hydrogen peroxide (peroxide), also known as hydrogen peroxide, hydrogen dioxide, is a kind of peroxide disinfectant, is the product of some reducing substances and oxidation in nature, very rare, only trace exists in some plant SAP and rain and snow. The molecular formula of hydrogen peroxide is H2O2 and the molecular weight is 34.015. Oxygen atoms take unequal sp3 hybrid orbitals to bond, the molecules are covalent polar molecules, and the three-dimensional structure is like two pages of a half-opened book.
Hydrogen peroxide is a strong oxidizing agent, weakly acidic, colorless and odorless transparent liquid. As long as the storage conditions are good, no impurity pollution, pure hydrogen peroxide is relatively stable, can be stored for a long time and rarely decomposed, but when heated to 153 ° C or higher temperatures will violently explosive decomposition. The decomposition rate of hydrogen peroxide in alkaline medium is much faster than that in acidic medium, and the important factors affecting its stability are impurities (many heavy metal ions such as: Fe2+, Mn2+, Cu2+, Cr3+), pH value, temperature, light, and the roughness of the internal surface of the storage container. High concentration of hydrogen peroxide can cause many organic solvents to burn and react with manganese dioxide to explode. Therefore, hydrogen peroxide should be placed in a plastic container closed, stored in a cool place, strictly prohibited in the sun exposure, and avoid pollution and violent shaking.
Hydrogen peroxide is a highly effective chemical disinfectant, and a certain concentration of hydrogen peroxide solution can kill microorganisms including bacterial propagans, spores, fungi and viruses.
ONE
Action mechanism
1. Hydrogen peroxide decomposes under the catalysis of photochemistry, ionizing radiation, heavy metals and conversion metal ions to produce various chemical groups, such as active oxygen species and derivatives, OH groups, etc., which has a strong killing effect on microorganisms. By changing the permeability barrier of microorganisms, the protein enzymes, amino acids and nucleic acids of microorganisms are destroyed, leading to the death of microorganisms.
2. Hydrogen peroxide is an oxidizing agent that can ionize the molecules or atoms of bacterial cells and cause the lipid chain on the cell wall to break, thus destroying the cell wall.
3. Hydrogen peroxide can oxidize Sh-containing enzymes, resulting in loss of metabolic activation enzyme function, resulting in cell division and reproduction disorders.
4. After entering the bacteria, toxic OH group is produced, which acts on the phosphodiester bond of DNA and causes it to break.
TWO
Factors influencing disinfection effect
The bactericidal effect of hydrogen peroxide is affected by time, concentration, pH value, relative humidity, organic protection, physical and chemical factors, etc.
2.1 Action time
With the extension of time, the bactericidal effect was enhanced. When 10% hydrogen peroxide was applied to Bacillus subtilis black variant spores, the longer the treatment time, the more the spores died.
2.2 Concentration
With the increase of hydrogen peroxide concentration, the bactericidal effect was enhanced. Studies have shown that under the condition of 20℃, different concentrations of hydrogen peroxide were used to kill Bacillus subtilis black variant spores. The results showed that the higher the concentration of hydrogen peroxide, the shorter the sterilization time. Whether in liquid or gaseous form, the bactericidal effect of hydrogen peroxide is positively proportional to its concentration. Studies have proved that the n value of hydrogen peroxide killing Bacillus typhi (concentration coefficient or dilution coefficient, used to indicate the influence of chemical disinfectant concentration on disinfection effect, the greater the n value, the more obvious the influence of concentration change on disinfection effect) is 0.5, and the dilution coefficient of killing Bacillus subtilis spores is 0.7~0.9. Zhang Wenfu et al. carried out killing experiments on Bacillus subtilis black variant spores at different concentrations of hydrogen peroxide at 20℃. The results showed that the higher the concentration, the shorter the killing time, and the correlation between concentration and action time was linearly negative (Y=2.944-1.134X, r =-0.989, P < 0.01).
