Adsorption of Co (II) ions from aqueous solution onto tea and coffee powder: equilibrium and kinetic studies

Abstract

Adsorption of Co(II) ions from aqueous solutions onto Tea and Coffee powders has been examined in a batch adsorption process. The adsorption of Co(II) ions was found to be dependent on contact time, pH of solution, initial metal ion concentration, and adsorbent dose. The experimental equilibrium adsorption data were studied by Langmuir, Freundlich, Temkin and Dubinin-Radushekiv isotherms models. The Langmuir model display demonstrated a superior fit than the other three models by higher correlation coefficient, R2. The maximum adsorption capacities calculated from the Langmuir isotherm model were 244 mg/g, for both coffee and tea at optimum circumstances. The kinetic studies denoted that the adsorption process of Co(II) ions followed well pseudo-second-order model. According to the adsorption capacity, coffee and tea powder considered as an effective, low cost, and environmentally friendly adsorbent for the removal of Co(II) ions from aqueous solutions.