Shanghai Zhongjing Environmental Protection Technology Co., Ltd. independently develops and manufactures micro/nano bubble generators, ozone micro/nano bubble all-in-one machines, and super oxygen micro/nano bubble all-in-one machines that are widely used in different industries, and has obtained national patent certificates (ZL 2018 2 0669759.2, 202120371588.7/20210371480.8, 202120371479.5). The core of ZJC-NM series of micro/nano bubble devices (nano generators, ozone generators) are independently developed by Zhongjing Company A modern high-tech enterprise that integrates design, manufacturing, sales, and service, has been committed to improving air, water, and soil. Create international leading technology for China's environmental protection industry, and successfully establish an expert image in controlling environmental pollution.
Zhongjing micro/nano bubble generator specifications: scientific research type micro/nano bubble generator, super oxygen micro/nano bubble integrated machine, ozone micro/nano bubble integrated machine, micro/nano bubble aerator, wastewater decolorization micro/nano generator, fruit and vegetable disinfection micro/nano generator, micro/nano bubble cleaning machine, micro/nano bubble organic waste gas treatment equipment...
Definition of bubbles
The presence of gases in liquids is known as bubbles. The formation of bubbles can be encountered in many processes in nature. When gases are subjected to shear forces in liquids, they form bubbles with different particle sizes and shapes.
Classification of bubbles
According to the order of bubble size from large to small, it can be divided into centimeter bubbles (CMB), millimeter bubbles (MMB), micrometer bubbles (MB), micro nano bubbles (MNB), and nano bubbles (NB). Micro and nano bubbles refer to bubbles with particle sizes ranging from several micrometers to hundreds of nanometers when bubbles occur. These bubbles are between micron bubbles and nano bubbles, and have physical and chemical properties that conventional bubbles do not possess.
Technical characteristics of micro and nano bubbles
Large specific surface area of micro and nano bubbles
The relationship between the volume and surface area of a bubble can be expressed by a formula. The volume formula of a bubble is V=4 π/3r3, and the surface area formula of a bubble is A=4 π r2. Combining the two formulas can obtain A=3V/r, that is, Vtotal=n · A=3Vtotal/r. When the total volume of a bubble remains constant (V remains constant), the total surface area of the bubble is inversely proportional to the diameter of a single bubble. According to the formula, the specific surface area of a 10 micron bubble is theoretically 100 times larger than that of a 1 millimeter bubble at a given volume. The contact area between air and water has increased by 100 times, and the various reaction speeds have also increased by 100 times.
The rising speed of micro and nano bubbles is slow
In Stokes' law, the rising speed of a bubble in water is proportional to the square of its particle size. The smaller the particle size of the bubble, the slower the rising speed of the bubble. From the graph of the relationship between the rising speed of a bubble and its diameter, it can be seen that a bubble with a diameter of 1 mm rises in water at a speed of 6 m/min, while a bubble with a diameter of 10 μ The rising speed of m bubbles in water is 3 mm/min, and the latter is 1/2000 of the former. With the increase of the specific surface area of micro and nano bubbles, the dissolution efficiency of micro and nano bubbles increases by 200000 times compared to that of ordinary air.
Self pressurized dissolution of micro and nano bubbles
There is a gas-liquid interface around micro and nano bubbles in water. When the gas-liquid interface exists, the bubbles will be affected by the surface tension of water. The surface tension of the bubble at the spherical interface of water can compress the gas inside the bubble, thereby dissolving more of the gas inside the bubble into water. In the Laplace equation? P=2 σ/ r,? P represents the value of pressure rise, σ Represents surface tension, and r represents bubble radius. The pressure exerted on bubbles with a diameter of more than 0.1 mm can be ignored, while the pressure exerted on bubbles with a diameter of 10 μ The tiny bubbles of m are subjected to a pressure of 0.3 atmospheric pressure, and the diameter is 1 μ M bubbles are subjected to a pressure of up to 3 atmospheres. The dissolution of micro and nano bubbles in water is a process of gradually shrinking bubbles. The increase in pressure will increase the dissolution rate of the gas. With the increase in specific surface area, the speed of shrinking bubbles will become faster and faster, and eventually dissolve into water. When the bubbles are about to disappear, the pressure they will be subjected to is infinite.
