Non-gravimetric measurement of Electro-Chemically Activated water as a biocidal assessment tool

Get Complete Project Material File(s) Now! »

Water: Introduction

Liquid water is the essential biological solvent of all life processes (Ludemann, 1993). It also represents the continuous phase of all living organisms. However despite being the most abundantly occurring inorganic liquid (Savage, 1993), its familiarity and ubiquitous nature has led to it being regarded as a bland, inert liquid, or a mere space filler for living organisms (Lehninger, 1975). Despite this, most biological molecules of a living organism only function in water, and thus it remains fundamental for the optimal functioning of all life processes (Prilutsky and Bakhir 1997). A most important consequence of the polar nature of water and of its dynamic capacity for hydrogen bonding (Stumm and Morgan, 1996) is that water is a so-called “universal solvent”, and as such is yet another reason why it is indispensable to life itself.
Water it is a highly reactive substance, and its ionization products, hydrogen and hydroxide, are important determinants of the characteristic structure and biological properties of proteins and nucleic acids, as well as the interaction with different organic or inorganic intracellular compounds, membranes, ribosome’s and many other cellular components (Lehninger, 1975; Prilutsky and Bakhir, 1997). Water: Structure and behavior As a chemical substance water is unique, and its composition and characteristics have no analogue in nature (Lehninger, 1975). Water is, in fact, considerably more complex than it appears at first sight; an indication of this is the complex configurations displayed by snowflakes.
Nevertheless, a very simplified description of water (H2O) is that it consists of molecules made up of two hydrogen (H) atoms and one oxygen atom (O). Water is capable of existing in a variety of states i.e. crystalline ice (11 variant forms), amorphous ice (non-crystalline), crystalline hydrates (organic and inorganic), liquid water (ordinary, super-cooled and vapour), aqueous solutions (ionic and non-ionic) and as a gaseous state (monomers and 2 clusters). The strong intermolecular forces in liquid water are caused by the specific distribution of electrons in the water molecule. Each of the two hydrogen atoms shares a pair of electrons with the oxygen atom, this through an overlap of the 1s orbital of the hydrogen atoms with the two hybridized sp3 orbitals of the oxygen atom (Lehninger, 1975, Stumm and Morgan, 1996).
This arrangement of electrons in the water molecule imparts its distinctive electrical asymmetry. The hydrogen atoms have an excess of positive charge and the oxygen atom an excess of negative charge. The highly electron negative oxygen atom tends to withdraw the single electrons from the hydrogen atoms leaving the hydrogen nuclei exposed – hence each hydrogen atom has a local positive charge (δ+ ) versus the local negative charge (δ- ) in the unshared orbital of the oxygen atom (Fig 1). Thus while the water molecule has no net charge, it still exists as an electric dipole (Lehninger, 1975, Stumm and Morgan, 1996). When water molecules approach each other, an electrostatic attraction between the partial positive charge of the hydrogen atoms of one water molecule and the partial negative charge of the oxygen atom of the adjacent water molecule arises. The ensuing redistribution of electrical charges gives rise to a complex electrostatic union referred to as a hydrogen bond (Lehninger, 1975; Stryer, 1981).
Hydrogen bonds are energetically weak when compared to covalent bonds. Hydrogen bonds in water are estimated to have a bond energy of approximately 18-20 kcal mol-1, compared to the covalent bond energy of 360-400 kcal mol-1 between the H-O atoms (Lehninger, 1975; Stumm and Morgan, 1996). The formation of a single hydrogen bond predisposes to the formation of additional hydrogen bonds between adjacent molecules, and facilitates an enhanced association between all solute molecules. This enhancement of the strength of attraction between two molecules arising from the cooperation of several weak bonds is termed cooperativity. This cooperativity of hydrogen bonding is also a characteristic that confers structure to proteins and nucleic acids.
This fact together with geometrical specificity and directionality, endows hydrogen bonds with a greater biological advantage over covalent bonds in biomolecular circumstances (Lehninger, 1975). Water is conventionally regarded as a ‘four-sided’ or tetrahedrally co-ordinated lattice of hydrogen bonded water molecules. However its behaviour under the different states of existence means that there is no uniform dictate which governs its structure. The basic characteristics of water structure are related to the maximisation of the number of hydrogen bonds.
This is coupled to the repulsive restrictions that other charged molecules will play in determining the resulting geometries and will directly affect the conventional tetrahedrality (Stryer, 1981; Savage, 1993). Due to the tetrahedral arrangement of electrons around the oxygen molecule, each water molecule is theoretically capable of hydrogen bonding with four neighbouring water molecules. It is this electrostatic attraction that confers the distinctive internal cohesion of liquid water. The conventional tetrahedral cluster of 5 water molecules has been determined to be 0.5 nm in diameter (Lehninger, 1975).

