### 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.

Translated title of the contribution | Modified leaching of ^{238} u and ^{232} th from water leach purification (WLP) residue |
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Original language | Malay |

Pages (from-to) | 965-972 |

Number of pages | 8 |

Journal | Malaysian Journal of Analytical Sciences |

Volume | 22 |

Issue number | 6 |

DOIs | |

Publication status | Published - 1 Dec 2018 |

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### Keywords

### ASJC Scopus subject areas

- Analytical Chemistry

### Cite this

^{238}u dan

^{232}th dari residu pemurnian larut lesap air (WLP))

*Malaysian Journal of Analytical Sciences*,

*22*(6), 965-972. https://doi.org/10.17576/mjas-2018-2206-06

** (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.

Research output: Contribution to journal › Article

^{238}u dan

^{232}th dari residu pemurnian larut lesap air (WLP)) '

*Malaysian Journal of Analytical Sciences*, vol. 22, no. 6, pp. 965-972. https://doi.org/10.17576/mjas-2018-2206-06

^{238}u dan

^{232}th dari residu pemurnian larut lesap air (WLP)) Malaysian Journal of Analytical Sciences. 2018 Dec 1;22(6):965-972. https://doi.org/10.17576/mjas-2018-2206-06

}

TY - JOUR

T1 - (Modifikasi larut lesap bagi 238 u dan 232 th dari residu pemurnian larut lesap air (WLP))

AU - Rashid, Nur Shahidah Abdul

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

PY - 2018/12/1

Y1 - 2018/12/1

N2 - 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.

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

UR - http://www.scopus.com/inward/record.url?scp=85061321480&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85061321480&partnerID=8YFLogxK

U2 - 10.17576/mjas-2018-2206-06

DO - 10.17576/mjas-2018-2206-06

M3 - Article

VL - 22

SP - 965

EP - 972

JO - Malaysian Journal of Analytical Sciences

JF - Malaysian Journal of Analytical Sciences

SN - 1394-2506

IS - 6

ER -