Keywords: cadmium(II) adsorption, activated carbons, heavy metals, cadmium removal, effluent pollution, desorption, recycling, Brazil, thermodynamics, chemisorption
Cadmium(II) adsorption by activated carbon: batch studies and reversibility
Adsorption of cadmium(II) by Brazilian activated carbons, in their original and nitric acid activated forms, was evaluated. The equilibrium was reached within the first 15 min of contact between carbon and metal solution, and obeys a pseudo-second order Lagergren model. The maximum adsorption capacity is higher than 64 mg/g for the oxidised sample. Negative ΔG0 values indicate the spontaneity of the adsorption process. Thermodynamic results emphasise that chemisorption plays an important role in the adsorption by oxidised carbon. Moreover, this sample can be efficiently recycled by treatment with HCl, allowing total recover of adsorbed cadmium(II) during four adsorption/desorption cycles.