Working in it, through it, and among it all day. Chrome Dust at J & J White of Rutherglen, 1893-1967

Article examining working conditions at J & J White of Rutherglen from 1893-1967

Genetic and Metabolic Controls for Sulfate Metabolism in \u3cem\u3eNeurospora crassa\u3c/em\u3e: Isolation and Study of Chromate-Resistant and Sulfate Transport-Negative Mutants

Mutants of Neurospora resistant to chromate were selected and all were found to map at a single genetic locus designated as cys-13. The chromate-resistant mutants grow at a wild-type rate on minimal media but are partially deficient in the transport of inorganic sulfate, especially during the conidial stage. An unlinked mutant, cys-14, is sensitive to chromate but transports sulfate during the mycelial stage at only 25% of the wild-type rate; cys-14 also grows at a fully wild-type rate on minimal media. The double-mutant strain, cys-13;cys-14, cannot utilize inorganic sulfate for growth and completely lacks the capacity to transport this anion. The only biochemical lesion that has been detected for the double-mutant strain is its loss in capacity for sulfate transport. Neurospora appears to possess two distinct sulfate permease species encoded by separate genetic loci. The transport system (permease I) encoded by cys-13 predominates in the conidial stage and is replaced by sulfate permease II, encoded by the cys-14 locus, during outgrowth into the mycelial phase. The relationship of these new mutants to cys-3, a regulatory gene that appears to control their expression, is discussed

Use of Desulfovibrio and Escherichia coli Pd-nanocatalysts in reduction of Cr(VI) and hydrogenolytic dehalogenation of polychlorinated biphenyls and used transformer oil

BACKGROUND Desulfovibrio spp. biofabricate metallic nanoparticles (e.g. ‘Bio-Pd’) which catalyse the reduction of Cr(VI) to Cr(III) and dehalogenate polychlorinated biphenyls (PCBs). Desulfovibrio spp. are anaerobic and produce H2S, a potent catalyst poison, whereas Escherichia coli can be pre-grown aerobically to high density, has well defined molecular tools, and also makes catalytically-active ‘Bio-Pd’. The first aim was to compare ‘Bio-Pd’ catalysts made by Desulfovibrio spp. and E. coli using suspended and immobilised catalysts. The second aim was to evaluate the potential for Bio-Pd-mediated dehalogenation of PCBs in used transformer oils, which preclude recovery and re-use.\ud RESULTS Catalysis via Bio-PdD. desulfuricans and Bio-PdE. coli was compared at a mass loading of Pd:biomass of 1:3 via reduction of Cr(VI) in aqueous solution (immobilised catalyst) and hydrogenolytic release of Cl- from PCBs and used transformer oil (catalyst suspensions). In both cases Bio-PdD. desulfuricans outperformed Bio-Pd E. coli by ~3.5-fold, attributable to a ~3.5-fold difference in their Pd-nanoparticle surface areas determined by magnetic measurements (Bio-PdD. desulfuricans) and by chemisorption analysis (Bio-PdE. coli). Small Pd particles were confirmed on D. desulfuricans and fewer, larger ones on E. coli via electron microscopy. Bio-PdD. desulfuricans-mediated chloride release from used transformer oil (5.6 $\pm$ 0.8 $\mu$g mL-1 ) was comparable to that observed using several PCB reference materials. \ud CONCLUSIONS At a loading of 1:3 Pd: biomass Bio-PdD. desulfuricans is 3.5-fold more active than Bio-PdE. coli, attributable to the relative catalyst surface areas reflected in the smaller nanoparticle sizes of the former. This study also shows the potential of Bio-PdD. desulfuricans to remediate used transformer oil

Ion-exchange hollow fibers

An ion-exchange hollow fiber is prepared by introducing into the wall of the fiber polymerizable liquid monomers, and polymerizing the monomers therein to form solid, insoluble, crosslinked, ion-exchange resin particles which embed in the wall of the fiber. Excess particles blocking the central passage or bore of the fiber are removed by forcing liquid through the fiber. The fibers have high ion-exchange capacity, a practical wall permeability and good mechanical strength even with very thin wall dimensions. Experimental investigation of bundles of ion-exchange hollow fibers attached to a header assembly have shown the fiber to be very efficient in removing counterions from solution

Étude des facteurs contrôlant la sorption de Cr(VI) sur une hydrotalcite de synthèse