Surface charging of micro and nano bubbles
Pure water liquids are composed of water molecules and a small amount of H+and OH - generated by ionization. The gas-liquid interface formed by bubbles in water is easy to accept the characteristics of H+and OH -. Generally, cations are easier to leave the gas-liquid interface than anions, leaving the interface often with negative charges. The surface that has been charged tends to absorb counter ions in the medium, especially those with high valence, thereby forming a stable double electric layer. The potential difference generated by the surface charge of microbubbles is often utilized ζ Potential, ζ The potential is an important factor determining the adsorption performance of the bubble interface. When micro and nano bubbles contract in water, charged ions are rapidly concentrated and enriched at a very narrow bubble interface, as shown in ζ A significant increase in electric potential can form a very high electric potential at the interface before the bubble bursts ζ Potential value.
Micro-nano bubbles generate a large number of free radicals
At the moment of microbubble rupture, due to the drastic changes in the disappearance of the gas-liquid interface, the accumulated chemical energy will be released immediately by the high concentration ions accumulated on the interface. At this time, microbubbles can be excited to generate a large number of hydroxyl radicals. Hydroxyl radicals have an extremely high oxidation and reduction potential, and their strong oxidation can degrade pollutants such as phenol that are difficult to oxidize and decompose under normal conditions in water, achieving a purification effect on water quality.
High mass transfer efficiency of micro and nano bubbles
Gas-liquid mass transfer is a speed limiting step in many chemical and biochemical processes. In practical applications, the gas liquid mass transfer rate and efficiency are inversely proportional to the diameter of the bubble. The diameter of the microbubble is very small, and it has significant advantages over traditional bubbles in mass transfer processes. When the bubble diameter is small, the surface tension at the microbubble interface has a significant impact on the bubble characteristics. At this time, surface tension exerts a compression effect on the internal gas, causing the microbubbles to continuously contract and exhibit their own pressurization effect during the rising process. As the diameter of the bubble decreases infinitely, the specific surface area of the bubble interface also increases infinitely. Finally, due to the self pressurization effect, the internal pressure can increase to infinity. Therefore, during the volume contraction process of microbubbles, due to the continuous increase in specific surface area and internal pressure, more gas is dissolved into water through the bubble interface, and as the bubble diameter decreases, the effect of surface tension becomes increasingly apparent. Finally, the internal pressure reaches a certain limit value, leading to the bubble interface fracture and disappearance. Therefore, the self pressurization characteristics of microbubbles during the contraction process promote gas liquid? The mass transfer efficiency at the interface is continuously enhanced, and the characteristics of micro and nano bubbles enable the micro bubbles to continue the gas mass transfer process even when the gas content in the water reaches saturation conditions, resulting in a supersaturated state.
High gas solubility of micro and nano bubbles
Micro and nano bubbles have the characteristics of slow rising speed and self pressurized dissolution. During the slow rising process, micro and nano bubbles gradually reduce to nano scale, and finally reduce the solubility in water, which can greatly improve the solubility of gases (air, oxygen, ozone, carbon dioxide, etc.) in water, enabling the dissolved oxygen in water to reach a supersaturated state. In the experiment, the oxygen content in water can be as high as
400%。 If ordinary bubbles exist, the solubility of the gas is often affected and limited by environmental pressure, and there is a saturation solubility. In standard environments, the solubility of gases is difficult to reach above saturation solubility. Due to the fact that the internal pressure of Zhongjing micro/nano bubble technology is higher than the ambient pressure, the gas supersaturation dissolution condition calculated based on the assumption of atmospheric pressure can be broken.
Application fields of micro/nano bubble technology
It is applied to the sewage treatment of offshore and onshore oil and gas fields of CNOOC, PetroChina, and Sinopec, and is the preferred technology for upgrading the old gas floatation technology to save energy and reduce consumption. Provide high-quality micro bubble dissolved water for air flotation facilities in oil and gas fields, refining, coal chemical, steel, printing and dyeing, paper making, municipal and other industries, and improve the efficiency of decontamination. Provide micro bubble dissolved water for oil and gas field settling tanks, inclined plate oil removers, etc., to improve oil removal efficiency. Algae removal and purification of water bodies and restoration of natural landscape water bodies.
