Debasis Nanda, Chirasmayee Mohanty, Priyanka P. Mishra, Bankim Chandra Tripathy, Nigamananda Das, Ajaya K. Behera
ABSTRACT A polyaniline‐coated banana biochar composite (PB‐10) was synthesized as a high‐performance, sustainable adsorbent for simultaneous removal of cationic (methylene blue), anionic (Congo red), and heavy metal [Cr(VI)] pollutants from water. PB‐10 features a spongy porous structure with a surface area of 37.8 m 2 g −1 and a pore diameter of 19.9 nm, offering abundant active sites for pollutant adsorption. Maximum capacities of 82 mg g −1 (Congo red), 58 mg g −1 (methylene blue), and 75 mg g −1 (Cr(VI)) were achieved under optimized conditions. Adsorption followed pseudo‐second‐order kinetics and fitted with Langmuir–Freundlich isotherms, indicating chemisorption and multilayer adsorption, respectively. Thermodynamic analysis confirmed a spontaneous, endothermic process (ΔH = 25.084 kJ mol − 1 ) was obtained. PB‐10 also exhibited excellent reusability over five cycles, highlighting its potential as a good adsorbent and versatile material for practical wastewater treatment.