This study addresses the critical issue of organic dye pollution by developing environmentally friendly and efficient adsorbents for wastewater treatment. It investigates the impact of synthetic solvents on the surface properties and adsorption performance of microspheres composed of kraft lignin (KL), beta-cyclodextrin (β-CD), and polyethyleneimine (PEI). Microspheres were synthesized using sodium hydroxide (β-CD-KL-PEI (Na)) and potassium hydroxide (β-CD-KL-PEI (K)) as solvents. The β-CD-KL-PEI (Na) exhibited a smoother, more uniform surface, enhancing adsorption efficiency and achieving 98% methyl orange (MO) removal under optimized conditions: 0.48 g.L−1 adsorbent, pH 5.8, and a 15-min contact time. In contrast, β-CD-KL-PEI (K) demonstrated reduced performance due to surface roughness, which hindered dye interaction. Adsorption optimization was performed using Design-Expert software, and the reusability of β-CD-KL-PEI (Na) was validated through several adsorption-desorption cycles. The findings highlight the critical role of surface morphology and solvent selection in microsphere synthesis for enhanced adsorption of anionic dyes. This work also demonstrates the potential of β-CD-KL-PEI (Na) microspheres as cost-effective, efficient, and reusable adsorbents, offering significant industrial applications for wastewater treatment and environmental sustainability. These results provide insights into developing advanced bio-based adsorbents for removing organic pollutants.

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