Electrochemical monitoring of metal ions removal in Fe 0 /H 2 O systems: competitive effects of cations Zn 2+ , Pb 2+ ,
- PDF / 1,739,574 Bytes
- 13 Pages / 595.276 x 790.866 pts Page_size
- 20 Downloads / 163 Views
ORIGINAL PAPER
Electrochemical monitoring of metal ions removal in Fe0/H2O systems: competitive effects of cations Zn2+, Pb2+, and Cd2+ Marquise Touomo‑Wouafo1,3 · Joël Donkeng‑Dazie2,3 · Ivan Jirka3 · Brice D. Btatkeu‑K1 · Jean Bosco Tchatchueng1 · Chicgoua Noubactep4 · Jiří Ludvík3 Received: 27 June 2020 / Accepted: 1 September 2020 © Springer-Verlag GmbH Austria, part of Springer Nature 2020
Abstract Metallic iron (Fe0) is a reactive material that is widely used for industrial water treatment. The course of the metal ion removal process using Fe0 (iron powder) was monitored electrochemically (differential pulse polarography). As probe species, Zn2+, Pb2+, and C d2+ were selected for their different (1) adsorptive affinity to iron corrosion products (FeCPs), (2) redox properties, (3) precipitation ability at various pH. Batch experiments were carried out with binary ( Zn2+/ Pb2+ and Z n2+/ Cd2+) 2+ 2+ 2+ and ternary ( Zn /Cd /Pb ) systems to reveal the mutual interference of these cations. Detailed time monitoring of iron aging for up to 14 days as well as concentration decay of individual removed cations represent important data for mechanistic discussions. The aqueous concentration of Fe2+ was also monitored. FeCPs were characterized using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Results showed that the presence of P b2+ delays the Zn2+ 2+ 2+ removal whereas the presence of Cd in solution accelerates its removal. The removal of Pb by FeCPs was not affected by the presence of Zn2+ and C d2+, moreover, the Pb2+ inhibited the effect of Cd2+ on the removal of Zn2+. XPS has proven existence of F e2O3 and hydrated Fe oxidic phase, whilst the SEM showed that the original Fe grains were partly dissolved into buffered ambient under formation of fine particles of FeCPs. Results confirm that reductive transformation of any contaminant in a Fe0/H2O system is the consequence and not the cause of iron corrosion. Graphic abstract 2+
Delay of Zn
2+
2+
Acceleration of Zn
removal by Pb
2+
Zn 2+ Zn 2+ Zn 2+ Zn
0.30
2+
Pb , 2+ Pb , 2+ Pb , 2+ Pb ,
1 1 1 1
: : : :
0 0.5 1 2
2+
Zn 2+ Zn 2+ Zn 2+ Zn
0.25 -3
0.15
2+
0.10
0.10 0.05
0.00
0.00
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
Elapsed time / d
2+
Cd , 2+ Cd , 2+ Cd , 2+ Cd ,
1 1 1 1
: : : :
0 0.5 1 2
0.25
-3
0.15
0.05
: : : :
0.30
0.20
[Zn 2+] / mmol.dm
0.20
2+
removal by Cd
0.30
[Zn ] / mmol.dm
2+
[Zn ] / mmol.dm
-3
0.25
: : : :
0.20 0.15 0.10 0.05 0.00 0.00 0.05 0.10 0.15 0.20 0.25 0.30 Elapsed time / d
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
Elapsed time / d
Keywords Heavy metals · Multiple cations · Electrochemistry · Water treatment · Aged zero-valent iron * Jiří Ludvík jiri.ludvik@jh‑inst.cas.cz 1
National School of Agro‑Industrial Sciences, University of Ngaoundere, P.O. Box 455, Ngaoundere, Cameroon
2
Chemical Engineering and Mineral Industries School, University of Ngaoundere, P.O. Box 454, Ngaoundere, Cameroon
3
J. Heyrovsky Institute of Phy
Data Loading...
