Hubble Asteroid Hunter III. Physical properties of newly found asteroids
Andreas Tzachristas C2021-16605.pptx
1. Scale Formation and Wetting of Surfaces: A Microfluidics
Investigation
Α. Tzachristas, R.E. Malamoudis, D.G. Kanellopoulou, J. Parthenios,
P.G. Koutsoukos, C.Α. Paraskeva, V. Sygouni
Department of Chemical Engineering, University of Patras
Institute of Chemical Engineering Sciences, Foundation for Research and Technology,
GR26504 Patras, Greece
Corrosion, NACE 2021 1
2. Review
• Multiphase flow in porous media: oil recovery, CO2 storage, fuel cells, desalination, membranes etc.
• Evolution of two-phase flow processes depends on:
the morphology of the porous structure
the pore surface wettability
the viscosity ratio of fluids
the values of dimensional numbers such as capillary and Bond number (Avraam & Payatakes,
1995, Tzimas et al., 1997).
• Deposition and growth of salts: during oil recovery or enhanced oil recovery (EOR), CO2 or gas
storage, several industrial applications, geothermal energy production and utilization and membrane
filtration processes
• Reduction of the local rock permeability or tube clogging (Moghadasi et al., 2003, 2004; El-Said et al.,
2009; Salman et al., 2007; Osode et al., 2015).
• Increase of oil production costs, abandonment of drilled wells with entrapped oil.
• Water and wastewater treatment: Reduction of reverse osmosis membranes.
• Desired controlled precipitation of sparingly soluble salts: waterproofing of underground structures
(e.g. tunnels), prevention of soil erosion using consolidation, stabilization of unconsolidated rocks
(Paraskeva et al., 2000; Larsen et al., 2006; Arvaniti et al., 2010). 2
3. • Parameters investigated in previous studies:
• pH
• temperature
• presence of foreign substance
• presence of seeds
(Reddy and Nancollas, 1971; Xyla et al., 1992; Wiechers et al., 1975; Orkoula et al, 1999; Hafez et al., 2011;
Kofina et al., 2009; Lioliou et al., 2007, 2008).
• Salt precipitation is heterogeneous. Initially an embryo develops on a substrate.
• The formation of the pre-existing nuclei (embryo) crystal phase depends on the interfacial energy
between the substrate-crystal embryo, crystal embryo-water phase and substrate-water phase (Usami
et al., 1984).
• During heterogeneous nucleation, the required energy for the formation of crystal embryo on the
substrate is smaller than the corresponding value for homogeneous nucleation, where crystal
formation takes place in the bulk of the supersaturated solution.
• The driving force for crystal nucleation is the solution supersaturation with respect to the
corresponding crystal phase. Besides thermodynamic effects, fluid dynamics may also play significant
role on crystal formation.
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4. 4
Salt precipitation in a channel in the absence and in the presence of organic phases
Jaho et al.,
Crystal
Growth and
design,
2015;2016.
2, 6, 8, & 10 cm
from the inlet
(25 °C,
SRinitial= 10.7,
IS=0.15 mol/L.
SEM 6 cm from the inlet (a) SRinitial = 10.5, (b &
c) SRinitial=21.28.
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5. 5
Crystal Characterization using
Raman analysis
Calcite (blue) & vaterite (green) SRinitial =10.5 in
the presence of n-dodecane.
Zone A
B (a), C (b) & D (c)
Zone r
A 0.38
B 1.18
C 1.25
D 2.34
r (surface ratio
calcite/vaterite)
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SEM Images (a) Calcite, (b) aragonite and (c) vaterite (SRinitial = 21.28
in the presence of n-dodecane, Τ=25 °C, IS = 0.15 M NaCl).
In summary, in the presence of organic
phases:
1. The time of the observance of the
first crystal is reduced
2. The number of observed crystals is
increased.
3. Except calcite, other morphologies;
vaterite and aragonite are stabilized.
6. AIM OF THIS STUDY
In the present study an investigation of the effect of pore surface wettability on
salt precipitation in microchips is performed.
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7. “WetμFluid- Effect of Pore Surface Wettability on Mineral Scaling, a μFluidic
approach”
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http://www.wetufluid.gr/
Entrance
A1
B1
C5 C1
D5
Exit
Fluid A
Fluid B
A5
B5
E5
…
…
…
…
…
Microchip’s characteristics
Width (μm) 205
Length (cm) 1,5
Height (μm) 100
Volume between the Y
junction (μL)
0,2
Microchip’s volume (μL) 0,36
Roughness (nm) 5
P: Microfluidic pumps
AP: Air pump
C: micro-channel
MVC: microscope and a video-camera
C: Computer
Total fluids flux 0.5L/min, Reynolds number=
0,052
8. Experimental Conditions
A/A Wettability Initial Solutions
Concentration (mmol/L)
Initial
Supersaturation (SR)
Observation time of the first crystal
(h)
CaCl2.2H2O NaHCO3
1 Hydrophilic 13 13 10.5 34
2 Hydrophobic 13 13 10.5 3
3 Hydrophilic 35 35 50.6 8
4 Hydrophobic 35 35 50.6 1
5 Hydrophilic 40 40 61.7 4
6 Hydrophobic 40 40 61.7 0.5
The ionic strength of the solutions was adjusted to 0.15M, with the addition of the appropriate amount of sodium
chloride stock solution
Total Flow rate 0,50 μL/min.
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11. Hydrophobic Microchip SR=10.5
3 hrs
t =126 hrs
Flow Direction
t =141hrs
Results
Raman spectroscopy showed that all points correspond to Aragonite crystals
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12. 12
Results
Hydrophilic Microchip SR=50.6
40 h
24 h
8 h
30 h
12 h
48 h
0
20
40
60
80
100
120
140
0 5 10 15 20 25 30
Crystal
Size
(μm)
Time (h)
Crystal size vs Time
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48 h
Flow Direction
16. Conclusions
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• For similar values of supersaturation, in the case of hydrophobic microchips, the first
crystal is observed earlier.
• In the case of hydrophobic microchips, the formation of aragonite is favored.
• Hydrophobicity favors the formation of smaller but of higher number crystals
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17. Thank you for the attention
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We acknowledge support of this work by the Project
“WetμFluid” (Code 172) which is implemented under
the Action “1st Call for H.F.R.I. Research Projects for the
support of Post-doctoral Researchers” funded by
Hellenic Foundation for Research and Innovation.
Corrosion, NACE 2021
