<p>This study presents novel insights into the use of polymer inclusion membranes (PIMs) to effectively recover nickel ions (Ni(II)) from industrial effluents, demonstrating the significant potential of PIMs in industrial and environmental applications. PIM is composed of cellulose triacetate (CTA) as the polymer, acetylated kraft lignin (AKL) as a biofiller and matrix modifier, and di(2-ethylhexyl)phosphoric acid (D2EHPA) as the carrier without any additional plasticizer. The resulting PIM was characterized by scanning electron microscopy (SEM). The study of ion transport across the prepared PIM was performed with regard to parameters such as feed pH, D2EHPA concentration in the membrane phase, HNO₃ concentration in the strip phase, and membrane thickness. The Ni(II) extraction process was described by a second-order model (<i>R</i>² = 0.998), and the optimum conditions were determined based on this model. At the 5% significance level, the results of the ANOVA showed that the model was a good fit for the experimental data. The study of Ni(II) transport through PIM under optimum conditions requires the initial fluxes, recovery efficiency, and stability over multiple cycles to be determined. Compared with the performance of a supported liquid membrane (SLM), the stability of PIM increased, although the initial flux slightly decreased to approximately 11.3 10^–6&#xa0;mol/m².s, and approximately 58% recovery efficiency was observed. SEM images were used to characterize the degradation of the SLM. Additionally, the prepared membrane was used to investigate the separation factor between Cd(II) and Ni(II) ions in industrial effluent.</p>