Comparison of impinging jet mixers by using barium sulfateprecipitation and stabilisation of precipitated nanosuspensionsRicco Kügler, Josefine Morgenstern, Martin Kucher, Matthias Kind
Dipl.-Ing. Ricco Kügler0721-608 [email protected]
same initial particle sizes about x = 40 nm50,3
(initial precipitation conditions at S = 1000, R = 5 and T = 25 °C)a
aggregation at different temperatures:
Stabilisation
Aggregation after precipitation
Detergents:
Roughton-mixer
faster aggregation kinetics at higher temperaturesaggregation despite electrostatical stabilisationfull suppression by sterical stabilisation?
Institute of Thermal Process Engineering (TVT)
Kaiserstrasse 12
76131 Karlsruhe (Germany)
www.tvt.uni-karlsruhe.de
Mixing
Experimental setup
Experimental setup
162
Tween® 20, Span® 20,Melpers® 0045
Results and discussion
Y-mixerT-mixer
d2
luñæ Äp
2
fluid
tube×
×××=
Outlook
particle sizes resulting from
barium sulfate precipitation in Y-mixer 1
after t = 2 s (equilibrium achieved for usedsupersaturation) addition of the additivesin Y-mixer 2
Motivation
particle size analysis by laserlightscattering (Zetasizer Nano ZS)
åå--=transitiontubeexpmix
ÄpÄpÄpÄp
2
uñ0,4 Äp
2
fluid
transition
××=
First results
Supersaturation
What is the right coefficient to compare the mixing quality of different impinging jet mixers?
Reaction:
Measured pressure drop at V = 200 ml/min:total
by theY-Mixer = 0.64 bar at
to achieve the initial supersaturation and initialfree lattice ion ration:
() () ()̄®+-+
s4
2
aq4
2
aqaSOBSOaB
() 2
2
l
mol11
SP1082.9C25K -×=°
free
SO
free
Ba
24
2
c~c~
R-
+
=
SP
free
SO
free
Ba
SP
free
SO
free
Ba
aK
c~c~
K
aaS
24
224
2 -+-+ ×g=
×= ±
Initialsupersaturation:
Initial freelattice ion ratio:
with
Mixing: Stabilisation:
reactionmixingôô <
Example: S = 1000, R = 5, T = 25 °Ca
c = 0.297 mol/l, c = 0.088 mol/l[1](calculation with Bromley model )
BaCl2
add~Na SO42
add~
expÄp
[2] C. Kim, Y.C. Hsieh. Wetting and absorbency of nonionic surfactant solutions on cotton fabrics. Colloid Surf. A, 385:187-188, 2001
no dimensions of themixers are taken intoaccount
useful, when the jet tubeshave the same geometriesReynolds-number in themixing zone of the shownRoughton-mixer is unknown
no dimensions of themixing zone are taken into account
best way, but determi-nation of the pressuredrop in the mixing zone is difficult
mixÄp
fluidmix
mixmean
ñV
ÄpVå
×
×=&
.
x = f(R) ?50,3
faster aggregation with Tween and Spanvery good stabilisation with Melpers 0045
® 20 ® 20
®
Y-mixer and T-mixer show at a total volume streamof 300 ml/min no more influence of the mixingY-mixer increase slower than the particle sizes from the T-mixer at total volume streams under 300 ml/min
Roughton-mixer remain a function of the mixing (higher total volume streams/pressure drop limited by gear pumps)
Testing of some surfacant concentrations
Pressure drop in the mixer
comparison of the mixing qualitywith a Roughton mixer in acomparable design (same jet tubeand tube of the mixing zone)
[1] L.A. Bromley. Thermodynamic properties of strong electrolytes in aqueous solutions. AIChE Journal, 19(2):313-320, 1973.
optimisation of the steric stabilisation with
Melpers® 0045(adding time, concentration)stabilisation by increasing the viscosity (thickening agents)
Mixer
additiveNa2SO4 BaCl2 deionised water
Y-mixer 1
Y-mixer 2gear pump 3
gear pump 2gear pump 1
ô
FIC
FIC
FI
waste
direct samplefrom free jet
sample from stirred tank
Na2SO4 BaCl2 deionised water
mixer
gear pump 1 gear pump 2
FIC FIC
waste
direct samplefrom free jet
PDI
0.14 0.08
0.41 bar
0.01
KIT - University of the State of Baden-Wuerttemberg andNational Research Center of the Helmholtz Association
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