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Updated: Jul 8, 2026

Quantification of Humic and Fulvic Acids in Humate Ores, DOC, Humified Materials and Humic Substance-Containing Commercial Products
Published on: March 18, 2022
Sorption behavior of selenium on humic acid under increasing selenium concentration or increasing solid/liquid ratio
Nao Kamei-Ishikawa1, Yasuo Nakamaru, Keiko Tagami
1Office of Biospheric Assessment for Waste Disposal, National Institute of Radiological Sciences, Anagawa 4-9-1, Inage, Chiba 263-8555, Japan. nao@nirs.go.jp
Abstract:
The sorption of selenium (Se) on humic acid (HA) was investigated in order to better understand the fate of stable and radioactive Se in soils and sediments. An ultrafiltration technique was used to determine size distributions of HA-sorbed-Se when increasing Se concentration and solid/liquid ratio. The results showed that the Se sorption onto HA followed the Freundlich isotherm. No solid/liquid ratio-dependence was observed especially when <3 kDa molecular size fraction was used from solid/liquid separation. The Freundlich isotherm parameters K(F) and n obtained using the <3 kDa molecular size fraction for solid/liquid separation were 3.7 x 10(2) and 0.82, respectively. In addition, since dissolved HA increased with decreased ionic strength in the HA suspension, ionic strength could promote aggregation of HA. The conformational change of HA could affect the sorption behavior of Se on HA.
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