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Abstract
The biosorption potential of cost-effective and agricultural residue, Ipomoea carnea wood (ICW) was examined by the removal of cationic dye, methylene blue (MB) from aqueous solution. The surface morphology, structural and thermal properties of untreated ICW were analyzed using Scanning Electron Microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and Thermo-gravimetric Analysis (TGA), respectively. The effects of different parameters namely concentration of biosorbent, initial pH, initial MB composition and temperature on biosorption capacity and biosorption (%) were studied. The kinetic and equilibrium models were developed to fit the experimental data on MB biosorption. The maximum biosorption capacity of 39.38 mg g−1 was obtained at 40 °C using Langmuir model. The removal of MB was found to be significantly varying with temperature. Box–Behnken design was applied to optimize the biosorption parameters. The optimized condition for MB biosorption was evaluated as dosage of 3.1 g L−1, pH of 7.04, Temperature of 49.1 °C, MB concentration of 30.48 mg L−1 and maximum biosorption (%) of 83.87. The regeneration of ICW was investigated by five cycles using a suitable eluting agent. Hence, ICW without any pretreatment and chemical modification is a potential candidate for the removal of MB in terms of availability and economy of the process.
Ipomoea carnea wood (ICW) without any pretreatment explored a potential biosorbent for the removal of methylene blue (MB) in terms of availability and economy of the process.
The physico-chemical properties of ICW characterized using Scanning Electron Microscopy, Fourier transform infrared spectroscopy and Thermo-gravimetric Analysis showed ICW as a promising biosorbent for MB removal.
Presence of heterogeneous with rugged morphological structure, cavities, irregular shape and size of large pores provide the better biosorption capability for MB molecules using ICW without any pretreatment or chemical modification.
Analysis of kinetic and isotherm models was performed to examine the better fitness of experimental data with model. Thermodynamic parameters indicating feasible and endothermic MB biosorption.
Statistical design of experiments is used to optimize the condition and corresponding maximum MB removal using Derringer’s desired function methodology.
Untreated ICW is a potential reusable biosorbents, effectively employed in successive biosorption and desorption process for the removal of MB from aqueous solutions.
Novelty statement
Acknowledgements
All authors are thankful to the Management SASTRA Deemed to be University, Thanjavur, Tamil Nadu, India for providing the necessary facilities.
Nomenclature
| Qe | = | Equilibrium dye concentration on ICW (mg g−1) |
| Co | = | Initial MB concentration in aqueous solution (mg L−1) |
| Ce | = | Equilibrium MB concentration in aqueous solution (mg L−1) |
| V | = | Volume of the MB solution (mL) |
| D | = | ICW Doasge (g L−1) |
| R2 | = | Coefficient of determination |
| Qm | = | Maximum biosorption capacity using Langmuir model (mg g−1) |
| KL | = | Langmuir constant (L mg−1) |
| RL | = | Separation factor |
| KF | = | Freundlich constant (L g−1) |
| nF | = | Freundlich heterogeneity factor |
| R | = | Universal gas constant (8.314 J mol−1 K−1) |
| T | = | Absolute temperature (K) |
| b | = | Temkin isotherm constant |
| B | = | Temkin constant related to heat of biosorption (J mol−1) |
| AT | = | Temkin equilibrium binding constant (L g−1) |
| Qs | = | Theoretical isotherm saturation capacity (mg g−1) |
| kb | = | Dubinin-Radushkevich isotherm constant (mol2 J−2) |
| ε | = | Dubinin-Radushkevich isotherm constant |
| E | = | Mean free energy (KJ mol−1) |
| Qt | = | Biosorption capacity at time, t |
| kf | = | Pseudo first order rate constant (min−1) |
| PSF | = | Pseudo first order model |
| IPD | = | Intraparticle diffusion model |
| ks | = | Pseudo second order rate constant (g mg−1 min−1 |
| PSS | = | Pseudo second order model |
| kintra | = | Intraparticle diffusion model constant (mg g−1 min−0.5) |
| yi | = | Coded values of independent factors |
| Yi | = | Uncoded values of independent factors |
| ΔYi | = | Change in real value of a independent factor |
| ΔGo | = | Change in Gibbs free energy (KJ mol−1) |
| ΔSo | = | Change in entropy (KJ mol−1 K−1) |
| ΔHo | = | Change in Enthalpy (KJ mol−1) |
| Keq | = | Equilibrium constant |
| SD | = | Standard deviation |
| CV | = | Coefficient of variation |