NaOH (Sodium Hydroxide - Lye): Properties, Applications & Price Quotes for 2025
Summary: NaOH — Sodium Hydroxide, also known as lye, flake lye, liquid lye, or caustic soda — is a strong alkaline chemical used in most heavy and light industries. This article compiles comprehensive information on NaOH: physical and chemical properties, commercial forms, industry-specific applications, a comparison of liquid caustic soda and flake caustic soda, and a guide to purchasing from Loc Thien Chemicals.
1. What is NaOH?
Sodium Hydroxide (chemical formula: NaOH) is an inorganic compound classified as a strong base, existing as white crystals at room temperature. In industry and daily life, NaOH is known by many names:
| Name | Context of Use |
|---|---|
| Caustic Soda / Caustic Lye | Common name, emphasizing its strong corrosiveness |
| Caustic Soda Flakes | Solid form, thin flakes, NaOH content ≥ 99% |
| Liquid Caustic Soda | Solution form, common concentrations 20%–50% |
| Caustic Soda | International trade name |
| Sodium Hydroxide | English IUPAC name |
Basic Technical Specifications
| Parameter | Value |
|---|---|
| Chemical Formula | NaOH |
| CAS Number | 1310-73-2 |
| Molecular Weight | 40.00 g/mol |
| HS Code (Customs) | 2815.11.00 (solid) / 2815.12.00 (solution) |
| Density (solid) | 2.13 g/cm³ |
| Melting point | 318°C |
| Boiling point | 1,388°C |
| Solubility in water | 1,110 g/L at 20°C (strongly exothermic) |
NaOH is primarily produced by electrolysis of table salt (NaCl) using membrane cell or diaphragm cell technology—the two most common methods currently used at major chemical plants worldwide. In Vietnam, most NaOH is imported from China, India, Thailand, and Taiwan, and then distributed through companies such as Loc Thien Chemicals.
2. Physical & Chemical Properties
2.1 Physical Properties
- State: Under normal conditions, pure NaOH is a white, odorless crystalline solid. The common commercial forms are thin flakes or small granules.
- Hygroscopicity: NaOH is hygroscopic (extremely moisture-absorbing). When exposed to air, NaOH flakes rapidly absorb water vapor and CO₂, causing the surface to become damp and turn opaque white due to the formation of Na₂CO₃ (soda). This is why solid NaOH must always be stored in sealed, moisture-proof packaging.
- Solubility: Infinitely soluble in water, with a strongly exothermic reaction (ΔH ≈ −44.5 kJ/mol). When solid NaOH is added to water, the solution may boil locally and splatter—never pour water onto solid NaOH; instead, slowly add the NaOH to water while stirring continuously.
- pH: At a concentration of 1 M (~4%), pH ≈ 14 — extremely alkaline, causing skin burns and corroding most amphoteric metals.
2.2 Chemical Properties — Characteristic Reactions
NaOH is a strong base and participates in most of the characteristic reactions of alkali metal hydroxides.
a. Neutralization Reaction with Acids
NaOH reacts with all strong and weak acids to form salts and water:
NaOH + HCl → NaCl + H₂O
2NaOH + H₂SO₄ → Na₂SO₄ + 2H₂O
NaOH + CH₃COOH → CH₃COONa + H₂OThis is the core mechanism when using NaOH to adjust the pH of industrial wastewater — neutralizing excess acid before discharging the wastewater into the environment.
b. Saponification Reaction (Ester Hydrolysis)
NaOH hydrolyzes triglycerides (animal and vegetable oils/fats) into glycerol and sodium salts of fatty acids — which are soap:
(RCOO)₃C₃H₅ + 3NaOH → C₃H₅(OH)₃ + 3RCOONa
Triglyceride Glycerol SoapThis is the fundamental reaction in the soap and detergent manufacturing industry.
c. Reactions with Amphoteric Metals
NaOH reacts with Al, Zn, Sn, and Pb (but does not react with Fe, Cu, or carbon steel under normal conditions):
2Al + 2NaOH + 6H₂O → 2Na[Al(OH)₄] + 3H₂↑
Zn + 2NaOH + 2H₂O → Na₂[Zn(OH)₄] + H₂↑Note: Do not store liquid NaOH in aluminum, tin, or zinc containers.
d. Reaction with CO₂ (carbonation)
When exposed to air, NaOH absorbs CO₂ to form Na₂CO₃:
2NaOH + CO₂ → Na₂CO₃ + H₂OThis is why solid NaOH loses its reactivity when left exposed to air for a long time—it must be stored in an airtight container.
e. Reaction with Nonmetals and Acidic Oxides
2NaOH + Cl₂ → NaCl + NaClO + H₂O (production of bleach)
2NaOH + SiO₂ → Na₂SiO₃ + H₂O (corrosive to glass)
NaOH + Al₂O₃ → 2NaAlO₂ + H₂O (aluminum surface treatment)⚠️ Important Safety Note: NaOH reacts with glass (SiO₂) at high concentrations and high temperatures, forming sodium silicate—do not use glass containers to store concentrated NaOH for extended periods.
