Preparation of superhydrophobic biomedical pulp from rice straw coated with a stearic acid-cellulose composite

This study reported pulp preparation with superhydrophobic properties to determine its potential applications in generating greener bioproducts, such as biomedical pulp, from a reported optimized kraft pulping method of rice straws. The composite was prepared by mixing stearic acid (SA) and cellulose (C) with a ratio of 2:3 to create a superhydrophobic surface. Interestingly, based on water-resistant and superhydrophobic tests, the addition of SA to the cellulose chain resulted in a superhydrophobic surface for the biomedical pulp. This was proven by the FTIR spectrum, which showed a C[dbnd]O stretching vibration at 1720 cm⁻¹, indicating the presence of ester-linked acetyl groups connecting hemicelluloses. The addition of SA resulted in a high-water contact angle of 153°, with perfect spherical drops due to the long hydrophobic chains of SA pointing towards the surface of the pulp. This coating treatment significantly improved the superhydrophobic properties, as demonstrated by its water resistance for up to seven days in room temperature water (25 °C).