Simple gold recovery from e-waste leachate by selective precipitation using a quaternary ammonium salt

Precipitation processes, if selective, present a simple and economical alternative for the recovery of critical metals from primary and secondary ores including electronic wastes. In this work, the recovery of gold by precipitation from both mono-elemental solutions and real CPU leach solution was demonstrated using hydrophilic quaternary ammonium salts. The gold precipitation yield is shown to be dependent on the apolar volume of the precipitant, with the addition of tetrabutylammonium-based salts resulting in the recovery of over 90 % of gold from synthetic solutions. The origin of gold precipitation selectivity relative to common metal ions upon addition of tetrabutylammonium nitrate ([N4444][NO3]) was assigned by X-ray crystal structure to the formation of size selective apolar cavity between neighbouring [N4444]+ cation and the [AuCl4]- anion. Following optimisation as a function of the gold to precipitant molar ratio, aqua regia concentration and time, approximately 70 % of gold could be recovered from waste CPU leach solution with a final purity of 91.4 % (mol/mol). [N4444][NO3] proved to be a versatile gold extractant and could be further applied as part of an acidic aqueous biphasic system at higher aqua regia concentrations were precipitation yields decreased, ensuring a selective gold recovery across a range of leachate conditions. The disclosed results improve the circularity of gold by providing a new avenue for its simple recycling.publishe

Synthesis And Characterization Of Zno And Zno:ga Films And Their Application In Dye-sensitized Solar Cells

Highly crystalline ZnO and Ga-modified zinc oxide (ZnO:Ga) nanoparticles containing 1, 3 and 5 atom% of Ga 3+ were prepared by precipitation method at low temperature. The films were characterized by XRD, BET, XPS and SEM. No evidence of zinc gallate formation (ZnGa 2O 4), even in the samples containing 5 atom% of gallium, was detected by XRD. XPS data revealed that Ga is present into the ZnO matrix as Ga 3+, according to the characteristic binding energies. The particle size decreased as the gallium level was increased as observed by SEM, which might be related to a faster hydrolysis reaction rate. The smaller particle size provided films with higher porosity and surface area, enabling a higher dye loading. When these films were applied to dye-sensitized solar cells (DSSCs) as photoelectrodes, the device based on ZnO:Ga 5 atom% presented an overall conversion efficiency of 6% (at 10 mW cm -2), a three-fold increase compared to the ZnO-based DSSCs under the same conditions. To our knowledge, this is one of the highest efficiencies reported so far for ZnO-based DSSCs. Transient absorption (TAS) study of the photoinduced dynamics of dye-sensitized ZnO:Ga films showed that the higher the gallium content, the higher the amount of dye cation formed, while no significant change on the recombination dynamics was observed. The study indicates that Ga-modification of nanocrystalline ZnO leads to an improvement of photocurrent and overall efficiency in the corresponding device. © 2008 The Royal Society of Chemistry.1114871491O'Regan, B., Gratzel, M., (1991) Nature, 353, p. 737. , -740Kroon, J.M., Bakker, N.J., Smit, H.J.P., Liska, P., Thampi, K.R., Wang, P., Zakeeruddin, S.M., Tulloch, G.E., (2007) Prog. Photovoltaics, 15, p. 1. , -18Ma, T., Akiyama, M., Abe, E., Imai, I., (2005) Nano Lett., 5, p. 2543. , -2547Ko, K.H., Lee, Y.C., Jung, Y.J., (2005) J. Colloid Interface Sci., 283, p. 482. , -487Kakiuchi, K., Hosono, E., Fujihara, S., (2006) J. Photochem. Photobiol., A, 179, p. 81. , -86Keis, K., Magnusson, E., Lindstrom, H., Lindquist, S.-E., Hagfeldt, A., (2002) Sol. Energy Mater. Sol. Cells, 73, p. 51. , -58Horiuchi, H., Katoh, R., Hara, K., Yanagida, M., Murata, S., Arakawa, H., Tachiya, M., (2003) J. Phys. Chem. B, 107, p. 2570. , -2574Katoh, R., Furube, A., Tamaki, Y., Yoshihara, T., Murai, M., Hara, K., Murata, S., Tachiya, M., (2004) J. Photochem. Photobiol., A, 166, p. 69. , -74Keis, K., Vayssieres, L., Rensmo, H., Lindquist, S.-E., Hagfeldt, A., (2001) J. Electrochem. Soc., 148, p. 149. , -A155Rensmo, H., Keis, K., Lindstrom, H., Sodergren, S., Solbrand, A., Hagfeldt, A., Lindquist, S.E., Muhammed, M., (1997) J. Phys. Chem. B, 101, p. 2598. , -2601Minami, T., Sato, H., Nanto, H., Takata, S., (1985) Jpn. J. Appl. Phys., 24, p. 781. , -L784Park, S.-M., Ikegami, T., Ebihara, K., (2006) Thin Solid Films, 513, p. 90. , -94Nonaka, M., Matsushima, S., Mizuno, M., Kobayashi, K., (2002) Chem. Lett., p. 580. , -581Ohkita, H., Cook, S., Ford, T.A., Greenham, N.C., Durrant, J.R., (2006) J. Photochem. Photobiol., A, 182, p. 225. , -230Haque, S.A., Tachibana, Y., Willis, R.L., Moser, J.E., Gratzel, M., Klug, D.R., Durrant, J.R., (2000) J. Phys. Chem. B, 104, p. 538. , -547Haque, S.A., Tachibana, Y., Klug, D.R., Durrant, J.R., (1998) J. Phys. Chem. B, 102, p. 1745. , -1749Gonçalves, A.S., Lima, S.A.M., Davolos, M.R., Antônio, S.G., Paiva-Santos, C.O., (2006) J. Solid State Chem., 179, p. 1330. , -1334Roberts, N., Wang, R.P., Sleight, A.W., Warren, W.W., (1998) Phys. Rev. B, 57, p. 5734Wang, R., Sleight, A.W., Cleary, D., (1996) Chem. Mater., 8, p. 433. , -439Passlack, M., Schubert, E.F., Hobson, W.S., Hong, M., Moriya, N., Chu, S.N.G., Konstadinidis, K., Zydzik, G.J., (1995) J. Appl. Phys., 77, p. 686. , -693Bhosle, V., Tiwari, A., Narayan, J., (2006) J. Appl. Phys., 100, p. 033713. , -033716Nazeeruddin, M.K., Kay, A., Rodicio, I., Humphrybaker, R., Muller, E., Liska, P., Vlachopoulos, N., Gratzel, M., (1993) J. Am. Chem. Soc., 115, p. 6382. , -6390Imai, Y., Watanabe, A., (2005) J. Mater. Sci., 15, p. 743. , -749Willis, R.L., Olson, C., O'Regan, B., Lutz, T., Nelson, J., Durrant, J.R., (2002) J. Phys. Chem. B, 106, p. 7605. , -7613Green, A.N.M., Palomares, E., Haque, S.A., Kroon, J.M., Durrant, J.R., (2005) J. Phys. Chem. B, 109, p. 12525. , -1253

