Pyroelectrometallurgical processing of bismuth-containing oxides

In this work, we substantiate and develop a general pyroelectrometallurgical technology for processing bismuth dross and oxides (the intermediate products of lead bullion refining by the Betterton-Kroll process) to obtain crude bismuth. The research focuses on bismuth dross (3–5% Bi; 80–85% Pb) remelted at 500–600°С in the presence of NaNO3 and NaOH, as well as the obtained alkaline melt (bismuth oxides, 1–5% Bi; 60–70% Pb). The conducted experiments allowed us to determine optimal parameters of the main steps of processing bismuth oxide, as well as the characteristics of obtained products. Reduction smelting of bismuth oxides at 1150°C (with the addition of sodium carbonate, quartz and fine coke in the amount of 66, 25 and 5% of bismuth oxides mass, respectively) is proposed, leading to bismuth lead formation. Its decoppering is carried out at 350–600°C with 2.0% sulfur (by its weight), added to the melt. We propose to carry out the alkaline treatment of the decoppered Pb-Bi alloy at 500oC in contact with sodium hydroxide, sodium nitrate and sodium chloride, taken in amounts up to 10.2, 8.3 and 1.4% by weight of bismuth lead, respectively. Subsequent electrolysis comprises electrolytic processing of purified Pb-Bi alloy ingots at 550oC. The electrolyte consists of a melt with the following composition, %: NaCl – 7, KCl – 35, PbCl2 – 18 and ZnCl2 – 40. As a result, two end products were obtained by the proposed bismuth oxide processing. The anodic product at the second stage of electrolysis, crude bismuth (yielded 1.1% by the weight of oxides) contains 93.62% Bi and 4.14% Pb, extraction from oxides amounts to 19.0% Bi and 0.1% Pb. About 1.2% Bi and 9.1% Pb of their initial content in the oxides are transferred to the cathodic product containing 0.033% Bi and 97.83% Pb (the yield equalled 5.1% of the oxides).

Electrodes for Paracetamol Sensing Modified with Bismuth Oxide and Oxynitrate Heterostructures: An Experimental and Computational Study

In this work, novel platforms for paracetamol sensing were developed by the deposition of Bi2O3, Bi5O7NO3 and their heterostructures onto screen-printed carbon-paste electrodes. An easy and scalable solid state synthesis route was employed, and by setting the calcination temperatures at 500 °C and 525 °C we induced the formation of heterostructures of Bi2O3 and Bi5O7NO3. Cyclic voltammetry measurements highlighted that the heterostructure produced at 500 °C provided a significant enhancement in performance compared to the monophases of Bi2O and Bi5O7NO3, respectively. That heterostructure showed a mean peak-to-peak separation Ep of 411 mV and a sensitivity increment of up to 70% compared to bare electrodes. A computational study was also performed in order to evaluate the geometrical and kinetic parameters of representative clusters of bismuth oxide and subnitrate when they interact with paracetamol.

French Fries-Like Bismuth Oxide: Physicochemical Properties, Electrical Conductivity and Photocatalytic Activity

Bismuth oxide synthesis using hydrothermal method has been conducted. This study aims to examine the effect of the hydrothermal reaction time on product characteristics and photocatalytic activity in degrading methyl orange dye. Bismuth oxide synthesis was initiated by dissolving bismuth nitrate pentahydrate (Bi(NO3)3.5H2O) and Na2SO4 in a distilled water and added NaOH gradually. The solution formed was transferred into a Teflon-lined autoclave and heated at 120 °C with time variations of 8–16 h. The formation of bismuth oxide was indicated by the vibrations of the Bi−O−Bi and Bi−O groups and the crystal structure consisting of a-Bi2O3, β-Bi2O3, and g-Bi2O3. In addition, the highest photocatalytic activity can be examined through several factors, such as: content of Bi−O−Bi and Bi−OH groups, crystal structure, band gap values, morphology, and surface area, acquired as a result of the effect of hydrothermal reaction time. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).