Transformation of Sulfonamide Antibiotics on Soil Mineral Oxides

90 Pages·2016·1.58 MB·English

Clemson University
TigerPrints
All Theses Theses
12-2008
Transformation of Sulfonamide Antibiotics on Soil
Mineral Oxides
Baishu Guo
Clemson University, [email protected]
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Recommended Citation
Guo, Baishu, "Transformation of Sulfonamide Antibiotics on Soil Mineral Oxides" (2008).All Theses. 517.
https://tigerprints.clemson.edu/all_theses/517
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TRANSFORAMTION OF SULFONAMIDE ANTIBIOTICS ON
SOIL MINERAL OXIDES

A Thesis
Presented to
the Graduate School of
Clemson University

In Partial Fulfillment
of the Requirements for the Degree
Master of Science
Environmental Engineering and Science

by
Baishu Guo
December 2008

Accepted by:
Dr. Treavor A. Kendall, Committee Chair
Dr. Cindy M. Lee
Dr. Elizabeth R. Carraway
ABSTRACT
Determining the occurrence and potential adverse effects of antibiotic
pharmaceuticals released into the environment is a critical step towards responsible
environmental stewardship. Under aqueous conditions typically found in soils and natural
waters, the antibiotic agent sulfamethoxazole (SMX) was transformed in the presence of
pyrolusite MnO via oxidative pathways. At least 50% loss of SMX was observed after
2
269 hr in acidic and basic solutions (pH 3-9). A maximum of 100% loss was recorded at
pH 3 and 66% loss was recorded at circumneutral pH. Concomitantly, aqueous
manganese concentrations increased to around 10 µM at pH 3 and 2 µM at pH 6 over the
same time period which suggests an oxidative transformation associated with the mineral
surface. Initial pseudo-first order reaction rate constants (k ) increase with decreasing
init
pH from 0.0039 hr-1 at pH 9 to 0.019 hr-1 at pH 3. HPLC results showed similar
transformation products at different pH values. Mass spectrometry of the reaction
products collected at pH 3 and 4 confirm an oxidative pathway by which oxidation and
hydroxylation occurs at the aniline moiety and isoxazole ring of SMX, and hydrolysis
occurs at the sulfonamide moiety. Transformation kinetics of SMX on the surface of
manganite was also studied. The initial transformation of SMX on manganite was faster
than on pyrolusite at pH 4 to 9; however, at pH 3, the transformation rate was much
slower. The observed transformation of SMX by manganese oxides suggests that this
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ubiquitous component of soils and sediments likely plays an important role in the fate of
this antibiotic agent in the environment.
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DEDICATION
This Thesis is dedicated to my dear husband Jianghong Chen and my son Shawn
Chen who have supported me all the way since the beginning of my studies.
Also, this thesis is dedicated to all mothers who redoubled their efforts on
children and school lives.
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ACKNOWLEDGEMENTS
With my deep sense of gratitude, I wish to express my sincere thanks to Dr.
Treavor A. Kendall for his immense help in selecting the research topic and executing the
work in time. Profound knowledge and timely wit came as boon under his guidance, his
valuable suggestions as final words during the process of research are greatly
acknowledged.
My sincere Thanks are due to my committee members Dr. Cindy M. Lee and Dr.
Elizabeth R. Carraway, for their providing me constant encouragement and the valuable
discussion that I had with them during the course of research and their helps in arranging
the LC/MS and ICP analysis which are very important to this research.
Words fails me to express my appreciation to my husband Jianghong Chen whose
sharing the load of family trivial and taking care of the child, makes it possible for me to
start this thesis. Furthermore, his scientific advices and knowledgeable in Chemistry
helps a lot to get this thesis deeper and further. My son Shawn deserves special mention
for his cooperative support and encouragement, his love and growth are always the
motivations for my achievement.
The appreciations are due to Drs. Colleen Rostad, Shujuan Zhang and Kathy
Moore for LC/MS, BET surface area, and ICP analysis, respectively.
Finally, I would like to thank everybody who was important to the successful
realization of these, as well as expressing my apology that I could not mention personally
one by one.
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TABLE OF CONTENTS
Page
TITLE PAGE................................................................................................................i
ABSTRACT..................................................................................................................ii
DEDICATION..............................................................................................................iv
ACKNOWLEDGEMENTS..........................................................................................v
LIST OF TABLES........................................................................................................viii
LIST OF FIGURES......................................................................................................ix
CHAPTER
1 INTRODUCTION.........................................................................................1
2 BACKGROUND AND MOTIVATION.......................................................5
Properties and sorption of SMX................................................................5
Degradation of SMX in engineered systems.............................................6
Properties and reactivities of goethite, pyrolusite and manganite.............7
3 RESEARCH OBJECTIVES..........................................................................10
4 TRANSFORAMTION OF SMX ON MANGANESE DIOXIDES..............11
Abstract.....................................................................................................11
Introduction...............................................................................................12
Materials and methods...............................................................................14
Results.......................................................................................................19
Discussion.................................................................................................24
5 TRANSFORMATION AND ADSORPTION OF SMX ON
GOETHITE....................................................................................................31
Introduction...............................................................................................31
Materials and methods...............................................................................32
Results and Discussion..............................................................................33
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Table of Contents (Continued)

