Fine Bubble Transport in Porous Media towards Application for Soil Remediation

Transcription

1 Fine Bubble Transport in Porous Media towards Application for Soil Remediation HAMAMOTO Shoichiro Abstract Transport of fine bubbles (FBs) in porous media has drawn increasing ention, as a promising technology for soil and groundwater remediation. Understanding the transport characteristics of FBs in soils is essential to optimize FB-based remediation techniques. FB transport is highly influenced by flow rate, gas species, chemical properties of FB water such as ph and ionic strength. Transport models for colloidal particles including colloid filtration theory are applicable for characterizing FB transport in the porous media. In addition, DLVO theory representing interaction energy between colloidal particles and collector was helpful for understanding achment mechanism of FBs in the porous media. Keywords: Transport characteristics, Transport model, Porous media, Attachment, Colloid, Interaction energy 1. FB 1 nm nm 1 [1] FB FB CO [-5] FB FB FB [4, 6] FB FB * ** TEL: (3) FAX: (3) shoichi@soil.en.a.u-tokyo.ac.jp FB Jenkins [4] FB p-xylene FB p-xylene Rothmel [6] FB FB FB FB FB FB 混相流 3 巻 1 号 (18) 19

2 FB. FB FB FB FB Wan [7] FB.7- m m m FB FB1 m m FB Wan [7] Hamamoto [8] 1 m FB.1 mm FB FB FB Fig. 1 FB FB FB FB Fig. 1 FB Fig. 1 Relative FB concentration (FB conc. in the effluent / applied FB conc.) during FB transport experiments at two different flow conditions (HF: high flow, LF: low flow). The two vertical lines represent pore volume when starting injection of FB water (around 1 on x-axis) and when starting injection of reference solution (around 6.5 on x-axis), respectively [8]. FB [9]Ushikubo [9] Hamamoto [8] ph FB FB FB FB ph [1-1] FB FB FB ph FB Hamamoto [8]Fig. 1 EC FB Fig. FB FB Japanese J. Multiphase Flow Vol. 3 No. 1(18)

3 Fig. Changes in relative Air-FB concentration and EC with number of pore volumes after starting injection of pure water [8]. ph FB Hamamoto [13] FB FB FB FB FB FB ph FB FB 3. FB Wan [7] FB Fig. 3 Relative FB concentration (FB conc. in the effluent / applied FB conc.) during FB transport experiments under three different ph conditions [13]. FB Hamamoto [13] ph ph = 5, 8, 11 FB ph = 5 FB FB Fig. 3 FB FB ph = 11FB Fig. 3 FB C C C R D v k ac (1) t z z C (L -3 ) FB R D (L T -1 )v (L T -1 )ka FB (T -1 ) ka 3 ( 1 ) k a v () d g (L 3 L -3 )dg (L) FB Yao [14] Rajagopalan Tien[15] 混相流 3 巻 1 号 (18) 1

4 p 4. 1 / 3 s [ A N A N N / 3 Pe s 1 / 8 LO 1 5 / 8 R A N N ] (3) s G p (1-) 1/3 As p NPeNLONGNR van der Waals = FB Molnar [16] Wan [7] Hamamoto [13](1) FB Fig. 3 (1)FB Hamamoto [8] FB FB C C C D v E t z z E S t R E str (4a) k c k dets (4b) Sstr Estr k strc (4c) t E (M L -3 T -1 ) Estr (M L -3 T -1 ) FB (M L -3 ) S FB (M M -1 )k kdet (T -1 ) FB Sstr FB (M M -1 )kstr (T -1 ) FB Hamamoto [8] FB FB FB Fig. 1 LF (1)(4) (4)(1) 4. FB FB FB Derjaguin, Landau, Verwey, and OverbeekDLVO [17-18] DLVO van der Waals FB ( h ) ( h ) ( h ) ( h ) (5) el vdw h (L) (M L T - ) el (M L T - )vdw (M L T - )hd (M L T - ) van der Waals [19]van der Waals -[] hd 1 exp h h) { 1 ln 1 exp h el ( ln1 exp (6) 1 h 1 14 vdw Hr ( ) c h h 1 6 (7) h (M -1 L -3 T 4 A - ) 1 FB (V) (V) Deby-Huckel H (M L T - ) Hamakar=-1.1 x 1 - J rc (L) FB 87.5 nm Hamamoto [13] Chrysikopoulos Syngouna [1] d h hd ( h ) r c AB d exp( ) (8a) K13 d (8b) h AB AB } Japanese J. Multiphase Flow Vol. 3 No. 1(18)

5 Fig. 4 potentials for FB and glass beads at different ph conditions [13]. cos 1 cos 3 log K (8c) Fig. 5 Total interaction energy at different ph conditions using Eq. (5) (kb and T are Boltzmann constant and temperature, respectively). AB (L)= 1 nm d (L) =.5 nm d [M T - ] h = d Lewis acid-base K13 (M L T - ) 1 3 ( o ) FB 18 o o (5)-(8) ph () FB FB 1 mm ph FB Hamamoto [13]Fig. 4FB Fig. 4 ph FB FB Fig. 5 ph FB ph 3 ph nm ph FB Fig. 6 Total interaction energy considering surface roughness at different ph conditions using Eq. (9) (kb and T are Boltzmann constant and temperature, respectively). ph 5 Hamamoto [13] FB Bradford [] 混相流 3 巻 1 号 (18) 3

6 ' h 1 f h h f h ' (9) r r fr hr (L)Fig. 6 fr =.1 hr = nm ph ph 5 'max 7.8 kbt 1/1 Fig. 6hr fr FB FB Hamamoto [8, 13] Fig. FB 5. FB FB FB ph FB FB FB FB FB FB FB FB r JSPS 16H Nomenclature C : FB concentration [L 3 ] R : retardation factor [-] D : dispersion coefficient [L T -1 ] v : pore velocity [L T -1 ] ka : rate coefficient for achment [T -1 ] k : rate coefficient for reversible achment [T -1 ] kdet : rate coefficient for reversible detachment [T -1 ] kstr : rate coefficient for irreversible achment [T -1 ] dg : diameter of the collector [L] rc : radius of FB [L] S : FB concentration at solid phase due to reversible achment [M M -1 ] S : FB concentration at solid phase due to reversible achment [M M -1 ] h : separation distance [L] d : distance between surfaces at contact [L] K13 : hydrophobic interaction constant [M L T - ] fr : nanoscale roughness fraction [-] hr : nanoscale roughness height [L] Greek letters : porosity [L 3 L -3 ] : collector efficiency [-] : collision efficiency [-] : bulk density of porous media [M L -3 ] : total interaction energy [M L T - ] el : electrostatic interaction energy [M L T - ] vdw : van der Waals interaction energy [M L T - ] hd : hydrophobic interaction energy [M L T - ] d : Lewis acid-base free interaction energy [M T - ] : dielectric constant [-] : permittivity in a vacuum [M -1 L -3 T 4 A - ] 1 : zeta potential of FB [V] : zeta potential of collector [V] : Debye-Huckel parameter [L -1 ] 4 Japanese J. Multiphase Flow Vol. 3 No. 1(18)

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