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Photocatalytic Advanced Oxidation Processes for Neutralizing Free Cyanide in Gold Processing Effluents in Arequipa, Southern Peru

Author

Listed:
  • David C. Vuono

    (Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO 80401, USA)

  • Johan Vanneste

    (Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO 80401, USA)

  • Linda A. Figueroa

    (Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO 80401, USA)

  • Vincent Hammer

    (Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO 80401, USA)

  • Fredy N. Aguilar-Huaylla

    (School of Metallurgical Engineering, National University of San Augustín, Arequipa 04000, Peru)

  • Aaron Malone

    (Department of Mining Engineering, Colorado School of Mines, Golden, CO 80401, USA)

  • Nicole M. Smith

    (Department of Mining Engineering, Colorado School of Mines, Golden, CO 80401, USA)

  • Pablo A. Garcia-Chevesich

    (Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO 80401, USA
    International Hydrological Program—IHP, UNESCO, Montevideo 11200, Uruguay)

  • Héctor G. Bolaños-Sosa

    (School of Chemistry, National University of San Augustín, Arequipa 04000, Peru)

  • Francisco D. Alejo-Zapata

    (School of Process Engineering, National University of San Augustín, Arequipa 04000, Peru)

  • Henry G. Polanco-Cornejo

    (School of Chemistry, National University of San Augustín, Arequipa 04000, Peru)

  • Christopher Bellona

    (Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO 80401, USA)

Abstract

Cyanide (CN − ) from gold processing effluents must be removed to protect human health and the environment. Reducing the use of chemical reagents is desirable for small centralized and decentralized facilities. In this work, we aimed to optimize the use of ultraviolet (UV) radiation coupled with hydrogen peroxide (H 2 O 2 ) to enhance the rate and extent of CN − removal in synthetic and actual gold processing effluents, from one centralized and one decentralized facility in southern Peru. Bench-scale studies conducted using H 2 O 2 and ambient UV showed no significant effects on CN − destruction; however, experiments with higher UV intensity and H 2 O 2 accelerated free CN − degradation. When a 1:1 stoichiometric ratio of CN − :H 2 O 2 was tested, the highly concentrated effluent (1 g CN − /L) had a slower pseudo first-order rate constant (k = 0.0066 min −1 ) and took ~5 h longer to reach 99% destruction, compared with the low concentration effluent (100 mg CN − /L; k = 0.0306 min −1 ). Lastly, a TiO 2 photocatalyst with low stoichiometric CN − :H 2 O 2 ratios (1:0.1 and 1:0.2), in a compound parabolic solar concentrator, was tested to investigate the degradation of a high concentration effluent (1.28 g CN − /L). These results show a significant improvement to degradation rate within a 20 min period, advancing treatment options for mineral processing facilities.

Suggested Citation

  • David C. Vuono & Johan Vanneste & Linda A. Figueroa & Vincent Hammer & Fredy N. Aguilar-Huaylla & Aaron Malone & Nicole M. Smith & Pablo A. Garcia-Chevesich & Héctor G. Bolaños-Sosa & Francisco D. Ale, 2021. "Photocatalytic Advanced Oxidation Processes for Neutralizing Free Cyanide in Gold Processing Effluents in Arequipa, Southern Peru," Sustainability, MDPI, vol. 13(17), pages 1-15, September.
    • Handle: RePEc:gam:jsusta:v:13:y:2021:i:17:p:9873-:d:627921
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    References listed on IDEAS

    as
    1. Fritz, Morgane M.C. & Maxson, Peter A. & Baumgartner, Rupert J., 2016. "The mercury supply chain, stakeholders and their responsibilities in the quest for mercury-free gold," Resources Policy, Elsevier, vol. 50(C), pages 177-192.
    2. Lisa Y. Stein, 2015. "Cyanate fuels the nitrogen cycle," Nature, Nature, vol. 524(7563), pages 43-44, August.
    3. Morgane M.C. Fritz & Peter Maxson & Rupert Baumgartner, 2016. "The mercury supply chain, stakeholders and their responsibilities in the quest for mercury-free gold," Post-Print hal-02547259, HAL.
    Full references (including those not matched with items on IDEAS)

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