Cleaning Up the Water Supply: Cleaning Up the Water Supply: Using Photolysis to Destroy Using Photolysis to Destroy Trace Waterborne ContaminantsTrace Waterborne Contaminants

Presented by Daniel Whitley

Project Mentor: Dr. Eduardo Saez

NASA Space Grant Symposium

April 17, 2010

Overall Research ObjectiveOverall Research Objective

To improve water quality through the removal of trace organic contaminants using an inexpensive, easily implementable, scalable process

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GoalsGoals

Characterize Photolysis & H2O2 Photolysis Rates of Different Compounds

Identify Organic Contaminants: Nonylphenol, p-Cresol, Aniline

Identify Method: UV Photolysis

Quantify Rates of Degradation at Different Scales

BackgroundBackground

•Nonylphenol, cresols, and other phenolic compounds have a variety of household and industrial uses

•These compounds (or their precursors) often get dumped into rivers and lakes, and can survive traditional effluent treatment methods

Coater at the Madawaska Maine Fraser Paper Mill. Image courtesy of Studio Laporte http://www.toucherdubois.ca/tdb/page.php?menu=20

•These compounds are endocrine disruptors, harming wildlife and possibly even people

Basic Reaction MechanismBasic Reaction Mechanism

2OHhνOH 22

2COproducts OHtarget

HOHOOH OH 2222

Research MethodsResearch Methods

Lamp outlet Reactor

Tubular UV ReactorSolar Experiments

Xe M-U-T Lamp & Reactor

Size: 20 mL 600 mL 30 L

Intensity:

Xe Lamp ExperimentsXe Lamp Experiments

Over period of

20 hours, 75% of

target compound

destroyed

Can calculate reaction rate from plot

0

50

100

150

200

250

300

350

0 5 10 15 20 25Time (hours)

[p-C

] (µ

M)

50 mM H2O2

Solar ExperimentsSolar Experiments

0

40

80

120

0 1 2 3 4Time (hours)

[p-C

] (μ

M) no IP

1.42 mM IP

14.2 mM IP

100 mM H2O2 for all experiments

Effect of increasing H2O2

concentrations on the

degradation of nonylphenol

(left)

Effect of isopropanol

(hydroxyl radical

scavenger) on photolysis

rate (right)

0

5

10

15

20

25

30

0 1 2 3 4 5 6

Time (hours)

[NP

] (µ

M)

50 mM

75 mM

100 mM

0 mM

H2O2

Tubular UV Reactor ExperimentsTubular UV Reactor Experiments

High light intensity means target compound

degradation through H2O2 photolysis occurs very fast

0

20

40

60

80

100

120

0 10 20 30

Time (minutes)

[p-C

] ( M

)

0 mM

2 mM

50 mMNo H2O2

H2O2

Direct photolysis

(no H2O2) starts fast

but then slows as

byproduct forms,

absorbing light and

thus reducing

available photons

μ

ConclusionsConclusions

H2O2 photolysis using ultraviolet light is effective in

destroying nonylphenol, p-cresol, and any other compound

that reacts with OH•.

High intensity ultraviolet sources can degrade organic

compounds directly (direct photolysis), albeit at a slower

rate than with H2O2 photolysis.

Hydroxyl radical scavengers can slow the rate of reaction of

the compound of interest.

Thanks to . . .Thanks to . . .

My Professors: Dr. Eduardo Saez and Dr. Robert Arnold

My Research Team: Mario Rojas, Fernando Perez, Amy Gobel, and Cary Leung

The Atmospheric Sciences Department, especially Eric Betterton and Brian Barbaris

And the NASA Space Grant Internship Program for making it all possible!