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Abstract
Copper–gold mining in the eastern Alps, Austria, has
produced sulfide-rich tailings that continue to release arsenic (As) into
the environment. This study examined the effectiveness of removing
arsenic from mining waste using various chemical extractants,
nanoparticle (NP) dosages, and different sample grain sizes. The goals
are to extract arsenic and produce a concentrate for recovering valuable
metals, such as copper and gold, through metallurgical processes. This
paper presents an integrated experimental framework designed to
simulate realistic remediation scenarios using hematite nanoparticles
(HMNPs). Multiple extractants—ultrapure water (UPW), nitric acid
(HNO₃), monosodium dihydrogen phosphate (NaH₂PO₄), and
hydrogen peroxide (H₂O₂)—were used to explore arsenic mobilization
under different chemical stress conditions. Among the tested
extractants, 0.1 M HNO₃ showed the highest arsenic removal
efficiency, significantly outperforming UPW, 0.1 M NaH₂PO₄, and 3%
H₂O₂. The addition of NPs improved overall arsenic removal;
however, the efficiency did not increase proportionally with higher NP
concentrations. A concentration of 0.05 HNPs g/L resulted in slightly
higher arsenic removal rates compared to 2.5 HNPs g/L and 5 HNPs
g/L, likely due to particle aggregation at higher concentrations, which
reduced the available reactive surface area. The texture of the mining
waste also influenced removal efficiency. Finer particles promoted
greater arsenic release under the H₂O₂ + HNP treatment, whereas
coarser particles showed better responses to UPW and NaH₂PO₄. In
contrast, HNO₃ consistently delivered high removal efficiencies across
all particle sizes by directly dissolving the mineral compositions. The
distinct oxyanion behavior of As underscores the necessity for strong
extractants or NP-assisted approaches, as conventional methods
optimized for cationic metals are less effective. Overall, HNO₃ proved
to be the most effective single extractant, achieving removal
efficiencies of up to 87.6% for As, 63.8% for Zn, 90.7% for Pb, and
85.97% for Cu. Post-treatment filtrates were analyzed using
Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and
Instrumental Neutron Activation Analysis (INAA) to quantify As
removal.
