Kinetic and thermodynamic study of cobalt adsorption by spent coffee

The biosorption of cobalt from aqueous solution onto a spent coffee (SC) was carried out to assess the effectiveness of the adsorbent used in the removal of Co(II) from aqueous solution by batch tests. Adsorption of Co(II) as a function of contact time, pH, and temperature was investigated. The kinetic study revealed that adsorption followed better a second-order type reaction with high correlation coefficient (R-2=0.999). Adsorption data were described using Freundlich and Langmuir models. The thermodynamic study for the Co(II) adsorption onto SC showed that the process was spontaneous with a raised affinity for Co(II) (G degrees<0 and S degrees>0), exothermic (H degrees<0), and occurred with physical adsorption mechanism (E-a=10.922kJmol(-1)).