| Summary: | Corn (Zea mays) cob, an agricultural biomass residue, was carbonized by chemical activation with H2 SO4 and examined for its suitability as a low-cost adsorbent for methylene blue (MB) adsorption from aqueous solution. Carbonized corn cob (CCC) was characterized by a CHNS-O analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction (XRD), Brunauer–Emmett–Teller, and point-of-zero charge (pHpzc ) analysis. Batch mode adsorption studies were conducted by varying operational parameters such as adsorbent dosage (0.02–0.20 g), solution pH (3–10), initial MB concentrations (50–300 mg/L), and contact time (0–360 min). The equilibrium data were well correlated by the Freundlich isotherm compared with Langmuir and Temkin models. The maximum adsorption capacity (qmax ) of CCC for MB adsorption at equilibrium was 216.6 mg/g at 303 K. The kinetic uptake profiles were well-described by the nonlinear pseudo-first-order model. The thermodynamic adsorption parameters such as standard enthalpy (ΔH°), standard entropy (ΔS°), and standard free energy (ΔG°) showed that the adsorption of MB onto CCC surface is endothermic in nature and spontaneous under the experimental conditions. The above-mentioned results indicate that the CCC can be feasibly employed for the removal of MB from aqueous solution. © 2018, Desalination Publications. All rights reserved.
|
|---|