Polytechnic University of Valencia

About: Polytechnic University of Valencia is a education organization based out in Valencia, Spain. It is known for research contribution in the topics: Catalysis & Population. The organization has 16282 authors who have published 40162 publications receiving 850234 citations.

Gold on Diamond Nanoparticles as a Highly Efficient Fenton Catalyst

Abstract: The Fenton reaction consists of the generation of highly aggressive hydroxyl radicals from hydrogen peroxide and is widely used to degrade organic pollutants. Due to its general applicability, the Fenton reaction is employed in water and soil disinfection/remediation and for removal of non-biodegradable chemicals. The main limitation of the Fenton reaction is the consumption of stoichiometric amounts of transition metals, mostly iron. There is considerable incentive in developing a catalytic Fenton process using exclusively hydrogen peroxide and a catalyst. Herein we report that gold nanoparticles grafted on nanoparticulate diamond catalyze the formation of hydroxyl radicals from hydrogen peroxide with at least 79 % efficiency and reach a turnover number of 321 000, many orders of magnitude higher than any currently available catalysts. This extraordinary activity is derived directly from the nanometric diameters of gold and diamond (“nanojewels”) and from the remarkable inertness of the diamond surface. The Fenton reaction, in which highly aggressive hydroxyl radicals (HOC) are generated from H2O2 by reduction with Fe II ,C u II , or other transition metal salts, is a general process that can be used for the degradation/mineralization of recalcitrant organic pollutants as well as for disinfection. [1–4] In spite of the wide applicability of the Fenton reaction for decomposing almost any organic compound, its widespread use for pollution abatement and disinfection is limited by the need for stoichiometric amounts of Fe II or other transition metals. Most of the efforts to transform the Fenton reaction from a stoichiometric to a catalytic process have met with failure or at best can produce HOC with remarkably low efficiency. [5] For instance, the photo-Fenton process requires transparency of the solution (a prerequisite not frequently fulfilled in polluted waters or soils) and consumes “expensive” photons as stoichiometric reagents. A large number of iron-containing solids such as iron-exchanged zeolites and montmorillonites have also been reported as heterogeneous

MHD flow and mass transfer of an electrically conducting fluid of second grade in a porous medium over a stretching sheet with chemically reactive species

Abstract: An analysis is carried out to study the flow, chemical reaction and mass transfer of a steady laminar boundary layer flow of an electrically conducting fluid of second grade in a porous medium subject to a transverse uniform magnetic field past a semi-infinite impermeable stretching sheet. The governing partial differential equations are converted into ordinary differential equations by a similarity transformation and an analytical solution for this flow is utilized, whereas the concentration profiles are obtained numerically for higher-order reactions. The variations of dimensionless surface concentration and dimensionless surface concentration gradient as well as mass transfer characteristics with various parameters are graphed and tabulated. Our numerical computations show that the effect of destructive chemical reaction is to diminish the concentration boundary layer. This phenomenon is quite the opposite when a generative reaction is present.