![Sample our Environment & Sustainability journals, sign in here to start your access, latest two full volumes FREE to you for 14 days]({"type":"image" , "src" : "/sda/5935/TOC-Subject-Sample-2021-Environment-Sustainability.jpg"})
ABSTRACT
Fennel seed spent (FSS)—an inexpensive nutraceutical industrial spent has been used as an efficient biosorbent for the removal of Congo red (CR) from aqueous media. Results show that the conditions for maximum adsorption would be pH 2-4 and 30°C were ideal for maximum adsorption. Based on regression fitting of the data, it was determined that the Sips isotherm (R2 = 0.994, χ2 = 0.5) adequately described the mechanism of adsorption, suggesting that the adsorption occurs homogeneously with favorable interaction between layers with favorable interaction between layers. Thermodynamic analysis showed that the adsorption is favorable (negative values for ΔG°) and endothermic (ΔH° = 12–20 kJ mol−1) for initial dye concentrations of 25, 50, and 100 ppm. The low ΔH° value indicates that the adsorption is a physical process involving weak chemical interactions like hydrogen bonds and van der Waals interactions. The kinetics revealed that the adsorption process showed pseudo-second-order tendencies with the equal influence of intraparticle as well as film diffusion. The scanning electron microscopy images of FSS show a highly fibrous matrix with a hierarchical porous structure. The Fourier transform infrared spectroscopy analysis of the spent confirmed the presence of cellulosic and lignocellulosic matter, giving it both hydrophilic and hydrophobic properties. The investigations indicate that FSS is a cost-effective and efficient biosorbent for the remediation of toxic CR dye.
Abbreviations
| CR | = | Congo red |
| Ea | = | activation energy (KJ mol−1) |
| FSS | = | fennel seed spent |
| FTIR | = | Fourier transform infrared spectroscopy |
| NIS | = | nutraceutical industrial spent |
| nF | = | heterogeneity factor |
| qe | = | adsorption capacity (mg g−1) |
| qm | = | maximum adsorption capacity (mg g−1) |
| qt | = | adsorption capacity at time “t” (mg g−1) |
| R2 | = | correlation coefficient |
| RL | = | separation factor |
| SEM | = | scanning electron microscopy |
| SSE | = | sum of square errors |
| χ2 | = | chi-square test |
| ΔG° | = | standard free energy |
| ΔH° | = | enthalpy change |
| ΔS° | = | entropy change |
Acknowledgments
The author (SNT) gratefully acknowledges the University of Malaya for the award of Post Graduate Research Grant (PG 213-2014B) and University of Malaya Research Grant (RP019A-14AFR).
