Co(II) Adsorption onto Ferrous Chloride and Thermally Modified Diatomite: Surface Properties and Adsorption Mechanism

Abstract

As a potential alternative for heavy metal removal, adsorption using various low-cost materials is one of the most effective methods. This study presents the efficiency of local diatomite modified by ferrous chloride and heat treatment in removing Co(II) from an aqueous solution. The samples were characterized by ICP, XRD, TG-DTA, FTIR, SEM, and BET analyses and the adsorption efficiency of the samples for Co(II) ions was investigated under different factors such as contact time and pH. The adsorption equilibrium was well described by the Langmuir isotherm model, with the maximum adsorption capacities of DA, DM, DM-550°C and DM-850°C at about 18.18 mg L-1, 28.65 mg L-1, 48.30 mg L-1, and 66.22 mg L-1, respectively. The kinetic data were best fitted to the pseudo-second-order model. In addition, ion exchange and electrostatic surface complexation were predicted to play dominant roles in the adsorption mechanism. The results showed that the selected modification methods were effective in removing heavy metals from aqueous solutions, making the samples potentially cost-effective adsorbents to remove the water pollution problem.