Micromorphology Influence on the Color Performance of Lignin and Its Application in Guiding the Preparation of Light-colored Lignin Sunscreen

The lignin with different color degree was obtained by micromorphology regulation and was characterized by SEM, brightness test, bulk density, particle diameter, zeta potential, specific surface area, and visible light diffusion to investigate the relationship between micromorphology and color performance. The results show that the lignin that consists of fine particles and contains dense interval space between particles exhibits obvious advantages on color reduction which is highly lightened by more than 3 times compared with the untreated lignin. The loose structure of lignin leads to a low bulk density which by the way decreases the concentration of chromophores in the macroscopic scale. Rely on the new fundamental basis for the color reduction of lignin, a kind of light-colored lignin was obtained and was used as additive in the preparation of sunscreen. The lignin-based sunscreen reached SPF 50.69 under an addition amount of 5 wt %, and barely showed staining on skin.