| HS Code | 149801 |
| Product Name | Caustic Soda 20KG |
| Chemical Name | Sodium Hydroxide |
| Chemical Formula | NaOH |
| Cas Number | 1310-73-2 |
| Molecular Weight | 40.00 g/mol |
| Purity | 98-99% |
| Physical State | White solid (pearls/flakes/prills) |
| Packaging Size | 20 kg bag |
| Melting Point | 318 °C (604 °F) |
| Boiling Point | 1,388 °C (2,530 °F) |
| Density | 2.13 g/cm³ at 25 °C |
| Solubility In Water | 1110 g/L at 20 °C |
| Ph Of 1 Percent Solution | 13 |
| Storage Temperature | Store in a cool, dry, well-ventilated area below 25 °C |
| Shelf Life | 24 months from manufacturing date |
| Hazard Class | Corrosive (Class 8) |
As an accredited Caustic Soda 20KG factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Caustic soda 20KG supplied in 20 kg quantities, packed in durable woven polypropylene bags with moisture-proof inner liners. |
| Container Loading (20′ FCL) | Loading 20-foot FCL with 20kg caustic soda bags, ensuring secure palletization, proper ventilation, and safe segregation for transport. |
| Shipping | Caustic Soda 20KG ships in sealed, corrosion-resistant bags or drums, properly labeled as hazardous material. Ensure upright, dry storage away from moisture and incompatible substances. Use gloves, goggles, and protective clothing when handling. Transport via licensed carriers following local dangerous goods regulations to prevent leaks or spills. |
| Storage | Store Caustic Soda 20KG in a cool, dry, well-ventilated area, away from moisture, acids, and incompatible materials. Keep containers tightly sealed to prevent absorption of atmospheric moisture. Use corrosion-resistant secondary containment to manage spills. Ensure clear labeling and restrict access to trained personnel equipped with appropriate PPE. |
| Shelf Life | Shelf life is indefinite if stored sealed and dry; avoid moisture and air to prevent caking. |
In alumina refineries operating with gibbsitic or boehmitic bauxite feedstocks, solid caustic soda from 20 kg resealable packages is introduced into the recirculating spent liquor loop to maintain digestion Na₂O concentrations in the range of 180 g/L to 260 g/L for gibbsite extraction at 145 °C to 155 °C, and 240 g/L to 300 g/L for boehmitic and diasporic ores where tube digesters operate above 240 °C.
| Bauxite type | Digestion temperature | Na₂O concentration | Primary caustic loss driver |
|---|---|---|---|
| Gibbsitic | 145–155 °C | 180–260 g/L | Sodalite/cancrinite precipitation from reactive silica |
| Boehmitic | 220–270 °C | 240–300 g/L | Evaporation load and heat exchanger scale |
| Diasporic | 250–270 °C | 260–300 g/L | High-liquor corrosivity and titanium dissolution |
The downstream process route comprises bauxite grinding, predesilication, high-pressure digestion, red mud separation in high-rate thickeners, pregnant liquor filtration, seeded alumina trihydrate precipitation, and rotary or fluid-bed calcination. Caustic addition ratio is not fixed at a single value; it is derived from the alumina-to-caustic ratio, ball-mill charge alkalinity, and reactive silica content. A typical consumption range of 60–140 kg NaOH per tonne of smelter-grade alumina is observed across plants, with lower values for low-reactive-silica gibbsite ores and higher values for boehmitic feeds. Regulatory compliance for EU-bound product requires REACH (EC) No 1907/2006 Article 31 SDS transmission and CLP (EC) No 1272/2008 Table 3.1 classification as Skin Corr. 1A H314; U.S. facilities follow OSHA 29 CFR 1910.1200 for hazard communication and ANSI/ISEA Z358.1-2014 for emergency shower and eyewash placement. Terminal products include smelter-grade alumina, chemical-grade alumina, aluminium hydroxide filter cake, and zeolite precursor feed. Operational boundary: sodium carbonate surface film forms in opened 20 kg bags exposed to humid air; when carbonated solid is added to digester liquor, batch alkalinity measured by thermometric titration can deviate from target unless the package is resealed and stored below 60% relative humidity.
