Sorption of thallium(I) ions by peat

The increasing industrial use of thallium has raised the need for removal of this highly toxic element from wastewater. Thallium is more toxic than cadmium, copper, zinc, lead and mercury and as it is easily accumulated in humans, animals and plants, it poses a threat to both the environment and human health. Peat has been used as an effective, relatively cheap and easily available sorbent to treat waters containing heavy metals. In this study, peat was characterized and used as sorbent for the removal of Tl(I) ions from aqueous solution. The effect of initial Tl(I) concentration, pH, contact time, temperature and ionic strength was studied in batch mode. The maximum sorption capacity of peat reached 24.14 mg/g at 20 °C and initial Tl(I) concentration of 500 mg/L. Sorption capacity was found to be pH dependent and maximum uptake occurred at pH 10. Kinetic data revealed that sorption was relatively rapid – 82.8% of Tl(I) ions were sorbed in the first 10 min. The kinetics of sorption was analyzed using pseudo-first order and pseudo-second order models. Results show that peat can be used as an effective sorbent to remove Tl(I) ions from aqueous solutions.