Main applications of PSA nitrogen in nano silver production

Main applications of PSA nitrogen in nano silver production

Nano-silver has extremely small particle sizes, ranging from approximately 1 to 100 nm. Its tiny size and ultra-large specific surface area give it four unique properties: antibacterial, conductive, optical, and catalytic. It is widely used in industries such as electronics, photovoltaics, medical, environmental protection, and chemicals.

Nano-silver particles are extremely small in size, and zero-valent silver is highly chemically reactive. Even trace amounts of oxygen can directly oxidize the silver, causing the particles to turn black, reducing their electrical conductivity, and rendering their antibacterial properties unusable. Reducing agents used in the production process, such as ethylene glycol, are prone to premature oxidation when exposed to oxygen, increasing the risk of combustion and explosion. They also cause a significant decrease in reduction efficiency, affecting the particle size distribution of nano-silver. The presence of oxygen during high-temperature calcination and other stages can cause silver particles to agglomerate, affecting the size of the nano-silver and causing it to lose its dimensional properties.

Pressure swing adsorption (PSA) nitrogen generators use air as raw material and carbon molecular sieves as adsorbents to separate oxygen and nitrogen, continuously producing 95% to 99.9995% high-purity nitrogen on-site, replacing liquid nitrogen in cylinders, and providing a stable supply of protective gas throughout the entire process. It is the mainstream gas supply solution for the production of nano-silver materials.

Main applications of PSA nitrogen in the production of nano silver:

1. Inert gas protection for the reactor

The mainstream method for producing nano-silver involves using sodium borohydride or similar reducing agents to reduce AgNO3 to Ag0. High-purity nitrogen is continuously introduced into the reactor before feeding the nano-silver into the reactor to replace air and moisture at the top, inhibiting oxidation of the reducing agent and preventing Ag oxidation.

2. Pipeline and equipment purging and replacement

Before the reaction begins or after production line maintenance, pipelines and reaction vessels must be purged with high-purity nitrogen to replace residual oxygen and moisture. After the reaction is complete, nitrogen can also be used to purge and dry the product to prevent cross-contamination and oxidation residues that could cause abnormalities in the next batch.

3. Post-processing, storage and packaging

PSA nitrogen purging of the air inside the packaging bag extends the shelf life of nano-silver and prevents the conductive silver from deteriorating; nitrogen-sealed silo protection prevents the ultrafine silver powder from spontaneously combusting or oxidizing.

Nano-silver is extremely sensitive to impurities such as water and oil. Contamination of nano-silver colloids can lead to decreased conductivity, therefore, a complete compressed air pretreatment system is essential, and some processes require a dew point ≤ -60℃. Nano-silver production also requires extremely high nitrogen purity, needing to meet a purity of 99.99%-99.9995% or higher. The PSA nitrogen generator plays a crucial role in the production of nano-silver materials, acting as an "invisible guardian" by providing continuous, stable, and high-purity nitrogen, fundamentally ensuring the narrow particle size distribution and excellent dispersibility and conductivity of nano-silver particles.