Nowadays, nanoparticle technology is investigated for being applied in a lot of fields, for example, in catalysis, materials, electronics and biomedicine, one of the most promising. This versatility is because of their properties associated to their size and morphology, such as surface absorption plasmon effect, specific area, reduction of melting point, reduction of superconductivity transition temperature, and increment of metal magnetic force. In order to achieve the desired properties,

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... al synthesis methods have been developed, top down methods that involves a chemical or mechanical size reduction, and bottom up methods in which the particle grows from smaller entities. The main disadvantage of these methods is the use of organic toxic solvents and extreme operation conditions. Novel processes must be environmental sustainable for their application in the real world, because of the growing concern about the planet damage. Green chemistry and engineering provides all the necessary tools to achieve the design of new processes or the modification of existing processes to accomplish this important target. Novel processes must decrease or eliminate wastes production, generate nontoxic product wherever possible and eliminate or replace solvents by benign solvents as supercritical fluids, ionic liquids, water or ethanol. Moreover the processes must be energetically efficient, avoid separation steps, use catalysts when it is possible to increase the efficiency and use renewable feedstocks. The aim of this thesis is the study of some processes related to nanoparticle technology with green chemistry tools. In chapter 1, metal nanoparticles have been synthetized by bioreduction with grape pomace extract. This process uses water as solvent, natural nontoxic reagents, near ambient conditions and renewable feedstocks instead of toxic compounds, high pressure/temperature conditions and high costs, that the traditional process imply. Chapter 2 deals with nanoparticle formulation, a lipid is loaded with metal nanoparticles by PGSS ® , and this process uses supercritical carbon dioxide, being a green option. Also, the process is fast and the solvent is eliminated by decompression, avoiding separation steps. Traditional method uses organic toxic compounds and needs solvent separation. Finally in chapter 3 and 4, a nanoparticle coating process has been developed by supercritical anti-solvent process in a fluidized bed. The solvents used are supercritical CHAPTER 1 Abstract The synthesis of metallic nanoparticles is a promising field where Green Chemistry approach is specially focused in to propose novel processes to reduce the dangerous organic compounds used in conventional techniques. In this study bioreduction is proposed as green alternative process to synthesize copper nanoparticles from a copper salt using grape pomace extract as reducing agent. This extract, a byproduct of red wine production, has both the reducing compounds, as phenolic acids, and capping agents, as flavonols, that control the size during the reaction. The influence of process variables in yield and copper particle size was studied using a Box-Behnken design of experiments varying temperature (30ºC -80ºC), reaction time (60 -180 minutes), and antioxidant -copper ion ratio (0.01 -0.1 g GAE/g Cu ion). Nanoparticles growth was followed over reaction time finding a first controlled phase where particle size remains essentially constant and a second phase where size increases rapidly due to the insufficient concentration of capping agents in the medium. Metallic copper state of nanoparticles was verified by EDS and XRD. Particle morphology was shown by TEM.