title: A microfluidic approach to water-rock interactions using thin rock sections: Pb and U sorption onto thin shale and granite sections.
abstract: The feasibility of using microfluidic tests to investigate water-rock (mineral) interactions in fractures regarding sorption onto thin rock sections (i.e., shale and granite) of lead (Pb) and uranium (U) was evaluated using a synthetic PbCl2solution and uranium-containing natural groundwater as fluids. Effluent composition and element distribution on the thin rock sections before and after microfluidic testing were analyzed. Most Pb removal (9.8mg/cm2) occurred within 3.5h (140 PVF), which was 74% of the total Pb removal (13.2mg/cm2) at the end of testing (14.5h, 560 PVF). Element composition on the thin shale sections determined by μ-XRF analysis indicated that Pb removal was related primarily to Fe-containing minerals (e.g., pyrite). Two thin granite sections (biotite rich, Bt-R and biotite poor, Bt-P) exhibited no marked difference in uranium removal capacity, but a slightly higher amount of uranium was removed onto the thin Bt-R section (266μg/cm2) than the thin Bt-P section (240μg/cm2) within 120h (4800 PVF). However, uranium could not be detected by micro X-ray fluorescence (μ-XRF) analysis, likely due to the detection limit. These results suggest that microfluidic testing on thin rock sections enables quantitative evaluation of rock (mineral)-water interactions at the micro-fracture or pore scale.
authors.affiliation: Institute of Mine Reclamation Technology, Mine Reclamation Corp., 2 Segye-ro, Wonju-si, Gangwon-do, 26464, Republic of Korea.
authors.forename: Youn Soo
authors.initials: YS
authors.lastname: Oh
authors.affiliation: Department of Earth and Environmental Sciences, Korea University, Anam-dong, Seongbuk-gu, Seoul, 02841, Republic of Korea. Electronic address: hyjo@korea.ac.kr.
authors.forename: Ho Young
authors.initials: HY
authors.lastname: Jo
authors.affiliation: Korea Atomic Energy Research Institute, 1045 Daedeokdaero, Yuseong-gu, Daejeon, 34057, Republic of Korea.
authors.forename: Ji-Hun
authors.initials: JH
authors.lastname: Ryu
authors.affiliation: Korea Atomic Energy Research Institute, 1045 Daedeokdaero, Yuseong-gu, Daejeon, 34057, Republic of Korea.
authors.forename: Geon-Young
authors.initials: GY
authors.lastname: Kim
keywords: Lead; Microfluidics; Sorption; Uranium; Water-rock interaction