Dendritic Polymers as Biocompatible Oil Spill Dispersants: Effectiveness and Mechanisms with Crude...
22
Dendritic Polymers as Biocompatible Oil Spill Dispersants: Effectiveness and Mechanisms with Crude Oil Ying Tu Master’s Thesis Defense Thesis Committee: Dr. David Ladner (Advisor) Dr. David Freedman Dr. Tanju Karanfil 1
Dendritic Polymers as Biocompatible Oil Spill Dispersants: Effectiveness and Mechanisms with Crude Oil Ying Tu Master’s Thesis Defense Thesis Committee:
Dendritic Polymers as Biocompatible Oil Spill Dispersants:
Effectiveness and Mechanisms with Crude Oil Ying Tu Masters Thesis
Defense Thesis Committee: Dr. David Ladner (Advisor) Dr. David
Freedman Dr. Tanju Karanfil 1
Slide 2
Outline Background and Motivation Literature Review and
Hypothesis Experiment Methodology Results and Discussion
Conclusions and Recommended future work 2
Slide 3
Oil spill dispersants 3 A U.S. Air Force Reserve plane sprays
Corexit over the Deepwater Horizon oil spill in the Gulf of Mexico
(http://en.wikipedia.org/wiki/Corexit) BP Deepwater Horizon oil rig
ablaze (Photo: U.S. Coast Guard)
Slide 4
Dendritic polymers 4 Dendrimers Branch Out, Chemical &
Engineering News, June 13, 2005, Volume 83, Number 24, pp. 30-36.
Dendritic polyethylenimine is a highly functional aliphatic
polyamine with a globular structure.
(http://www.hyperpolymers.com/prodinf.html) Dendrimer terminal
groups NH OH o NH 2 NH OH o Amino Amidoethanol Succinamic Acid
PAMAM HY-PEI Same chemical structure but different molecular
weight; 1.2, 1.8, 10, 70, 750 kDa.
Slide 5
Model compounds study and hypothesis 5 N.K. Geitner, P.
Bhattacharya, M. Steele, R. Chen, D.A. Ladner, and P.C. Ke*,
Understanding Dendritic Polymer-Hydrocarbon Interaction for Oil
Dispersion, RSC Advances 2 (2012), 9371. C16 partitioned into
polymer C16 capping by polymer C16 end to end interaction
Hydrophobic interaction C16-polymer complexation Dendritic polymers
are capable of encapsulating both polyaromatic and linear
hydrocarbons
Slide 6
A few oil/water emulsion stabilization mechanisms 6
Venkataraman, P. & Tang, J. (2013) Attachment of a
Hydrophobically Modified Biopolymer at the OilWater Interface in
the Treatment of Oil Spills. Applied Materials and Interfaces:
35723580. Ye, A., Zhu, X. & Singh, H. (2013) Oil-in- water
emulsion system stabilized by protein-coated nanoemulsion droplets.
Langmuir: the ACS journal of surfaces and colloids 29:
1440310.
Slide 7
Objectives Test and verify the hypothesis that dendritic
polymers can disperse oil Develop methods to adequately
characterize the effectiveness of the dendritic polymers Gain a
fundamental understanding of the interactions of dendritic polymers
with crude oil 7
Slide 8
8 Small vials trialmethod development and preliminary results
Dispersant to oil ratio (DOR) 0.02 Mixing time 30 min Mixing speed
200 rpm Settling time 15 min
Slide 9
Higher volume effectiveness test 9 Sample preparation 120 ml
artificial seawater 100 l crude oil Dispersant with DOR 0.02 Mixing
and Settling Mixing at 200 rpm for 30 min Settling for 15 min in
separatory funnel Drain each 30 ml water column segment into
centrifuge tubes Oil extraction and analysis Add 10 ml
dichloromethane (DCM) in each 30 ml mixture UV spectrophotometer at
340 nm 105 ml 45 ml 75 ml 15 ml
Slide 10
HY-PEI dispersion effectiveness -effects of molecular weight
10
Slide 11
HY-PEI dispersion effectiveness -effects of molecular weight 11
Larger polymers were more effective, but on an equal-mass basis
increasing size gave diminishing returns Further analysis confirms
that larger size polymers entrap more oil molecules.
Slide 12
PAMAM dispersion effectiveness -effects of surface charge 12
Positively charged dendrimers were the most effective
dispersants
Slide 13
Interfacial tension test 13 Video frames of oil drop shapes
varied with time. 0.0125g/L HY-PEI 10kDa at time of 20 s, 70 s and
115 s. Needle diameter is 0.632 mm. As the age of drop increasing,
the drop shapes became elongated. Oil phase: crude oil only Water
phase: dispersant solution prepared with artificial seawater at
concentrations of 0.1, 0.05, 0.025 & 0.0125 g/L Record videos
from 0 to 120 s
Dynamic interfacial tension 15 Data were recorded for 120
seconds or until the drop separated from the needle. The 100 mg/L
data are not shown for some materials because drops were not
sufficiently stable. For clarity, symbols are shown on only the
final data point of each series.
Coulter counter & Microscope imaging 18 Size distribution
graph was obtained by analyzing 20 microscope images in a Matlab
script Microscope pictures of oil drops taken under 40x
magnification; many drops are out of focus. Diluted
oil-water-dispersant mixture measured by Coulter counter; most oil
drops smaller than 7 m.
Slide 19
Conclusions Method development Small volume resulted in
significant variability in effectiveness results. High volume gave
more reproducible results. A conceptual model of oil-dendritic
polymer interactions was developed. Hybrid Pickering surfactant
mechanism. Other possibilities exist. Positively charged dendrimers
were more effective than the neutral or negatively charged
dendrimers. This suggests an adsorption, charge reversal mechanism.
19
Slide 20
Conclusion 20
http://schema-root.org/technology/chemical/agents/dispersants/
Gong, Y., Zhao, X., Cai, Z., OReilly, S. E., Hao, X., & Zhao,
D. (2014). A review of oil, dispersed oil and sediment interactions
in the aquatic environment: influence on the fate, transport and
remediation of oil spills. Marine Pollution Bulletin, 79(1-2),
1633. Surfactant mechanism Pickering emulsion mechanism Our
mechanism: hybrid Pickering-surfactant
Slide 21
Recommended future studies Use equal molar ratios on high
volume effectiveness tests Examine the polymer with equal charge
but different surface functional groups Further develop oil droplet
size measurement techniques 21
Slide 22
Acknowledgements 22 Thanks to Dr. Ladner for all the
instruction and guidance kindly provided during this research
Thanks to Dr. Freedman and Dr. Karanfil for helping me with thesis
writing Thanks to our coworkers Nick Geitner, Dr. Ding from Clemson
Physics and Astronomy Thanks to EPA Thanks to our group members
Erin Partlan, Mengfei Li, Muriel Steele, Peng xie for helping me
with experiments Thank you all audience for coming to my thesis
defense RD835182