3. Commercial Forms & Concentrations
In the Vietnamese market, NaOH is distributed in two main forms: Solid caustic soda (flakes/granules) and Liquid caustic soda (solution).
3.1 Flake Caustic Soda (Solid NaOH)
| Property | Description |
|---|---|
| NaOH Content | 98% – 99.5% |
| State | Thin white flakes, ~3–8 mm in diameter |
| Common Origins | China (Xinjiang, Tianyuan, Dongying), India, Taiwan |
| Packaging | 25 kg bags (2 layers of PE + woven PP), can be packed in 500 kg – 1,000 kg jumbo bags |
| Storage | Store in a dry place, away from moisture; seal tightly after each use |
Advantages: High concentration, easy to transport over long distances, lower cost per kg of NaOH. Disadvantages: Requires on-site mixing, generates significant heat during dissolution, risk of chemical splashes.
3.2 Liquid Caustic Soda (NaOH Solution)
| Concentration (%) | NaOH Content (kg/metric ton) | Typical Applications |
|---|---|---|
| 20% | 200 kg/metric ton | Mild neutralization, CIP cleaning in the food industry |
| 32% | 320 kg/metric ton | Paper industry, textile dyeing |
| 45% | 450 kg/metric ton | Wastewater treatment, chemical production |
| 48% | 480 kg/metric ton | Electroplating, aluminum production |
| 50% | 500 kg/metric ton | Heavy industry, petrochemicals |
Liquid Caustic Soda Shipping Specifications:
- HDPE Plastic Drums: 30 L, 200 L
- IBC Tanks: 1,000 L
- Tanks (ISO Tanks / Tank Containers): For orders of 10 metric tons or more
- Specialized tank trucks: Door-to-door delivery with capacities of 5–20 m³
Advantages: Ready to use, no mixing required, low risk of exothermic reactions. Disadvantages: Higher transportation costs (requires carrying water), and storage requires compatible containers.
4. Major Applications of NaOH
NaOH is one of the five basic chemicals with the highest global consumption (along with H₂SO₄, Cl₂, NH₃, and ethylene). Below are the main application sectors in Vietnam:
4.1 Industrial wastewater treatment
This is the largest application of NaOH in the Vietnamese market:
- pH Adjustment: Wastewater from electroplating plants, textile dyeing facilities, battery manufacturing plants, and food processing plants typically has an acidic pH (2–4). NaOH is added to equalization tanks to raise the pH to a range of 6.5–8.5 before discharge.
- Precipitation of heavy metals: NaOH precipitates metal ions (Fe³⁺, Cu²⁺, Ni²⁺, Cr³⁺, etc.) in the form of insoluble hydroxides:
FeCl₃ + 3NaOH → Fe(OH)₃↓ + 3NaCl
CuSO₄ + 2NaOH → Cu(OH)₂↓ + Na₂SO₄- For centralized wastewater treatment systems, 32%–45% liquid caustic soda is preferred because it is easy to dose using a chemical injection pump.
4.2 Soap & Detergent Production
NaOH is an indispensable saponification agent in the production of bar soap. Tallow, palm oil, and coconut oil are heated with NaOH to form sodium soap (RCOONa). NaOH used in this industry requires high purity (≥ 99%) and low NaCl content.
4.3 Paper & Pulp Industry
NaOH is used in the pulp cooking stage (Kraft process) to dissolve lignin in wood chips and release cellulose fibers. 32% liquid caustic soda is the standard in paper mills, with consumption reaching hundreds of metric tons per month.
- Additionally, NaOH is used for pulp bleaching and recycling waste paper (ink removal).
4.4 Textile and Dyeing Industry
- Cotton Fiber Treatment (Mercerization): Soak cotton fibers in 20%–25% NaOH to increase luster, tensile strength, and dye uptake.
- Adjusting the pH of dyeing baths: Many reactive dyes require an alkaline environment (pH 10.5–11) to fix the color to the fabric.
