Magnesium alloys and graphite wastes encapsulated in cementitious materials: Reduction of galvanic corrosion using alkali hydroxide activated blast furnace slag

Chartier, D.; Muzeau, B.; Stéfan, Lavinia; Sanchez-Canet, J.; Monguillon, C.

doi:10.1016/j.jhazmat.2016.12.022

Cited by 14 publications

(3 citation statements)

References 18 publications

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“…However, this nearneutral pH is expected to be detrimental to Mg metal passivation, as shown via the E-pH diagram of magnesium (Figure 1) [10]. Studies about the immobilization of Mg-Zr alloy radwaste have shown that binders having initially a highly alkaline pore solution (such as metakaolin and blast-furnace slag activated by concentrated sodium silicate and sodium hydroxide, respectively [31][32][33]), are more appropriate candidates to mitigate the corrosion of magnesium. Data about Al-Mg alloys are still very limited.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Behavior of Al/Mg Alloys Immobilized in a Magnesium Potassium Phosphate Cement-Based Mortar

et al. 2023

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Portland cement is extensively used for the conditioning of radioactive waste. However, its high alkalinity is a serious obstacle to the stabilization of waste containing aluminum metal since aluminum is oxidized by the pore solution with the production of dihydrogen. This work investigates the potential of an alternative binder, magnesium potassium phosphate (MKP) cement, for the stabilization of Al–Mg alloys comprising 2 to 4.5 wt% of Mg and other metallic impurities. The objective is to assess the influence of the alloy composition on its reactivity in the cementitious matrix at earlier ages, as well as at later ages, when the cement has reached a significant reaction degree. Two complementary techniques are used. Gas chromatography shows that the dihydrogen release, resulting from the corrosion process, is not influenced by the magnesium content in the alloy. Electrochemical impedance spectroscopy provides qualitative information about the corrosion but also makes it possible to assess the corrosion current using an equivalent electrical circuit linked to the kinetic parameters of the postulated corrosion mechanism. Over a one-year period, the corrosion current of the alloys, regardless of their Mg content, is reduced by almost three orders of magnitude in MKP mortar as compared to Portland-cement-based mortar.

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Section: Introductionmentioning

confidence: 99%

Electrochemical Behavior of Al/Mg Alloys Immobilized in a Magnesium Potassium Phosphate Cement-Based Mortar

et al. 2023

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“…A water/(MgO + KH 2 PO 4 ) mass ratio of 0.5 for mortars and 0.3 for cement pastes were employed. The FA/(MgO + KH 2 PO 4 ) and H 3 BO 3 /(MgO + KH 2 PO 4 ) mass ratios were 1 and 0.02, respectively, according to [ 22 ]. In mortars, a standardized graded sand with 99% silica content was incorporated with a sand/solid mass ratio of 1.…”

Section: Materials and Methodologymentioning

confidence: 99%

MgO/KH2PO4 and Curing Moisture Content in MKPC Matrices to Optimize the Immobilization of Pure Al and Al-Mg Alloys

Fernández-García,

Alonso,

Bastidas

et al. 2024

Materials

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Magnesium Potassium Phosphate Cements (MKPCs) are considered a good alternative for the immobilization of aluminium radioactive waste. MKPC composition and moisture curing conditions are relevant issues to be evaluated. The corrosion of pure aluminium (A1050) and AlMg alloys (AA5754) with 3.5% of Mg is studied in MKPC systems prepared with different MgO/KH2PO4 (M/P) molar ratios (1, 2, and 3M) and moisture curing conditions (100% Relative Humidity (RH) and isolated in plastic containers (endogenous curing)). The Al corrosion potential (Ecorr) and corrosion kinetic (icorr and Vcorr) are evaluated over 90 days. Additionally, the pore ion evolution, the matrix electrical resistance, the pore structure, and compressive strength are analysed. The corrosion process of Al alloy is affected by the pH and ion content in the pore solution. The pore pH increases from near neutral for the 1M M/P ratio to 9 and 10 for the 2 and 3M M/P ratio, increasing in the same way the corrosion of pure Al (AA1050) and AlMg alloys (AA5754). The effect of Mg content in the alloy (AA5754) becomes more relevant with the increase in the M/P ratio. The presence of phosphate ions in the pore solution inhibits the corrosion process in both Al alloys. The MKPC physicochemical stability improved with the increase in the M/P ratio, higher mechanical strength, and more refined pore structure.