According to the following concentration coefficient formula: n =[(LGt2-LGT1)/(lgC1-lgC2)], when the concentration of hydrogen peroxide changes between 5% and 25%, its concentration coefficient (n) is 1.13. According to the concentration coefficient, within the range of experimental values, the concentration of hydrogen peroxide is reduced by half, and the required action time is extended by 2.19 times.
2.3 Temperature
Other conditions remain unchanged, the bactericidal effect of hydrogen peroxide liquid is enhanced with the increase of temperature. When 10% hydrogen peroxide was used to kill Bacillus subtilis black variant spores, the solution temperature was negatively correlated with the logarithm of the time required to kill bacterial spores. At 70℃, 10% hydrogen peroxide can kill all spores in just 1min, while at 10℃ it takes 205min to achieve the same effect.
2.4 Relative Humidity
The relative humidity in the air is too low or too high, which has an adverse effect on the bactericidal effect of hydrogen peroxide. In the experiment of killing staphylococcus albicans with air disinfectant based on hydrogen peroxide, the results showed that the killing rate was 91.13% when the relative humidity was 52% ~ 54% for 10min. The killing rate was 98.53% when the relative humidity was 72%-74%. When the relative humidity is 90% ~ 92%, the killing rate is 68.98%.
2.5 pH value
Whether it is pure hydrogen peroxide or hydrogen peroxide with other components such as potassium iodide, the bactericidal ability in acidic environment is stronger than that in alkaline environment.
2.6 Organic Matter
The protection of organic matter has certain influence on the bactericidal action of hydrogen peroxide. When killing microorganisms contaminated by blood, pus, sputum and urine, the action time should be extended. However, some studies have pointed out that the bactericidal effect of high concentration of hydrogen peroxide is very small, especially in high temperature environment, the sterilization effect is not obvious.
2.7 Synergies
In recent years, the results show that ultraviolet light, metal ions, negative ions and other physicochemical factors have synergistic effects on the bactericidal effect of hydrogen peroxide.
(1) Ultraviolet light has a synergistic effect on hydrogen peroxide sterilization. Ultraviolet radiation can promote the decomposition of hydrogen peroxide to produce free radicals, which act on the spore protein and cortex, causing the rapid death of microorganisms. The results showed that the killing rate of Bacillus subtilis black variant was 99.90% when 3% hydrogen peroxide and 70uw/cm2 ultraviolet light were used for 5min, while the killing rate was 17.72% and 99.20% when hydrogen peroxide and ultraviolet light were used alone.
(2) The bactericidal synergistic effect of potassium iodide on hydrogen peroxide has been proved at home and abroad. The synergistic coefficient of 0.125% hydrogen peroxide and 0.125% potassium iodide for 3min is higher than that of 0.250% hydrogen peroxide and 0.250% potassium iodide for the same time. The greater the synergy coefficient, the stronger the effect.
(3) Hydrogen peroxide is mixed with glutaraldehyde to produce aldehyde peroxide, which can improve the bactericidal effect. The results showed that when 5% hydrogen peroxide and 0.5% glutaraldehyde acted together for 10 ~ 30min, the killing rate of Bacillus subtilis nigrospora was up to 99.99%, which was significantly higher than that of 60.12% and 88.18% when hydrogen peroxide and glutaraldehyde were used alone.
(4) Hydrogen peroxide is coordinated with ultrasound. It has been reported that high-intensity ultrasound and 6% hydrogen peroxide can kill Bacillus cereus and Candida albicans in only 10min, while 30min treatment with ultrasound or hydrogen peroxide alone is still not enough to kill them.
(5) Hydrogen peroxide cooperates with plasma, and the synergistic bactericidal effect is due to the fact that hydrogen peroxide is easily decomposed into various free active groups in the plasma state.
(6) Hydrogen peroxide is coordinated with metal ions (Fe2+, Cu2+, Ag+), and metal ions can also promote the decomposition of hydrogen peroxide to produce free radicals and accelerate the death of microorganisms.
(7) The coordination of hydrogen peroxide and surfactant has been found that the addition of surfactant D-33 or Sulfonol during the disinfection of hydrogen peroxide sol can narrow the diameter of the aerosol, thus improving the sterilization effect.
