The chemical formula of zinc borate is 2ZnO · 3B ₂ O3 · 3.5H ₂ O, which is a white crystalline or amorphous powder. Its molecular structure contains zinc ions (Zn ² ⁺), borate ions (BO ∝⁻), and crystal water. This structure endows zinc borate with the following characteristics:
1. Solubility in water
The solubility of zinc borate in water is relatively low, only 0.28 g/100 mL at room temperature. This means that at room temperature in water, zinc borate is almost insoluble and mainly exists in solid form.
2. The effect of temperature on solubility
As the temperature increases, the solubility of zinc borate slightly increases, but the increase is not significant. For example, at 80 ℃, its solubility is about 0.5 g/100 mL. However, zinc borate still belongs to insoluble substances.
3. The influence of pH value on solubility
The solubility of zinc borate is greatly affected by pH value. In acidic environments, zinc borate reacts with acid to form soluble zinc salts and boric acid, thereby increasing its solubility. For example, in hydrochloric acid:
2ZnO·3B₂O₃·3.5H₂O + 12HCl → 2ZnCl₂ + 6H₃BO₃ + 3.5H₂O
In alkaline environments, zinc borate reacts with alkali to form zincate and borate salts, which also increase its solubility.
1. Flame retardant materials
The low water solubility of zinc borate makes it an important application in flame retardant materials. For example, in plastic and rubber products, when zinc borate is used as a flame retardant, it will not affect the material's performance due to water absorption.
2. Anti corrosion coating
In anti-corrosion coatings, the low water solubility of zinc borate helps to form a stable protective film, prevent moisture penetration, and thus improve the anti-corrosion performance of the coating.
3. Ceramic and glass industry
The application of zinc borate in the ceramic and glass industries also benefits from its low water solubility. For example, adding zinc borate to glaze can improve the hardness and glossiness of the glaze without causing cracking due to water absorption.
4. Environmental remediation
The low water solubility of zinc borate makes it potentially applicable in environmental remediation. For example, in soil remediation, zinc borate can serve as a slow-release agent, gradually releasing zinc and boron elements to improve soil quality.
Zinc borate has a low solubility in water and is almost insoluble in water at room temperature. However, its solubility is greatly affected by temperature and pH value, and it may decompose and increase solubility in acidic or alkaline environments. This characteristic makes zinc borate widely applicable in fields such as flame retardancy, corrosion resistance, ceramics, etc. In the future, with the deepening of research and the advancement of technology, the solubility regulation of zinc borate will open up new possibilities for its application.