Two-stage oxygen delignification in softwood kraft fibre lines consumes sodium hydroxide as an alkali buffer to maintain carboxylate ionisation and to neutralise organic acids released during oxidative lignin cleavage. For Scandinavian softwood pulp with a kappa number entering at 28–32, the oxygen stage addition ratio is typically 1.5 wt% to 3.0 wt% NaOH on oven-dry pulp at 10%–12% consistency, 85 °C to 100 °C, and 400–800 kPa oxygen partial pressure measured at the reactor headspace. The downstream production sequence places the oxygen reactor between a two-stage brownstock washer and a post-oxygen wash press; medium-consistency feed is dispersed through a high-shear mixer and then reacts in a pressurised upflow/downflow tower for 45–70 minutes. Sodium hydroxide from 20 kg bags is dissolved in recovered condensate to 5–10% w/v before injection into the medium-consistency pump suction to avoid localised overcooking and fibre damage. Extraction stages in elemental chlorine-free bleaching add 0.8–2.0 wt% NaOH on pulp to maintain a final extraction pH of 10.5–11.5, preventing re-adsorption of dissolved lignin onto fibre surfaces. EU mill permits operate under the BAT Conclusions for pulp, paper and board under Commission Implementing Decision 2014/687/EU, with kappa number tested according to ISO 302:2004 and effluent COD monitored by ISO 6060. Terminal product types include bleached softwood kraft pulp, bleached hardwood kraft pulp, dissolving-grade pulp, and coated board furnish. The main operational limitation is post-oxygen carry-over of sodium and dissolved lignin into the washing stage; washed pulp entering the D₀ stage with a pH above 9.0 buffers chlorine dioxide and shifts brightening chemistry toward chlorate formation.
In full-boiled batch saponification using palm, coconut, or tallow charges, the caustic soda addition ratio is calculated from the saponification value of the oil fraction and the free fatty acid titre. For a coconut oil with a saponification value of 250–264 mg KOH/g, the stoichiometric sodium hydroxide charge is 0.713 × SV kilograms NaOH per metric ton of neutral oil, equivalent to roughly 178–188 kg NaOH per tonne; process excess is maintained at 0.05 wt% to 0.30 wt% free caustic alkali in the neat soap to prevent residual unreacted triglycerides from producing soft, rancidity-prone soap. Production equipment includes jacketed crutchers, continuous saponification reactors with high-shear recirculation loops, and vacuum spray dryers. The 20 kg solid package is pre-dissolved to 25%–35% w/v in process water before addition because direct flakes can create localised caustic-rich zones that trigger hard-grained soap formation in the crutcher. Finished soap is washed or neutralised with citric acid or stearic acid to adjust free alkali; soap noodles are then air-dried, mixed with chelating agents and antioxidants, and plodded into bars. Compliance parameters include ASTM D460-91(2014) for total alkali and moisture, ISO 684 for free caustic alkali, and EU Detergent Regulation (EC) No 648/2004 labelling for sodium hydroxide content in industrial cleaning products. Terminal product types cover laundry bar soap, toilet soap noodles, castile liquid soap base, and industrial wire-drawing lubricant soap. The most common batch failure is free alkali drift during the finishing stage; if free alkali exceeds 0.5 wt%, the soap becomes skin-irritant and fails the ASTM D460 ethanol-soluble alkali specification.
