Preparation of organic acid lignin submicrometer particle as a natural broad-spectrum photo-protection agent.

Valorization of lignin by-product is an urgent issue in the context of biorefinery. Lignin is a natural anti-UV active ingredient with great potential applications. In this study, a natural broad-spectrum photo-protection agent was prepared using lignin from organic acid extraction process. The submicrometer particles were prepared by dialysis lignin recovered from the pretreatments with organic acid extraction processes (formic acid, formic acid/hydrogen peroxide, and acetic acid/hydrogen peroxide/HCl) and they served as active ingredients in sunblock formulation. The structures of the lignin submicrometer particles were characterized by multiple spectroscopies. The submicrometer particles from organic acid lignin showed high capacities to enhance the sun protection factor values of lotion by 2.80-3.53 at the dosage of 5%, and the lotions containing lignin submicrometer particles had good UV-blocking properties. In addition, the UVA/UVB values (i.e., the ratio of absorbance at UVA to that at UVB) were in the range of 0.69-0.72 for the organic acid lignin submicrometer particles, indicating that they exhibited superior properties. The results indicated that the lignin submicrometer-based lotions with excellent antioxidant and UV protection capacities offered a natural source for sunblock cosmetics.