Processes for working with plastics Technology Offers

Universidad de Alicante posted this:

This method has two stages: 1) Dispersion of, at least, an inorganic material in water. 2) Addition of, at least, an organic coloring solubilized by agitation. The following parameters might be changed in order to obtain different kinds of nanopigments: • Inorganic material concentration. • Organic coloring concentration. • pH. • Temperature. • Ionic strength. The optical response of nanopigments changes as a function of the particle size of the inorganic material (or materials) used by the diffusion. This method makes it possible to produce new hybrid nanopigments with optical and colloidal properties for tailored applications. Mainly, the customizaton of the behaviour of this materials is achieved by controlling organic/inorganic ratio in the material. The morphology of the material is hybrid (laminar/fibrillar). The organic coloring is selected among different types: azoic complexes, metallic, sulphurose, iminoquinone, antraquinone, ftalocianine, etc. In general words, they can be both natural or synthetic. Products can be used in printing inks, painting and dyes, paper, synthetic or natural fibers, polymer materials, cosmetics, etc. With this method the following features can be achieved: Color range control: Through the control over the different spectral species, the optical response is modified too, so the color range can be enlarged. Increase in the colouring power: The ability of the material for increasing the absorption on the surface is linked to three parameters. First, absorption coefficient of the nanopigment in relation to the coloring solution coefficient. Second, light dispersion caused by nanoparticles and addtiional coverage of the surface to fill. Third, reology and fisico-chemical properties of the material are able to obtain homogeneous dispersions. Environmental impact reduction: Some of the usual pigments contain heavy metals in its composition while inorganic solids used in this method are free of heavy metals and can even be used in cosmetics. Natural coloring can be combined with these nanopigments and obtain a new product which will be environmental safe.

Universidad de Alicante posted this:

The new mixed oxide catalyst of cerium-praseodymium (CexPr1-XO2) allow the efficient combustion of chlorinated volatile organic compounds (especially 1,2-dichloroethane). These new catalytic systems are able to work in gas streams at temperatures between 250-500 º C in an dynamic and continuous way without suffering a significant deactivation process. In recent years, environmental legislation has restricted the air emissions permissible levels, and particularly the emission of volatile organic compounds (VOCs) harmful for both the environment and human health There is a wide variety of VOCs, of different chemical nature (aliphatic, aromatic, oxygenated and halogenated compounds) and consequence of different emission sources (waste gases from chemical plants, soil and water decontamination, solvents evaporation , etc..), but 1,2-dichloroethane (DCE, C2H4Cl2) is the most lasting, dangerous and commonly used in industry (used, for example, massively in the process of polyvinyl chloride production and consequently chemical plants produce significant amounts of waste that require efficient treatment). Until a few years ago, VOCs were usually eliminated by thermal incineration. However, new legislation on VOC emissions has originated significant improvements on treatment technologies. This is the case of the catalytic oxidation that in recent years has shown its ability to destroy VOCs at temperatures below those used in thermal incineration and has also produced a significant reduction of secondary pollutants (nitrogen oxides). Currently, catalytic oxidation processes require heating large gas flows that contain a small amount of VOCs and put the gas in contact with solid catalysts that can either be • Those containing noble metals as active phase: they have a excellent oxidation efficiency, although their cost is very high and gradually lose their activity with the presence of chlorine in the reaction mixture. • Those containing transition metals: they have a lower cost and are more stable and durable, although less active than those containing noble metals.