For Spanish-style green olive processing, food-grade sodium hydroxide from 20 kg packages is dissolved into potable water to prepare lye baths of 2.0% to 4.5% w/v depending on olive variety, fruit ripeness, and solution temperature; the addition ratio is monitored by titratable free alkali rather than weight alone because oleuropein buffering and dissolved phenolics reduce effective hydroxide activity during penetration. The downstream lye treatment stage is a temperature-controlled immersion process at 15–25 °C for 6–14 hours, with lye penetration checked at two-thirds depth of the mesocarp; the olives are then water-washed in at least three counter-current rinses to remove sodium oleuropeinate and excess hydroxide before anaerobic brine fermentation at 8–10% NaCl with final pH 4.2–4.6. Lye peeling of root vegetables and stone fruit used in canning operations applies 1.5%–10% w/v sodium hydroxide at 60–95 °C for residence times of 30 seconds to 3 minutes, followed by steam peeling and acid neutralisation with citric or malic acid. Food-grade compliance is governed by FDA 21 CFR 184.1763 GRAS conditions, the Food Chemicals Codex 12th edition sodium hydroxide monograph, and in the EU by Regulation (EC) No 1333/2008 and Regulation (EC) No 2023/2006 on good manufacturing practice for food contact materials. Terminal product types include debittered green table olives, lye-peeled canned peaches, peeled tomato dice, and alkali-treated cocoa mass. Operational boundary: carbon dioxide ingress into opened food-grade bags forms sodium carbonate surface films that reduce free hydroxide activity and may produce uneven olive penetration; storage below 50% relative humidity and immediate resealing are mandatory.
Chlorine absorption into sodium hydroxide solution follows a mass-controlled absorption regime where reaction selectivity to sodium hypochlorite depends on maintaining a pH above 10.0 and a temperature below 20 °C. In a continuous eductor-driven reactor, 20 kg caustic soda is first dissolved to 15–20% w/v using softened water; chlorine gas is drawn into the recirculation loop at controlled partial pressure to produce a final product with 12–15% w/v available chlorine and 0.3–1.0 wt% free sodium hydroxide excess.
| Parameter | Control window | Effect on product |
|---|---|---|
| Reactor pH | 10.5–12.5 | Prevents chlorate formation and chlorine off-gas |
| Liquor temperature | 15–20 °C | Suppresses autocatalytic hypochlorite decomposition |
| Free NaOH excess | 0.3–1.0 wt% | Stabilises available chlorine during storage |
| Dissolved iron | <0.5 mg/L | Prevents catalytic decomposition of sodium hypochlorite |
The downstream process consists of a packed absorption column or eductor contactor, a plate-and-frame cooler, a sealed hypochlorite storage tank, and a vent scrubber. Caustic addition ratio is stoichiometrically 1.128 kg NaOH per kg chlorine gas, with excess alkali controlled by continuous pH compensation. Compliance references include EN 901:2013 for sodium hypochlorite used in drinking water treatment, REACH (EC) No 1907/2006 Article 31, and CLP (EC) No 1272/2008 Skin Corr. 1A H314 for the packaged solid. Terminal product types include household bleach, industrial disinfection solutions, water treatment sodium hypochlorite, and swimming pool chlorinating liquid. The critical operating boundary is pH depression below 10.0; this sharply increases chlorate formation and releases chlorine gas, while temperatures above 25 °C accelerate hypochlorite autocatalytic decomposition at a rate roughly doubling per 10 °C increase.
Mercerising of 100% cotton knitted or woven fabric requires uniform sodium hydroxide penetration into the cellulose lattice at concentrations of 20%–24% w/v under lengthwise tension for yarn-dimensional stability and dye yield improvement; slack mercerising of tubular knit cloth may operate at 25%–30% w/v to achieve controlled shrinkage and lustre. The 20 kg solid package is metered into the recycle loop of a mercerising range to replenish caustic lost to wash water and neutralisation, with fresh bath strength verified by density meter or refractometer against a calibration chart. Downstream processing consists of singeing, desizing, scouring, mercerising, stretching while wet, washing under tension in sequential compartments, and final souring with acetic acid to pH 5–6. The recovered weak lye is concentrated in an evaporator and reused; a typical loss of 8–15 kg NaOH per tonne of fabric is discharged in washwater and must be neutralised before biological treatment to maintain wastewater pH below discharge permit limits. Compliance under ZDHC Wastewater Guidelines and EU BAT conclusions for textile processing requires residual sodium in effluent to be measured by ion chromatography using ISO 14911. Terminal products are mercerised cotton yarn, high-lustre woven shirting fabric, dyed tubular knit fabric, and mercerised sewing thread. The processing limit is inhomogeneous fibre swelling when bath temperature exceeds 25 °C or caustic concentration falls below 18% w/v; both conditions reduce barium activity number measured by AATCC TM 89-2019 and produce non-uniform dye uptake after reactive dyeing.
