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

Membranes 2022
Sergejs Beļuns, Oskars Platnieks, Jekaterina Ševčenko, Māra Jure, Gerda Gaidukova, Līga Orlova, Sergejs Gaidukovs

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 com-pared. 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.

Keywords
byproduct application | circular economy | dip‐coating | green technology | spray‐coating
DOI
10.3390/membranes12050537
Hyperlink
https://www.mdpi.com/2077-0375/12/5/537

Beļuns, S., Platnieks, O., Ševčenko, J., Jure, M., Gaidukova, G., Grase, L., Gaidukovs, S. Sustainable Wax Coatings Made from Pine Needle Extraction Waste for Nanopaper Hydrophobization. Membranes, 2022, Vol. 12, No. 5, Article number 537. Available from: doi:10.3390/membranes12050537

Publication language
English (en)