Cationic and anionic modifications of oil palm empty fruit bunch fibers for the removal of dyes from aqueous solutions

- Oil palm empty fruit bunch (EFB) fibers were using as adsorbent for dye removal.
- Modifications were carried out using citric acid (CA) and polyethylenimine (PEI).
- CA-EFB adsorbed methylene blue up to 130 mg/g.
- PEI-EFB adsorbed phenol red up to 171 mg/g.
- Both EFBs can be reused up to seven cycles of adsorption/desorption processes.