For low-turbidity surface waters with alkalinity below 30 mg/L as CaCO₃, a 20 kg package of caustic soda is dissolved to 5%–25% w/v stock solution and metered via positive-displacement diaphragm pumps into the treated water main after coagulation, flocculation, sedimentation, and membrane filtration to raise finished water pH to 7.0–8.2 for corrosion control and lead/copper solubility suppression, with dose rates typically from 10 mg/L to 150 mg/L as NaOH for low-alkalinity surface waters and 200–1,000 mg/L for acidic industrial wastewater neutralisation, complying with EN 896:2012 and NSF/ANSI/CAN 60 for drinking water chemical additives and AWWA B501-19 for receiving inspection, producing municipal potable water, demineralised boiler feedwater after mixed-bed polishing, and neutralised industrial effluent.
The preparation of sodium methoxide from 20 kg solid caustic soda and dry methanol is strongly exothermic and requires methanol with water content below 0.5 wt% to suppress soap formation. The addition ratio used in the methoxide mixing tank is 20 kg NaOH per 80 L methanol to yield approximately 25% w/v sodium methoxide; this solution is then injected into refined low-free-fatty-acid feedstock at a catalyst dose of 0.5–1.0 wt% sodium hydroxide equivalent based on oil mass when feedstock free fatty acid is below 0.5 wt%. The downstream transesterification process is operated in a closed stirred reactor at 55–65 °C for 1–2 hours with methanol-to-oil molar ratio of 6:1, followed by glycerol settling, methanol recovery, water washing or dry-sorbent purification, and vacuum drying of methyl ester. Sodium methoxide from 20 kg packages must be prepared in a nitrogen-blanketed, pressure-relieved tank because the dissolution is strongly exothermic and releases methanol vapour. Compliance references include ASTM D6751 and EN 14214 for fatty acid methyl ester quality, with methanol content in the final biodiesel measured by EN 14110 and free glycerol by ASTM D6584. Terminal product types include fatty acid methyl ester biodiesel, crude glycerine, and demethylated fatty acid derivatives. The critical boundary is moisture and free fatty acid in the oil; water above 0.5% or free fatty acid above 1.5% consumes caustic as soap, reduces phase separation, and may result in final biodiesel failing the EN 14214 sodium-plus-potassium limit of 5 mg/kg.
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Caustic Soda 20KG is a packaged anhydrous sodium hydroxide solid supplied as flakes or pearls with a nominal net mass of 20 kg per moisture-barrier bag. The commercial term does not denote a distinct chemical model or homolog; the 20KG suffix is a packaging identifier commonly seen as “NaOH flake 99% 20KG PE-lined bag” rather than a separate chemical grade designation. The active substance, NaOH, has molecular weight 39.997 g/mol, melting point 318 °C, boiling point 1,388 °C, and density 2.13 g/cm³ at 20 °C. Transport classification is UN1823, Class 8, Packing Group II. The package is selected when a site requires solid alkali in manual-add quantities, or when bulk liquid storage of 50% NaOH is rejected because of freeze protection, footprint, or low throughput.