The Mexican consensus on the diagnosis, treatment, and prevention of NSAID-induced gastropathy and enteropathy

Más de 30 millones de personas consumen diariamente antiinflamatorios noesteroideos (AINE) en el mundo, y este consumo se ve incrementado anualmente. Aunque losAINE poseen propiedades analgésicas y antiinflamatorias, sus eventos adversos gastrointesti-nales son bien reconocidos. En nuestro país no existía un consenso respecto al diagnóstico,tratamiento y prevención de la gastropatía y la enteropatía por AINE, por lo que la AsociaciónMexicana de Gastroenterología reunió a un grupo de expertos para establecer recomendacionesde utilidad para la comunidad médica. En este consenso se emitieron 33 recomendaciones. Elconsenso destaca que el riesgo de toxicidad gastrointestinal de los AINE varía según el fármacoempleado y su farmacocinética, lo cual debe ser considerado al momento de su prescripción. Losfactores de riesgo de complicación gastroduodenal por AINE son: antecedente de úlcera pép-tica, edad mayor a 65 a˜nos, dosis altas del AINE, infección por Helicobacter pylori (H.pylori), ypresencia de comorbilidades graves. Los síntomas y el da˜no gastroduodenal inducido por AINEson variables ya que puede cursar asintomático o manifestarse como anemia por deficiencia dehierro, hemorragia, estenosis y perforación. La cápsula endoscópica y la enteroscopia son méto-dos diagnósticos directos en la enteropatía por AINE. Respecto a la prevención, se recomiendaprescribir la dosis mínima necesaria de un AINE para obtener el efecto deseado y durante elmenor tiempo. Finalmente, los inhibidores de la bomba de protones (IBP) representan el están-dar de oro para la profilaxis y tratamiento de los efectos gastroduodenales, mas no son útilesen la enteropatía

The SUSY-QCD beta function to three loops

A number of DR-bar renormalization constants in softly broken SUSY-QCD are evaluated to three-loop level: the wave function renormalization constants for quarks, squarks, gluons, gluinos, ghosts, and epsilon-scalars, and the renormalization constants for the quark and gluino mass as well as for all cubic vertices. The latter allow us to derive the corresponding beta functions through three loops, all of which we find to be identical to the expression for the gauge beta function obtained by Jack, Jones, and North [Jack:1996vg] (see also Ref. [Pickering:2001aq]). This explicitely demonstrates the consistency of DRED with SUSY and gauge invariance, an important pre-requisite for precision calculations in supersymmetric theories.Comment: Latex, 16 pages, reference added; v2: matches published version in Eur.Phys.J.