Simultaneous removal of anionic and cationic dyes from wastewater with biosorbents from banana peels

Abstract Untreated banana peel (BP) is able to adsorb efficiently cationic dyes like methylene blue (MB) but weakly anionic orange G (OG). One way enhance the sorption capacity for both convert BP into activated carbon (BPAC) after thermochemical treatment. Among various BPACs tested, highest was achieved when modified with NaOH and pyrolyzed at 700°C (BPAC‐NaOH‐700). The pore structure of adsorbents analyzed scanning‐electron‐microscopy (SEM), nitrogen isotherms, mercury intrusion porosimetry (MIP), meso‐ micro‐pore size distribution BPAC‐NaOH‐700 narrowest one smallest mean value specific surface area. Equilibrium tests in batch mode were fitted extended Langmuir Freundlich isotherms used estimate thermodynamic properties. MB OG dynamics onto approximated multi‐compartment model, external internal mass‐transfer coefficients estimated. maximum found be equal 323 mg/g 76 OG, higher than corresponding values BP, fully consistent high its area ( = 530 m 2 /g) total volume 1.81 cm 3 /g). synergistic interaction associated a push‐pull mechanism, while selective attributed very slow rates diffusion micro‐porosity, respectively. adsorption exothermic endothermic OG.