Pseudo-Zero-Order Kinetics: Diffusion through a

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PSEUDO-ZEROORDER KINETICS:
DIFFUSION THROUGH A POLYMER
MEMBRANE USING A SATURATED
SOLUTION RESERVOIR SYSTEM
Jan-alfred Aquino | Christopher Chen |
Yanglu Chen | Zachariah DeGiulio |
Katherine Dong | Christina Floristean |
Michelle Guo| Alexandra Kapadia | Robert
Kolchmeyer | Erik Massenzio | Adam
Richardson | Jessica Xu
Dr. David Cincotta | Alberto Rivera
Controlled Release
• Zero-order kinetics
• Rate independent
of concentration
• Does not often
occur in nature
• Applications:
o Medicine
o Agriculture
o Cosmetics
Pseudo-Zero-Order Kinetics
Fick's Law:
A pseudo-zero-order system would
achieve a constant rate of release,
but would not be independent of
concentration.
This can be done by holding the
concentration gradient constant.
Hypothesis
• IF: An apparatus is made that
•
•
allows for diffusion of a saturated
solution into a body of water
across a membrane
THEN: Pseudo-zero-order diffusion
should be observed
Maintain a constant
concentration gradient
Polymer Membrane
• Repeating structural
units of monomers
• Amorphous structures
•
more easily allow
diffusion than crystalline
structures
Ethylene-vinyl acetate
o 10% EVA
o 12% EVA
Choosing Citric Acid
• Solid at room temperature
• Chosen over maleic acid
and sodium chloride
• Conductivity & pH probe
• Continuously measured
•
over longer periods of
time
Most consistent results
Citric acid
Maleic acid
Experimental Design: Saturated
Solution Reservoir System
•
•
•
•
Saturated solution of citric acid added to petri dishes
Solute passes through the membrane
Additional solid citric acid added to continuously resaturate the solution
Pseudo-zero-order
Water Basin
Petri Dish
Saturated Solution
Solid Citric Acid
Polymer Membrane
Final Setup
Experimental Design
Design Features:
Water-tight petri dishes
Petri dish supports
Maximize water and
solution contact with
the membrane
Surface area
optimization
Uniform water level
with respect to the
petri dish
•
•
•
•
•
Results - The Diffusion of Citric Acid
across a 10% EVA Membrane
Results – The Diffusion of Citric Acid Across
10% and 12% EVA Membranes
• With additional
solute
• 10% EVA (top
graph)
• 12% EVA (bottom
graph)
• Suspected pH
10% EVA Trials
meter issue
resulting in a few
nonlinear curves
12% EVA Trials
Results – The Diffusion of Citric
Acid Solution Across 12% EVA
• 12% EVA with 2g solid
• Trials with 2g extra solid are zero order
Discussion
• Rate was faster
in first few hours
• Tested with 10%
•
•
EVA and 12%
EVA
Polarity
accounts for
permeation
Reproducible
rates remain
elusive
Conclusion
• Achieved pseudo-zero-order
kinetics with reservoir system
• Polar likes polar: Citric acid
•
•
•
diffused through 12% EVA more
effectively than 10% EVA
Novel method for modeling a
controlled-release system
Data was supportive of
hypothesis
More needs to be done to
conclusively accept or refute
the hypothesis
Future Studies
• Explore alternate methods of
measuring diffusion
• Solute embedded in polymer
• Biodegradable polymers
• Solute with lower solubility
• Mathematical models based
•
on parameters of polymer
membrane and solute
Generalized curve fits
References
1. Prisciandaro M. and Pepe F. Absorption with zero and Pseudo-Zero order chemical reaction. The Canadian Journal of Chemical
Engineering; (2006) [Internet] [accessed July 29, 2011] 362 – 368p..
Available from : http://onlinelibrary.wiley.com/doi/10.1002/cjce.5450750212/abstract
2. Nic M., Jirat J., Kosata B. Compendium of Chemical Terminology. IUPAC Goldbook; (2006).[Internet] [ accessed July 27, 2012]
Available from : http://goldbook.iupac.org/P04937.html
3. Blackmond DG., Hodnett NS., Lloyd-Jones GC., Mechanistic Implications of Pseudo Zero Order Kinetics in Kinetic Resolutions. JACS
Communications; (2006). [Internet] [accessed July 29, 2011] 7450 - 7451p.
Available from : http://pubs.acs.org/doi/pdfplus/10.1021/ja062173f
4. Jones D. FASTtrack: Pharmaceutics: Dosage Form and Design. London:
Pharmaceutical Press; (2008). [Internet] [accessed 2012] Available from :
http://www.pharmpress.com/files/docs/FT_Pharmaceutics_Drug_Delivery_sample.pdf
5. Basic Property of EVA Resin. SNE Research; (2006) [Internet] [accessed July 26, 2012] Available from :
http://www.sneresearch.com/eng/info/show.php?c_id=4938&pg=6&s_sort=&sub_cat=&s_type=&s_word=
6. Ionization Constants of Heteroatom Organic Acids. Michigan State University. [Internet] [accessed July 26, 2012] Available from :
http://www2.chemistry.msu.edu/faculty/reusch/VirtTxtJml/acidity2.htm
7. Material Safety Data Sheet - Citric Acid. Science Lab. [Internet] [accessed July 24, 2012] Available from :
http://www.sciencelab.com/msds.php?msdsId=9923495
8. Periodontics: Controlled release delivery system. British Dental Journal; (2003). [Internet] [accessed July 30, 2012] 195 - 224p.
Available from : http://www.nature.com/bdj/journal/v195/n4/full/4810497a.html
9. Controlled release of triprolidine using ethylene-vinyl acetate membrane and matrix systems. European Journal Pharmaceutics
and Biopharmaceutics. (2002) [Internet] [accessed 2012] 201 - 206p. Available from :
http://www.sciencedirect.com.ezproxy.drew.edu/science/article/pii/S0939641102000516
10. Gupta C., Chauhan A.Drug transport in HEMA conjuctival inserts containing precipitated drug particles.Journal of Colloid and
Interface Science ; (2010). [Internet] [accessed July 30, 2012] 31 - 42p.
Available from : http://www.sciencedirect.com.ezproxy.drew.edu/science/article/pii/S0021979710003267
11. Drabczyk K., Panek Piotr. A Comparative Study of EVA with and without thermal history for different lamination process
parameters. Material Sciences and Engineering: B; (2011). [Internet] [accessed July 29, 2012]
Available from : http://www.sciencedirect.com/science/article/pii/S0921510712002541
12. Krishnan KA., Sreejalekshmi KG., Varghese S. Adsorptive Retention of Citric Acid Onto Activated Carbon Prepared From Havea
Braziliansis Sawdust: Kinetic and Isotherm Overview. Desalination; (2010). [Internet] [accessed July 30, 2012] 46 - 52p.
Available from : http://www.sciencedirect.com/science/article/pii/S001191641000144X
Acknowledgements
Dr. David Cincotta, Advisor
Alberto Rivera, Assistant
Dr. David Miyamoto, Director
New Jersey Governor's School in the Sciences and its Sponsors

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