations of high-protein algae and high-lipid swine manure were used to develop biorejuvenators having different concentrations of alkane chains, nitrogen-containing functional groups, and fused aromatics. The study results showed that biorejuvenators made from a combined biomass of algae and manure are more effective than biorejuvenators made from either algae or manure individually, owing to the synergy between lipid-rich swine manure combined with protein- and nucleic acid-rich algae. This blend is called "Swilgae"in this paper. Although all the blends of algae and manure were found to be effective rejuvenators, the blend obtained by liquefaction of a feedstock containing a 4:1 ratio of algae and swine manure was found to be the most efficient combination studied. Our computational analysis showed that molecules present in the Swilgae biorejuvenator have the potential to weaken the π-πinteractions within asphaltene stacks and consequently decrease the size of oxidized asphaltene nanoaggregates. In addition, these molecules have a peptizing effect on oxidized asphaltene molecules and are capable of distributing small asphaltene aggregates throughout the medium. The outcome of the study provides an in-depth understanding about rejuvenation mechanism and highlights significant effects of rejuvenators' chemical composition on their efficacy.