| HS Code | 795053 |
| Chemical Name | Sodium Hydroxide |
| Chemical Formula | NaOH |
| Cas Number | 1310-73-2 |
| Molecular Weight | 40.00 g/mol |
| Appearance | White solid flakes or pellets |
| Purity | 98-99% |
| Density | 2.13 g/cm³ |
| Melting Point | 318 °C |
| Boiling Point | 1388 °C |
| Solubility | Soluble in water, ethanol, methanol; exothermic |
| Ph 1 Solution | Approximately 13 |
| Packaging Size | 5 kg |
| Hazard Classification | Corrosive; causes severe skin burns and eye damage |
As an accredited Caustic Soda 5KG factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Packaged in a sturdy, resealable plastic bucket containing 5 kg of caustic soda beads, with safety labeling and tamper-evident seal. |
| Container Loading (20′ FCL) | Description: 20′ FCL loading of Caustic Soda 5kg bags, palletized, shrink-wrapped, with proper hazard segregation and secure bracing for safe transit. |
| Shipping | Caustic Soda 5KG ships as a hazardous material (Class 8 corrosive) via ground transport only. It is securely packaged in UN-approved containers with clear corrosion warnings. Handle with care, avoid moisture, and keep upright. Professional carriers require proper labeling, documentation, and trained personnel for safe delivery. |
| Storage | Store Caustic Soda 5KG in a cool, dry, well-ventilated area in its original, tightly sealed, corrosion-resistant container. Keep away from moisture, acids, and incompatible chemicals. Place on spill trays, off the floor, and ensure the area is clearly labelled and accessible to trained personnel only. |
| Shelf Life | Shelf Life: 2 years from manufacture date when stored unopened in original container in a cool, dry environment. |
In bauxite digestibility screening, a 5 kg sodium hydroxide charge is used to prepare synthetic Bayer liquor at total alkali concentrations from 150 g/L to 300 g/L as Na2O, depending on whether the feed is gibbsite, boehmite, or diaspore. A weighed mass of solid sodium hydroxide is dissolved in deionized water under cooling to avoid flash boiling from the exothermic heat of solution. The liquor is then charged to a 2 L to 5 L nickel 200 or Monel 400 autoclave containing the test bauxite at a liquor-to-ore mass ratio of 3:1 to 10:1, with the ratio adjusted for reactive silica and alumina grade. The sealed vessel is heated to 190°C to 250°C and held for 10 min to 90 min. During the run, filtrate samples are withdrawn for aluminium and caustic analysis, and digestion efficiency is calculated as the mass of Al2O3 extracted per mass of digestible feed after correcting for soda losses to sodium aluminosilicate desilication products. The terminal product is smelter-grade alumina or chemical-grade alumina trihydrate for calcination. Raw ingredient quality is controlled by ASTM E291-20, which specifies methods for total alkalinity, carbonate, sulfate, iron, and insoluble matter. Carbon steel and 304 stainless steel require stress relief and may be unsuitable for welded autoclave components at these caustic concentrations and temperatures because caustic stress corrosion cracking can propagate from residual stress zones. Published data for smaller autoclave configurations remains limited; therefore, liquor-to-ore ratio and holding time are preferably validated against plant-specific refinery circuits before scale-up.
White liquor preparation begins with dissolution of 5 kg sodium hydroxide in water together with sodium sulfide to reach an effective alkali charge of 14% to 20% Na2O on oven-dry wood and a sulfidity of 25% to 35%. In a 4 L Parr reactor fabricated from 316L stainless steel or nickel alloy, the liquor is mixed with chip or milled fibre at a liquor-to-wood ratio of 3.5:1 to 5:1 and heated to 165°C to 175°C. Delignification is controlled by the H-factor, an integrated time-temperature parameter. Typical softwood trials run to a target H-factor of 1,400 to 1,800 until the required Kappa number is reached. Residual alkali in black liquor is titrated to determine alkali consumption. Finished brownstock pulp is washed and evaluated for reject content and drainage on a laboratory flat screen. The terminal products are unbleached kraft pulp, linerboard, sack paper, or dissolving-grade pre-hydrolysis kraft pulp after subsequent bleaching. Fibre Kappa number is measured according to TAPPI T 236 cm-99, and the raw sodium hydroxide is checked by ASTM E291-20 for sodium carbonate and heavy metals. If the sodium hydroxide has absorbed atmospheric CO2, white liquor active alkali is depressed. The charge must then be corrected to prevent undercooking and elevated reject content. Mixing of concentrated sodium hydroxide with sodium sulfide should be completed under fume extraction because hydrogen sulfide can be generated if the solution pH is reduced.
