A sustainable composite of whole pine needle biomass with succinic acid‐doped polyaniline for effective adsorption of anionic and cationic dyes

Abstract Herein, we report the valorization of whole lignocellulosic biomass, pine needles, to a polymer composite by in situ polymerization of aniline doped with succinic acid. The as‐synthesized composite was characterized using Fourier transform infrared spectroscopy, X‐ray diffraction, scanning electron microscopy–energy‐dispersive X‐ray analysis, thermogravimetric analysis and zeta potential analysis. The composite was investigated for the elimination of anionic and cationic dyes from their solutions, and the best adsorbed anionic dye, rose Bengal (RB), and cationic dye, crystal violet (CV), were selected for detailed adsorption studies using a parametric framework. The adsorption mechanism was studied by kinetic models, namely intraparticle diffusion, pseudo‐first order, Elovich and pseudo‐second order (PSO), along with adsorption isotherms, namely Freundlich, Langmuir and Temkin. The maximum removal efficiencies for RB and CV were found to be 97.20% and 96.12%, with adsorption capacities of 327.58 and 333.16 mg g −1 , respectively. The adsorption process followed PSO kinetics and the Langmuir isotherm model. The practical applicability of the composite was validated by using it for treating industrial effluent, and the effluent mixed with dye solutions under optimized adsorption conditions, showing marked decolorization and high removal efficiency. Reusability studies affirmed the high regeneration and reusability for 12 cycles, establishing the composite as a low‐cost, sustainable and reusable adsorbent for real wastewater treatment. © 2025 Society of Chemical Industry.