La sorption des ions chromate de solutions aqueuses sur une hydrotalcite de synthèse et sur son produit de calcination a été étudiée. L’interaction de ces matériaux avec les ions chromate montre que la cinétique de sorption est rapide et suit une expression de vitesse de sorption réversible du premier ordre. Les influences du pH, de la concentration en ions chromate de la solution et de la température ont été étudiées afin d’optimiser la sorption. Le traitement de solutions contenant de 10 à 200 mg L-1 de Cr(VI) a donné de bons résultats. Les capacités de sorption de ces matériaux sont 1,3 et 2,4 mmol g‑1 de Cr(VI), respectivement. L’étude de la réversibilité de la sorption des ions chromate indique qu’il est possible d’utiliser les hydrotalcites calcinées comme sorbants recyclables. Ceci suggère notamment que ces derniers pourraient constituer d’intéressants supports pour le piégeage d’ions chromate.The sorption of chromate ions from aqueous solutions onto a synthetic hydrotalcite and its calcination product was investigated. The interaction of these materials with chromate ions shows that the kinetics of sorption are fast and follow a first-order reversible model. The effects of pH, chromate ion concentration and temperature on the sorption were studied. Solutions containing from 10 to 200 mg L‑1 of Cr(VI) were successfully treated. The sorption capacities of these materials are approximately 1.3 and 2.4 mmol CrO42-, per g, for the hydrotalcite and its calcination product, respectively. The reversibility of the sorption of chromate ions suggests the possible use of the calcined hydrotalcites as recyclable sorbents, which may constitute useful supports for trapping chromate ions

Storage and Release of Soluble Hexavalent Chromium from Chromate Conversion Coatings on Al Alloys Kinetics of Release

The release of chromate ions from chromate conversion coatings (CCCs) on Al alloys was studied, and the effect of aging of CCCs on the chromate release kinetics was investigated. Chromate release from CCCs into aqueous solutions was monitored by measuring the change in the chromate concentration in solution using UV-visible spectroscopy. Heat-treatment of the CCC greatly reduced the chromate release rate. The chromate release rate also decreased with increasing aging time at room temperature. A diffusion-control model was proposed based on the notion that the CCC in an aqueous solution is a porous, two-phase structure consisting of a solid phase with adsorbed Cr(VI) species that is in local Langmuir-type equilibrium with an interpenetrating solution phase. This model results in a concentration gradient of soluble Cr(VI) in the solution phase of the CCC as chromate is released. The concentration and diffusion coefficients of soluble Cr(VI) in CCC were estimated. The estimated diffusion coefficient tended to decrease with aging time, suggesting that the CCC is modified with aging time.This work was supported under Air Force Office of Scientific Research Multidisciplinary University Research Initiative contract no. F49620-96-1-0479

Chromate uptake characteristics of the pristine layered double hydroxides of Mg with Al

The layered double hydroxides (LDHs) of Mg with Al readily scavenge dissolved chromate ions under a wide range of conditions. While the chromate uptake is quantitative in the LDH containing 33 mol% Al, the uptake is only 58% of the stoichiometric value in the LDH containing 25 mol% Al. This indicates that the lower symmetry of the NO3− ions in the LDH with 33 mol% Al facilitates the intercalation of chromate ions even under conditions of equilibration with excess dissolved nitrate ions. The chromate uptake obeys the Langmuir adsorption isotherm suggesting that the entire interlayer region of the LDH behaves like a surface. This surface is structural rather than morphological as the chromate uptake correlates negatively with the BET surface area of the LDHs

Corrosion Resistance of Steel/Zinc with Silicate Nanoparticles/Polyurethane Paint Systems in NaCl Solution

Surface characteristics and corrosion behaviour of bare electrogalvanized steel coated with polymer/nano-silicate particles added to the electrogalvanizing bath were studied by scanning electron microscopy (SEM), energy dispersive spectrometer (EDXS) and electrochemical impedance spectroscopy (EIS). After applying a barrier polyurethane paint, the paint hardness, porosity, flexibility, colour, gloss, blistering and rusting degrees, and anticorrosive protective properties in 0.05 mol·L-1 NaCl solution were also evaluated. The results correlated well and, being demonstrative of the very slow deterioration rate of the immersed coated electrogalvanized steel, they enabled to assume that if a chemically analogous but thicker coating system was applied; it could be an acceptable alternative in real service conditions.Fil: Célia R. Tomachuk. Energy And Nuclearresearch Institute; BrasilFil: Elsner, Cecilia Ines. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Tecnología de Pinturas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones en Tecnología de Pinturas; ArgentinaFil: Di Sarli, Alejandro Ramón. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Tecnología de Pinturas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones en Tecnología de Pinturas; Argentin