On dairy and beverage processing lines, 5 kg of food-grade sodium hydroxide is typically diluted to 1.0% to 1.5% w/v with potable water at 75°C to 80°C. The solution is recirculated through plate heat exchangers, stainless steel tubing, and balance tanks at a flow velocity of 1.5 m/s to 2.5 m/s. The alkaline cleaning fluid hydrolyzes protein films, saponifies fats and oils, and loosens mineral-organic deposits. The cleaning cycle is normally sequenced as a pre-rinse, alkaline circulation, post-rinse, and acid wash, followed by sanitization. Contact time can be 15 min to 30 min depending on soil load and line design. The terminal output is not a physical product but a sanitized internal surface ready for pasteurized milk, whey concentrate, UHT desserts, or liquid dairy intermediate production. For food-contact use in the United States, sodium hydroxide is covered by FDA 21 CFR 184.1763 as a direct food substance and FDA 21 CFR 178.1010 for sanitizing solutions used on stainless steel food-handling equipment. Operational limits include avoiding chlorinated alkaline products in 316L systems above 85°C because chloride-induced pitting can initiate. Caustic exposure on stressed 304 welded areas should also be minimized because caustic embrittlement may occur. Aluminium, zinc, galvanized steel, and tin are excluded from CIP circuits cleaned with hot sodium hydroxide.
A 0.1 N sodium hydroxide solution is prepared on a pure NaOH basis by dissolving 4.0 g of the material per litre of deionized water. A 5 kg container therefore yields 1,250 L of standard neutralizing reagent. The solution is injected by a diaphragm metering pump into a pipe with a static mixer upstream of a pH analyser. The control loop trims finished water pH to a setpoint typically between 7.4 and 8.0 for distribution stability and lead/copper corrosion control. Raw material compliance is assessed by ANSI/AWWA B501-19, and resulting water alkalinity is verified by titration according to ISO 9963-1:2011. Dilution with hard water must be avoided because calcium and magnesium carbonates precipitate. Tanks and piping should be constructed of 316L stainless steel or compatible polymer such as high-density polyethylene. Aluminium, zinc, galvanized steel, and tin are excluded.
Caustic soda peeling of potatoes, tomatoes, peaches, and root vegetables is carried out with a 5 kg sodium hydroxide charge dissolved to 6% to 20% w/v sodium hydroxide and maintained at 60°C to 95°C in a stainless steel immersion bath or spray peeling tunnel. The hot alkali hydrolyzes pectic substances and cuticle waxes, loosening the skin. Immersion time is usually 30 sec to 3 min depending on cultivar, maturity, and peel thickness. Spray lye peeling can use higher concentrations and shorter residence times. After peeling, the product is subjected to high-pressure potable water rinsing and a dilute citric acid neutralization dip to remove residual alkali and prevent softening. Finished products include canned diced tomatoes, aseptic fruit segments, frozen French fries, and pre-cut root vegetable pieces. Under FDA 21 CFR 184.1763, sodium hydroxide is permitted in food processing when used in accordance with current good manufacturing practice and residual levels are reduced by rinsing. No chemically defined maximum residual exists but monitoring of final surface pH is standard. The main equipment risk is caustic stress corrosion cracking in welded 304 stainless steel at high temperature; 316L with smooth welds is specified for continuous immersion. Aluminium and galvanized steel must not be used in contact with the peeling solution due to aggressive hydrogen evolution.
Before transesterification pilot batches are charged, 5 kg sodium hydroxide is dissolved in dry methanol to a concentration of 9% to 12% w/v, forming sodium methoxide in situ. This exothermic dissolution must be conducted in a closed 316L steel vessel with venting and temperature control below the methanol boiling point. The resulting catalyst solution is dosed into low-acid feedstock at 0.3% to 0.5% by weight of oil on a pure sodium hydroxide basis, with a methanol-to-oil molar ratio of approximately 6:1 and a reaction temperature of 55°C to 65°C for 1 h to 2 h. High free fatty acid oils are not directly compatible because soap formation consumes catalyst and reduces methyl ester yield. Feedstock acid value should be below 2 mg KOH/g unless a two-step acid esterification precedes the alkaline step. Water content in the oil must be below 0.1% w/w because water promotes saponification and creates emulsions. The finished product is fatty acid methyl ester meeting ASTM D6751 for B100 biodiesel, with glycerin phase separation accelerated by gravity settling after reaction. Raw sodium hydroxide should have low sodium carbonate content because atmospheric exposure converts the hydroxide to carbonate, reducing catalyst solubility in methanol. ASTM E291-20 analysis provides carbonate content. Acidulation of the glycerin phase and methanol recovery are downstream unit operations outside the direct caustic soda application.
