(Modifikasi larut lesap bagi 238 u dan 232 th dari residu pemurnian larut lesap air (WLP))

Translated title of the contribution: Modified leaching of 238 u and 232 th from water leach purification (WLP) residue

Nur Shahidah Abdul Rashid, Zetty Izzaty Saleh, Nurul Syiffa Mahzan, Siti Nur Ain Sulaiman, Khoo Kok Siong Kok Siong, Mohd Idzat Idris, Syazwani Mohd Fadzil

Research output: Contribution to journalArticle

Abstract

In recent years, the importance of actinide element mobile fractions in risk assessment evaluation of contaminated sites has increased. The knowledge of the sorption kinetics of 238 U and 232 Th and the thermodynamics behind the sorption process on radioactive waste is important to understand their mobility. In this study, the leaching process of 238 U and 232 Th from water leach purification (WLP) residue of Lynas Advanced Materials Plant was investigated to obtain the optimum leaching conditions by combining synthetic precipitation leaching procedure and batch method for the simulation of acid rain and heavy flooding, correspondingly. The initial 238 U and 232 Th concentrations, and the concentration at varies pH and contact time of 238 U and 232 Th from the WLP residue were studied. Results show that the initial concentrations of 238 U and 232 Th in the WLP residue are 6.6 and 206.1 mg/kg, respectively. In general, the highest values of the concentration after the leaching process of 238 U and 232 Th are 0.363 and 8.288 mg/kg, correspondingly. These results show the maximum potential remobilisation of 238 U and 232 Th at pH 4 with the same contact time of 14 days. At a similar duration, the maximum percentages of leaching are 5.50% and 3.99% for 238 U and 232 Th, respectively. Moreover, at pH 7, the minimum leaching percentages of 238 U and 232 Th are 4.7% and 3.61%, correspondingly. Thus, remobilising 238 U and 232 Th shows that the rate of leaching is influenced by the pH of leachant used. The maximum concentrations of 238 U and 232 Th are obtained at low pH such as pH 4. At pH 7 and 8, the leached amounts of 238 U and 232 Th are minimum. Therefore, combining the SPLP and batch method is practical for estimating the leaching and remobilisation of 232 Th and 238 U from WLP residues. The combined method may be useful for monitoring and risk assessment in environmental studies.

Original languageMalay
Pages (from-to)965-972
Number of pages8
JournalMalaysian Journal of Analytical Sciences
Volume22
Issue number6
DOIs
Publication statusPublished - 1 Dec 2018

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Leaching
Purification
Water
Risk assessment
Sorption
Acid Rain
Actinoid Series Elements
Radioactive Waste
Thermodynamics
Kinetics
Monitoring

ASJC Scopus subject areas

  • Analytical Chemistry

Cite this

(Modifikasi larut lesap bagi 238 u dan 232 th dari residu pemurnian larut lesap air (WLP)) . / Rashid, Nur Shahidah Abdul; Saleh, Zetty Izzaty; Mahzan, Nurul Syiffa; Sulaiman, Siti Nur Ain; Kok Siong, Khoo Kok Siong; Idris, Mohd Idzat; Mohd Fadzil, Syazwani.

In: Malaysian Journal of Analytical Sciences, Vol. 22, No. 6, 01.12.2018, p. 965-972.

Research output: Contribution to journalArticle

Rashid, Nur Shahidah Abdul ; Saleh, Zetty Izzaty ; Mahzan, Nurul Syiffa ; Sulaiman, Siti Nur Ain ; Kok Siong, Khoo Kok Siong ; Idris, Mohd Idzat ; Mohd Fadzil, Syazwani. / (Modifikasi larut lesap bagi 238 u dan 232 th dari residu pemurnian larut lesap air (WLP)) In: Malaysian Journal of Analytical Sciences. 2018 ; Vol. 22, No. 6. pp. 965-972.
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AU - Saleh, Zetty Izzaty

AU - Mahzan, Nurul Syiffa

AU - Sulaiman, Siti Nur Ain

AU - Kok Siong, Khoo Kok Siong

AU - Idris, Mohd Idzat

AU - Mohd Fadzil, Syazwani

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AB - In recent years, the importance of actinide element mobile fractions in risk assessment evaluation of contaminated sites has increased. The knowledge of the sorption kinetics of 238 U and 232 Th and the thermodynamics behind the sorption process on radioactive waste is important to understand their mobility. In this study, the leaching process of 238 U and 232 Th from water leach purification (WLP) residue of Lynas Advanced Materials Plant was investigated to obtain the optimum leaching conditions by combining synthetic precipitation leaching procedure and batch method for the simulation of acid rain and heavy flooding, correspondingly. The initial 238 U and 232 Th concentrations, and the concentration at varies pH and contact time of 238 U and 232 Th from the WLP residue were studied. Results show that the initial concentrations of 238 U and 232 Th in the WLP residue are 6.6 and 206.1 mg/kg, respectively. In general, the highest values of the concentration after the leaching process of 238 U and 232 Th are 0.363 and 8.288 mg/kg, correspondingly. These results show the maximum potential remobilisation of 238 U and 232 Th at pH 4 with the same contact time of 14 days. At a similar duration, the maximum percentages of leaching are 5.50% and 3.99% for 238 U and 232 Th, respectively. Moreover, at pH 7, the minimum leaching percentages of 238 U and 232 Th are 4.7% and 3.61%, correspondingly. Thus, remobilising 238 U and 232 Th shows that the rate of leaching is influenced by the pH of leachant used. The maximum concentrations of 238 U and 232 Th are obtained at low pH such as pH 4. At pH 7 and 8, the leached amounts of 238 U and 232 Th are minimum. Therefore, combining the SPLP and batch method is practical for estimating the leaching and remobilisation of 232 Th and 238 U from WLP residues. The combined method may be useful for monitoring and risk assessment in environmental studies.

KW - Leaching

KW - Thorium

KW - Uranium

KW - WLP residue

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