4. Conclusions
In summary, for the first time, paper waste can be successfully converted into a green cellulose aerogel with high water
and oil absorption capacities, good thermal insulation, and water repellent properties. The material was prepared via a simple alkaline/urea and freeze drying method. Field-emission scanning electron microscopy revealed the macroporous structure of the material. Water and oil absorption tests showed that the uncoated and the coated aerogels have high liquid absorption capacities of 18–20 times their own weights and can be easily reused by a simple squeezing to remove the absorbed liquid. The aerogel showed good flexibility and mechanical property. Thermal conductivities
of 0.029–0.032Wm−1K−1 were found for the green aerogel confirming that it is an excellent alternative material for thermal insulation applications. With a hydrophobic coating, the material displayed good water repellent property and stability.