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The product designated Caustic Soda 5KG is a 5 kg net-weight package of anhydrous sodium hydroxide, NaOH, CAS 1310-73-2, UN1823, Class 8, Packing Group II. The solid is supplied as white deliquescent flakes or pearls with a solid density of 2.13 g/cm³, a molar mass of 39.997 g/mol, and a melting point of 318 °C under anhydrous conditions. The package model refers to net weight and granulation rather than to a fixed chemical grade; technical, food, and analytical grades must be specified separately by certificate of analysis. The 5 kg HDPE pail uses an induction-sealed lid and is intended for pilot-scale dosing, small cleaning-in-place skids, and make-up alkali addition where full-drum quantities are excessive.
Certified compositional limits are established by acidimetric titration and gravimetric methods rather than by package size. ASTM E291-18 is the primary analytical procedure for total alkalinity, carbonate, chloride, sulfate, and iron in solid caustic soda. When the material is used for drinking-water treatment, EN 896 and ANSI/AWWA B501-19 are additional compliance references. Direct food use is subject to 21 CFR 184.1763 GRAS conditions. The values below are representative acceptance limits for technical-grade solid caustic soda and must be confirmed against the supplier certificate of analysis.
| Parameter | Method | Representative solid grade |
|---|---|---|
| Total alkalinity as NaOH | ASTM E291-18 | ≥ 98.0% w/w |
| Sodium carbonate as Na2CO3 | ASTM E291-18 | ≤ 0.8% w/w |
| Sodium chloride as NaCl | ASTM E291-18 | ≤ 0.1% w/w |
| Iron as Fe | ASTM E291-18 | ≤ 10 ppm |
| Heavy metals as Pb | Food Chemicals Codex monograph | ≤ 20 ppm |
| Water-insoluble matter | Gravimetric | ≤ 0.05% w/w |
When a 5 kg charge is added to water, the process is exothermic; the differential heat of solution at infinite dilution is approximately -44.5 kJ/mol. A 5 kg charge contains 125 mol NaOH, so adiabatic dissolution in 50 L of water would release roughly 5.56 MJ and raise the bulk temperature by approximately 26 °C, assuming pure water and no heat loss. The solid should be added to water, never water to solid, and the water-to-solid mass ratio should be maintained at or above 4:1 in unjacketed HDPE tanks. Solubility at 20 °C is 109 g NaOH per 100 g water, equivalent to approximately 52 wt% NaOH. In a production mix tank, the limiting factor is often the dissolution front rather than final solubility: a stagnant layer of solid flakes can form a carbonate crust in contact with atmospheric CO₂, so the mixer should be activated before addition and the tank lid kept closed when possible. Batch logs from plant-scale make-up vessels indicate that pearl granulation dissolves faster than large flake material; a mixed flake-pearl 5 kg package should not be assigned a fixed dissolution time until the granulation is known.
In cleaning-in-place systems, the 5 kg package is used to prepare 2.0–5.0 wt% NaOH solution at 70–85 °C. A single 5 kg charge is sufficient for 100 L of 5% caustic solution, although actual circuit volume includes return tanks and spray pipe holdup. The critical process parameters are flow velocity, temperature, and contact time. A centrifugal pump delivering 1.5–2.5 m/s linear velocity through 51 mm sanitary tubing is common for dairy and brewery circuits; velocities below 1.0 m/s risk deposit adhesion in dead legs and reduced wall shear. Caustic soda saponifies fats and hydrolyzes protein, but it does not remove mineral scale; acid cleaning with nitric or phosphoric acid must follow in a separate step. Aluminum and zinc fittings must be isolated because caustic solutions corrode them and generate hydrogen. The process window is narrower for elastomer gaskets: EPDM and PTFE are preferred, whereas natural rubber and polyurethane can swell or degrade at 80 °C and high pH.
