Facile synthesis of high iron content activated carbon-supported nanoscale zero-valent iron for enhanced Cr(VI) removal in aqueous solution

Purpose. To substantiate the efficiency of processing hematite raw materials at the Krivoy Rog Mining and Processing Plant of Oxidized Ores using the direct reduction technology itmk3®. Metodology. Analysis of the results of the itmk3® direct restoration technology developed by Kobe Steel Ltd., Japan and Hares Engineering GmbX, Austria, with a view to using it to process Krivbass hematite ores into granulated iron (so-called “nuggets”). Findings. The involvement in the production of hematite ores (oxidized quartzite) of Krivbass with high iron content, but with low magnetic properties for their processing into granular cast iron is grounded. Originality. The use of itmk3® direct reduction technology from Kobe Steel Ltd., Japan and Hares Engineering GmbH, Austria for the processing of Krivbass hematite ores into granular cast iron is justified for the first time. Practical value. The efficiency of the use of hematite ores (oxidized quartzite) has been substantiated, which can significantly reduce the costs in the mining cycle for the economical production of metallurgical products.

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Effects of copper and zirconium contents on microstructure and magnetic properties of Sm(Co,Fe,Cu,Zr) magnets with high iron content

Journal of Rare Earths ◽

10.1016/j.jre.2020.03.002 ◽

2020 ◽

Cited By ~ 2

Author(s):

Zhifeng Shang ◽

Dongtao Zhang ◽

Zhihong Xie ◽

Yunqiao Wang ◽

Muhammad Haseeb ◽

...

Keyword(s):

Magnetic Properties ◽

Iron Content ◽

High Iron Content ◽

High Iron ◽

Microstructure And Magnetic Properties

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Efficient Sequestration of Hexavalent Chromium by Graphene-Based Nanoscale Zero-Valent Iron Composite Coupled with Ultrasonic Pretreatment

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18115921 ◽

2021 ◽

Vol 18 (11) ◽

pp. 5921

Author(s):

Haiyan Song ◽

Wei Liu ◽

Fansheng Meng ◽

Qi Yang ◽

Niandong Guo

Keyword(s):

Aqueous Solution ◽

Removal Efficiency ◽

Inhibitory Effect ◽

Ultrasonic Cavitation ◽

Zero Valent Iron ◽

Ultrasonic Pretreatment ◽

Nanoscale Zero Valent Iron ◽

Passivation Layers ◽

Initial Ph ◽

Two Phases

Nanoscale zero-valent iron (nZVI) has attracted considerable attention for its potential to sequestrate and immobilize heavy metals such as Cr(VI) from an aqueous solution. However, nZVI can be easily oxidized and agglomerate, which strongly affects the removal efficiency. In this study, graphene-based nZVI (nZVI/rGO) composites coupled with ultrasonic (US) pretreatment were studied to solve the above problems and conduct the experiments of Cr(VI) removal from an aqueous solution. SEM-EDS, BET, XRD, and XPS were performed to analyze the morphology and structures of the composites. The findings showed that the removal efficiency of Cr(VI) in 30 min was increased from 45.84% on nZVI to 78.01% on nZVI/rGO and the removal process performed coupled with ultrasonic pretreatment could greatly shorten the reaction time to 15 min. Influencing factors such as the initial pH, temperature, initial Cr(VI) concentration, and co-existing anions were studied. The results showed that the initial pH was a principal factor. The presence of HPO42−, NO3−, and Cl− had a strong inhibitory effect on this process, while the presence of SO42− promoted the reactivity of nZVI/rGO. Combined with the above results, the process of Cr(VI) removal in US-nZVI/rGO system consisted of two phases: (1) The initial stage is dominated by solution reaction. Cr(VI) was reduced in the solution by Fe2+ caused by ultrasonic cavitation. (2) In the following processes, adsorption, reduction, and coprecipitation coexisted. The addition of rGO enhanced electron transportability weakened the influence of passivation layers and improved the dispersion of nZVI particles. Ultrasonic cavitation caused pores and corrosion at the passivation layers and fresh Fe0 core was exposed, which improved the reactivity of the composites.

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