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“…However, the high processing temperatures (>1000 °C) warrant the exploration of low-temperature waste forms that do not destabilize 99 Tc and other radionuclides . CWF is an alternative to glass waste forms with lower processing temperatures and could be more suitable for immobilization of 99 Tc. , Currently, CWFs are comprehensively used for the immobilization of various LAW/LLW globally. − …”

Section: Immobilization Of 99tc In Waste Formsmentioning

confidence: 99%

Design and Application of Materials for Sequestration and Immobilization of ⁹⁹Tc

Singh

Mahzan

Rashid

et al. 2023

Environ. Sci. Technol.

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99Technetium (99Tc) is a hazardous radionuclide that poses a serious environmental threat. The wide variation and complex chemistries of liquid nuclear waste streams containing 99Tc often create unique, site specific challenges when sequestering and immobilizing the waste in a matrix suitable for long-term storage and disposal. Therefore, an effective management plan for 99Tc containing liquid radioactive wastes (such as storage (tanks) and decommissioned wastes) will likely require a variety of suitable materials/matrixes capable of adapting to and addressing these challenges. In this review, we discuss and highlight the key developments for effective removal and immobilization of 99Tc liquid waste in inorganic waste forms. Specifically, we review the synthesis, characterization, and application of materials for the targeted removal of 99Tc from (simulated) waste solutions under various experimental conditions. These materials include (i) layered double hydroxides (LDHs), (ii) metal–organic frameworks (MOFs), (iii) ion-exchange resins (IERs) as well as cationic organic polymers (COPs), (iv) surface modified natural clay materials (SMCMs), and (v) graphene-based materials (GBMs). Second, we discuss some of the major and recent developments toward 99Tc immobilization in (i) glass, (ii) cement, and (iii) iron mineral waste forms. Finally, we present future challenges that need to be addressed for the design, synthesis, and selection of suitable matrixes for the efficient sequestration and immobilization of 99Tc from targeted wastes. The purpose of this review is to inspire research on the design and application of various suitable materials/matrixes for selective removal of 99Tc present globally in different radioactive wastes and its immobilization in stable/durable waste forms.

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Magnesium alloys and graphite wastes encapsulated in cementitious materials: Reduction of galvanic corrosion using alkali hydroxide activated blast furnace slag

Cited by 14 publications

References 18 publications

Electrochemical Behavior of Al/Mg Alloys Immobilized in a Magnesium Potassium Phosphate Cement-Based Mortar

Electrochemical Behavior of Al/Mg Alloys Immobilized in a Magnesium Potassium Phosphate Cement-Based Mortar

MgO/KH2PO4 and Curing Moisture Content in MKPC Matrices to Optimize the Immobilization of Pure Al and Al-Mg Alloys

Design and Application of Materials for Sequestration and Immobilization of ⁹⁹Tc

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Magnesium alloys and graphite wastes encapsulated in cementitious materials: Reduction of galvanic corrosion using alkali hydroxide activated blast furnace slag

Cited by 14 publications

References 18 publications

Electrochemical Behavior of Al/Mg Alloys Immobilized in a Magnesium Potassium Phosphate Cement-Based Mortar

Electrochemical Behavior of Al/Mg Alloys Immobilized in a Magnesium Potassium Phosphate Cement-Based Mortar

MgO/KH2PO4 and Curing Moisture Content in MKPC Matrices to Optimize the Immobilization of Pure Al and Al-Mg Alloys

Design and Application of Materials for Sequestration and Immobilization of 99Tc

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Design and Application of Materials for Sequestration and Immobilization of ⁹⁹Tc