A Direct and Continuous Supercritical Water Process for the Synthesis of Surface-Functionalized Nanoparticles
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- 作者：Robert I. Gruar ; Christopher J. Tighe ; Paul Southern ; Quentin A. Pankhurst ; Jawwad A. Darr
- 刊名：Industrial & Engineering Chemistry Research
- 出版年：2015
- 出版时间：August 5, 2015
- 年：2015
- 卷：54
- 期：30
- 页码：7436-7451
- 全文大小：987K
- ISSN：1520-5045
文摘
A new processing methodology is presented for the direct synthesis of surface-functionalized nanoparticles through modification of a single-step continuous supercritical water process. The processing methodology utilizes inexpensive metal salt precursors that form nanoparticles upon mixing the metal salt solution with a supercritical water flow (24 MPa and 450 掳C). Surface functionalization is achieved through introducing a supplementary flow of capping agent (citric acid in this example) to the stream of nascent (newly formed) nanoparticles using a novel reactor design. It was found that certain process attributes were key to effective functionalization of the nascent nanoparticle stream, and that high grafting densities of the capping agent were obtained in a relatively narrow process window. We have also used the core design of the reactor to devise and test a scale-up methodology to produce large quantities of surface-functionalized nanoparticles. A method for scaling-up the reactor is described, using a newly developed pilot plant designed to process flow rates 20脳 greater than the equivalent laboratory-scale process, which yields products at rates of ca. 1 kg/h (effectively semi-industrial-scale production). The method enables large-scale production without recourse to expensive or environmentally damaging reagents and uses water as the only process solvent, a significant advantage over many methods commonly used to produce surface-functionalized nanoparticles. We report the synthesis and characterization of citrate-functionalized Fe3O4 nanoparticles as a model system and present detailed characterization of the materials obtained at both processing scales.