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Yamashita, Yuji; Tanabe, Yosuke*; Adachi, Yasuhisa*
Nogyo Noson Kogakkai Rombunshu, 81(6), p.33 - 37, 2013/12
We obtained breakthrough curves of humic acids with different molecular weight through the column packed with glass beads with various NaCl concentrations. Each breakthrough curve of each humic acid reached almost a stable plateau at which the relative concentration was less than unity. The relative concentrations at each plateau decreased with an increase in the NaCl concentration. Dimensionless deposition rate constants and collision efficiencies of humic acids were calculated. Collision efficiencies were plotted as a function of NaCl concentration to draw a colloidal stability curve. In both humic acids, the obvious boundary points, which were known as the critical deposition concentration (CDC), were obtained from the colloidal stability curve. The value of CDC of smaller molecular weight fraction was higher than that of larger one. In the slow deposition condition, the slope of the stability curve of larger molecular weight fraction was steeper than that of smaller one.
Adachi, Yasuhisa*; Kobayashi, Motoyoshi*; Feng, L.*; Tsujimoto, Yoko*; Yamashita, Yuji
Oreo Saiensu, 13(7), p.299 - 307, 2013/07
The electrical double layer is a well-known concept of a charged surface in an electrolyte solution. In the present article, we go back to the original history of electrokinetics to note how the concept has been established. In the first approximation, we pay attention to one dimensional plate model and discuss on the effectiveness of the DLVO theory in relation to the stability of colloidal dispersion. It is already about seventy years from the proposal of the DLVO theory and its effectiveness has been discussed in many respects. Nevertheless, there still exist unanswered important questions on the flocculation of charged colloids moving with diffusive electrical double layer. In terms of history and progress in technology, an approach using fluid mechanics will be essentially important in future.
Nagao, Seiya*; Niibori, Yuichi*; Tanaka, Tadao; Sasaki, Takayuki*; Saito, Takumi*; Kirishima, Akira*; Yoshikawa, Hideki; Iijima, Kazuki; Hama, Katsuhiro; Iwatsuki, Teruki; et al.
Genshiryoku Bakkuendo Kenkyu (CD-ROM), 20(1), p.3 - 14, 2013/06
This paper shows a current status of groundwater colloids studies on the performance assessment of geological disposal of radioactive wastes in Japan, and summaries realistic approach of the colloids studies at a substantial research network for Japanese universities and institutes.
Yamashita, Yuji*; Tanaka, Tadao; Adachi, Yasuhisa*
Colloids and Surfaces A; Physicochemical and Engineering Aspects, 417, p.230 - 235, 2013/01
Times Cited Count：11 Percentile：28.04(Chemistry, Physical)Transport behavior of humic acid was studied from the aspects of colloidal stability. Deposition kinetics of purified Aldrich humic acid was investigated over a wide range of monovalent and divalent electrolyte concentrations at pH 3.0 by using packed-bed technique. Spherical glass beads with diameters of 0.2 mm were utilized as model collectors. Breakthrough curves of humic acid were measured with UV-VIS spectrophotometer. The values of C/C0 (C and C0 are the effluent and influent concentrations of humic acid, respectively) decreased with increasing electrolyte concentrations. Experimental collision efficiencies were determined from measured single collector efficiencies. The results are presented as stability curves, which is the logarithm of the collision efficiency as a function of the logarithm of salt concentration. Stability curves of humic acid obviously showed favorable and unfavorable regimes and critical deposition concentration in the presence of both electrolytes. As a consequence, it is indicated that transport behavior of humic acid is primarily controlled by electrostatic interaction between humic acids and collectors.
Yamashita, Yuji*; Tanaka, Tadao; Adachi, Yasuhisa*
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no abstracts in English
Yamashita, Yuji*; Tanaka, Tadao; Adachi, Yasuhisa*
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no abstracts in English
Yamashita, Yuji*; Tanaka, Tadao; Adachi, Yasuhisa*
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no abstracts in English
Yamashita, Yuji*; Adachi, Yasuhisa*; Tanaka, Tadao
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no abstracts in English
Tanaka, Tadao; Yamashita, Yuji*; Adachi, Yasuhisa*
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no abstracts in English
Tanaka, Tadao; Tanabe, Yosuke*; Adachi, Yasuhisa*; Yamashita, Yuji*
no journal, ,
no abstracts in English
