Document Type : ORIGINAL RESEARCH ARTICLE

Authors

1 Department of Extractive Metallurgy, Escuela Politécnica Nacional, Ladrón de Guevara, Quito 170517, Ecuador

2 Instituto de Investigación Geológico y Energético, Quito, Ecuador

3 Universidad Central del Ecuador, UCE-GIIP, EC170521, Quito, Ecuador

Abstract

BACKGROUND AND OBJECTIVES: Cyanide is a commonly-used substance in the gold recovery processes due to its high affinity for forming complexes with the precious metal, but inadequate handling and its final arrangement can lead to severe environmental contamination. In this context, this research focuses on the preparation of nickel ferrite-activated carbon catalysts for catalytic oxidation of cyanide ion in the presence of air. 
METHODS: Hydrated salts of nickel (Ni(NO3)2·6H2O) and iron (Fe(NO3)3·9H2O) were used as precursors. The preparation pathways of ferrite and of ferrite-activated carbon composites were hydro-chemical with oxalic acid (C2H2O4) and co-precipitation with sodium hydroxide. The parameters evaluated for catalyst preparation were Ni/Fe molar ratios (1/1.5 and 1/2), calcination times and temperatures (2-4 h/600-900°C), and ferrite-activated carbon mass ratios in the case of composites (1/1, 1/2 and 1/3). 
FINDINGS: Oxidation results showed that the ideal Ni/Fe molar ratio was 1/2, and the calcination time was 4 h at 600 and 900ᵒC for co-precipitation and hydro-chemical pathways of nickel ferrites, respectively. The catalyst that showed the greatest capacity for cyanide transformation was that obtained by the hydro-chemical pathway with oxalic acid, achieving efficiencies of 96.3% oxidation of cyanide ion. It was also determined that the largest impregnation of ferrite on the carbonaceous surface was 52.6% through the treatment with oxalic acid, with which the composite was obtained with the best catalytic properties of cyanide ion. 
CONCLUSION: Nickel ferrite is able to oxidize cyanide ion to cyanate ion; being the ferrite-activated carbon combination, with which composite materials with catalytic properties of cyanide ion are obtained. Because of this, the materials studied could be applied in the detoxification of cyanurate solutions from metallurgical processes.

Graphical Abstract

Cyanide ion oxidation by catalytic effect of nickel ferrites activated carbon composites

Highlights

  • Nickel ferrite obtained by the co-precipitation pathway at 600ᵒC oxidized 90% cyanide, ferrite obtained by the hydro-chemical pathway at 900ᵒC oxidized 95% cyanide at 8 h;
  • The ferrite nickel-activated carbon composite prepared by the oxalic acid pathway presented the highest oxidations of cyanide ion;
  • The largest impregnation of nickel ferrite over granular activated carbon was achieved by the hydro-chemical pathway, with 53% impregnation;
  • The preparation of ferrite-activated carbon composites achieved the highest efficiencies of cyanide oxidation when compared to working with catalysts separately.

Keywords

Main Subjects

OPEN ACCESS

This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit: http://creativecommons.org/licenses/by/4.0/

Citation Metrics & Captures

Google Scholar Scopus Web of Science | PlumX Metrics Altmetrics Mendeley |

Letters to Editor

GJESM Journal welcomes letters to the editor for the post-publication discussions and corrections which allows debate post publication on its site, through the Letters to Editor. Letters pertaining to manuscript published in GJESM should be sent to the editorial office of GJESM within three months of either online publication or before printed publication, except for critiques of original research. Following points are to be considering before sending the letters (comments) to the editor.

[1] Letters that include statements of statistics, facts, research, or theories should include appropriate references, although more than three are discouraged.
[2] Letters that are personal attacks on an author rather than thoughtful criticism of the author’s ideas will not be considered for publication.
[3] Letters can be no more than 300 words in length.
[4] Letter writers should include a statement at the beginning of the letter stating that it is being submitted either for publication or not.
[5] Anonymous letters will not be considered.
[6] Letter writers must include their city and state of residence or work.
[7] Letters will be edited for clarity and length.

CAPTCHA Image