Preparation of Pineapple Peel Cellulose Nanocrystals and Their Environment Stability in Pickering Emulsions

In recent years, with the gradual increase of pineapple sales, the resource waste problem of pineapple peel needs to be urgently solved. Pineapple peel residue is rich in insoluble cellulose, which provides a possibility for the derivative development of cellulose extracted from pineapple peel residue. In order to discuss the potential in the preparation and application of pineapple peel cellulose nanocrystals (PCNCs), this paper prepared pineapple peel residue cellulose nanocrystals PPeNc and PTNc by sulfuric acid hydrolysis and 2, 2, 6, 6-tetramethylpiperidine oxide (TEMPO) oxidation, respectively, and applied them to the Pickering emulsion (made into PPeNc-P and PTNc-P) for the environmental stability study. Fourier transform infrared spectroscopy, X-ray diffraction and thermal gravimetric analysis show that both PPeNc and PTNc retain the original structure of cellulose, but the crystallinity and thermal stability of PTNc are lower than those of PPeNc. Atomic force microscopy show that the aspect ratio of PTNc is as high as 54.11. As compared with PPeNc, PTNc exhibits higher aspect ratio and longer diameter. Furthermore, it is found that the stability of PTNc-P is better than that of PPeNc-P in the range of pH = 2 ~ 12, and the ionic strength is below 70 mmol/L or the oil-water ratio is below 5:5. The storage experiment shows that the storage period of PPeNc-P is within 70 days, while PTNc-P can be stored stably for more than five months. The research results in this paper indicate that PCNCs prepared by TEMPO oxidation show greater potential in stabilizing Pickering emulsion, which provides a theoretical basis for the storage and further application of PTNc in Pickering emulsion. It is conducive to realizing the high-value utilization of pineapple peel residue. © 2022, Editorial Department, Journal of South China University of Technology. All right reserved.