Phytoremediation of engineered nanoparticles using aquatic plants and decomposition of trichloroethylene (TCE) by Cu2O/Pd light-activated nanostructures

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Ebrahimbabaie, Parisa
Pichtel, John
Zahran, Elsayed M.
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Thesis (Ph. D.)
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Study 1 Engineered nanoparticles (ENPs) are used in many industrial and commercial applications; however, concern has arisen regarding potential adverse environmental impacts from the inadvertent release of ENPs into water bodies. Certain plants have been identified with the capability to take up metallic ENPs via roots, thus indicating possible application for phytoremediation. The reported study evaluates the potential for aquatic plants (cattail, Typha latifolia and sedge, Carex rostrata) for uptake of selected ENPs (Ag, ZnO, TiO2, BiVO4, and Cu2O) in a mesocosm-scale constructed wetland. In most cases, roots accumulated substantially greater concentrations of ENP metals compared to shoots. The translocation factor (TF) of several ENPs in certain treatments (ZnO and Cu2O, sedge; TiO2, cattail) was > 1.0, indicating the potential for phytoextraction. Plant physiological response (chlorophyll content, activities of carbonic anhydrase and catalase, leaf area, shoot and root length) varied according to ENP type and dosage, and plant species. In certain cases, ENP application enhanced plant response. Sedge is proposed as a promising aquatic species for phytoextraction of certain ENPs. Study 2 Trichloroethylene (TCE), a common industrial solvent, is one of the most frequently detected volatile organic compounds (VOCs) in groundwater in the United States. The novel photocatalyst, i.e., Cu2O nanostructures, was synthesized using three methods, resulting in particles sizes 400, 600 and 700 nm. The nanostructures were subsequently coated with palladium nanoparticles. The Pd/Cu2O nanostructures were applied for decomposition of TCE in the presence of light (350-750 nm) via both oxidation and reduction mechanisms. Using the oxidation pathway, the n600 Pd/Cu2O photocatalyst showed greater TCE degradation (36%) compared to the n700 and n400 Pd/Cu2O nanostructures (29% and 14%, respectively). When TCE was reacted with the photocatalyst via the reduction pathway, the n400 Pd/Cu2O nanostructures decomposed 42% of TCE, compared with 16.02% and 30.0% decomposition by the n700 and n600 Cu2O/Pd nanostructures, respectively. The reported results indicate that light-activated nanomaterials offer promise as a technology for remediation of hazardous VOCs.