A Study on Antimicrobial Effects of Nanosilver for Drinking Water Disinfection

ISBN-13: 9789811097355 / Angielski / Miękka / 2018 / 71 str.

Xu Yang

Spis treści

TABLE OF CONTENTS
ACKNOWLEDGEMENT    I
SUMMARY    V
LIST OF TABLES    VIII
LIST OF FIGURES    IX
LIST OF ABBREVIATIONS    XI
CHAPTER 1    INTRODUCTION    1
1.1    DRINKING WATER SAFETY    1
1.2    CURRENT AND EMERGING WATERBORNE PATHOGENS    2
1.2.1    Bacterial pathogens    2
1.2.2    Viral pathogens    3
1.3    SELECTION OF DISINFECTION STRATEGIES    4
1.3.1    Chlorine and related chemicals    5
1.3.2    Ozone    6
1.3.3    Ultraviolet irradiation    7
1.4    SILVER AS ANTIMICROBIAL AGENT    9
1.5    STATE-OF-THE-ART    11
1.6    OBJECTIVES AND RESEARCH SCOPE    14
1.7    ORGANIZATION OF DISSERTATION    17
CHAPTER 2    LITERATURE REVIEW    19
2.1    SYNTHESIS OF SILVER NANOPARTICLES    19
2.1.1    Chemically-Synthesized silver nanoparticles    20
2.1.2    Biologically-synthesized silver nanoparticles    24
2.2    ANTIMICROBIAL EFFECTS OF SILVER NANOPARTICLES    28
2.2.1    Effects of silver nanoparticles’ properties    29
2.2.2    Effects of water matrices    31
2.2.3    Antibacterial and antiviral effects of silver nanoparticles    34
2.3    ANTIMICROBIAL MECHANISM OF SILVER IONS AND SILVER NANOPARTICLES    42
2.3.1    Mechanisms of aqueous silver disinfection    42
2.3.2    Antibacterial mechanisms of silver nanoparticles disinfection    44
2.3.3    Antiviral mechanisms of silver nanoparticles disinfection    49
2.4    CONTINUOUS DISINFECTION SYSTEM WITH SILVER NANOPARTICLES    51
CHAPTER 3    MATERIALS AND METHODS    55
3.1    SILVER NANOPARTICLES    55
3.1.1    Chemically-synthesized silver nanoparticles    55
3.1.2    Biologically-synthesized silver nanoparticles    56
3.1.3    Characterization of silver nanoparticles    56
3.2    MICROORGANISMS CULTIVATION AND ENUMERATION    58
3.2.1    Incubation of E. coli and MS2 coliphage    58
3.2.2    Enumeration of E. coli and MS2 coliphage    58
3.3    DISINFECTION EXPERIMENTS    59
3.4    EFFECTS OF WATER MATRICES    60
3.5    MECHANISM STUDY    61
3.5.1    Mode of action of nanosilver    61
3.5.2    Viral damage    63
3.6    CONTINUOUS FLOW SYSTEM WITH NANOSILVER    66
3.7    DATA INTERPRETATION    69
CHAPTER 4    RESULTS AND DISCUSSION    70
4.1    SELECTION OF DIFFERENT NANOSILVER    70
4.1.1    Characterization of different nanosilver    70
4.1.2    Comparison of effects of different nanosilver against E. coli    73
4.1.3    Comparison of effects of different nanosilver against MS2 coliphage    75
4.1.4    Viral inactivation profile of biologically-synthesized silver nanoparticles    77
4.2    EFFECTS OF WATER MATRICES    78
4.2.1    Effects of chloride    79
4.2.2    Effects of Ca/Mg/ionic strength    80
4.2.3    Effects of TOC    83
4.2.4    Effects of pH    84
4.3    MECHANISM STUDY OF VIRAL INACTIVATION    85
4.3.1    Mode of action of nanosilver    85
4.3.2    Viral damage caused by nanosilver    92
4.4    CONTINUOUS FLOW SYSTEM WITH NANOSILVER    95
4.4.1    Continuous flow system to remove E. coli    95
4.4.2    Continuous flow system to remove MS2 coliphage    99
CHAPTER 5    SUMMARY, CONCLUSIONS AND RECOMMENDATIONS    102
5.1    SUMMARY    102
5.2    CONCLUSIONS    103
5.3    RECOMMENDATIONS    106
LIST OF PUBLICATIONS    108
REFERENCES    109
APPENDIX    121

O autorze

Xu Yang was conferred his PhD degree by National University of Singapore(NUS) in 2015. Before joining NUS, he gained his B.Sc in Chemistry in Fudan University, P. R. China. He also spent two years as a lab assistant when he was an undergraduate. The experience greatly spurned his interest in nanomaterial and led him to pursue a PhD in the Department of Civil and Environmental Engineering in NUS. Xu Yang is currently working as an engineer in a construction wastewater treatment and environmental consulting firm based in China.

Blurb

This thesis examines the feasibility of using silver nanoparticles (AgNPs) as a viable disinfectant. It explores the opportunities and challenges of using AgNPs as an antimicrobial agent, and includes the latest research findings. It compares three kinds of AgNPs with regard to their antibacterial and antiviral effects; their sustainability in real water matrices; and their antiviral mechanisms. The outcome of this research equips the water industry with a better understanding of the capacity, extent and mechanisms of nanosilver disinfection. It is of interest to graduate students, academics and researchers in the area of nanotechnology and environmental engineering.