Adsorptive removal of Pb2+ ions from aqueous solutions by peat

Abstract

Peat has been evaluated as an efficient sorbent. In this paper, peat for removal of Pb 2+ ions from aqueous solution was studied. Peat samples were analyzed for total lead, pH, humidity, and TC (total carbon). Major factors involved, including initial Pb concentration, contact time, and pH, also were investigated. The aqueous solution of lead(II) (0.25 mg/L, 25.0 mg/L, 50.0 mg/L, 75.0 mg/L, and 100.0 mg/L) was agitated at a fixed speed of 20 rpm for 5, 10, 20, 45, 90, 180, and 360 minutes, respectively. At the end of each contact time, the solid was removed by filtration through a 0.45 μm glass filter and then analyzed with an atomic absorption spectrophotometer. Adsorption capacity of peat increases with increasing contact time, initial lead(II) concentration, and was significantly affected by initial pH value in the range from 4.0-7.0. The amount of Pb adsorbed on peat was greatest at pH 6.0, 360 min contact time, and 100 mg/L lead(II) concentration, i.e. 9.489 mg/g. The Freundlich and Langmuir models were used to interpret the sorption behaviour of Pb 2+ ions, and the results showed that the Freundlich model shows a better fitting than the Langmuir model according to correlation coefficients (R 2 >0.98, Freundlich model, R 2 >0.58 Langmuir model).