Particulate matter (PM) has been always a significant environmental and public health concern due to its adverse effects on air quality and respiratory health. This study evaluates the efficiency of hydrophobic nanostructured bioaerogels as PM filters under both normal and high-humidity conditions. Bioaerogels were prepared using nanocellulose and chitosan and modified with varying concentrations of tetraethyl orthosilicate (TEMS). At normal humidity, the 3% TEMS-modified bioaerogel demonstrated the highest average PM removal efficiency of 91.6%, attributed to its optimized balance of hydrophobicity, porosity, and mechanical strength. Under high-humidity conditions, the unmodified 0% TEMS bioaerogel exhibited a significant decline in performance due to water absorption, reducing its efficiency by over 15% after prolonged exposure. Conversely, the hydrophobic 3% TEMS bioaerogel maintained its efficiency at 91.4%, highlighting its ability to resist water-induced degradation. This study provide valuable insights into the design of bioaerogel-based filters for realworld applications where variable humidity poses a challenge.

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 hydro - phobic 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.

This study investigates the enhanced extraction of sodium alginate (SA) from Dictyota menstrualis using microwave-assisted techniques and its subsequent application in fabricating green thermal insulators. Utilizing optimized microwave parameters, we achieved a notable increase in SA yield, peaking at 18.5%, significantly higher than the 14.2% obtained through conventional methods. This process not only underscores the efficiency of microwave-assisted extraction by improving yield by approximately 30% but also highlights its environmental sustainability due to reduced solvent use and shorter processing times. The study demonstrates that increasing sodium alginate concentration from 1 to 5% enhances the mechanical strength and thermal insulation properties of bioaerogel scaffolds, evidenced by an increase in density from 0.171 to 0.234 g/cm³ and a decrease in porosity from 93.6 to 89.6%. Additionally, the thermal conductivity and diffusivity measurements of 0.065 W/(m·K) and 0.294 mm²/s, respectively, affirm the excellent thermal insulation stability of these scaffolds. The study demonstrates the potential of microwave-assisted extraction as a scalable and eco-friendly approach for biopolymer recovery, and the feasibility of using the extracted SA in creating effective, green thermal insulators, marking a significant step towards sustainable material development.