Beeswax-modified biopolymer aerogel: A sustainable approach to hydrophobic oil absorbing materials

Abstract

This study presents for the first time a sustainable approach to hydrophobic modification of nanocellulose/chitosan bioaerogels using beeswax emulsion. The incorporation of beeswax into the aerogel matrix resulted in increasing the density from 35.1 to 298 mg/cm3, while the porosity decreased from 96.4 to 62%. Fourier transform infrared spectroscopy (FT-IR) analysis confirmed the successful integration of beeswax into the nanocellulose/chitosan matrix, with distinct peaks corresponding to the characteristic functional groups of beeswax, such as C–H stretching vibrations, further validating the hydrophobic modification. The mechanical properties showed increased hardness, from 0.24 to 0.95 N/mm2, indicating that higher beeswax content enhanced the rigidity of the aerogels. Contact angle measurements confirmed a dramatic improvement in hydrophobicity, with angles increasing from 47.68 to 134.40 and 128.11° for NC/CH 60-40-15. Water absorption capacity decreased from 17.5 g/g in the control sample to 8 g/g at the highest beeswax concentration, while oil absorption increased significantly, with fresh engine oil absorption rising from 3 to 45 g/g and used engine oil absorption from 2.5 to 40 g/g respectively. These results confirm the successful green modification of bioaerogels using beeswax, providing a sustainable and eco-friendly approach that enhances hydrophobicity, mechanical strength, and selective absorption properties.