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Yoo, Jongchan,Jeon, Pilyong,Tsang, Daniel C.W.,Kwon, Eilhann E.,Baek, Kitae Elsevier 2018 Environmental pollution Vol.243 No.1
<P><B>Abstract</B></P> <P>Sediments nearby harbors are dredged regularly, and the sediments require the stringent treatment to meet the regulations on reuse and mitigate the environmental burdens from toxic pollutants. In this study, FeCl<SUB>3</SUB> was chosen as an extraction agent to treat marine sediment co-contaminated with Cu, Zn, and total petroleum hydrocarbons (TPH). In chemical extraction process, the extraction efficiency of Cu and Zn by FeCl<SUB>3</SUB> was compared with the conventional one using inorganic acids (H<SUB>2</SUB>SO<SUB>4</SUB> and HCl). Despite the satisfactory level for extraction of Cu (78.8%) and Zn (73.3%) by HCl (0.5 M) through proton-enhanced dissolution, one critical demerit, particularly acidified sediment, led to the unwanted loss of Al, Fe, and Mg by dissolution. Moreover, the vast amount of HCl required the huge amounts of neutralizing agents for the post-treatment of the sediment sample via the washing process. Despite a low concentration, extraction of Cu (70.1%) and Zn (69.4%) was done by using FeCl<SUB>3</SUB> (0.05 M) through proton-enhanced dissolution, ferric-organic matter complexation, and oxidative dissolution of sulfide minerals. Ferric iron (Fe<SUP>3+</SUP>) was reduced to ferrous iron (Fe<SUP>2+</SUP>) with sulfide (S<SUP>2-</SUP>) oxidation during FeCl<SUB>3</SUB> extraction. In consecutive chemical oxidations using hydrogen peroxide (H<SUB>2</SUB>O<SUB>2</SUB>) and persulfate (S<SUB>2</SUB>O<SUB>8</SUB> <SUP>2-</SUP>), the resultant ferrous iron was used to activate the oxidants to effectively degrade TPH. S<SUB>2</SUB>O<SUB>8</SUB> <SUP>2-</SUP> using FeCl<SUB>3</SUB> solution (molar ratio of ferrous to S<SUB>2</SUB>O<SUB>8</SUB> <SUP>2-</SUP> is 19.8–198.3) removed 42.6% of TPH, which was higher than that by H<SUB>2</SUB>O<SUB>2</SUB> (molar ratio of ferrous to H<SUB>2</SUB>O<SUB>2</SUB> is 1.2–6.1). All experimental findings suggest that ferric is effectively accommodated to an acid washing step for co-contaminated marine sediments, which leads to enhanced extraction, cost-effectiveness, and less environmental burden.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ferric chloride is the most suitable to remediate contaminated marine sediments. </LI> <LI> Protons generated by hydrolysis of ferric iron preferentially extract labile metals. </LI> <LI> Ferric iron enhances the metal removal via oxidative dissolution of metal-sulfides. </LI> <LI> Ferric chloride reduces further chemical costs in chemical remediation processes. </LI> <LI> Ferric chloride has less influence on damaging to sediment destruction. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
잔류 불산에 의한 모델 지질토양시료의 광물 용해 및 비소 용출 특성
전필용,문희선,신도연,현성필,Jeon, Pilyong,Moon, Hee Sun,Shin, Doyun,Hyun, Sung Pil 한국지하수토양환경학회 2018 지하수토양환경 Vol.23 No.2
This study explored secondary effects of the residual hydrofluoric acid (HF) after a hypothetical acid spill accident by investigating the long-term dissolution of minerals and leaching of pre-existing arsenic (As) from two soil samples (i.e., KBS and KBM) through batch and column experiments. An increase in the HF concentration in both soil samples resulted in a dramatic increase in the release of major cations, especially Si. However, the amounts of mineral dissolved were dependent on the soil type and mineral characteristics. Compared to the KBM soil, relatively more Ca, Mg and Si were dissolved from the KBS soil. The column experiment showed that the long-term dissolution rates of the minerals are closely associated with the acid buffering capacity of the two soils. The KBM soil had relatively higher effluent pH values compared to the KBS soil. Also, more As was leached from the KBM soil, with a more amorphous hydrous oxide-bound As fraction. These results suggest that the potential of heavy metal leaching by the residual acid after an acid spill will be influenced by heavy metal speciation and mineral structure in the affected soil.