Fast-thermoresponsive carboxylated carbon nanotube/chitosan aerogels with switchable wettability for oil/water separation

The use of aerogels to selectively recover oil from oily wastewater is effective but challenging. In this study, a new carboxylated carbon nanotube/chitosan aerogel (CCNT/CA) with switchable wettability was developed as a smart adsorbent for fast oil absorption and oil recovery. Vinyltrimethoxysilane and thermoresponsive poly(Nisopropylacrylamide) (PNIPAAm) was grafted onto the surface of the CCNT/CA skeleton, and the resulting smart aerogel (PNI-Si@CCNT/CA) exhibited temperature responsiveness. PNI-Si@CCNT/CA exhibited an excellent reversible conversion between hydrophilicity and hydrophobicity when the temperature was changed to below or above the lower critical solution temperature (LCST) of PNIPAAm (similar to 32 degrees C). Most importantly, CCNT significantly increased the oil absorption capacity, improved the mechanical properties, accelerated phonon conduction, enhanced thermal conductivity (80.57 mW m(-1) K-1), improved the temperature response rate, shortened the oil desorption time (15 min), and improved the oil/water separation efficiency of PNI-Si@CCNT/ CA because a strong interface interaction occurred between CCNT and chitosan. Moreover, PNI-Si@CCNT/CA absorbed oil at 45 degrees C and released the absorbed oil at 25 degrees C. It maintained its good adsorption performance after 15 cycles, and this was ascribed to its excellent mechanical properties and stable structure.

Automated summary

In this study, a new smart aerogel with switchable wettability was developed for fast oil absorption and oil recovery. The smart aerogel showed excellent performance in terms of reversible hydrophilicity and hydrophobicity, increased oil absorption capacity, improved mechanical properties, enhanced thermal conductivity, and improved temperature response rate.