Study on the Leaching and LIBS Spectral Detection Method of Rare Earth Elements in Deep-Sea Sediments
HAN Yan1, 5, DU Zeng-feng1, TIAN Ye3, LU Yuan3, SHI Xue-fa2, 4, LUAN Zhen-dong1, 5, YU Miao4, ZHANG Xin1, 2, 5*
1. Key Laboratory of Marine Geology and Environment & Center of Deep Sea Research, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
2. Laoshan Laboratory, Qingdao 266061, China
3. Department of Information Science and Engineering, College of Physics and Optoelectronic Engineering, Ocean University of China, Qingdao 266100, China
4. Key Laboratory of Marine Geology and Mineralization, Ministry of Natural Resources, First Institute of Oceanography, Ministry of Natural Resources, Qingdao 266061, China
5. University of Chinese Academy of Sciences, Beijing 100049, China
Abstract：Deep-sea rare earth, refers to the sediments rich in rare earth elements in deep-sea basins. It is the fourth deep-sea metal mineral discovered after polymetallic nodules, cobalt-rich crusts, and polymetallic sulfides, and has great resource potential. The research on the investigation and detection technology of deep-sea rare earth resources in China is very weak. There is a lack of complete technical means to detect rare earth elements (REY) in deep-sea sediments in real-time, and rare earth elements cannot be accurately detected from deep-sea sediments. Laser-induced breakdown spectroscopy (LIBS) has unique advantages, such as in-situ, real-time, continuous, and non-contact. In recent years, LIBS has been gradually applied to underwater elemental analysis. Therefore, this paper proposes a new method for deep-sea rare earth detection, that is, the rare earth elements in deep-sea sediments are leached by inorganic acid. Then, the ionic rare earth elements in the leaching solution of deep-sea sediments are detected using LIBS underwater analysis. After the pretreatment of deep-sea sediments, the leaching experiments of different inorganic acid types and concentrations, solid-liquid ratio, and time conditions were carried out, and the effects of various conditions on the leaching process of rare earth elements were studied. By comparing the leaching rate of rare earth elements in each leaching solution, the optimum leaching conditions were obtained, that is, HNO3 concentration 1.5 mol·L-1, liquid-solid ratio 2∶1, leaching time 5 min. LIBS was used to analyze the rare earth elements (Y, La, Nd) in the leaching solution. After the spectrum was averaged and corrected by wavelength shift difference algorithm (WASS), univariate regression (UVR) and partial least squares (PLS) analysis were performed. The regression coefficients of the best linear regression results of rare earth elements (Y, La, Nd) obtained by UVR analysis were 0.87, 0.83, 0.80, respectively, and the corresponding detection limits were 3.55, 4.09, 5.71 μg·g-1; PLS obtained significantly better regression results than UVR and obtained better regression coefficients, which were 0.97, 0.99, 0.97, respectively. The results show that PLS is more suitable for quantitatively analyzing deep-sea sediments than UVR. It also proves that LIBS can detect deep-sea, in-situ rare earth elements. It is feasible to use LIBS combined with multivariate regression analysis to detect and evaluate rare earth elements in deep-sea sediments and provide data support for LIBS deep-sea rare earth detection.
韩 焱，杜增丰，田 野，卢 渊，石学法，栾振东，于 淼，张 鑫. 深海沉积物中稀土元素浸出及LIBS光谱探测方法研究[J]. 光谱学与光谱分析, 2025, 45(02): 469-475.
HAN Yan, DU Zeng-feng, TIAN Ye, LU Yuan, SHI Xue-fa, LUAN Zhen-dong, YU Miao, ZHANG Xin. Study on the Leaching and LIBS Spectral Detection Method of Rare Earth Elements in Deep-Sea Sediments. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2025, 45(02): 469-475.
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