Removal of Wastewater Pharmaceutical Chemical Contaminants Using AOPs
Stephen P. MezykDepartment of Chemistry and Biochemistry
California State University at Long BeachLong Beach, CA, 90840, USA
HN
NO
O
S
OOH
It’s all about potable water!
▪ Current lack of potable water▪ Human population increasing
▪ Water pollution increasing▪ Climate change occurring
▪ Increased water demand:▪ Human consumption▪ Agricultural needs
• Desalination? – Costly, but getting better – Environmental problems (retentate)
• Conservation? YES of course!
• Reusing our wastewater?– ~1012 litres wastewater/day in US!
• Direct toilet to tap – Public perception is bad– Costs????
Where can we get more water?
What’s in our wastewater?PathogensPesticides
Carcinogens
Pharmaceuticals
Industrial chemicals
NH
N
O
F
OH
OOHOHNH
N
O
F
OH
OOHOH
NH
N
NN
NH
Cl
HO
HO
R
N N
O
R'
H3C
CO
CH3
CH3
H3C
HN
NO
O
S
OOH
DOM HCO3-
NO3-/NO2
-
How do we clean wastewater?
▪ More than current 1o and 2o wastewater
treatment!
▪ Use ionizing radiation radical based treatment?
▪ Orange County Water District CA!
▪ Advanced Oxidation Processes (AOPs)
▪ Most work on ●OH, can maybe use SO4-●?
▪●OH radicals (Eo = 2.8V), SO4
-● (Eo = 2.4V)
▪ What is the cost of using AOPs?
An •OH radical is an •OH radical!
•OH
Electron beam
Beams
Gamma Radiation
Non-thermal
Plasmas
Electrohydraulic
Cavitation &
Sonolysis
O3/UV
H2O2/O3
H2O2/UV
H2O2/O3/UV
Supercritical Water
Oxidation
H2O -/\/\ 0.28 •OH + 0.27e-aq +0.06H•
+ 0.07H2O2 + 0.05H2 + 0.27H+
Orange County Water CA District approach:
Why Do We Care?• Trace antibiotic levels can cause
major health problems
• Unnecessary environmental exposure causes development of dangerous resistant strains MRSA, NDM-1, CRE of bacteria
• Allergies and sensitivities• Public concern over detection
of estrogenic chemicals in waterHO
HO
What do we need to understand the chemistry?
▪ Computer models that accurately predicts chemistry
of removal for quantifying costs of AOPs
▪ Contaminants minor wastewater constituents (< 0.1%)
▪ Kinetic computer models combine engineering and
chemistry:
▪ Rate constants for all relevant radical reactions
▪ Mechanisms of reactions
▪ Efficiencies of contaminant removal (impact of
wastewater matrix)
b-lactam antibiotics:
▪ Rate constants for ●OH and SO4-● radical in pure water
well established.