4.5 Food Industry
NaOH is approved by the FDA and the Vietnamese Ministry of Health for use as an acidity regulator and processing aid in food production, provided it is neutralized or thoroughly rinsed out of the final product:
| Application | Description |
|---|---|
| Soaking olives, fresh bamboo shoots | Removes bitterness and toxins (cyanogenic glycosides in bamboo shoots) |
| Production of noodles, rice vermicelli | Increases chewiness and transparency (NaOH is neutralized after boiling) |
| Fruit peeling | Peeling tomatoes and industrial potatoes |
| CIP (Clean-in-Place) sanitation | Cleaning pipes and tanks in breweries, dairy plants, and soft drink facilities |
| Monosodium glutamate (MSG) production | Adjusting pH during fermentation and purification |
4.6 Electroplating & Metal Surface Treatment
- Degreasing: A 5%–10% NaOH bath at 60°C–80°C to remove grease from metal surfaces before plating.
- Aluminum Surface Etching: NaOH etches the aluminum surface to create a fine, rough texture prior to anodizing.
- Neutralizing Acid Waste: Acid solutions from the rust removal tank (HCl, H₂SO₄) are neutralized with NaOH before discharge.
4.7 Other Applications
| Industry | Specific Applications |
|---|---|
| Petrochemicals | Crude oil refining, removal of sulfur compounds and organic acids |
| Chemical Production | Production of NaOCl (bleach), Na₃PO₄, Na₂SiO₃, Na₂CO₃, and other sodium salts |
| Energy | Electrolyte in alkaline batteries |
| Construction | Anti-freeze additive, concrete surface treatment |
| Pharmaceuticals | Synthesis of pharmaceutical intermediates, pH adjustment |
5. Comparison of Liquid Caustic Soda vs. Caustic Soda Flakes
The choice between liquid caustic soda and caustic soda flakes depends on production scale, storage tank infrastructure, and logistics requirements. Below is a detailed comparison table:
| Criterion | Liquid Caustic Soda (NaOH 32% – 50%) | Caustic Soda Flakes (NaOH 99%) |
|---|---|---|
| NaOH Content | 320–500 kg NaOH per metric ton of product | 990 kg NaOH per metric ton of product |
| Cost (per 1 kg of pure NaOH) | 10–15% higher (due to water transport) | Lower, saving on raw material costs |
| Shipping Costs | High (transported with water), requires tank trucks / IBCs | Lower (25-kg bags are easy to load and unload, shipped in containers) |
| Ease of Use | Ready to use; only requires a metering pump | Must be diluted; requires mixing and cooling equipment |
| Storage | Requires carbon steel or HDPE storage tanks; avoid contact with Al and Zn | Store in a dry, well-ventilated area; keep bags sealed to prevent moisture. Shelf life ~12 months |
| Operational Safety | Low dust, low risk of heat release during mixing. However, leaks are more dangerous due to large volume | Caustic soda dust is corrosive to the skin and respiratory tract; releases intense heat when dissolved |
| Suitable for | Plants with consumption ≥ 5 metric tons/month, equipped with fixed storage tanks and a central wastewater treatment system | Small plants, soap manufacturing facilities, flexible demand |
Selection Recommendations from Loc Thien Chemicals
| Consumption Scale | Recommended Form |
|---|---|
| < 1 metric ton/month | Caustic soda flakes, 25 kg/bag — flexible, easy to store |
| 1 – 5 metric tons/month | 45% liquid caustic soda in 1,000-liter IBCs or combined with caustic soda flakes |
| 5 – 20 metric tons/month | 32% – 50% liquid caustic soda, delivered by tanker truck, with a regular supply contract |
| > 20 metric tons/month | Direct price negotiation, storage tank installation support, delivery via ISO Tank |
6. Guide to Purchasing NaOH at Loc Thien Chemicals
6.1 Order Specifications
| Product | Specifications | Minimum Order Quantity |
|---|---|---|
| 99% NaOH Flakes | 25 kg bags / 500–1,000 kg jumbo bags | 1 bag |
| 32% Liquid Caustic Soda | 200L drums / 1,000L IBCs / Tank Truck | 1 drum |
| 45% – 50% Liquid Caustic Soda | 200L Drum / 1,000L IBC / Tank Truck / ISO Tank | 1 drum |
6.2 Warehouse System — Nationwide Delivery
Loc Thien Chemicals has a warehouse system spanning key industrial regions:
| Warehouse Location | Service Area | Delivery Time |
|---|---|---|
| Ho Chi Minh City (Main Warehouse) | Ho Chi Minh City, Binh Duong, Long An, Tay Ninh | 4–24 hours |
| Ba Ria – Vung Tau | Ba Ria–Vung Tau, Dong Nai (Nhon Trach, Long Thanh) | 24 hours |
