Na4EDTA and EDTA were adopted as new additives to intensify the seeded precipitation process of sodium aluminate solution. The effects of the two additives at certain concentrations on the seeded precipitation rate of sodium aluminate solution, particle size distribution (PSD) and morphology of precipitated gibbsite were investigated using titration method, particle size analyzer and scanning electron microscope (SEM), respectively.
Tetrasodium salt of ethylenediaminetetraacetic acid is chelating agent and it is an aqueous solution. Na4EDTA is the strongest, most versatile, and widely used chelant for controlling metal ions over a broad pH range in aqueous systems. It will not chelate monovalent metal ions such as sodium or potassium, but will chelate most multivalent metal ions (e.g., Fe, Cu, Mn, Ca, Mg, Zn) in a 1:1 molar ratio. The chelation reaction is virtually instantaneous in most cases. Calcium and other alkaline earth metals are most effectively chelated above pH 4.
Na4EDTA chelates most transition metals below pH 12. It is completely miscible with water, but is not soluble in organic systems. Na4EDTA is stable under widely varying conditions of temperature, acidity, alkalinity, and the presence of other chemicals. Na4EDTA is attached, however, by strong oxidizing agents such as hypochlorite bleach. In some applications, Na4EDTA can be reclaimed for reuse.
Applications of Na4EDTA
Removes calcium oxalate, calcium sulfate, calcium carbonate, barium sulfate, and other type scales from process equipment. Used in radioactive decontamination processes.
I & I Cleaners:
Dissolves scale, prevents scale formation, improves detergency of surfactants. Prevents turbidity inconcentrated liquid cleaners and shampoos. Minimizes effects of polyvalentmetal ions on emulsions, lubricants and polishes.
Removal of oxide films from metal articles; alkaline derusting; antistreak agents for pickling baths; alkaline degreasing.
Controls metal ions in scouring, boil-off, bleaching, dyeing, stripping, and finishing operations. Protects fluorescent whitening agents from metal catalyzed oxidation and degradation. Protects dyes from color change.
Improves efficiency of hydro bleach; reduces metal catalyzed brightness reversion. Used in descaling process equipment. Protects dyes from precipitation with metals.
Prevention of calcium and magnesium soap formation; improve detergency of soaps and detergents. Stabilizes perborate and percarbonate bleaches.
Enhanced Oil Recovery:
Boiler steam flooding; added top reflush or caustic flush plug to prevent magnesium and calcium silicate precipitates; ties up hardness ions that may cause precipitation of expensive surfactants during micellar flooding.