Fabrication of chitin nanofiber-PDMS composite aerogels from Pickering emulsion templates with potential application in hydrophobic organic contaminant removal

Natural polymers have aroused increasing attention in water treatment but their application in removing hydrophobic organic contaminants (HOCs) was limited due to their hydrophilicity. Herein, hydrophobic aerogels were successfully fabricated from Pickering emulsions stabilized by chitin nanofibers (ChNF) with polydimethylsiloxane (PDMS) as dispersed phase and glutaraldehyde as a crosslinking agent, and their performance in HOCs removal were evaluated. The Pickering emulsions with PDMS ratios of 2.5-20% v/v showed high stability, demonstrating great potential as aerogel templates. The solidified PDMS droplets were evenly distributed within the matrix, contributing to homogeneous and permanent hydrophobicity. The composite aerogels with water contact angles of over 130 degrees could selectively remove non-aqueous phase HOCs from water. The CCl4 adsorption capacity was 521-2820 wt%, depending on PDMS contents. Meanwhile, the mechanical resilience of the composite aerogels was significantly improved, facilitating the adsorbent regeneration by simple mechanical squeezing. The adsorption capacity remained above 85% for 24 cycles. Moreover, the aerogels could also remove dissolved HOCs from water with a maximum adsorption capacity of 1.34 mg/g for 10 mg/L TCE. This work reveals the potential of Pickering emulsions in the fabrication of composite hydrophobic materials from natural biopolymers with promising application in HOCs related water treatment.

Automated summary

This study successfully prepared hydrophobic aerogels from Pickering emulsions stabilized by chitin nanofibers, showing great potential in removing hydrophobic organic contaminants (HOCs) from water. The composite aerogels exhibited high stability, homogeneous hydrophobicity, and selective adsorption capacity for non-aqueous phase HOCs, with improved mechanical resilience and regeneration capabilities. Additionally, they also demonstrated the ability to remove dissolved HOCs from water, highlighting their promising application in HOCs-related water treatment.