Biosorption of Copper by a Natural Byproduct Material: Pressed Black Cumin Cakes

Abstract

A natural waste material, pressed black cumin cake, was characterized as an adsorbent for copper (II) ions. The pressed black cumin cake waste was obtained after the cold pressing of black cumin seeds in order to extract black cumin oil. The press cake was used as an adsorbent after washing with cold water for the removal of copper (II) ions. The effects of pH and adsorbent dose on the removal efficiencies were investigated. The point of the zero charge was determined. Isotherm studies were performed using Langmuir, Freundlich, and Dubinin-Radushkevich models. The adsorption of the copper (II) was found to comply with the Langmuir isotherm model. The maximum adsorption capacity calculated from the Langmuir isotherm was found to be 106.38 mg/g. Thermodynamic studies were also carried out. Furthermore, three kinetic models, the pseudo first-order, pseudo second-order, and intraparticle diffusion, were investigated. The adsorption adhered to the pseudo second order kinetic model. The regeneration of the adsorbent was also investigated. An environmentally friendly, low cost, fast, and easily accessible adsorbent was developed for the efficient removal of copper (II). It is advantageous in terms of stability for long-term use.