Toda United Indusrial (Zhejiang) Co., Ltd.

Iron oxide yellow powdery yellow transparent pigments. The relative density of 3.5. Stable chemical properties. Particle size of 0.01 ~ 0.02μm. Large surface area (about 10 times the ordinary iron oxide), with a good performance strongly absorb ultraviolet light, atmosphere and the like. Made of a transparent film, excellent properties. How Preparation Iron oxide yellow it?

Method a: ferrous sulfate oxidation reaction of iron sulfate and ferrous sulfate, and sodium hydroxide was added into the prepared nuclei through air oxidation, and then addition of ferrous sulfate and iron nuclei in suspension, heated air is blown oxidation, pressure filtration, rinsed, dried and pulverized to obtain Iron oxide yellow.

Fe + H2SO4 → FeSO4 + H2 ↑
FeSO4 + 2NaOH → Fe (OH) 2 + Na2SO4
4Fe (OH) 2 + O2 → 4FeOOH + 2H2O
H2SO4 + Fe + 7H2O → FeSO4 · 7H2O + H2 ↑

FeSO4 · 7H2O + O2 → 2Fe2O3 · H2O ↓ + 4H2SO4 + 2H2O Reaction conditions: The iron was added 74g 1000ml 15% sulfuric acid in the reaction to the disappearance of the iron to form a concentration of about 200g / L of ferrous sulfate. To the above ferrous sulfate solution prepared by adding sufficient 30% sodium hydroxide, stirring constantly to make a total of 40% of the iron into ferrous hydroxide [Fe (OH) 2], at 30 ~ 35 ℃ through the air so that Fe is oxidized to Fe nucleation. Thereto was added 90g / L of treated iron, the resulting 7g / L of nuclei and 40g / L of ferrous sulfate and heating was continued to 85 deg.] C, to 600L / h rate of air oxidation 64h of the drum, then filtered, washed with dried, pulverized to obtain an aqueous Iron oxide yellow.

Method Two: oxidation of aromatic nitro compounds can produce aromatic amino matter. Reaction equation is as follows:

Fe + H2O + R-NO2 → Fe2O3 · H2O + R-NH2

Reaction conditions were as follows: 560 parts of water was added to the reaction vessel, 36.5 parts of 32% hydrochloric acid, 160 parts of iron powder and 10 parts of aluminum powder. With 16 ~ 24h was added to the reaction vessel containing 1460 parts of an aqueous solution of 253 parts of naphthalenesulfonic acid and 5-nitro-8-nitro-naphthalene sulfonic acid, pH value of an aqueous solution of 6-naphthalene sulfonic acid, a temperature of 80 ~ 85 ℃. The reactor temperature at 95 ~ 100 ℃, pH value of 6 to 6.5, under reaction conditions 2h, 8 parts of 25% ammonia water was added, the reaction further 4h, filtered and the filter cake washed three times with 560 parts of the filter after washing cake was mixed with 1000 parts of water, heated at 95 ~ 100 ℃, 45 parts of 32% hydrochloric acid was added, stirred 2h, filtered and the filter cake was washed with water until acid free and dried to obtain 160 parts available Iron oxide yellow pigment, and to give an amino-naphthalenesulfonic acid yield 96%.