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Courtesy of Alzet Osmotic Pumps
•Pharmaceutics
Cancer Treatments
Painkillers •Agriculture
Fertilization of crops
•Fragrances Air
freshener Bug
repellant
#1: Semi-permeable membranes and controlled concentrations can create a zero-order rate of diffusion.
#2: Polar membranes diffuse polar substances like alcohols at a zero-order rate.
(Ra)2 = 4(δD1-δD2)2 + (δP1-δP2)2 + (δH1-δH2)2
RED = Ra/Ro
δD = London dispersion forces
δP = Dipole-dipole interactions
δH = Hydrogen bonding
Ra = Solubility differenceRo = Solubility radiusRED = Relative energy difference
• Thickness vs. Polarity Constant thickness (40
mils) Varied polarity Hypothetically: more polar
membrane should increase diffusion rates of electrolytes
• Experimentation for film composition: Ethylene Vinyl Acetate
(EVA), Poly Vinyl Alcohol (PVA), Poly Ethylene Glycol (PEG)
30-40% EVA produced most uniform films
• The Process:1. Prepare the EVA solutions2. Prepare the Doctor Blade and
glass slides3. Cast films4. Dry in Oven
• Strong Electrolytes– Sodium Chloride (NaCl)– Calcium Sulfate Dihydrate (CaSO₄ ∙
2H₂O)
• Weak ElectrolytesCitric Acid Ascorbic Acid Acetylsalicylic
Acid
147.76 g/100 mL 33.O g/100 mL 0.30 g/100 mL
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
-10
-5
0
5
10
15
20
Sodium Chloride
NaCl 40% EVA; 50 mils; 2000 range
NaCl 40% EVA; 25 mils; 2000 range
NaCl 40% EVA; 50 mils; 200 range
NaCl 40% EVA; 25 mils; 200 range
NaCl 40% EVA; 40 mils; 2000 range
Time (hrs)
Co
nd
ucti
vit
y (
µS
/cm
)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 200
5
10
15
20
25
30
35
Calcium Sulfate Dihydrate
CaSO4 40% EVA; 25 milsCaSO4 40% EVA; 30 milsCaSO4 40% EVA; 40 mils
Time (hrs)
Conduct
ivit
y (
µS
/cm
)
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 500
0.0001
0.0002
0.0003
0.0004
0.0005
0.0006
0.0007Ascorbic Acid
Ascorbic Acid 35% EVAAscorbic Acid 30% EVA
Time (hrs)
H3O
+ C
once
ntr
ati
on (
mol/L)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 190
0.0005
0.001
0.0015
0.002
0.0025
0.003Citric Acid
Citric Acid 30% EVA
Citric Acid 35% EVA
Citric Acid 40% EVA
Time (hrs)
H3
O+
Co
nce
ntr
ati
on
(m
ol/
L)
0 5 10 15 20 25 300
1
2
3
4
5
6
Gravimetric Analysis of Alcohols
Methanol 40% EVA Linear (Methanol 40% EVA)
Propanol 30% EVA Linear (Propanol 30% EVA)
Ethanol 40% EVA Linear (Ethanol 40% EVA)
Ethanol 35% EVA Linear (Ethanol 35% EVA)
Ethanol 30% EVA Linear (Ethanol 30% EVA)
Time (Hours)
Ma
ss L
ost
(gra
ms)
• Strong electrolytes do not diffuse in up to 40% EVA membranes
• Most weak electrolytes do not diffuse, except for citric acid
• Methanol, ethanol, and propanol diffuse
• Pseudo zero order diffusion achieved
A Very Special Thanks to:
• Dr. David Cincotta, advisor• Tony Chen, assistant• Dr. Adam Cassano &
Dr. Steve Surace, co-directors• Anna Mae Dinio-Bloch,
Program Manager
Generous Financial Support from:• Laura (NJGSS ’86) and John Overdeck• NJGSS Alumnae and Parents of
Alumnae• State of New Jersey• Drew University• AT&T • Celgene• Novartis• Independent College Fund of NJ• Johnson & Johnson• Bayer Healthcare• Actavis Pharmaceuticals• Board of Overseer’s, New Jersey
Governor’s Schools