4A Molecular Sieve Related Knowledge Analysis

Feb 14, 2019

Molecular sieves are synthetic, silicoaluminates with a microporous cubic lattice. According to the size of the internal pores of the crystal adsorption or exclusion of different substances of molecules, so called "molecular sieve". Materials with a molecular diameter smaller than the aperture of the molecular sieve crystal can enter the molecular sieve crystal and be adsorbed, otherwise they will be rejected. The properties of molecular sieve are as follows:

1. Ion exchange performance -- softening water function: each oxygen atom in the framework of 4A molecular sieve is Shared by two adjacent tetrahedrons. This structure forms large crystal cavities which can be occupied by cations and water molecules. These cation and water molecules have greater fluidity, allowing cation exchange and reversible dehydration. The ion exchange of the 4A zeolite is carried out on a skeleton with aluminum ions, and each aluminum ion has a negative charge, which can bind not only sodium ions but also other cations. Calcium and magnesium ions can enter the macrocrystalline pore occupied by original sodium ions and replace the sodium ions in the 4A molecular sieve -- that is, the sodium ions in the 4A molecular sieve can conduct ion exchange and can combine with Ca2 +, Mg2 + ions in hard water. Exchange to achieve the purpose of softening water quality.

The 4A molecular sieve binds calcium and magnesium ions at a slower rate than sodium tripolyphosphate, and has a weaker binding capacity to magnesium ions. However, the 4A molecular sieve can easily remove a small amount of harmful heavy metal ions (such as Pb2 +, Cd2 +, and Hg2 +) in the aqueous solution, which is of great significance for purifying water quality.

2. Adsorption of surfactant -- carrier function: due to the pore structure of 4A molecular sieve crystal and the large specific surface area of particles, 4A molecular sieve has a strong adsorption performance.

For the adsorption of nonionic surfactant, 4A molecular sieve is 3 times as much as NTA (secondary aminotriacetate) and sodium carbonate, and 5 times as much as sodium tripolyphosphate (STPP) and sodium sulfate. This property is used for agglomeration molding. It is meaningful to produce more concentrated surfactant in high concentration detergent to produce products with good washing and flow properties. Through experiments, the liquid carrying capacity of 4A molecular sieve is 30%. The addition of 4A molecular sieve in the production of washing powder can increase the fluidity of the material and adjust the viscosity, so as to obtain products with good appearance and anti-agglomeration. 

3. detergency: through the experiment, the same formula of adding different additives, change the detergency of additives, found that 20% of STPP 4%, 20%, molecular sieve, polymer decontamination effect is equivalent to 40% STPP adding 10% sodium carbonate and without phosphorus formula 4 polymer, 5% to 20% in the molecular sieve can obtain excellent detergency of the product.

4. Redeposition resistance: 4A molecular sieve has good oil adhesion. When zeolite was added to sodium carbonate, CMC, sodium silicate and sodium sulfate, the oil adsorption capacity of nylon cloth decreased obviously. When zeolite size is 0 0x75 4 101775 m, the dispersion is better and the adhesion to the fabric can be prevented.

Although the dispersion of 4A molecular sieve is not as good as that of STPP, it can solve the dirt dispersion problem mixed with sodium polyacrylate.

5. Compatibility with other additives: 4A molecular sieve and other additives can make their properties complementary. Compared with STPP, 4A molecular sieve has better dispersion of dirt and hardness ions, but when 4A molecular sieve is mixed with STPP, the detergency can reach the effect of single STPP. This is because STPP can rapidly compound calcium and magnesium ions from the solid surface and transfer them to the 4A molecular sieve through an aqueous medium. The 4A molecular sieve has a poor ability to bind magnesium ions and can be compensated by complexing silicate and carbonate in the molecular sieve.

6. PH buffering: 4A molecular sieve is alkaline, 1% water solution PH 11, 0, so it has a certain buffer alkalinity.

7. Safety: 4A molecular sieve is non-toxic and safe for human body. No irritation to eyes, skin, will not cause allergy, safe and reliable use. It can be washed and deposited in the soil, causing no pollution and improving the soil. 4A molecular sieve has no adverse effect on ecology.