READ Topological String Theory: Coupling to Gravity

Table of Contents :

Contents
Acknowledgements
Declaration
List of Abbreviations
Glossary of Electrochemically Activated radical species
Summary
Chapter 1: Introduction and historical development
- 1.1 Water – Introduction
- 1.2 Water: Structure and behaviour
- 1.3 Water as a solvent
- 1.4 Energetic status of water
- 1.5 Electrolysis
- 1.5.1 History of Electrolysis
- 1.5.2 Energy of Electrolysis
- 1.5.3 Chemistry of Electrolysis
- 1.5.4 Conventional Brine electrolysis
- 1.5.5 Electrochemical Activation (ECA) of water
- 1.5.5.1 History of Electro-Chemical Activation
- 1.5.5.2 Principles of Electrochemical Activation of water
- 1.5.5.3 Relaxation
- 1.5.5.4 ECA Reactor design
- 1.5.5.5 Physical and chemical activities of ECA solutions
- 1.5.5.6 Effect of Mineralisation on Activation product ratios
- 1.5.5.7 Attributes of ECA solutions
- 1.5.5.8 Types of ECA Solutions
- 1.5.5.9 ECA Devices
- 1.6 Conclusions
- 1.7 References
Chapter 2: Microbial energetics
- 2.1 Introduction
- 2.2 Molecular structures
- 2.3 Microbial structures
- 2.4 Energy conservation
- 2.5 Response to environmental change
- 2.6 Oxidation- Reduction Potential (ORP)
- 2.7 Cell Surface interactions
- 2.8 ORP and pH covariant analysis
- 2.9 Conclusions
- 2.10 References
Chapter 3: Biocides and mechanisms of action
- 3.1 Introduction
- 3.2 Biocidal effects of physical agents
- 3.3 Biocidal effects of chemical agents
- 3.3.1 Cell walls
- 3.3.2 Cytoplasmic membrane
- 3.3.3 Nucleic Acids
- 3.4 Chemical classification of biocides
- 3.4.1 Non-Oxidising biocides
- 3.4.2 Oxidising biocides
- 3.4.2.1 Chlorine
- 3.4.2.1.1 Basic Chlorine chemistry
- 3.4.2.1.2 Mechanism of Action
- 3.4.2.1.3 Free Chlorine
- 3.4.2.1.4 Chlorine demand
- 3.4.2.2 Oxy-chlorine products
- 3.4.2.2.1 Hypochlorous acid
- 3.4.2.2.2 Hypochlorite anion
- 3.4.2.2.3 Chlorine Dioxide
- 3.4.2.2.4 Chloramines
- 3.4.2.3 Bromine Compounds
- 3.4.2.4 Peroxides
- 3.4.2.4.1 Hydrogen Peroxide (H2O2)
- 3.4.2.4.2 Organic peroxides – Peracetic acid
- 3.4.2.5 Oxygen Radicals
- 3.4.2.6 Ozone
- 3.4.3 Electric fields
- 3.4.4 Electro-Chemically Activated (ECA) solutions
- 3.4.4.1 Mechanism of action
- 3.5 Conclusions
- 3.6 References
Chapter 4: Review of general ECA solution applications
- 4.1 Food applications
- 4.2 Oxidation effects
- 4.3 Reducing effects
- 4.4 Agricultural Applications
- 4.5 Medical Applications
- 4.6 Veterinary Applications
- 4.7 Disinfection Bi-Products (DBP’s)
- 4.8 Corrosion
- 4.9 Conclusions
- 4.10 References
Chapter 5: Non-gravimetric measurement of Electro-Chemically Activated water as a biocidal assessment tool
- 5.1 Abstract
- 5.2 Introduction
- 5.3 Electro-Chemical Activation (ECA) of water
- 5.4 Objective of the study
- 5.5 Material and Methods