| Dong Nai | Bien Hoa, Amata Industrial Park, Bien Hoa Industrial Parks 1 & 2 | 12–24 hours |
| Can Tho | Mekong Delta: Can Tho, Hau Giang, An Giang, Ca Mau | 24–48 hours |
| Da Nang | Central Region: Da Nang, Quang Nam, Quang Ngai, Hue | 24–48 hours |
| Bac Ninh | Northern Region: Bac Ninh, Hanoi, Hung Yen, Bac Giang | 24–48 hours |
6.3 Quotation Policy
- Same-day quotations — via Zalo, email, or by calling the Hotline directly at 0979 891 929
- Prices depend on: NaOH concentration, quantity, delivery warehouse, purchase frequency
- Support for framework agreements for regular customers, with fixed quarterly prices
- Full VAT invoices issued, with CO/CQ (Certificate of Origin / Certificate of Quality) attached to each shipment
6.4 Shipping
| Method | Applies to |
|---|---|
| In-city delivery by light truck (1–5 metric tons) | Individual orders, drums, a few bags |
| Tank truck delivery (5–20 m³) | Liquid caustic soda for wastewater treatment plants, paper mills |
| Container / ISO Tank | Large orders, interprovincial shipments |
| Passenger bus / freight carrier | Small, individual orders to other provinces, express delivery within 24 hours |
7. Frequently Asked Questions (FAQ)
7.1 Is NaOH flammable or explosive?
NaOH itself is non-flammable and non-explosive. However, when solid NaOH dissolves in water, the exothermic reaction can cause the solution to boil and splash the chemical, resulting in burns. Additionally, NaOH reacts with Al, Zn, and Sn to produce hydrogen (H₂)—a gas that is flammable and explosive when accumulated in enclosed spaces.
7.2 Should liquid caustic soda or flake caustic soda be used for wastewater treatment systems?
If the system has a storage tank and a metering pump, 32%–45% liquid caustic soda is the optimal choice: it is easy to dispense, causes minimal pH fluctuations, and requires no mixing. Caustic soda flakes are suitable for small systems, manual operations, or when maximizing raw material cost savings is a priority.
7.3 How long can caustic soda flakes be stored? What are the signs of deterioration?
Under sealed, dry storage conditions, the shelf life is approximately 12 months. Signs of deterioration:
- Flakes change from pure white to cloudy white and become damp
- Clumping and leaching occur
- Reduced effectiveness when diluted (NaOH has absorbed CO₂ to form Na₂CO₃)
7.4 Can NaOH be used in food?
Yes, but it must be Food Grade NaOH (compliant with the FCC — Food Chemicals Codex) and may only be used as a processing aid; it must be thoroughly rinsed or neutralized out of the final product. Standard industrial-grade NaOH is not permitted for use in food.
7.5 Does Loc Thien Chemicals offer weekend delivery?
Yes. Loc Thien Chemicals offers delivery on both Saturdays and Sundays for urgent orders in Ho Chi Minh City and neighboring provinces. Please place your order before 3:00 PM to arrange for same-day delivery.
8. Conclusion
NaOH — Sodium Hydroxide — is an indispensable alkaline chemical in modern industrial production chains. From wastewater treatment, soap production, paper manufacturing, and textile dyeing to food processing and electroplating, each industry has its own specific requirements regarding the form and concentration of NaOH. Choosing the right type of NaOH—99% flake caustic soda or 32%–50% liquid caustic soda—not only optimizes operating costs but also ensures workplace safety and compliance with environmental standards.
Loc Thien Chemicals is proud to be a trusted partner of hundreds of factories and industrial parks nationwide, with a network of six warehouses stretching from Bac Ninh to Can Tho, committed to:
- Genuine products with complete CO/CQ certificates
- Competitive pricing with same-day quotes
- Fast delivery — within 4 hours in Ho Chi Minh City, 24–48 hours to other provinces
- Free technical support: consultation on concentration selection, NaOH dosing system design, and safety guidelines
📞 Contact us now to get a NaOH quote today:
🏭 Loc Thien Chemicals — Specializing in industrial chemicals, wastewater treatment, and basic chemicals
📱 Hotline/Zalo: 0979 891 929
📍 Main Warehouses: Ho Chi Minh City | Ba Ria – Vung Tau | Dong Nai | Da Nang | Can Tho | Bac Ninh
🌐 Website: hoachatlocthien.com
Competitive pricing — Nationwide delivery — 24/7 technical support