The Uptake Characteristics of Prussian-Blue Nanoparticles for Platinum-Group Metal and Molybdenum Ions in a Nitric Acid Solution Toward Application for the Recovery of Precious Metals from Nuclear and Electronic Wastes

We have examined the uptake mechanisms of platinum-group-metals (PGMs) and molybdenum (Mo) ions into PBNPs in a nitric acid solution for 24-h sorption test, using inductively coupled plasma atomic emission spectroscopy, powder XRD, and UV-Vis-NIR spectroscopy in combination with first-principles calculations, and revealed that the Ru4+ and Pd2+ ions are incorporated into PBNPs by substitution with Fe3+ and Fe2+ ions of the PB framework, respectively, whereas the Rh3+ ion is incorporated into PBNPs by substitution mainly with Fe3+ and minorly with Fe2+ ion, and Mo6+ ion is incorporated into PBNPs by substitution with both Fe2+ and Fe3+ ions, with maintaining the crystal structure before and after the sorption test. Assuming that the amount of Fe elusion is equal to that of PGMs/Mo substitution, the substitution efficiency is estimated to be 39.0% for Ru, 47.8% for Rh, 87% for Pd, and 17.1% for Mo6+. This implies that 0.13 g of Ru, 0.16 g of Rh, 0.30 g of Pd, and 0.107 g of Mo can be recovered by using 1g PBNPs with a chemical form of KFe(III)[Fe(II)(CN)6].

Nitric acid solution after treating miscanthus as a growth regulator of seed peas (Pisum sativum L.)

All over the world, miscanthus is positioned as an extremely promising and rapidly renewable cellulose- containing raw material for the production of a large number of substances of chemical and biotechnological synthesis. The Institute for Problems of Chemical and Energetic Technologies of the Siberian Branch оf the Russian Academy of Sciences has been developing its own methods of treating miscanthus using diluted solutions of nitric acid. While the amount of a waste solution (liquid phase) is 20 times greater than the target product — a solid phase -- intended for enzymatic hydrolysis and further microbiological synthesis of bioethanol, bacterial cellulose and other valuable products. The hypothesis states that a nitric acid solution after treatment with miscanthus, which was neutralized with ammonium hydrate (hereinafter referred to as the preparation), is a combined lignohumic fertilizer. Testing this hypothesis has required studying the growth-regulating activity of the preparation using the example of sowing pea seeds. The results show that, depending on the degree of dilution and the exposure time, the preparation acts in two ways: either as a stimulant or as a growth inhibitor. Thus, at a dilution rate of 1:10, the preparation acts as an inhibitor, and at a dilution rate of 1:1,000,000, its effect ceases. The working range includes the dilution rate between 1:100 and 1:10,000, when an increase in germination energy and rate is observed by 2–6% compared to the control and root growth is stimulated by 21–29%, i.e. an auxin-like growth-stimulating effect is observed. With prolonged endurance during the 4th day, the preparation showed a growth-inhibiting effect, indicated by the decrease in the germination energy and rate, the length of the stems and roots of the sowing pea. The new preparation showing growth-stimulating activity under certain conditions, supposedly confirms the hypothesis that it is a combined lignohumic fertilizer.

A Study on the Leaching of Rare Earth Elements from Waste Phosphor Powder

This study was carried out to obtain data to design a process to recover rare earth elements, specifically Y(Yttrium), La(Lanthanum), Ce(Cerium), Eu(Europium), Tb(Terbium) from waste phosphor powder. For this purpose, we investigated the effect of temperature, concentration, time and acids on leaching of the rare earth elements. The effect of roasting temperature, roasting time, roasting agent and its dosage on the leaching of rare earth elements were also investigated. 92% of the Yttrium, 70% of the Europium and 8% of the Cerium contained in the waste phosphor powder was leached at the condition of 50 oC and 0.3N HCl solution for 3hours. However, Terbium and Lanthanum were never leached at this condition. The leaching ratio increased to 100% of Yttrium and Europium, 98% of Cerium, 92% of Terbium and 89% of Lanthanum by leaching after soda ash roasting. In the leaching experiment with unroasted phosphor at 80 oC, the initial leaching reaction rate of Yttrium was 0.035 mol/L·s in 0.3N sulfuric acid solution, 0.033 mol/L·s in nitric acid solution and 0.028 mol/L·s in 0.3N hydrochloric acid solution. And the initial leaching reaction rate of Europium was 0.0017 mol/L·s in 0.3N sulfuric acid solution, 0.00114 mol/L·s in nitric acid solution and 0.00113 mol/L·s in 0.3N hydrochloric acid solution. For Cerium, the initial leaching reaction rate was 0.00019 mol/L·s in 0.3N sulfuric acid solution, 0.00025 mol/L·s in nitric acid solution and 0.00014 mol/L·s in 0.3N hydrochloric acid solution.

Ecofriendly and low-cost sample preparation methods for magnesium determination in beer

Ultrasound-assisted extraction and direct analysis were compared with total digestion for magnesium determination in beer samples by flame atomic absorption spectrometry. The method for total digestion used concentrated nitric acid under plate heating. In optimized instrumental conditions, validation of the analytical method was promoted, with good linear range (0.06 to 0.5 mg L�1), low limits of detection and quantification (0.04 and 0.12 �g g�1, respectively), good precision, relative standard deviation (RSD) less than 3.4%, and accuracy (recovery levels of 91.5 to 99.0%). The characteristic concentration (C0) was 9 �g L�1. The extraction procedure was performed in a 1:1 nitric acid solution for 55 min in an ultrasonic bath at 60 �C, while the direct analysis involved a dilution of the samples in a 2% v/v nitric acid solution. The different sample preparation methods were applied to 13 beer samples and at a 95% confidence level, no significant differences were observed. Thus, direct analysis proved to be more suitable for quality control routines of beer samples in the industry.