- 5.5.1 Generation of ECA Biocide
- 5.5.2 Physicochemical titrations
- 5.5.3 Antibacterial efficacy titration
- 5.5.4 Preparation of the cell suspension
- 5.5.5 Test procedure
- 5.6 Results
- 5.6.1 Halide based Anolyte – NaCl
- 5.6.1.1 Physicochemical titrations
- 5.6.1.2 Antibacterial efficacy titration
- 5.6.1.3 Antibacterial efficacy
- 5.6.2 Non-halide based Anolyte – NaHCO
- 5.6.2.1 Physicochemical titrations
- 5.6.2.2 Antibacterial efficacy titration
- 5.6.2.3 Antibacterial efficacy
- 5.7 Discussion
- 5.8 Conclusion
- 5.9 Acknowledgements
- 5.10 References
Chapter 6: Evaluation of the biocidal effects of ECA solutions using Atomic Force Microscopy (AFM)
- 6.1 Abstract
- 6.2 Introduction
- 6.3 Objective of the study
- 6.4 Materials and Methods
- 6.4.1 AFM Imaging
- 6.4.2 Preparation of microbial samples
- 6.4.3 Generation of ECA solutions
- 6.5 Results and Discussion
- 6.5.1 Image processing – 2D colour mapping
- 6.5.2 Three Dimensional image manipulation
- 6.5.3 Image measurement
- 6.5.4 Image collation
- 6.6 Conclusion
- 6.7 References
Chapter 7: The efficacy of Electro-chemically Activated (ECA) water against aerosolised Bacillus subtilis, Serratia marcescens, Mycobacterium parafortuitum and M tuberculosis in a controlled environment
- 7.1 Introduction
- 7.2 Aims and Objectives
- 7.2.1 Phase I
- 7.2.2 Phase II
- 7.2.3 Phase III
- 7.3 Material and Methods
- 7.3.1 Preparation of bacterial culture suspensions
- 7.3.2 Aerosolisation and air sampling of bacteria
- 7.3.3 Animal husbandry
- 7.3.4 Environmental parameters
- 7.3.5 Preparation of Actsol®
- 7.3.6 Aerosolisation of Actsol®
- 7.3.7 Preparation of M. tuberculosis H37Rv suspensions
- 7.3.8 Experimental process
- 7.3.9 Guinea pig health surveillance
- 7.3.10 Tuberculin skin testing
- 7.3.11 Repeat exposure
- 7.4 Results
- 7.5 Discussion
- 7.6 Conclusions
- 7.7 Acknowledgements
- 7.8 References
Chapter 8: Application of ECA solutions to control nosocomial infections in a Neonatal Intensive Care Unit
- 8.1 Abstract
- 8.2 Introduction
- 8.3 Objectives of the study
- 8.4 Materials and Methods
- 8.4.1 Sample Collection and Analyses
- 8.5 Results
- 8.5.1 Surface sampling
- 8.5.2 NICU and PNW disinfection
- 8.5.3 Extension of the Study to the Surgical Wards
- 8.6 Discussion
- 8.7 Conclusions
- 8.8 Acknowledgements
- 8.9 References
Chapter 9: Antimicrobial efficacy of Actsol®, an Electro-Chemically Activated (ECA) oxidant solution against multi-drug resistant bacteria
- 9.1 Abstract
- 9.2 Introduction
- 9.3 Materials and Methods
- 9.3.1 Description of Actsol®
- 9.3.2 Source of bacterial strains
- 9.3.3 Test conditions, Exposure time and Neutralisation
- 9.4 Results
- 9.5 Discussion
- 9.6 Conclusions
- 9.7 Acknowledgements
- 9.8 References
- 9.10 Appendices
- Patents
- Publications