Photochemical treatment of flowback water for
pentachlorophenol using UV-light and fructose
Shaila Nayak, Sean-Erik O’Donnell, Saeed Keshani, Christopher Sales, Rohan Tikekar, Juan Muniz
Center for Hospitality & Sport Management and Civil, Architectural & Environmental Engineering departments, Drexel University
INTRODUCTION
• Hydraulic fracturing process: Well stimulation
technique in which rock is fractured by a hydraulically
pressurized liquid
(made of water, sand and chemicals).
• Many concerns have risen over its
potential environmental impacts
such as groundwater contamination.
• Flowback water: Water released within
the initial two weeks following the hydraulic
fracturing process.
• This water is highly saline (about 15% w/v) and
contains large number of organic contaminants
exceeding their MCL.
• Pentachlorophenol (PCP) has been detected at an
average level of 33 µg/L in flowback waters.
• PCP is carcinogenic and toxic to plants,
animals and humans (causing mutations)
• Fructose has shown significant reactivity
upon exposure to 254 nm UV light.
• Past studies have shown that UV exposure of fructose
generates miscellaneous reactive oxygen species
(ROS), however, characterization and identification of
these species have not been done.
• This is the first study that involves a novel use of
fructose as a photo-catalytic compound for degradation
of PCP in flowback water.
Hydraulic fracturing
process
Flowback water
Photochemical
treatment
For removal of
organic contaminants
For removal of solids
and colloidal particles
OBJECTIVES
• To investigate and quantify the oxidative species
generated during UV-light exposure of aqueous
fructose solution
• To degrade PCP using UV- light and fructose and
compare it with UV- TiO2 system.
RESEARCH POSTER PRESENTATION DESIGN © 2012
www.PosterPresentations.com
MATERIALS AND METHODS
1) UV treatment of fructose solution (at λ= 254nm, I= 48
mW/cm2)
a) Effect of pH on photosensitization by
fructose
Fructose solution in
Fructose solution in distilled water phosphate buffer
+ 1µM Fluorescein dye solution
(pH 6.7) + 1µM
Fluorescein dye solution
Bench top
UV chamber
RESULTS
a) Effect of pH on photosensitization by fructose
Sample
Fructose in
DW
10 mM
100 mM
500 mM
Fructose in 10 mM
phosphate
100 mM
buffer of pH 500 mM
6.7
d) Photochemical degradation of PCP
Fluorescein degradation
Rate constant (min-1)
0.05±0.001
0.56±0.1
1.35±0.17
0.03±0.01
0.18±0.05
0.58±0.34
pH of 500 mM solution decreased from 5.79±0.01 to
3.53±0.25
Measure fluorescence of
fluorescein at
excitation/ emission
λ= 485/510 nm
b) Hydrogen peroxide generated by fructose
b) Detection of hydrogen peroxide generated by
fructose
Ferrous oxidation- xylenol orange method (FOX assay)
Xylenol orange + Ferrous
sulfate + sorbitol + sulfuric
acid + UV exposed fructose
solution
Measure absorbance
at 560 nm using
UV- Vis
spectrophotometer
c) Detection of singlet oxygen generated by
fructose
SOSG- EP
UV exposed fructose solution +
(endoperoxides)
Singlet oxygen sensor green
probe(SOSG)
Measure fluorescence of
SOSG- EP at excitation/ emission
λ= 504/ 525 nm
2) Photochemical degradation of pentachlorophenol
(PCP)
a) PCP + Distilled water (DW)
b) PCP + 500 mM
fructose solution in DW
c) PCP + 10% salt solution
d) PCP + 500 mM
fructose solution in
10% salt
Bench top UV chamber
λ=254 nm, I= 48 mW/cm2
Solution
PCP degradation rate
constant (min-1)
Control 1 (Distilled water)
0.58 ± 0.08
Control 2 (10% salt
solution)
500 mM fructose (in DW)
0.076 ± 0.03
500 mM fructose (in 10%
salt)
125 mM TiO2 (in 10% salt)
0.47 ± 0.13
1.18 ± 0.03
0.139 ± 0.02
CONCLUSIONS
Solution
Fructose (in DW)
Fructose (in buffer of pH
4.5)
Fructose (in buffer of pH
6.7)
Hydrogen peroxide
generated after 7 min of
UV exposure (µM)
63.7±1.11
52.91±1.07
67.08±1.08
c) Singlet oxygen generated by fructose
• Fructose on exposure to UV light at 254 nm generates
• Acidic species
• Hydrogen peroxide
• Singlet oxygen
• These oxidative species are capable of degrading PCP
in highly saline water at a rate that is 6.18 times faster
than the control and 3.38 times faster than TiO2
REFERENCES
• Aachen Elsinghorst, Rohan V. Tikekar (2014).
Generation of oxidative species from ultraviolet light
induced photolysis of fructose. Food Chemistry, 154,
276–281
• Can He, Xuhan Wang, Wenshi Liu, Elise Barbot,
Radisav D. Vidic (2014) Microfiltration in recycling of
Marcellus Shale flowbackwater: Solids removal and
potential fouling of polymeric microfiltration
membranes. Journal of Membrane Science, 462, 88–95
ACKNOWLEDGEMENTS
Collect samples
after every
1 min of
UV treatment
up to 4 minutes
This research was supported by IExE Seed Grant and
USDA-NIFA award.
CONTACT
HPLC for measuring
PCP concentration
Shaila Nayak.
Email id: srn38@Drexel.edu Phone: 316-210-2500