ORCID Profile
0000-0001-6889-2226
Current Organisation
Curtin University of Technology
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Publisher: MDPI AG
Date: 27-11-2017
DOI: 10.3390/MET7120529
Publisher: MDPI AG
Date: 31-05-2021
DOI: 10.3390/MIN11060590
Abstract: Acid mine drainage (AMD) is a serious environmental issue associated with mining due to its acidic pH and potentially toxic elements (PTE) content. This study investigated the performance of the Fe-Al bimetallic particles for the treatment of combined AMD-gold processing effluents. Batch experiments were conducted in order to eliminate potentially toxic elements (including Hg, As, Cu, Pb, Ni, Zn, and Mn) from a simulated waste solution at various bimetal dosages (5, 10, and 20 g/L) and time intervals (0 to 90 min). The findings show that metal ions with greater electrode potentials than Fe and Al have higher affinities for electrons released from the bimetal. Therefore, a high removal ( %) was obtained for Hg, As, Cu, and Pb using 20 g/L bimetal in 90 min. Higher uptakes of Hg, As, Cu, and Pb than Ni, Zn, and Mn also suggest that electrochemical reduction and adsorption by Fe-Al (oxy) hydroxides as the primary and secondary removal mechanisms, respectively. The total Al3+ dissolution in the experiments with a higher bimetal content (10 and 20 g/L) were insignificant, while a high release of Fe ions was recorded for various bimetal dosages. Although the secondary Fe pollution can be considered as a drawback of using the Fe-Al bimetal, this issue can be tackled by a simple neutralization and Fe precipitation process. A rapid increase in the solution pH (initial pH 2 to in 90 min) was also observed, which means that bimetallic particles can act as a neutralizing agent in AMD treatment system and promote the precipitation of the dissolved metals. The presence of chloride ions in the system may cause akaganeite formation, which has shown a high removal capacity for PTE. Moreover, nitrate ions may affect the process by competing for the released electrons from the bimetal owing to their higher electrode potential than the metals. Finally, the Fe-Al bimetallic material showed promising results for AMD remediation by electrochemical reduction of PTE content, as well as acid-neutralization/metal precipitation.
Publisher: Elsevier BV
Date: 09-2012
Publisher: Elsevier BV
Date: 10-2022
Publisher: Elsevier BV
Date: 04-2009
Publisher: Elsevier BV
Date: 04-2015
Publisher: Elsevier BV
Date: 11-2019
DOI: 10.1016/J.JENVMAN.2019.109367
Abstract: This paper presents an overview of unit processes that lead to potential mercury contamination during gold processing, which can pose serious health, environmental and technical concerns. Mercury release in gold processing streams is attributed to its dissolution from mercury bearing gold ores during cyanide leaching, and its mobile nature in the subsequent stages (e.g., carbon adsorption, elution, Zn precipitation/electrowinning, and smelting) and tailing storage facilities. Although retorting prior to smelting and sulphur-impregnated carbon filters have been developed to ensure minimal mercury contamination, these methods deal with gaseous mercury which is highly toxic and still a serious threat for both the environment and workers. Moreover, spent carbon filters containing high mercury concentrations introduce a new environmental issue. Therefore, there is a demonstrated need for safer and more efficient removal and sequestration techniques. Thus, this work includes a review of mercury removal from activated carbon as well as current mercury treatment and stabilization practices including precipitation, adsorption, cementation, ion exchange and solvent extraction. In addition, emerging mercury remediation materials such as nanomaterials and bimetals with a promising potential in sustainable management, sequestration, and stabilization of mercury from aqueous media will be highlighted. In summary, the results show a high mercury removal capacity of the outlined materials and techniques (between 70 to around 100% removal). However, one of the issues that emerges from these studies is the lack of selectivity of reagents for mercury capture from aqueous solutions containing precious metals. In this regard, future studies with more focus on the selective mercury removal from activated carbon, and then its precipitation from solutions using substances with a greater adsorption capacity to mass ratio (suitable for safe disposal), are therefore recommended.
No related grants have been discovered for Elham Aghaei.