Procurement of this material is governed by chemical assay and package integrity rather than by a model number. Membrane-grade solid caustic soda in 20 kg bags is commonly certified according to GB/T 209-2018, EN 896, or ANSI/AWWA B501, depending on jurisdiction. Table 1 lists a conservative membrane-grade flake specification. Diaphragm-grade material may show higher chloride and lower active alkali; some diaphragm-grade flakes are certified at 98.0–99.0% with NaCl up to 0.5%. This variation is relevant when caustic is used for oxide dissolution, chlor-alkali derivative synthesis, or food-contact formulations where chloride limits are tight.
| Parameter | Specification value | Test method |
|---|---|---|
| Sodium hydroxide (NaOH) | ≥99.0%, typical 99.2–99.5% | ASTM E291, ISO 979 |
| Sodium carbonate (Na2CO3) | ≤0.5% | ISO 3196 |
| Sodium chloride (NaCl) | ≤0.03% | ISO 3197 |
| Iron as Fe2O3 | ≤0.001% | ASTM E291 photometric |
The package construction is not incidental to the specification. A 20 kg flake bag typically has an inner 0.05–0.10 mm LLDPE liner inside a polypropylene woven outer sack. Moisture ingress through a broken liner converts surface NaOH into sodium carbonate crust, which dissolves more slowly and can reduce the active alkali available to the batch. In humid production areas, partially used bags must be resealed with a cable tie or bag sealer, or the remaining flake transferred into a closed HDPE bin.
Each 20 kg bag contains approximately 500 mol NaOH. Dissolution of the full bag in 200 L water at 25 °C releases about 22.25 MJ of heat; the adiabatic temperature increase is 26.6 °C, raising the batch to approximately 51.6 °C. In a 200 L open-top polyethylene tank, direct addition without recirculation can create a dense alkaline layer exceeding 1.2 g/cm³ and local interface temperatures above 80 °C, which can soften HDPE walls. The solid must be added slowly to water while maintaining a top-entering pitched-blade mixer at 100–300 rpm, or using a recirculating eductor. Water must not be added to a dry solid layer in a confined vessel.
In saponification, the stoichiometric NaOH demand is derived from the feedstock saponification value. For a triglyceride with a saponification value of 190 mg KOH/g, the equivalent NaOH requirement is 135.5 mg NaOH/g oil because the ratio of equivalent weights is 40.00 / 56.11. A single 20 kg bag at 99.0% active alkali therefore saponifies approximately 146 kg of that oil under ideal stoichiometry. Caustic Soda 20KG yields hard sodium soaps; replacement with potassium hydroxide produces soft potassium soaps and requires higher mass per equivalent. The same 20 kg NaOH charge is equivalent to 27.77 kg active KOH, or about 30.9 kg of 90% KOH flakes.
Water treatment make-down using solid caustic requires an agitated day tank and a positive-displacement or peristaltic dosing pump. For potable pH adjustment, the solid grade should be certified to ANSI/AWWA B501 and, where required, NSF/ANSI/CAN 60. For low-alkalinity water, sodium hydroxide demand is typically 5–50 mg/L as NaOH to reach pH 7.0–8.5. A 5 wt% solution prepared from one 20 kg bag in approximately 380 L water contains about 50 g NaOH/L. Actual dose is set by jar testing or in-line pH trim.
Mercerization of cotton cellulose requires 18–25 wt% NaOH at 15–30 °C to obtain fiber swelling and dye uptake. One 20 kg bag added to 80–100 L water produces a 16.7–20 wt% solution after cooling; active cooling is required because the solution exotherm can exceed 50 °C before dilution. Hot spots above 40 °C during make-down produce uneven swelling and reduced tensile strength. Liquid 50% NaOH can be diluted with less dust, but requires heated storage in climates below 12 °C.
In clean-in-place circuits, caustic soda 20 kg bags are used to prepare a 1–2 wt% NaOH wash solution at 70–80 °C for 10–20 min. In dairy or food-contact surfaces, the solution must meet 21 CFR 184.1763 or be followed by potable rinse. Hard-water calcium precipitates can scale heat-exchanger surfaces; softened water is normally specified for reuse circuits.
