Activated carbon is an excellent adsorbent. It is a recognized fact that it can remove many toxic and harmful substances in water and provide people with safe drinking water. Silver-loaded activated carbon, which not only continues to function as an adsorbent, but also has an antibacterial function. The antibacterial function of silver-loaded activated carbon is mainly due to the merits of silver.
Silver has an antibacterial effect, which is a fact that people have known for a long time. In the use of silverware in China, people in foreign countries put silver coins in fresh milk to extend the preservation time of milk, which is the first example of applying silver antibacterial. With the advancement of science, it has been found that colloidal silver (fine particles with a particle size between 10 and 100 nm) can effectively fight more than 650 different infectious diseases, and eight other bacteria can resist colloidal silver. Before the discovery of penicillin, silver was an "old antibiotic". The conclusions of foreign doctors were: "Silver silver is beneficial to the human body without harm." Many different kinds of antibiotic-resistant bacteria can be killed by colloidal silver. Off." Therefore, the FDA (US Food and Drug Administration) allows the sale of colloidal silver. It is because silver is both antibacterial and has a health-care effect on the human body (protecting the natural enzymes in our body and accelerating the repair of damaged tissues). Therefore, it is preferred as the material of the antibacterial agent. In foreign countries, antibacterial products have been formed into an industry. In 1993, Japan established the "Silver Research Institute for Inorganic Antibacterial Agents (Silver Institute)". In June 1998, it was established on the basis of members of the "Silver Research Institute". The "Antibacterial Products Technology Association" and established industry standards. The minimum inhibitory concentration (MIC) of silver (Ag+) is 2.0×10-6 (mol/L) for typhoid bacteria. The inhibition zone (mm) of Ag2O (with Al2O3 as carrier) increases with increasing content.
If we plot the Bacillus strain with the smallest inhibition zone, it can be clearly found that as the silver content increases, the inhibition zone also increases, but it is not a linear relationship, but tends to be saturated.
There are two theories about the bactericidal mechanism of silver: one is the mechanism of contact reaction. The theory is that silver ions (Ag+) are exposed to microorganisms, causing damage to the proteins of microorganisms, causing death or dysfunction of microorganisms. The contact principle is based on electrosorption. Because the cell membrane has a negative charge and the silver ion (Ag+) has a positive charge, both of them produce electrical adsorption and bind it firmly, the so-called "oligodynamic effect". As a result, silver ions penetrate the cell membrane into the microorganism and chemically react with the qiu group (-SH) on the protein in the microorganism.
This reaction causes the protein to coagulate, destroys the activity of the microbial synthetase, interferes with the synthesis of the microbial DNA, and causes the microorganism to lose its ability to divide and proliferate and die. At the same time, the combination of Ag+ and protein also destroys the microbial electron transport system, respiratory system and material transport system. Since Ag+ is uniformly distributed on the inner and outer surfaces of the activated carbon, it is gradually released during use, and silver has an antibacterial effect at a low concentration (2.0×10-6 mol/L). In addition, since Ag+ has a high oxidation-reduction potential (±0.798 ev, 25°), the reaction activity is large (the reduction potential increases as its valence state increases), and oxygen molecules in the surrounding space can be made ( O2) is converted into oxygen in an atomic state.
The second theory of silver sterilization mechanism is the active oxygen mechanism. According to the theory, after the activated carbon is loaded with silver, a trace amount of silver is distributed on the surface, which can act as a catalytic active center. The activated carbon-loaded activated carbon center can absorb the energy of the environment, activate the oxygen adsorbed on the surface of the activated carbon and the oxygen in the water to produce hydroxyl radicals (•OH) and reactive oxygen ions (O2-). These substances have strong oxidizing power and can Destroy the proliferative capacity of bacterial cells to achieve the purpose of inhibiting bacteria or killing bacteria.
Silver-loaded activated carbon, which meets the requirements of "good heat resistance, wide antibacterial spectrum and long effective period". Moreover, the inorganic antibacterial agent which does not produce resistance to microorganisms, in the past, the activated carbon is loaded with silver, and people often use the silver nitrate (AgNO3) water to dissolve and immerse and dry. This method does not change the structure of silver nitrate, so the water dissolves quickly and quickly. Later, some people converted silver nitrate to silver chloride to reduce the loss. We use the [Ag(NH3)2]+ complex to convert it into a substance that can be adsorbed by activated carbon. It is then calcined at a high temperature to make it elemental silver and silver oxide. The adsorption of silver-ammonia complex by activated carbon is physical adsorption, and its bond energy is van der Waals attraction. France's BLUE Industries Group uses plasma technology to combine the covalent bonding of silver and carbon (ie, chemisorption) for water sterilization. The relevant domestic units have proved through experiments that the effect is very good.
Physical adsorption lines and chemisorption lines. The intersection of the two curves means that the two adsorptions are convertible in terms of energy. The physically adsorbed molecules can be excited by absorbing energy and enter the chemisorption (point C) across the barrier X. The currently produced silver-loaded activated carbon is treated by plasma technology (giving excitation energy) to achieve a covalent bond form.
From a catalytic point of view, the silver surface is capable of absorbing hydrogen and oxygen, and is an atom of hydrogen and oxygen. This is the conclusion of many scholars studying catalysis at home and abroad. The inference is that an oxygen atom is adsorbed on a silver atom. It is inferred that the end of life of the silver-loaded activated carbon is saturated with the Ag atom or the oxygen atom.
Trapnell pointed out: "The clean silver evaporation film does not chemically adsorb hydrogen at room temperature, while the oxidized silver film has a slow adsorption. It is generally considered that silver, like copper, does not adsorb molecular hydrogen, but adsorbs Atomic hydrogen."
This process is slow because it is an endothermic process. Although this process is slow, it still causes a 1-2 ppm increase in dissolved oxygen in the water. This is what the French BLUE Industries Group pointed out when answering the questions raised by the China Building Research and Design Institute: “The effectiveness of scale inhibition and prevention of bacteria is derived from the catalysis of powdered silver-loaded charcoal.†Therefore, it can be concluded that: blue Water (Cartis) silver-loaded activated carbon has its unique advantages in the purification of drinking water. It is the most advanced drinking water treatment medium in the world.
This article answers the following questions about CARTIS media in water treatment:
1. Blue water--the formation mechanism of ecological oxygen [O]: Since Ag+ has a high oxidation-reduction potential (±0.798 ev, 25°), the reaction activity is large (as the valence state increases, the reduction potential It is also elevated) to convert oxygen molecules (O2) in the surrounding space into atomic oxygen [O].
2. Blue water - the mechanism of dissolved oxygen increase: The clean silver evaporation film does not chemically adsorb hydrogen at room temperature, while the oxidized silver film has slow adsorption. It is generally believed that silver, like copper, does not adsorb molecular hydrogen, but adsorbs atomic hydrogen. It can be inferred that its reaction with water is: this process is slow because it is an endothermic process. This process is slow and it still causes a 1-2 ppm increase in dissolved oxygen in the water.
3. Blue water--long-acting antibacterial. Anti-algae. Mechanism of anti-virus: After the activated carbon is loaded with silver, a trace of silver element is distributed on the surface, which can act as a catalytic active center. This active center absorbs the energy of the environment and activates the air adsorbed on the surface of the activated carbon and the oxygen in the water to produce hydroxyl radicals (•OH) and reactive oxygen ions (O2-). These substances have strong oxidizing power and can destroy bacteria. The cell's ability to proliferate can achieve the purpose of inhibiting or killing bacteria by silver-loaded activated carbon.
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