Synthesis of lignin based composites of TiO2 for potential application as radical scavengers in sunscreen formulation

Mohamad Nasir Mohamad Ibrahim; Anwar Iqbal; Chai Chuan Shen; Showkat Ahmad Bhawani; Farook Adam

doi:10.1186/s13065-019-0537-3

Synthesis of lignin based composites of TiO₂ for potential application as radical scavengers in sunscreen formulation

BMC Chem. 2019 Feb 4;13(1):17. doi: 10.1186/s13065-019-0537-3. eCollection 2019 Dec.

Authors

Mohamad Nasir Mohamad Ibrahim¹, Anwar Iqbal¹, Chai Chuan Shen¹, Showkat Ahmad Bhawani², Farook Adam¹

Affiliations

¹ 1School of Chemical Sciences, Universiti Sains Malaysia, 11800 Gelugor, Penang Malaysia.
² 2Department of Chemistry, Faculty of Resource Science and Technology, Universiti Malaysia Sarawak (UNIMAS), 94300 Kota Samarahan, Sarawak Malaysia.

Abstract

Titanium dioxide (TiO₂) is added in sunscreens due to its ability to absorb ultraviolet (UV) light. However, upon irradiation of UV light, reactive oxygen species particularly hydroxyl radical which can damage human skin will be generated. In this study, lignin/TiO₂ composites were employed to quench the hydroxyl radicals generated by the TiO₂. The lignin was extracted from oil palm empty fruit bunch (OPEFB) via kraft and soda pulping processes. The kraft lignin composite was labelled as KL/TiO₂ whereas the soda lignin composite was labelled as SL/TiO₂. The lignins and the composites were characterized by FTIR, UV spectroscopy, ¹³C NMR, SEM, EDX, and XRD. The relative hydroxyl radical production of composites and TiO₂ were compared through photo-oxidation of coumarin to 7-hydroxycoumarin as a test medium. The effect of types and amounts of lignin used were studied. The KL/TiO₂ composite showed the least radical production due to higher phenolic hydroxyl content of kraft lignin. The activity of the hydroxyl radicals will be quenched when it abstract hydrogen atoms from the phenolic hydroxyl groups.

Keywords: Hydroxyl radical; Lignin; Lignin/TiO2 composite; Oil palm empty fruit bunch; TiO2.