Immobilization of polychlorinated biphenyls in contaminated soils using organoclays

Background: Clay minerals especially organoclays modified by the introduction of organic molecules into the mineral structure show much promise for environmental remediation applications. Application of organic attapulgite (O-APG) and organic montmorillonite (O-MMT) as soil amendments to bind polychlorinated biphenyl (PCB) in contaminated soils and observe PCBs accumulated in the ryegrass shoots and roots was investigated. Results: Pot experiments in greenhouse indicated that organoclays could significantly fix the PCB in soils and reduce its contents in ryegrass shoots and roots. Compared with the control, the migration of concentrations of PCB into the environment in contaminated soils is reduced by about 28.5 and 44.1%, and concentrations of PCB in ryegrass roots and shoots were reduced within the range from 57.0 to 63.0% and 49.6 to 56.5%, respectively, through addition of 6% organic attapulgite and montmorillonite. There was a negative correlation between the accumulation of PCB in ryegrass and the amount of organoclay addition. The accumulations of PCB in ryegrass roots were significantly higher than those in the ryegrass shoots. Conclusions: The two organoclays had been proved effective as environmental amendments for reducing the mobility and bioavailability of PCB in contaminated soils. The results of this study provided an efficient method for the remediation of PCB contaminated soils. (C) 2014 Elsevier B.V. All rights reserved.