Cadmium Removal from Acqueous Solution by Adsorption on Spent Coffee Grounds

BAVASSO IRENE ; JORGE ENRIQUE SAMBETH; PATTERER SILVINA; MEDICI FRANCO

CHEMICAL ENGINEERINGTRANSACTIONS

The Italian Association of Chemical Engineering

Lugar: Roma; Año: 2017 vol. 60 p. 157 - 162

2283-9216

Cadmium is a highly toxic element and can cause serious damages to the health of human beings. It is on theseventh position on the Agency for Toxic Substances and Disease Registry (ATSDR, 2015) list for dangerouselements. The Environmental Protection Agency (EPA) and the International Agency for Research on Cancer(IARC) have also recognized cadmium as a carcinogen. For all these reasons, in the recent years stringentlimits have been set for this element both in industrial and drinking water. In this paper the potential of spentcoffee grounds (SCG) for the removal of cadmium from contaminated water was investigated. Batchexperiments were performed at different temperatures, i.e. 10, 25 and 40°C on untreated SCG. The size rangeof the SCG particles studied was ≤ 500 µm. The results obtained showed that the equilibrium of cadmium onSCG was reached after 3 hours. The Langmuir isotherm provided the best correlation for the adsorptionprocess, with a maximum adsorption capacity of 4.48 mg g?1at 10 °C. Thermodynamic analysis confirmed theexothermicity and spontaneity of the phenomenon. Kinetic studies have revealed that the cadmium adsorptiononto SCG followed a pseudo-second order kinetic model and the activation energy value calculated was of14.5 kJ mol-1, which have evidenced the physical nature of the process. Overall, this study strongly supportsthe use of SCG as an effective and economical adsorbent for the removal of cadmium from both industrial anddrinking water.