Adsorption, Kinetics and Equilibrium Studies on Removal of Catechol and Resorcinol from Aqueous Solution Using Low-Cost Activated Carbon Prepared from Sunflower (Helianthus annuus) Seed Hull Residues
This study reports on the feasibility of remediation of catechol- and resorcinol-contaminated water using low-cost sunflower seed hull activated carbon (SSHAC). Sunflower seed hull (SSH), an abundant agricultural waste in Malawi, was used as precursor to prepare highly porous activated carbon by physicochemical activation, with zinc chloride (ZnCl2) as an activating agent. The activated carbon was characterized by FTIR, SEM-EDS, XRD and BET analyses. In this work, pertinent parameters that affect the adsorption efficiency—pH, initial adsorbate concentration, contact time, adsorbent dosage, and solution temperature—were investigated in batch mode. At the same experimental conditions, more catechol was adsorbed than resorcinol may be due to the compound’s affinity towards water and the position of the hydroxyl group on the benzene ring. A maximum equilibrium adsorption of 271 and 250 mg/g was obtained at pH 9.0 and pH 8.0 for catechol and resorcinol, respectively. The adsorption behaviour of both adsorbates (catechol and resorcinol) on SSHAC can be well described by Langmuir isotherm model and pseudo-second-order kinetic model. The value ∆G, ∆S and ∆H indicated spontaneous and endothermic adsorption process. The adsorption process was readily reversible allowing reusability of the adsorbate. This study’s outcome is value addition to this category of wastes for environmental protection.
KeywordsSunflower seed hull Activated carbon Catechol Resorcinol Adsorption Kinetics
This work was supported by the Department of Chemistry Research Fund, Chancellor College, University of Malawi. Many thanks to the Excellence Centers for Exchange and Development (EXCEED) programme, through the German Academic Exchange Service (DAAD) and the German Federal Ministry for Economic Cooperation and Development (BMZ) for an award of a three-month research grant. The authors would like to thank the University of South Africa, for the use of their SEM-EDX, Zetasizer and TGA instruments for characterization.
Compliance with Ethical Standards
Conflict of Interest
The authors declare that there is no conflict of interest.
- Dariush, R. (2013). Pseudo-second-order kinetic equations for modeling adsorption systems for removal of lead ions using multi-walled carbon nanotube. Journal of Nanostructure in Chemistry, 3(55), 1–6.Google Scholar
- Francisco, J. E., & Leitão, A. L. (2013). Hydroquinone: environmental pollution, toxicity, and microbial answers. BioMed Research International, 1–14.Google Scholar
- Jigisha, P., Channiwala, S. A., & Ghosal, K. (2007). A correlation for calculating elemental composition from proximate analysis of biomass materials. Fuel, 86(12–13), 1710–1719.Google Scholar
- Kwiatkowski, M., Fierro, V., & Celzard, A. (2017). Numerical studies of the effects of process conditions on the development of the porous structure of adsorbents prepared by chemical activation of lignin with alkali hydroxides. Journal of Colloid and Interface Science, 486, 277–286.CrossRefGoogle Scholar
- Lee, S. G., Lee, B. H., Baik, M.-Y., Park, S. K., Kim, B.-Y., Park, S.-J., Lee, J. H., Lee, C. Y., & Kim, D.-O. (2015). Activated carbon treatment of water extracts of Artemisia princeps Pampanini to retain bioactive phenolic compounds and remove volatiles. Food Science and Biotechnology, 24(3), 1097–1103.CrossRefGoogle Scholar