Effective adsorption of cationic dye from aqueous solution using low-cost corncob in batch and column studies

Dye effluents and their degradation products disrupt the aquatic ecosystem functioning. Corncob was used as a low-cost biosorbent for decolorization of methylene blue (MB) dye. Batch and fixed-bed column adsorption were performed by varying temperature, pH, initial dye concentration, adsorbent dose, particle size, and bed height, flow rate and inlet dye concentration, respectively. High MB adsorption capacities of corncob were attained at pH 9, i.e. 45.86mgg(-1), 91.7%. Equilibrium data was best described by Langmuir II (R-2=0.999) followed by Freundlich (R-2=0.994) and Halsey (R-2=0.994) isotherm models, which indicates the favorable adsorption of MB dye onto corncob adsorbent. Moreover, chemisorption nature of corncob was confirmed through Dubinin-Radushkevich (E=16.01kJmol(-1)) and the best fit of pseudo-second-order kinetic model. Thermodynamic studies revealed spontaneous (G<0) and endothermic (H>0) nature of reaction with increased randomness (S>0) at the solid-liquid interface. The breakthrough curves were predicted using Thomas and BDST models. BDST reflected that 2.26min were required to exhaust 1cm of the fixed-bed column. MB dye-loaded corncob adsorbent could be regenerated (80%) and reused using 0.1M acetic acid.