Preparation and characterization of biodegradable lignin-sulfonate nanoparticles using the microemulsion method to enhance the acetylation efficiency of lignin-sulfonate.

In this study, a novel method is presented for producing lignin-sulfonate nanoparticles. Then, the effect of produced nanoparticles is investigated on enhancing the acetylation efficiency. For these purposes, lignin-sulfonate was isolated from black-liquor of pulp-and-paper mill wastewater. Next, lignin-sulfonate nanoparticles were obtained using the oil-in-water (O/W) microemulsion, followed by modification of micro/nano-lignin-sulfonate particles. The physical, chemical, and morphological properties of lignin sulfonate micro/nanoparticles and modified forms of both samples were analyzed using FTIR, DLS, FE-SEM, AFM, H NMR, and CNMR analyses. Surface morphology revealed that the nanoparticles were homogenized and spherical with an average diameter of 25.5 nm. The chemical structure of the nanoparticles was similar to that of the microparticles. On the other hand, the chemical structure of acetylated lignin-sulfonate was slightly different from that of unmodified samples. The results also showed that the production of nano-lignin-sulfonate increased the acetylation efficiency and reduced the time and temperature of acetylation.