Effects of Exogenetic Ferrite on Removal of Toluene in Sediments from a Typical Coastal Wetland

Abstract

Ferrite material is a kind of special ferromagnetic mental oxide with Fe3+ as a main component. Based on the assumption that the reduction of Fe3+ and the magnetic variations could produce potential active impacts on degradation of organic pollutants under anaerobic conditions, we took water and sediment samples from Chongming east intertidal flat, a typical coastal wetland, to investigate the effects of exogenetic addition of ferrite on the removal of toluene in sediments during an 11-day incubation. Ferrite (Fe12O19·Sr, M.W. 1061.75, Nanosized spherical material 800 nm, the purity >98%) was added into sediment samples by proportions of 0.0, 5.0, 10.0, 20.0 g/kg with 0.0, 0.2, 0.5, 1.0 ml/kg toluene, respectively. It is found that the rate of toluene removal is the highest when the ferrite added is 10.0 g/kg with toluene recovery rates of 0.24%, 20.79%, 30.36% for treatments of 0.2, 0.5, 1.0 ml/kg toluene addition by the end of 11th day of incubation, respectively. In contrast, the recovery rates are 1.85%, 50.05%, 55.68%, respectively, when ferrite content rises to 20.0 g/kg. In addition, all toluene recovery rates are less than 2% after 11 day incubations under the condition of 0.2 ml/kg toluene, indicating that the removal rate of toluene depends on the contents of toluene in sediments. In summary, it confirm that application of exogenetic ferrite material can effectively enhance the removal of toluene from the sediment.