Effects of Tween 80 on Degradation of Pyrene in Soils Growing &lt;em&gt;Sorghum sudanese&lt;/em&gt;

Shengwang Pan,Zhihua Lei,Maoping He,Xin Yuan

doi:10.19026/ajfst.12.2897

Abstract

Phytoremediation is becoming a cost-effective technology for the in-situ clean up of sites polluted with Hydrophobic Organic Contaminants (HOCs). The major factors limiting phytoremediation are the mass transfer, rate of plant uptake and microbial biodegradation of HOCs. To evaluate the potential of surfactants to enhance phytoremediation for HOC-contaminated sites, the efficacy of Sudan grass ( Sorghum sudanense ), at the absence or presence of polyoxyethylene sorbitan monooleate (Tween 80), on the degradation of pyrene in soils were investigated and mechanisms of Surfactant-Enhanced Phytoremediation (SEPR) were discussed. Results showed that the presence of Tween 80 enhanced dissipation of pyrene at initial contents ranging from 20.24 to 321.42 mg/kg. During the 70-d SEPR-experiments, about 801.84~539.99‰ of pyrene was removed from planted soils, only 242.28~122.79‰ degradation of pyrene occurred in unplanted ones. With the presence of Tween 80, the dissipation ratios of pyrene in planted ones were increased up to 863.94~609.63‰, which was 77.27~129.14‰ higher than those in corresponding soils without surfactant. Among all possible pathways, contribution of plant-microbial interactions on dissipation of pyrene was the most significant, either at the presence (456.73‰) or absence (515.58‰) of Tween 80, were the primary means of contaminant degradation. Results suggested SEPR may be a feasible way for reinforcing removal of HOCs in contaminated sites.

Highlights

Phytoremediation is a promising approach to soil remediation due to its convenience, cost-effectiveness and environmental acceptability (Yi and Crowley, 2007)
It has been shown that addition of surfactants facilitates the uptake of Hydrophobic Organic Contaminants (HOCs) by plants. These results indicate a promising opportunity to use surfactants to enhance phytoremediation efficacy
Were on average 27.2% and 16.6% greater than those grown in spiked soils, but the differentiation in the total biomass of seedlings growing in variously spiked soils (C0~C5) between at the presence of Tween 80 (PT) and absence of that (AT) was insignificant

Summary

Introduction

Phytoremediation is a promising approach to soil remediation due to its convenience, cost-effectiveness and environmental acceptability (Yi and Crowley, 2007). One serious limitation is that HOCs in soils usually exhibit low bioavailability to both microorganisms and plants due to their strong affinity to the soil matrix, especially to soil organic matter, which would limit the application of phytoremediation (Eriksen-Hamel and Whalen, 2008). Surfactants are amphiphilic molecules with a hydrophobic portion (usually a long hydrocarbon chain) and a hydrophilic (polar) head group. The Critical Micelle Concentration (CMC), the surface and Interfacial Tension (IFT) and the Hydrophile-Lipophile balance (HLB) are the three main parameters that help characterize surfactant activity in solutions. Surfactants may aid in remediation by decreasing the surface tension of the water and efficiently solubilizing or otherwise mobilizing nonaqueous phase liquids. As the surfactant concentration increases, the surface tension of the solution decreases until the CMC is reached. The addition of surfactants to a soil contaminated with HOCs might increase the mass transfer and the bioavailability of these compounds, facilitating their

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Conclusion