H2O -/\/\ 0.28 •OH + 0.27e-aq +0.06H•
+ 0.07H2O2 + 0.05H2 + 0.27H+
N2O saturated soln:
e-aq/H
● + N2O → ●OH
t-BuOH/N2/S2O82-
●OH/H● + t-BuOH → R●
e-aq + S2O8
2- → SO42- + SO4
-●
Compound k•OH (109M-1s-1)
Aminopenicillanic Acid 3.35 ± 0.06
Penicillin G 8.70 ± 0.32
Penicillin V 9.14 ± 0.12
Ampicillin 8.21 ± 0.29
Carbenicillin 7.31 ± 0.11
Cloxacillin 6.27 ± 0.13
Cephalothin 4.93 ± 0.15
Cefotaxime 9.29 ± 0.12
Kinetic data for β-lactams and •OH
Dail and Mezyk, JPCA, 114, 8391-5 (2010)
Average: kav ~
7.15 x 109 M-1 s-1
0.0 2.0 4.0 6.0 8.0-2.0
0.0
2.0
4.0
6.0
8.0
10.0
12.0
10
3 A
bsorb
ance
Time (s)
SO4•- and β-lactams
Compound kSO4• - (109 M-1s-1)
6-amino-
penicillanic acid
2.41 0.08
Amoxicillin 3.48 0.05
Ampicillin 1.87 0.30
Carbenicillin 0.59 0.30
Cloxacillin 0.86 0.13
Penicillin G 1.44 0.04
Penicillin V 2.00 0.05
Piperacillin 1.17 0.11
Ticarcillin 0.80 0.02
kav ~1.6 x 109 M-1 s-1N
S
HN
O
H
COOH
R1
Rickman and Mezyk, Chemosphere, 81, 359-365 (2010)
0.0 5.0 10.0 15.0
0.0
5.0
10.0
15.0
20.0
10
3 A
bsorb
ance
Time (s)
1.80 mM
1.38 mM
1.02 mM
0.61 mM
0.37 mM
0.20 mM
Species k•OH
M-1s-1
kSO4-•
M-1s-1
b-lactamsav 7.2 x 109 1.6 x 109
HCO3- 8.5 x 106 ~ 5 x 106
CO32- 4.0 x 108 4.1 x 106
NO3- ~ 0 5.0 x 104
NO2- 1.1 x 1010 9.0 x 108
DOM 6.27 x 108 3.8 x 107
Sulfate radical may be better choice!
vs
• HPLC measures parent loss
• •OH + β-lactam → β-lactam•
Watch peak area decrease
with degradation of compound
•●OH Efficiency
0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0 1 2 3
Ab
so
lute
Dif
fer
en
ce
Dose (kGy)
Cefazolin 60Co
•OH Reaction EfficiencyCompound ●OH Reaction
Efficiency
Ampicillin 49.7 ± 2.5%
Cefaclor 45.6 ± 2.6%
Cefazolin 78.4 ± 4.9%
Penicillin-G 75 ± 10%
• This means that we require 1-2 •OH reactions to
chemically remove one antibiotic molecule
• Have to quantitatively account for radical rate
constant and efficiency
What about biological efficiency?
• One oxidation will change chemical
structure, but may not perturb function.
• Monitor bacterial growth when exposed to
oxidized product. As the dose increases,
growth should increase as well.
Structure/Function Relationships:
Macrolides
prevent protein
elongation
MTS Assay
Metabolically Active Cell
Required Oxidations – β-lactams
Measured Parameters
Compound k•OH
(109 M-1s-1)
•OH
Oxidations
Penicillin 8.70 ± 0.32 5
Penicillin V 9.14 ± 0.12 6
Ampicillin 8.21 ± 0.29 4
Amoxicillin 6.94 ± 0.44 6
Cloxacillin 6.27 ± 0.13 5
Roxithromycin 4.85 ± 0.25 12
Neomycin 4.73 ± 0.12 11
SO4-• + Pen G P1
SO4-• + DOM P2
SO4-• + t-butanol P4
Pen G + DOM = Complex + t-butanol
k1
k4
k3k2
P1 P2P3 P4
K
Pen G + DOM = Complex K = ?SO4
-• + Complex P3
Real world - Interactions of Pen G and DOM
k3 =?
Second order rate constant for Pen G/DOM + SO4
-• was much slower than 2.08 x 109, so there must be an
interaction
Results
K = 130.0 ± 26
LCMS Oxidation productsNH2H
N
HN
SCH3
CH3
OHO
OOOH
NH2HN
N
SCH3
CH3
OHO
OO
HO
NH2HN
N
SCH3
CH3
OHO
OO
O OHN
N
SCH3
CH3
OHO
OO
HN
NO
O
S
OOH
Where are we now?• Understand kinetics, radical reaction efficiencies,
and products of multiple classes of antibiotics
• Initiated estrogenic steroid study• Estrogen-sensitive
MCF-7 human breast cancer cells
• Ultimately studyestrogen mimics
Thanks:• Radiation Laboratory, Univ.
of Notre Dame
• OCWD: Ken Ishida
• Any questions??