Mobility of Polyethylene Glycol-Modified Urethane Acrylate (PMUA) Nanoparticles in Soils

Abstract

Engineered nanoparticles (ENPs) have been reported for their potential to enhance in situ soil remediation due to their size and stability in water. These properties allow them to pass through soils with minimal loss in soil flushing or pump-and-treat process. The success of nanoparticle-facilitated soil flushing depends on the mobility of nanoparticles in the soil matrix. However, organic carbon content and soil texture can affect the mobility of nanoparticles in soils. This study compared the mobility of polyethylene glycol-modified urethane acrylate (PMUA) nanoparticles in three types of soils with varying organic contents. The results of two consecutive injection experiments showed that the recovery of injected nanoparticles through a soil column were 91 and 97% for sandy soil with carbon content of 0.01%, 81 and 85% for clay loam soil with organic carbon content of 1.20% and 67 and 73% for clay soil with organic carbon content of 3.25%. Furthermore, the batch experiments showed that the distribution coefficient (Kd) of PMUA nanoparticles between water and sandy soil, clay loam soil, and clay soil were 1.86, 2.34 and 3.01 mL/g, respectively. This conforms to the column experiment results and confirms that the increase in organic carbon content in soils increases the adsorption of PMUA nanoparticles, and therefore decreases the mobility of the nanoparticles through soils. Moreover, the distribution coefficient from batch experiments could be used to predict the mobility of PMUA nanoparticles in soils, and the viability of in situ PMUA-facilitated soil flushing method for specific contaminated soils.