Poly(PEI-catechol-tetraethylenepentamine) was prepared by “one-pot method” for removing Reactive Red 195

Wastewater containing dyes is frequently discharged by industrial processes and needs separation and recycling. To solve this problem, it is important to research and develop environmentally friendly, efficient adsorbent materials for pollutant separation and recovery. In this study, a poly(PEI-catechol-tetraethylenepentamine) (PPCT) adsorbent was synthesized using a simple catecholamine reaction. This adsorbent exhibited high adsorption capacity and excellent removal efficiency for Reactive Red 195 (RR-195) in wastewater. The material was characterized using SEM, FT-IR, TGA, EA, and XPS. Its performance was optimized by varying the type of polyethyleneimine and the amount added during the preparation process. The effects of temperature, pH, contact time, and salt concentration on the adsorption were systematically investigated. Additionally, the experimental data showed consistency with both the Langmuir and pseudo-second-order kinetic models, simultaneously. The maximum adsorption capacity can reach 1754 mg g −1 at 303 K, with a retention rate of 86.6% after two cycles. The removal rate exceeds 98% at a concentration of 400 mg g −1 or lower. Additionally, the protonated amine group in PPCT carries a positive charge under acidic conditions, enabling selective adsorption of the anionic dye RR-195. Consequently, PPCT exhibits an excellent adsorption effect on RR-195 and holds promising applications in pollutant removal.