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A novel strategy for selective recovery of chromium from ferronickel slag via microwave assisted sodium peroxide roasting followed by water leaching was proposed in this study. The experimental results showed that 94.21% of chromium was leached with 64.43% of sodium and 6.13% of silicon, while only 0.06 wt% chromium remained in the leaching residue when the mixture of ferronickel slag and sodium peroxide with the mass ratio of 1 was roasted at 600 °C for 20 min before leaching at 50 °C for 1 h with the liquid-to-solid ratio of 10 mL/g. In comparison with conventional roasting, the microwave roasting showed a much higher efficiency for recovering chromium from ferronickel slag with the recovery of chromium increased by 12.92%, resulting from the enhanced conversion of Cr 2 O 3 in the slag to NaCrO 2 and from the looser and more porous structure during the roasting process which was beneficial for subsequent water leaching. Unlabelled Image • A microwave roasting strategy was proposed for recovering Cr from ferronickel slag. • Microwave roasting promoted phase transformation of the slag during recovery of Cr. • The microwave-induced looser and more porous structure facilitated water leaching. [ABSTRACT FROM AUTHOR]

A protocol based on peroxide fusion has been developed for the determination of Au in metallurgical samples and ores covering a wide range of concentrations and diverse mineralogies. The quantity of Na 2 O 2 required was minimised, while maintaining lixiviant efficacy, by the use of mixed NaOH + Na 2 O 2 fluxes. The method was shown to be particularly applicable to the determination of coarsely-particulate gold. Fusion cakes were dissolved in hydrochloric acid and then extracted using methylisobutylketone to provide concentrations appropriate for quantification by graphite furnace atomic absorption spectroscopy and to minimise interferences from dissolved salts. The protocol was tested on a variety of certified reference materials and produced results in excellent agreement (at Au concentrations ranging from 0.05 to 47 μg g − 1 ) with the traditional lead fire assay method, while avoiding the health and safety issues associated with that technique. [ABSTRACT FROM AUTHOR]

The aluminum induced texturing method offers an effective light trapping scheme by random texture that is formed by U-shaped craters on the glass surface. The texture is mainly shaped by the reaction between Al and SiO 2 . However, the reaction mechanism is not totally understood. Besides, the influence of other components present in the glass such as Na 2 O, CaO, and MgO. is neglected. In this study, the evolution of Al films on soda-lime glass during annealing has been inspected by depth resolved X-ray photoelectron spectroscopy. The elemental distribution of Si, Al and O have been investigated for different annealing durations and compositional analysis has been conducted for Na, Ca and Mg in addition to Si, Al and O. According to results, a relevant evolution model for annealing process has been constructed. [ABSTRACT FROM AUTHOR]

A novel dietary fiber (MsCDF) based core of maize straw (Core) was prepared by using high boiling solvent of sodium peroxide by high pressure pretreatment (HBSHP). The composition of MsCDF, and several physicochemical properties for MsCDF related to its nutritional quality were investigated. The results revealed that the MsCDF contains high contents total dietary fiber (TDF), soluble dietary fiber (SDF), insoluble dietary fiber (IDF) and two main monosaccharaides, xylose and glucose. Meanwhile, the studies of physicochemical properties of MsCDF indicated that MsCDF performed well water-holding capacity (WHC), oil-holding capacity (OHC), Swelling, solubility (SOL), Glucose dialysis retardation index (GDRI) and adsorption capacity on cholesterol. The results of this study serve as evidence that MsCDF can be used as a functional food additive, Core can be used as a crude material to produce MsCDF and the technology of HBSHP can be used to modify the physico-chemical properties of Core. [ABSTRACT FROM AUTHOR]

Metal air batteries are considered as promising candidates for room-temperature batteries with high-energy densities. On discharge, atmospheric oxygen is reduced at the positive electrode which, in the ideal case, forms the discharge products in a reversible cell reaction. In Na-O 2 batteries upon discharge either sodium peroxide (Na 2 O 2 ) or sodium superoxide (NaO 2 ) is reported to be formed. So far, the charge carrier transport remains relatively unexplored but is expected to crucially determine the efficiency of such energy storage systems. Na 2 O 2 is predicted to be an electrical insulator wherein the transport presumably is determined by very slow hopping processes. Understanding the basic fundamental properties of the overall charge carrier transport, including also nanostructured forms of Na 2 O 2 , is key to developing high-energy metal oxygen batteries. The present study answers the question how overall, i.e. , total, conductivity changes when going from microcrystalline to nanocrystalline, defect-rich Na 2 O 2 . Nanocrystalline Na 2 O 2 was prepared via a top-down approach, viz by high-energy ball milling. Milling does not only shrink the average crystallite diameter but also introduces a large amount of defects which are anticipated to influence total conductivity. It turned out that even after vigorous mechanical treatment the conductivity of the sample is only increased by ca. one order of magnitude. The activation energy remains almost untouched. Thus, the increase seen might be attributed to an enhanced number of charge carriers. Low-temperature data reveals nearly constant loss relaxation behavior which has frequently explained in terms of strictly localized electrical relaxation processes. [ABSTRACT FROM AUTHOR]