Chemical manufacturing uses solid caustic for sodium hypochlorite, sodium phenolate, and hydrolysis reactions. For sodium hypochlorite, chlorine is absorbed into a 10–15 wt% NaOH liquor at 15–25 °C; one 20 kg bag in 115–180 L water produces an appropriate feed liquor for small chlorine absorbers. In petroleum caustic washing, a 5–10 wt% NaOH scrubbing solution is used for mercaptan removal.
Kraft pulp mills use solid NaOH for white liquor make-up and alkaline extraction. In oxidative extraction, NaOH charge is 0.5–1.5 wt% on oven-dry pulp at 60–80 °C. White liquor active alkali charge of 14–20% as Na2O equivalent on dry softwood is common. The 20 kg bag is generally limited to pilot digesters and bleach-plant make-down; continuous mill operations use bulk liquid or supersack loading.
When solid flakes are stored in an unventilated room containing aluminum or galvanized steel racks, the material can generate hydrogen if caustic dust and moisture form a corrosive film on the metal surface. Storage should use 304 or 316 stainless steel or polyethylene racks, not aluminum or zinc-coated steel. Partially used bags should be closed with a cable tie or bag sealer and used within 24–48 h in high-humidity environments. The material absorbs atmospheric moisture and carbon dioxide, forming surface carbonate that reduces dissolution rate and available alkalinity.
Dust from broken flakes is corrosive to the respiratory tract and skin. The dry solid is classified as Skin Corr. 1A, H314 under CLP. Handling requires chemical goggles, neoprene or butyl gloves, and face shield. Ventilation should maintain dust levels below the applicable occupational exposure limit, commonly 2 mg/m³ as NaOH particulate. Spills should be swept dry into a dry plastic container; aluminum scoops must not be used. Neutralization with dilute acid must be carried out slowly with pH monitoring to avoid thermal splatter.
Comparative alkaline input formats for batch formulation are shown in Table 2.
| Parameter | Caustic Soda 20KG solid | Caustic soda 50% liquid | Potassium hydroxide 90% flakes |
|---|---|---|---|
| Chemical formula | NaOH | NaOH | KOH |
| Equivalent weight | 40.00 g/mol | 40.00 g/mol | 56.11 g/mol |
| Active alkali mass fraction | ≥99.0% | 50.0% | ≥90.0% |
| Neutralizing capacity, pure alkali basis | 25.0 eq/kg | 12.5 eq/kg | 16.0 eq/kg |
| Physical state | solid flakes or pearls | liquid | solid flakes |
| Melting/freezing point | 318 °C | approx 12 °C | 360 °C |
| Typical package | 20 kg bag | 200 L drum or bulk | 25 kg bag |
| Saponification output | hard sodium soaps | hard sodium soaps | soft potassium soaps |
Because NaOH has an equivalent weight of 40.00 g/mol, a 20 kg bag of 99% solid provides 19.8 kg active NaOH and 495 equivalents. To match that capacity with 50% liquid NaOH, 39.6 kg solution is required, equivalent to about 26.0 L at density 1.52 g/cm³. With 90% KOH flakes, the equivalent gross charge is 30.9 kg. The solid 20 kg bag lowers the unit lift mass compared with 25 kg sacks, but increases bag cuts and liner waste per tonne. Published data for specific musculoskeletal injury rates by package size is limited.
Compared with soda ash, NaOH raises pH without adding carbonate alkalinity. On a mass basis, soda ash has neutralising capacity of 18.9 eq/kg; NaOH has 25.0 eq/kg on a pure alkali basis. However, solid caustic is more corrosive and more hygroscopic than soda ash, so the package type cannot be treated as a direct drop-in unless the dissolving system and storage racks are upgraded.
Closed containers are required. In storage, Caustic Soda 20KG must be segregated from strong acids, aluminium powder, magnesium powder, and chlorinated solvents such as trichloroethylene and dichloromethane. A 20 kg bag stored outdoors, even under a tarp, will degrade through liner condensation and crust formation; storage below 50 °C and away from direct flame is required. Segregation distances follow local fire code and the UN1823 Class 8 classification.
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