Adsorption of DDT and PCB Using Natural Soil and Carbon Nanotube

Abstract

Both DDT and PCB are amongst the contaminants quite often being release to the environment. They are not only carcinogen but also very persistent and being able to linger in the environment for a very long time. In addition, they are also very difficult to be cleaned up once once exposed or released to the environment. In this study, both of these contaminants were subjected to adsorption by natural soilcarbon nanotube system. Batch adsorption studies were conducted evaluate the efficiency of a local residual soil with various amounts of multiwalled nanotube (MWNT) to adsorb DDT and PCB in solution. For each set of test, the adsorption equilibrium time was also determined. It was found that the equilibrium time for adsorption of both contaminants were about 22 and 49 hours, respectively for DDT and PCB. As expected, the amounts of the contaminants adsorbed increases as the MWNT contents were increased. The maximum percentage of adsorption were about 90 and 80%, respectively for DDT and PCB for up to 10% of MWNT by weight of the original soil used. The results of the study were also analyzed with respect to the various adsorption isotherms, i.e. Freundlich, Langmuir, Temkin, and Redlich-Peterson. Linearized Langmuir adsorption isotherm showed the best fit for the experimental data for both systems while the linearized Redlich-Peterson was the least fit amongst the isotherms. In addition, it was also found that the linear form of the simple Temkin isotherm was able to fit all adsorption data quite well. Nevertheless all linearized isotherms tested showed sufficient capability to predict the data obtained.