Sodium peroxide (Na 2 O 2 ) fusion coupled to Inductively Coupled Plasma Tandem Mass Spectrometry (ICP-MS/MS) measurements was used to rapidly screen quartz-rich geological samples for rare earth element (REE) content. The method accuracy was checked with a geological reference material and Instrumental Neutron Activation Analysis (INAA) measurements. The used mass-mode combinations presented accurate results (only exception being 157 Gd in He gas mode) with recovery of the geological reference material QLO-1 between 80% and 98% (lower values for Lu, Nd and Sm) and in general comparable to INAA measurements. Low limits of detection for all elements were achieved, generally below 10 pg g −1 , as well as measurement repeatability below 15%. Overall, the Na 2 O 2 /ICP-MS/MS method proved to be a suitable lab-based method to quickly and accurately screen rock samples originating from quartz-rich geological areas for rare earth element content; particularly useful if checking commercial viability. [ABSTRACT FROM AUTHOR]

Highlights: [•] Interaction of O2 species with Na metal is studied. [•] Electrostatic interaction affects the binding process and complex geometries. [•] Na+/0·O2 complex has the strongest binding energy and shortest Na---O bond length. [•] Na·(O2)1–4 complexes have stronger binding energies than Na+·(O2)1–4 complexes. [•] Na·(O2)1–4 complexes have different geometries than those of Na ion complexes. [ABSTRACT FROM AUTHOR]

Recovery of Eu from BAM phosphors by a Na 2 O 2 system was developed and its decomposition kinetics and mechanism were investigated. • Eu was replaced by Na 2 O 2 from BAM and was recycled efficiently followed by acid leaching. • The decomposition kinetics of BAM was investigated systematically. • The phase transformation process of the decomposition was analyzed. • A probable reaction mechanism of BAM decomposition by Na 2 O 2 was proposed. An efficient process for recycling Eu from BaMgAl 11 O 19 : Eu3+ (BAM) waste phosphors has been developed. The treatment of BAM by the sodium peroxide (Na 2 O 2) calcining process followed by acid leaching was investigated. The results demonstrated that the calcination temperature and time more significantly influence the recovery efficiencies of metals than does the mass ratio of Na 2 O 2 to BAM. More than 99% of Eu was recovered under the optimal conditions of 425 °C, mass ratio 1:1 and 30 min duration. The decomposition kinetics of BAM were studied using a series of typical solid-solid reaction kinetic models. The apparent activation energies E a for the decomposition reactions of Eu, Ba, Al and Mg were calculated as 52.3 kJ/mol, 64.6 kJ/mol, 87.1 kJ/mol and 88.9 kJ/mol, respectively. XRD analysis indicated that the decomposition of BAM involved a multistep reaction. The reaction mechanism was also analyzed at the crystal structure level, which indicated that Ba and Eu atoms in the mirror plane of the unit cell of BAM were replaced by Na from Na 2 O 2 at the beginning, and that BaO 2 and Na 2 MgAl 10 O 17 were produced. Then, Na 2 MgAl 10 O 17 was decomposed to NaAl 7 O 11 and MgAl 2 O 4 , and finally, NaAlO 2 , MgO, BaCO 3 and Eu 2 O 3 were generated at a higher temperature (600 °C). SEM and EDS analysis also demonstrated the proposed substitution and decomposition reactions. This work is expected to open new avenues and provides a theoretical basis for the highly efficient recovery of Eu from waste rare earth phosphors. [ABSTRACT FROM AUTHOR]

A safer method of oxidation of Cr2O3-containing fecal samples from transit-time studies was developed using sodium peroxide to replace perchloric acid as the oxidizing agent. The percentage recovery of Cr2O3 with this method was compared with that of a perchloric acid method for samples containing quantities of fecal ash and Cr2O3 typical of those from rodent transit-time studies. Both methods gave relatively constant percentage recoveries for Cr2O3 contents from 0.4 to 10 mg. Over this range, mean (±SD) percentage recoveries of Cr2O3 for sodium peroxide fusion and the perchloric acid method were 75.5 ± 4.3 and 89.9 ± 2.5, respectively. As long as percentage recovery is constant, the transit time as determined by calculation of the time of 80% excretion of the total recovered Cr2O3 is not affected. Sodium peroxide fusion provides a useful and safer alternative to perchloric acid oxidation in transit-time studies using Cr2O3 as a nonabsorbable marker. [ABSTRACT FROM AUTHOR]