Industrial NaOH Production Process: Electrolysis, Membranes and Applications
|---|---|---| | Principle | Selective Na⁺ membrane | Physical porous barrier | Chemical reaction | | Output NaOH concentration | 30-35% | 10-12% | <10% | | Purity of 50% NaOH | Very high, NaCl <50 ppm | Medium, NaCl ~1% | Low, high carbonate | | Power consumption (kWh/ton NaOH) | ~2,100-2,500 | ~2,500-3,000 | No electricity | | Capital investment | Highest | Medium | Lowest | | Brine input requirements | Ultra-pure | Basic treatment | Not applicable | | Current status | Industry standard | Some legacy plants | Historical only |
50% NaOH Production Process — Step by Step
50% NaOH is the primary commercial form for bulk tanker transport and industrial consumption. The production process from raw materials to final product involves these steps:
Step 1: Brine treatment. Industrial salt (NaCl ≥ 97%) is dissolved into saturated solution ~300 g/L. The solution undergoes filtration and ion exchange to remove Ca²⁺, Mg²⁺, Fe³⁺ and heavy metal impurities — particularly stringent requirements for membrane technology.
Step 2: Electrolysis. Purified NaCl solution is fed into electrolysis cells. Direct current (DC) splits NaCl into NaOH at the cathode, Cl₂ at the anode, and releases H₂. Cell operating temperature is typically maintained at 80-90°C.
Step 3: Byproduct processing. Cl₂ from the anode is dried, compressed and liquefied for commercial sale or used as raw material for NaOCl, HCl, PVC production. H₂ is recovered as fuel or feedstock for hydrogen peroxide, ammonia.
Step 4: NaOH concentration. 30-35% NaOH solution from the cathode undergoes multi-effect vacuum evaporation to reach 50% concentration. For diaphragm technology, this step includes NaCl crystallization separation via centrifugation or filtration.
Step 5: Cooling and storage. 50% NaOH is cooled to 40-50°C before pumping into FRP (Fiberglass Reinforced Plastic) or carbon steel tanks — must maintain temperature above 12°C to prevent NaOH crystallization.
Step 6: Quality control and shipping. Each production batch is sampled for NaOH content, NaCl, Na₂CO₃, Fe according to TCVN or ASTM standards. Loc Thien provides COA per batch for factory customers. 50% NaOH is shipped via specialized tankers to industrial zones.
NaOH Applications in Manufacturing Processes
NaOH itself serves as a key input chemical for other production processes within industrial clusters:
- NaOCl (Bleach) production: Chlorine gas (from the same electrolysis process) is bubbled into NaOH solution to produce NaOCl — a disinfectant for water treatment and wastewater.
- Na₃PO₄ (Trisodium Phosphate) production: NaOH reacts with H₃PO₄ to form TSP — an industrial cleaner and food additive.
- PAC (Poly Aluminium Chloride) production: NaOH adjusts alkalinity during PAC synthesis from Al(OH)₃ and HCl.
- Acid waste neutralization: Electroplating and steel plants use 32-50% NaOH to neutralize acid waste before discharge into centralized wastewater treatment systems.
Industrial NaOH Quality Standards
Industrial NaOH quality is evaluated through key parameters per TCVN and manufacturer standards:
| Parameter | 32% NaOH | 50% NaOH | Test Method |
|---|---|---|---|
| NaOH content (% by weight) | 32.0 ± 0.5 | 50.0 ± 0.5 | Acid-base titration |
| NaCl (% max) | 0.01 - 0.05 | 0.01 - 0.05 | Mohr titration |
| Na₂CO₃ (% max) | 0.1 - 0.3 | 0.2 - 0.5 | Dual-indicator titration |
| Fe (ppm max) | 5 - 10 | 5 - 10 | AAS / ICP-OES |
| Density at 20°C | 1.348 | 1.52 | Hydrometer |
For stringent applications (pharmaceuticals, food, artificial fibers), NaOH must meet heavy metal (Hg, As, Pb) thresholds below specified limits. Each Loc Thien shipment includes COA and MSDS — factory engineers can directly compare with internal standards before production use.
Loc Thien — Nationwide Industrial NaOH Supplier
- 6-warehouse network: 32% and 50% NaOH available in Binh Duong, Dong Nai, Long An, Hai Phong, Bac Ninh warehouses — reducing delivery time to under 24h for most key industrial zones.
- 20 specialized tanker fleet: Stainless steel/FRP tanks ensure safe NaOH liquid transport compliant with dangerous goods regulations.
- Batch-specific COA/MSDS: Complete test documentation with each shipment, supporting QA/QC engineers in standard verification.
- Free technical consultation: Supports dosage calculation, storage system design, and NaOH dosing systems for wastewater treatment, boilers, production lines.
Frequently Asked Questions
32% vs 50% liquid NaOH — which to choose for factories?
50% NaOH saves transportation cost per ton of pure NaOH and requires less storage volume. However, 50% NaOH crystallizes below 12°C, needing heated or insulated tanks. Northern factories often choose 32% to avoid winter crystallization risks. Consult Loc Thien engineers to select the optimal type for your operating conditions.
What’s the difference between membrane and diaphragm-produced NaOH?
Membrane NaOH has <50 ppm residual NaCl, while diaphragm product contains ~1% NaCl. For most industrial applications (water treatment, paper, textiles), both meet requirements. Special applications like viscose fiber or high-purity chemical synthesis require membrane NaOH.
Why must 50% NaOH be kept warm during storage?
50% NaOH has a crystallization point around 12°C. Below this temperature, NaOH begins forming solid hydrates that clog pipes, pumps and valves. Storage tanks need insulation or steam/electric heating systems to maintain 20-30°C, especially in northern plants from November to March.
Can 50% NaOH be diluted to 32% at the factory?
Yes. Mixing 100 kg 50% NaOH with 56.25 kg clean water yields 156.25 kg 32% NaOH. Dilution is strongly exothermic — always add NaOH to water (never reverse), stir continuously, and use heat-resistant containers. If your plant has mixing systems, purchasing 50% NaOH saves transportation costs.
Where does Loc Thien deliver NaOH?
Loc Thien delivers 32% and 50% NaOH to all industrial zones in Binh Duong, Dong Nai, Ho Chi Minh City, Long An, Ba Ria-Vung Tau, Hai Phong, Bac Ninh, Hung Yen. Our 20-tanker fleet ensures 24h delivery for local orders and scheduled weekly deliveries for northern factories.
Request 32% & 50% NaOH Quotes
Hotline: 0979 891 929 — quotes within 15 minutes, including sample COA and estimated delivery schedule.
Liquid NaOH pricing is quoted in VND/kg or VND/ton based on your plant’s monthly volume. Submit requests via hotline or email — Loc Thien engineers will recommend the optimal NaOH type and delivery method for your production needs.
LOC THIEN CHEMICAL INVESTMENT & DEVELOPMENT CO., LTD Address: Lot B1-4, Street 3, Tan Dong Hiep B Industrial Park, Di An, Binh Duong Phone: 0979 891 929 Website: hoachatlocthien.com