Application Note
USD 3054
Mixing of Aluminum Hydroxide Gel in Water with
the PadMixer® System
Mixing system: PadMixer 1000 system
Mixing biocontainer: 500 L Mixer biocontainer
Application mixing type: Liquid-liquid
The PadMixer system is a scalable single-use mixing system. The heart of this mixer
is an innovative top-mounted mixing paddle that allows effective and uniform mixing
in demanding applications, such as preparation of contained high-solids solutions
or mixing of high-viscosity liquids.
Introduction
Alhydrogel (aluminum hydroxide gel) is a common pharmaceutical adjuvant. However,
maintaining it in a homogeneous aqueous suspension can be challenging because
alhydrogel tends to settle over time. Once settled, the viscous alhydrogel lower layer
can be difficult to remix.
In this experiment, a PadMixer 1000 system was fitted with a 500 L mix biocontainer
and used to prepare 500 L of a 1.4 g/L alhydrogel suspension.
Several mixing parameters were evaluated to determine their impact on mixing efficacy.
The objective was to obtain effective mixing with the lowest feasible paddle speed, thus
minimizing the risk of foaming or shear-related product damage.
Figure 1
Comparison of Top and Bottom Sampling
Mixing of Alhydrogel 1.4 g/L in water in a 500 L biocontainer
600
Turbidity / NTU
500
30 RPM, 9º angle, 30 days
sedimentation
30 RPM, 9º angle, 1 day
sedimentation
400
300
200
100
0
0
2
4
6
8 10 12 14 16 18 20 22 24 26 28 30 32
Time / Minutes
Experimental
A 500 L biocontainer was filled with 432 L of DI water and 68 L of 10.3 mg/mL alhydrogel. Once mixed, this resulted in
a suspension containing 700 g aluminum in 500 L (i.e. 1.4 g/L, or 0.14% w/v Al). The content of the biocontainer was
allowed to settle for 24 hours to ensure sedimentation. Once settled, the content was agitated using the PadMixer 1000
system. During mixing, samples of the mixed liquid were taken at 15 second intervals and tested for homogeneity using a
turbidity meter (Figure 1).
A series of mixing tests were performed to evaluate the effect of various paddle speeds and paddle angle settings. After
each mixing test, the liquid was allowed to settle for 24 hours before the next test was performed (Figure 2).
Results
Figures 1 and 2 show typical results for mixing under various conditions. In most cases, the alhydrogel was evenly
dispersed within the first 60 seconds. Even with the gentlest mixing conditions (30 rpm paddle speed at 9° paddle angle),
mixing was complete within 120 seconds.
Figure 2
Effect of Mixing Speed and Mixing Angle
Mixing of Alhydrogel 1.4 g/L in water in a 500 L biocontainer
600
Turbidity / NTU
500
30 RPM, 9º angle
40 RPM, 15º angle
70 RPM, 12.5º angle
70 RPM, 15º angle
90 RPM, 15° angle
400
300
200
100
0
0
1
2
3
Time / Minutes
4
5
Conclusions
The paddle mixing action of the PadMixer 1000 system is capable of high mixing efficiency in viscous liquid-liquid
applications, even when operated at its least vigorous, lowest-shear settings.
Visit us on the Web at www.pall.com/mixing
E-mail us at allegro@pall.com
Corporate Headquarters
Port Washington, NY, USA
+1.800.717.7255 toll free (USA)
+1.516.484.5400 phone
biopharm@pall.com e-mail
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Belgium, Brazil, Canada, China, France, Germany, India, Indonesia, Ireland, Italy, Japan, Korea, Malaysia, Mexico,
the Netherlands, New Zealand, Norway, Poland, Puerto Rico, Russia, Singapore, South Africa, Spain, Sweden,
Switzerland, Taiwan, Thailand, the United Kingdom, the United States, and Venezuela. Distributors in all major
industrial areas of the world. To locate the Pall office or distributor nearest you, visit www.pall.com/contact.
European Headquarters
Fribourg, Switzerland
+41 (0)26 350 53 00 phone
LifeSciences.EU@pall.com e-mail
The information provided in this literature was reviewed for accuracy at the time of publication. Product data may
be subject to change without notice. For current information consult your local Pall distributor or contact Pall directly.
Asia-Pacific Headquarters
Singapore
+65 6389 6500 phone
sgcustomerservice@pall.com e-mail
© 2015, Pall Corporation. Pall and
are trademarks of Pall Corporation. ® indicates a trademark registered
in the USA and TM indicates a common law trademark. Filtration.Separation.Solution. is a service mark of
Pall Corporation.
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