Surfactant assisted phase transfer of water-insoluble quantum dots

Quantum dots;environment;water;surfactant;phase transfer

Lin, Xiaowen ; Bhalerao ; Kaustubh

关键词: Quantum dots;    environment;    water;    surfactant;    phase transfer;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/45597/Xiaowen_Lin.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Nanotechnology is believed to have the potential of solving the biggest challenges for human beingsin areas such as environment protection, renewable energy, and disease detection and treatment.At the same time, this new technology could also pose unknown potential risk to the environment.While commercialization of nanotechnology is growing rapidly across a wide range of products,regulation of nanotechnology to limit the negative impacts is currently lacking.Among the impacts of nanotechnology on the environment, we are specifically interested in thetransformation of nanomaterials in the aqueous environment and their subsequent fate. The pri-mary objective of the research presented in this thesis is to study the role of surfactants in facilitatingthe phase transfer of hydrophobic nanomaterials from organic solvents into the aqueous phase.Without surfactants, hydrophobic nanomaterials would aggregate into micro-scale aggregatesin water, potentially reducing their bio-availability, mobility, and toxicity. However, biologicallyproduced surfactant-like molecules are ubiquitous in the aqueous environment, and it might alterthe hydrophobic surface into hydrophilic, increasing the environmental risk. Hence, the risk ofhydrophobic nanomaterials in the environment may be underestimated.To investigate the potential phase transfer phenomenon, we have chosen a model experimentalsystem consisting of quantum dots (QDs), a nanoparticle with fluorescence and a model surfactant,to study their interaction. A new scenario of quantum dots phase transfer in aqueous environmentwas proposed. The experimental result shows that there are several factors that affect the extentof phase transfer. These include the rate of addition of organic QDs solution to the surfactantsolution and absolute and relative concentrations of surfactant and QDs. The lower the ratio,the higher phase transfer efficiency. Also, as the concentration of surfactant increases, the phasetransfer efficiency will increase, as well as the saturation concentration of the phase transferredquantum dots. The stability of the phase transferred quantum dots is determined by the strength ofthe surfactant. With the surfactant we have tested, the phase transferred QDs eventually formsaggregates and settles out.After investigating the phase transfer of QDs, we are currently investigating the toxicity of thesephase transferred QDs on Synechococcus elongatus as well as on microbial communities in ananaerobic bio-digester.