In soap kettles and oleochemical saponification, the 5 kg pail is more commonly used for alkali correction than for full-batch saponification. The alkali requirement is calculated from the saponification value: mass NaOH in milligrams per gram of oil equals saponification value × 39.997 / 56.105. For an oil with saponification value 190 mg KOH/g, 1 kg oil requires 135.5 g NaOH. A 5 kg charge therefore saponifies approximately 36.9 kg of that oil. The main process conflict is not total alkali but localized excess: adding flakes too quickly to a hot oil-water mixture can create high local pH, causing soap curd and retarding phase separation. The addition is therefore controlled over several minutes with the agitator running. The vessel is vented because the neutralization of free fatty acids and saponification generate heat. Published data for specific fat blends is limited, so pilot trials are used to define the addition time for a given fat charge.
The difference among alkalis is best expressed as equivalents per kilogram. Sodium hydroxide supplies 25.0 eq/kg, potassium hydroxide 17.8 eq/kg, anhydrous sodium carbonate 18.9 eq/kg, and hydrated lime 27.0 eq/kg on a dry basis. However, hydrated lime has a solubility of only 0.173 g/100 g water at 20 °C, which limits its saturated pH to about 12.4 and makes it unsuitable for concentrated alkaline duty. Caustic potash is selected when potassium content is required, such as potassium soaps and certain drilling fluids, but it is less efficient per unit mass for neutralization. Soda ash is preferred where lower pH and carbonate buffering are needed; a 0.1 M solution of Na₂CO₃ has a pH near 11.4, whereas 0.1 M NaOH has a pH near 13.0. Compared with 50% liquid caustic soda, the 5 kg solid eliminates water freight but reintroduces exothermic mixing and dust control on site.
| Alkali | Molar mass (g/mol) | Alkali equivalents (eq/kg) | Solubility in water at 20 °C (g/100 g water) | pH of 0.1 M solution |
|---|---|---|---|---|
| Sodium hydroxide | 39.997 | 25.0 | 109 | 13.0 |
| Potassium hydroxide | 56.105 | 17.8 | 112 | 13.0 |
| Sodium carbonate | 105.988 | 18.9 | 21.5 | 11.4 |
| Calcium hydroxide | 74.093 | 27.0 | 0.173 | 12.4 saturated |
For acid-neutralization duty, the 5 kg NaOH package has 40% more equivalents than 5 kg KOH and 32% more equivalents than 5 kg Na₂CO₃. It does not, however, provide the buffering action of carbonate or the potassium cation function. Selection is therefore governed by downstream species requirements: sodium is generally acceptable in many industrial neutralization circuits, but potassium may be required in specialized formulations where sodium accumulation is undesirable.
In small demineralizer and deionization units, the 5 kg solid is used to prepare 4.0–8.0 wt% caustic solution for strong-base anion resin regeneration. The caustic brine is introduced at a typical rate of 2–4 bed volumes per hour for 45–90 minutes, followed by slow displacement rinse. The low chloride and low iron profile of the solid grade is relevant because chloride competes with sulfate during regeneration and iron can form insoluble hydroxide precipitates in resin voids, increasing pressure drop and reducing run length. Potable-water applications require compliance with EN 896 or ANSI/AWWA B501-19; the package label should bear the applicable certification mark when required by the local authority. For food-contact and food-processing use, the 21 CFR 184.1763 GRAS condition requires that the package be food grade and supported by lot traceability.
Store in a cool, dry, well-ventilated area with relative humidity below 60% and ambient temperature below 40 °C. Sodium hydroxide is deliquescent and reacts with atmospheric carbon dioxide to form sodium carbonate surface crust. Incompatible materials include strong acids, aluminum, zinc, tin, brass, nitromethane, acetaldehyde, maleic anhydride, and chlorinated solvents. The 5 kg HDPE pail is acceptable for normal storage but should be kept closed; prolonged UV exposure degrades the pail polymer. Transfer operations should use chemical-resistant gloves conforming to EN 374, eye protection conforming to EN 166, and local exhaust ventilation. If solid is spilled, collect it dry and avoid water flushing into drains because the heat of solution can cause localized boiling and splattering. Transport documentation must identify the material as UN1823, SODIUM HYDROXIDE, SOLID, Class 8, Packing Group II, with the CORROSIVE label. The 5 kg size may be subject to limited quantity packaging provisions under ADR, RID, or IMDG for Class 8 solids; the shipper must verify the current modal packaging instruction and outer package limits.
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