Oxidizing? Non-oxidizing? How to choose water treatment sterilization algaecide?
The bactericidal algaecide commonly used in water treatment is generally classified into an oxidative sterilizing (disinfecting) algicide and a non-oxidizing bactericidal algicide. This article describes in detail the mechanism and difference of the two types of bactericidal algaecide!
Oxidative sterilization (disinfection) algicide
1 Introduction
An oxidative bactericidal algicide is an agent that inactivates bacteria by inactivating the active enzymes in the bacteria or directly oxidizing the bacteria with strong oxidizing properties. Generally, oxidative bactericides can be used as disinfectants!
2 commonly used oxidative bactericidal algaecide
At present, the basic mechanism of action of oxidizing biocides is hypochlorite type bactericide (for example, chlorine, sodium hypochlorite, chlorine compounds such as chlorine ingot), bromine and bromine compounds, chlorine dioxide, ozone and the like.
3 mechanism of action
Hypochlorous acid type fungicide: mainly chlorine gas and sodium hypochlorite, hydrolyzed into hypochlorous acid in water, hypochlorous acid is small in volume, uncharged, easy to pass through the cell wall; at the same time, it is a strong oxidant, which can damage the cell membrane. Releases proteins, RNA, and DNA, and affects a variety of enzyme systems (mainly the sulfhydryl group of phosphoglucose dehydrogenase is destroyed by oxidation), thereby causing the bacteria to die. Because its mechanism of action is sterilized by the form of free hypochlorous acid, it is classified as a hypochlorous acid type fungicide!
Bromine and bromine compounds: similar to the principle of hypochlorous acid type fungicides, hydrolyzed in water to form free hydrogen bromide, hydrogen bromide enters the cell wall, and interacts with intracellular proteins, thereby destroying the protein structure and achieving sterilization purposes.
Chlorine Dioxide: Chlorine dioxide has strong adsorption and penetration ability to the microbial cell wall, can effectively oxidize the thiol-containing enzyme in the cell, and can quickly inhibit the synthesis of microbial protein to destroy the microorganism.
Ozone: Sterilization has the following three forms:
1. Ozone can oxidize and decompose the enzymes required for glucose inside the bacteria, causing the bacteria to inactivate and die.
2. Directly interact with bacteria and viruses, destroying their organelles and DNA, RNA, and destroying the metabolism of bacteria, leading to bacterial death.
3. Through the cell membrane tissue, invading the cells, acting on the outer membrane of lipoproteins and internal lipopolysaccharides, causing the bacteria to undergo permeability distortion and dissolve and die
Non-oxidizing bactericidal algaecide
1 Introduction
Non-oxidizing bactericidal algaecide does not kill bacteria by oxidation, but acts on a specific part of the microorganism in the form of a toxic agent, thereby destroying the cells or living parts of the microorganism to achieve sterilization purposes. Because the toxicity of non-oxidizing biocides is generally not used as a disinfectant!
2 commonly used non-oxidizing bactericidal algaecide
Divided into quaternary ammonium salts/quaternary phosphonium salts, heterocyclic compounds, thiazoles, chlorophenols, organic aldehydes, cyanide-containing compounds and heavy metals, etc. due to their structure and mechanism.
3 mechanism of action
The quaternary ammonium salt/quaternary phosphonium salt is mainly caused by electrostatic force, hydrogen bonding force and hydrophobic interaction between surfactant molecules and protein molecules, and adsorbs negatively charged bacteria, which accumulate on the cell wall and produce a ventricular resistance effect. It causes the growth of bacteria to be inhibited and dies. At the same time, its hydrophobic alkyl group can also interact with the hydrophilic group of bacteria, changing the permeability of the membrane, and then lysing, destroying the cell structure, causing cell lysis and death. The quaternary phosphonium salt structure is similar to the quaternary ammonium salt. Since the radius of the phosphorus atom is larger than that of the carbon atom, the polarization is stronger, making the quaternary phosphonium salt more susceptible to adsorption of negative electron-bearing bacteria.
Heterocyclic compounds mainly rely on the active moiety on the heterocycle, such as N, H, O and the base of DNA in the bacterial protein to form oxygen, adsorbed on the cell, thereby destroying the structure of the DNA in the cell and causing the DNA to lose its ability to reproduce. , thereby causing the cell to die.
Thiazole thiazoles can enter the bacteria to destroy the respiratory enzymes, inhibit the respiration, melt the cell wall, and break the balance between the internal and external environment. The active groups of thiazoles can react with the bases on the nucleic acids and hinder the formation of nucleic acids. , destroy the growth and reproduction of the bacteria.
Chlorophenolic chlorophenols can be adsorbed on the microbial cell wall and then diffused into the cell structure to form a colloidal solution in the cell, which precipitates the protein, thereby destroying the protein and killing the bacteria.
The organic aldehydes are aldehyde groups, the oxygen on the aldehyde groups is negatively charged, and the carbons are positively charged. The carbon with a positive 8-charge reacts with the amine NH: and the sulfur-based SH of the bacterial protein, thereby destroying the bacterial protein and causing the death of the bacteria.
The cyano-containing compound hydrolyzes to form a cyano-based SCN-, SCN- which can form a stable complex with the ferric ion Fe3+, so that the ability of Fe3+ to accept electrons from the bacterial dehydrogenase is weakened and plays a bactericidal action.
Heavy metals can enter the bacteria and react with proteins to denature the protein structure and kill the bacteria.
Advantages and disadvantages of oxidizing and non-oxidizing fungicides
Oxidizing bactericidal algaecide has the advantages of fast bactericidal algae killing speed, high broad spectrum of bactericidal effect, low processing cost, relatively little impact on environmental pollution, and microbial resistance to drug resistance. It is easy to use and has good bactericidal effect. Many water treatment agents are used together without affecting their function. The disadvantage is that it is greatly affected by the organic matter and the reducing substance in the water, the agent time is short, and the pH value of the water is also greatly affected, and at the same time, the dispersion penetration and the peeling effect are poor. Moreover, the hypochlorous acid type fungicide forms a carcinogen chloroform with organic matter in water.
Non-oxidizing bactericidal algaecide has high efficiency, broad spectrum, low toxicity, fast and lasting effect, strong penetrability and convenient use. It has a penetrating and stripping effect on sediments or slime, and is less affected by reducing substances such as hydrogen sulfide and ammonia, and is less affected by pH value in water. However, the treatment cost is higher than that of the oxidative bactericidal algaecide, which is likely to cause environmental pollution. The microorganisms in the water are prone to produce anti-drug type, so it is necessary to alternately add different types of non-oxidizing bactericidal algaecides.
