Preparation of TiO2/Lignin Composites with Agave sisalana Residue for Bisphenol-A Removal

Composites prepared from metal oxides and materials derived from agroforestry residues have been successfully applied to remove emerging contaminants. The lignin properties, high surface area and number of functional groups, are beneficial in the preparation of TiO2 composites. In the present work, sisal residue was used as a source of lignin, and after extraction, the lignin was applied in the preparation of an adsorbent composite with TiO2 to remove bisphenol-A. The optimal conditions for lignin extraction resulted in a lignin purity of 73%. Characterization proved that the synthesized composites have a high surface area (> 100 m2 g-1), homogeneous distribution of TiO2 particles and stable surface charge. Such characteristics resulted in a lignin/TiO2 composite with a maximum adsorption capacity of 13.7 mg L-1, capable of removing up to 97% of bisphenol-A. The adsorbent can be used in six cycles, removing over 70% by the third cycle, which indicates good stability.