Micro Segmented-Flow Technique for Continuous Synthesis of Fluorescent ZnO Micro- and Nanoparticles
Conference: MikroSystemTechnik - KONGRESS 2009
10/12/2009 - 10/14/2009 at Berlin, Germany
Pages: 3Language: englishTyp: PDFPersonal VDE Members are entitled to a 10% discount on this title
Li, Shuning; Günther, Mike; Köhler, J. Michael (Technische Universität Ilmenau, Fachgebiet Physikalische Chemie / Mikroreaktionstechnik, Weimarer Straße 32, PF 100565, 98684 Ilmenau, Germany)
The segmented-flow technique is used for continuous synthesis of ZnO nanoparticles under micro reaction conditions. The experimental setup consists of syringe pumps and T-type injectors, PTFE tubings as well as PTFE knot mixers in a thermostated bath. ZnO nanoparticles were obtained by generation under strong alkaline conditions and elevated temperature in aqueous solution and by precipitation under moderate alkaline conditions in DMSO solution. In aqueous solution, small compact nanoparticles (diameters below 100 nm) were obtained at high temperature (90 °C) and high reactant concentrations. Larger crystals, nano needles and nano flowers (submicro and lower micro range) were obtained at lower concentrations and a temperature of 70 °C. Compact nanocrystals with diameters of a few hundred nanometers are formed by the reaction of zinc acetate with tetramethylammonium hydroxide (TMAH) in the presence of polyethylene glycole (PEG) at 80 °C. In almost all cases, a strong effect of flow rate on nanoparticle quality was observed. Flow rates up to 5000 muL/min lead to an improvement of shape homogeneity and size distribution.