Potassium permanganate dye removal from synthetic wastewater using a novel, low-cost adsorbent, modified from the powder of Foeniculum vulgare seeds

Abstract

In this study, Seeds powder of Foeniculum vulgare was used to prepare a novel adsorbent, the modification of the prepared adsorbent was done by each of ZnCl₂, oxalic acid, and CuS, all samples have been characterized by different techniques and examined for Potassium permanganate (KMnO₄) adsorption. Among the four modified and unmodified adsorbents, the sample modified by oxalic acid has the highest percentage removal for KMnO₄ adsorption (%R = 89.36). The impact of KMnO₄ concentration, adsorbent dose, contact temperature, contact time, and solution pH on the adsorption performance was also investigated. The experimental data of this adsorption was analyzed by different kinetic and isotherm models. As Constants of thermodynamic ΔG°, ΔH°, and ΔS° have been also evaluated. Surface area, pore volume, and pore size of the modified oxalic acid F. vulgare seeds powder adsorbent were determined as 0.6806 m² g^-1, 0.00215 cm³ g^-1, and 522.063 Å, as pH_ZPC also was stated to be 7.2. The R² values obtained from applying different isotherm and kinetic models (0.999 and 0.996) showed that the adsorption performance of KMnO₄ follows the Langmuir and Pseudo 2nd order models. Furthermore, high adsorption capacities of 1111.11, 1250.00, and 1428.57 mg g^-1 were achieved at three temperatures that were used in this study. Constants of thermodynamic ΔG°, ΔH°, and ΔS° values indicate chemical and spontaneous adsorption at the adsorbent surface. Therefore, the modified adsorbent can be used to remove KMnO₄ dye from pollutant water samples.