Sustainable Wax Coatings Made from Pine Needle Extraction Waste for Nanopaper Hydrophobization

Abstract

We combine renewable and waste materials to produce hydrophobic membranes in the present work. Cellulose nanopaper prepared from paper waste was used as a structural component for the membrane. The pine wax was reclaimed from pine needle extraction waste and can be regarded as a byproduct. The dip-coating and spray-coating methods were comprehensively compared. In addition, the solubility of wax in different solvents is reported, and the concentration impact on coating quality is presented as the change in the contact angle value. The sensile drop method was used for wetting measurements. Spray-coating yielded the highest contact angle with an average of 114°, while dip-coating reached an average value of 107°. Scanning electron microscopy (SEM) was used for an in-depth comparison of surface morphology. It was observed that coating methods yield significantly different microstructures on the surface of cellulose fibers. The wax is characterized by nuclear magnetic resonance (NMR) spectroscopy and differential scanning calorimetry (DSC). Pine wax has a melting temperature of around 80 °C and excellent thermal stability in oxygen, with a degradation peak above 290 °C. Fourier transform infrared spectroscopy (FTIR) was used to identify characteristic groups of components and show the changes on coated nanopaper. Overall, the results of this work yield important insight into wax-coated cellulose nanopapers and a comparison of spray- and dip-coating methods. The prepared materials have a potential application as membranes and packaging materials.

Biodegradable Poly(butylene succinate) Laminate with Nanocellulose Interphase Layer for High-Barrier Packaging Film Application

“…Similar observations with solvent-promoting particle agglomeration were observed when applying spray-coated wax coatings [36]. The higher layer count of spray coating did not scale with surface properties, and too many layers created defects in the structure.…”

Investigating Water Storage Dynamics in the Litter Layer: The Impact of Mixing and Decay of Pine Needles and Oak Leaves

“…Thus, the water storage capacity of the litter layer should also be considered at the molecular level of the leaf and needle structure. This is because needles and leaves are chemically complex molecular structures with specific hygroscopic properties that affect their water-holding capacity [49][50][51].…”

Strategy of Coniferous Needle Biorefinery into Value-Added Products to Implement Circular Bioeconomy Concepts in Forestry Side Stream Utilization

“…Waxes consist of various components, including the highest hydrocarbons (C21-C35), primary and secondary alcohols (C12-C32), and diols (C12-C31, fatty acids, resin acids, ω-hydroxy acids as well as their esters and ethers) [54]. Among these components, nonacosan-10-ol has been identified in high concentrations, accounting for up to 60% of the wax mass [55][56][57]. Coniferous waxes have been suggested to create superhydrophobic coatings [58].…”

“…Among these components, nonacosan-10-ol has been identified in high concentrations, accounting for up to 60% of the wax mass [54][55][56]. Coniferous waxes have been suggested to create superhydrophobic coatings [57].…”