Page
6 TRANSFORMATION OF SMX ON MANGANITE...................................36
Introduction...............................................................................................36
Method.......................................................................................................36
Results and Discussion..............................................................................37
7 CONCLUSIONS............................................................................................39
8 FUTURE WORK...........................................................................................41
REFERENCES.............................................................................................................72
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LIST OF TABLES
Table Page
1 Properties of Goethite, Pyrolusite and Manganite................................................42
2 List of products identified from LC/MS...............................................................43
3 List of products identified from GC/MS...............................................................44
4 Initial reaction constant (K ) at different pH and SMX/MnO ratio..................45
init 2
5 UV-Vis absorption of SMX (24.88 µM) in DDI, HCl, and Fe (III) solutions......46
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LIST OF FIGURES
Figure Page
1 a. General structure of sulfonamide antibiotic; b. General structure of N4-
acetyl sulfonamide antibiotic; c. Structure of SMX (pK =1.6, pK =5.7
a1 a2
(30); K =8.222; C (25°C) =0.37 g L-1 (pH=4) (31));.........................................47
ow iw
2 Eh-pH diagram of goethite, pyrolusite, and manganite (Mn (II) and Fe (II)
= 10-5 M)...........................................................................................................48
3 a.Comparison of SMX transformation by pyrolusite at pH between pH 3
and 9 ([SMX] =4.4 µM, [pyrolusite] =5 g/l )...................................................49
0 0
4 SMX loss after 6 hr and after 269 hr at different pH in the presence of
pyrolusite...........................................................................................................50
5 Aseptic transformation of SMX on pyrolusite after 3 days (Error bars,
which represent 95% confidence intervals, are smaller than the symbols
used)..................................................................................................................51
6 Time-dependent Mn (II) concentrations increase as SMX reacts with
pyrolusite...........................................................................................................52
7 a. Overall kinetics of transformation of SMX by pyrolusite at the pH 3-9
([SMX] =4.4 µM, [pyrolusite] =5 g/l ); (b) Initial reaction kinetics of
0 0
SMX with pyrolusite at different pH................................................................53
8 Effect of pH on the initial rate constant of SMX oxidation by pyrolusite.
The initial reaction rate constant k (hr-1) was calculated based on the
init
pseudo-first-order reaction kinetics ([SMX] =4.4 µM, [pyrolusite] =5 g/l ).
0 0
Duplicates of experiments are reported with 95% confidence intervals...........54
9 HPLC profile of products of SMX by pyrolusite after 269 hr. a. pH=3; b.
pH=4..................................................................................................................55
10 Mass balance of SMX transformation on pyrolusite after 3 days.....................56
12 Proposed transformation pathway of SMX by pyrolusite.................................62
13 Plausible scheme of oxidation on aniline and benzene ring of SMX by
pyrolusite...........................................................................................................63
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