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(2016) Understanding bottom-up continuous hydrothermal synthesis of nanoparticles using empirical measurement and computational simulation. Nano Research, 9 (11). pp. 3377-3387. ISSN 1998-0000 Access from the University of Nottingham repository: http://eprints.nottingham.ac.uk/41016/1/1215_proof.pdf Copyright and reuse:The Nottingham ePrints service makes this work by researchers of the University of Nottingham available open access under the following conditions. This article is made available under the University of Nottingham End User licence and may be reused according to the conditions of the licence. For more details see: http://eprints.nottingham.ac.uk/end_user_agreement.pdf A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription. ABSTRACTContinuous hydrothermal synthesis was highlighted in a recent review as an enabling technology for the production of nanoparticles. In recent years, it has been shown to be a suitable reaction medium for the synthesis of a wide range of nanomaterials. Many single and complex nanomaterials such as metals, metal oxides, doped oxides, carbonates, sulfides, hydroxides, phosphates, and metal organic frameworks can be formed using continuous hydrothermal synthesis techniques. This work presents a methodology to characterize continuous hydrothermal flow systems both experimentally and numerically, and to determine the scalability of a counter current supercritical water reactor for the large scale production (>1,000 T•year -1 ) of nanomaterials. Experiments were performed using a purpose-built continuous flow rig, featuring an injection loop on a metal salt feed line, which allowed the injection of a chromophoric tracer. At the system outlet, the tracer was detected using UV/Vis absorption, which could be used to measure the residence time distribution within the reactor volume. Computational fluid dynamics (CFD) calculations were also conducted using a modeled geometry to represent the experimental apparatus. The performance of the CFD model was tested against experimental data, verifying that the CFD model accurately predicted the nucleation and growth of the nanomaterials inside the reactor.

This work presents experimental and model results from a new configuration of a cooled wall reactor working with two outlets: an upper outlet through which a salt-free hot effluent (500 -600 • C) is obtained and a lower outlet through which an effluent at subcritical temperature dissolving the precipitated salts is obtained. Different flow distributions were tested in order to find the best elimination conditions. Total organic carbon removal over 99.99% was obtained at injection temperatures as low as room temperature, when the fraction of products leaving the reactor in the upper effluent is lower than 70% of the feed flow. The performance of the reactor was tested with the oxidation of a recalcitrant compound such as ammonia, using isopropyl alcohol as co-fuel.Removals higher than 99% of N-NH + 4 were achieved in both effluents, working with temperatures near 700 • C. Slightly better eliminations were obtained in the bottom effluent because its residence time in the reactor is longer. The behavior of the reactor working with feeds with a high concentration of salts was also tested. Feeds containing up to 2.5% wt Na 2 SO 4 could be injected * Corresponding author. Phone: +34 983423166Email addresses: palabreras@gmail.com (Pablo Cabeza), joao.deq@gmail.com (Joao Paulo Silva Queiroz), mcriado_sastre@hotmail.com (Manuel Criado), crisbaterna@gmail.com (Cristina Jimenez), mdbermejo@iq.uva.es (Maria Dolores Bermejo), fidel@iq.uva.es (Fidel Mato), mjcocero@iq.uva.es (Maria Jose Cocero) 1 Present address: Dept. of Chemical Engineering -Universidade Federal de PernambucoProf. Artur de Sá, s/n, -Cidade Universitária -50740-521, Recife, PE -Brazil Preprint submitted to Energy March 2, 2015 in the reactor without plugging problems and a total organic carbon removal of 99.7% was achieved in these conditions. Upper effluent always presented a concentration of salt lower than 30 ppm. Finally, a theoretical analysis of the energy recovery of the reactor working with two outlets was made.