Polyaniline/chitosan composite: An eco-friendly polymer for enhanced removal of dyes from aqueous solution

Batch sorption system using eco-friendly polymer/bio-polymer composite (polyaniline/chitosan) as adsorbent was investigated to remove Congo Red, Coomassie Brilliant Blue, Remazol Brilliant Blue R, and Methylene Blue from aqueous solution. Scanning electron micrograph showed that the surface of the composite was rough with pleats, providing a good possibility for dye adsorption. X-ray diffractogram of the composite showed the main reflections of both chitosan and polyaniline (2θ = 9.8, 19.8, 20.0, and 25.3). Experiments were carried out as a function of contact time, initial dye concentration (100 mg L ^-1), pH (3), and adsorbent dose (0.1 g L ^-1). The maximum percentage removal was found to be 95.4% for Congo Red, 98.2% for Coomassie Brilliant Blue, and 99.8% for Remazol Brilliant Blue R. Langmuir model showed satisfactory fit to the equilibrium adsorption data of polyaniline/chitosan composite. The kinetics of the adsorption followed pseudo second-order rate expression, which demonstrates that intraparticle diffusion plays a significant role in the adsorption mechanism. Fourier transform infrared spectroscopy and desorption studies confirmed the involvement of amino and hydroxyl groups in dye adsorption. The results indicate that the polymer matrix could be used as an adsorbent for the removal of sulfonated dyes from aqueous solution.