In this study, oil palm biomass of empty fruit bunch (EFB) fibers was used as lignocellulosic-based material models for wastewater remediation. EFB fibers were improvised by enhancing its surface functionalization for the removal of the color in the actual effluent from the textile industry. Briefly, EFB fibers were modified using polyethyleneimine (PEI) and ethylenediaminetetraacetic acid (EDTA) to produce cationic and anionic adsorbents, respectively. The modified fibers (PEIEFB and EDTA-EFB) were used to study the efficiency in removing anionic and cationic ions from the effluents at different pHs, temperatures and initial dye concentrations. The optimum pH and temperature were investigated to be at pH 3 and 20ºC whereas the adsorption occurred efficiently. The comparison between the modified adsorbent shows higher adsorption capacity by cationic functionalization. The charge of the PEI-EFB was positive over the entire pH range, which suggests the successful modification of the EFB fibers by PEI. In the kinetics study, the adsorption capacity of PEI-EFB fibers in the removal of color can be up to 572.3 mg/g, which improved by ~five times of the adsorption capacity of the raw EFB fibers. Whereas, based on the experimental work and adsorption models fitting, PEI-EFB fitted on the Pseudo First-Order in comparison with the Pseudo Second-Order. Additionally, the isotherm model was fitted with the Freundlich model, contrary with the Langmuir model, its mechanism suggesting a monolayer and heterogeneous adsorption behavior of the adsorption processes.