Double-oil-capture design of upcycling waste PP into pH sensitivity and sustainable aerogel for oil-water separation

Oil capture ability suffers from an accumulated cake layer, and the "single oil-absorbing" layer formed by simple hydrophobic modification makes it difficult to establish efficient, visual and sustainable oil/water separation. Herein, a "double-oil-capture" (Cy/M/PP) aerogel was generated via recycling waste polypropylene (PP) and freeze-drying, then depositing anthocyanin coordination complex nanoparticles (Cy/M). Primary oil capture and monitor pH is taken by the "1st capture" from the Cy/M and the "2nd capture" and nanosized effect of the PP aerogel were used as supplementary capture. The aerogel exhibits excellent oil absorption performance (31-82 g/g), stable separation flux (770 L center dot m-2 center dot h-1) of mixtures, and outstanding separation efficiency (99.8 %) of emulsions. Particularly, the aerogel has strong corrosion resistance, and sensitive color development properties, which bestow the additional ascendancy of substantially decreasing the probability of likelihood of developing and persisting defects in the oil absorbent, as well as rapidly monitoring oily wastewater and feedback color signals, thus reducing the cost burden of sustainable management. More importantly, the scrapped aerogel could be reconstituted by re-dissolving in cetane and re-depositing anthocyanin particles with highpurity PP recovery, as well as pronounced the regeneration performance for multiple cycles. This work provides fresh perspectives in the areas of upcycling of waste PP, intuitive monitoring of pH of emulsion, and sustainable recovery of high oil capture absorbents with minimal environmental issues.