Zinc Oxide (ZnO)
Versatile inorganic compound used in rubber, ceramics, cosmetics, sunscreens, and pharmaceutical industries
Overview
Zinc Oxide (ZnO, CAS No: 1314-13-2) is a white powder inorganic compound. Widely used as a vulcanization activator in the rubber industry, UV blocker in cosmetics, opacifier in ceramics, and antiseptic in medicine.
Zinc oxide, with its wide bandgap (3.3 eV) and high thermal conductivity, is also used in electronic applications. Its nano-particle form increases surface area, enhancing catalytic and antimicrobial properties. It is insoluble in water but soluble in acids and alkalis.
Applications
Zinc Oxide has a wide range of industrial, cosmetic, and medical applications:
Rubber Industry
Used as an activator in rubber vulcanization. Increases mechanical strength and improves thermal conductivity of rubber products. Particularly critical in automotive tires.
Cosmetics and Sunscreens
Acts as a physical UV blocker for UVA and UVB rays. Used in powders, deodorants, and baby products for skin protection. Nano ZnO form allows use in transparent creams.
Ceramics and Glass Industry
Used as an opacifier and expansion coefficient regulator in ceramic glazes. Preferred in glass production for color adjustment and UV blocking properties.
Electronics and Optics
Used in transparent conductive oxide (TCO) films, LEDs, and solar cells. Its piezoelectric property makes it preferred in sensor applications.
Medical Applications
Used in ointments, toothpastes, and dermatological preparations due to its antiseptic properties. Wound healing and antibacterial effects are clinically proven.
Paints and Coatings
Used as a corrosion inhibitor in protective paints and as a fungicide in wood preservatives. Acts as a UV stabilizer in coatings.
Technical Specifications
| Property | Value | Unit | Test Method |
|---|---|---|---|
| Chemical Name | Zinc Oxide | - | - |
| CAS Number | 1314-13-2 | - | - |
| EC No | 215-222-5 | - | - |
| Formula | ZnO | - | - |
| Molecular Weight | 81.38 | g/mol | - |
| Appearance | White fine powder | - | Visual |
| Odor | Odorless | - | - |
| Purity | ≥99.5 | % | ISO 9298 |
| Zinc (Zn) Content | ≥80.0 | % | ISO 9297 |
| Lead (Pb) Content | ≤5 | mg/kg | ISO 172 |
| Cadmium (Cd) Content | ≤1 | mg/kg | ISO 3856 |
| pH Value (10% susp.) | 6.5-7.5 | - | ISO 787 |
| Density | 5.6 | g/cm³ | ISO 787 |
| Melting Point | 1975 | °C | ISO 6321 |
| Average Particle Size | 0.1-1.0 | μm | ISO 13320 |
| Surface Area | 10-50 | m²/g | BET |
| Water Content | ≤0.5 | % | Karl Fischer |
Safety Information
Hazard Symbols and Statements
Irritant Environmental Hazard
Personal Protective Equipment (PPE)
- Dust mask (N95 or equivalent)
- Chemical-resistant gloves (nitrile or neoprene)
- Protective goggles or face shield
- Dust-resistant work clothing
Storage Conditions
- Store in a cool, dry and well-ventilated place
- Keep in original packaging, tightly closed
- Storage temperature: 15-30°C
- Keep away from acids and strong oxidants
- Protect from moisture, prevent water contact
Fire Fighting
- Non-combustible substance
- May release zinc vapor at high temperatures
- Suitable methods: Water spray, dry chemical powder, CO₂
- Firefighting personnel must use full respiratory protection
Handling and Storage
Transportation
- Ensure containers are tightly closed
- Prevent moisture contact
- Transport separately from acids and strong oxidants
- Have absorbent material available for spills
- Provide ventilation during transport
Storage
- Store in dry, cool and well-ventilated areas
- Display appropriate signage in storage area
- Protect from direct sunlight
- Store on elevated shelves
- Storage temperature should not exceed 40°C
Spill Response Measures
- Evacuate exposed personnel from area
- Use appropriate personal protective equipment
- Collect spill by dry method (sweeping)
- Do not use water - may create dust cloud
- Vacuum clean the spilled area
Regulatory Information
GHS Classification
- Respiratory Irritation Category 2
- Eye Irritation Category 2
- Acute Aquatic Hazard Category 1
Important Regulations
- REACH: Registered
- EPA: Listed in TSCA inventory
- European Cosmetics Regulation: Approved
- FDA: GRAS (Generally Recognized As Safe) status
- EU: Food additive as E6
Compliance Certificates
- ISO 9001:2015 Quality Management System
- ISO 22716:2007 Cosmetic Production Standard
- USP, BP, Ph.Eur. Pharmacopoeia standards (for relevant grades)
- RoHS and REACH compliant
Environmental Information
Environmental Impact
Zinc oxide is moderately toxic to aquatic organisms. Nano-particle form requires special attention. In soil, it transforms into zinc ions that can be taken up by plants. Zinc ion removal is required in wastewater treatment systems.
Biodegradation
- Non-biodegradable
- Transforms into zinc ions in nature
- May form zinc salts in soil
Waste Management
- Classified as hazardous waste
- Should be processed at licensed waste disposal facilities
- Do not discharge to sewers or surface waters
- Can be sent to zinc recycling facilities for recovery
- Special disposal methods required for large quantities
Frequently Asked Questions
Why is zinc oxide used in sunscreens?
Zinc oxide provides broad-spectrum UV protection (UVA and UVB). As a physical blocker, it forms a protective layer on the skin surface. It causes fewer allergic reactions compared to chemical sun filters and exhibits photostable properties. Nano-particle form allows use in transparent creams.
What is the role of zinc oxide in the rubber industry?
Zinc oxide reacts with sulfur during rubber vulcanization to accelerate cross-linking formation. This increases mechanical strength, flexibility, and abrasion resistance of rubber products. It also improves thermal conductivity, reducing heat buildup.
What is the difference between nano zinc oxide and regular zinc oxide?
Nano zinc oxide has particle sizes between 1-100 nm. It has a higher surface area than regular ZnO, providing more effective UV absorption and antimicrobial activity. In cosmetic applications, it provides a transparent appearance. However, safety evaluation of nano particles requires more careful assessment.
What should I do if I inhale zinc oxide?
Move the affected person to fresh air. Provide oxygen if there is breathing difficulty and seek medical attention immediately. Those exposed to dust clouds may require medical monitoring. Pulmonary function tests are recommended in cases of continuous exposure.
How does zinc oxide exhibit antimicrobial effects?
Zinc oxide produces reactive oxygen species (ROS) that damage bacterial cell walls. Especially nano particles show more effective antimicrobial activity due to their high surface area. It is effective against Gram-positive and Gram-negative bacteria, some viruses, and fungi. This property makes it used in medical materials and textiles.