| HS Code | 498500 |
| Chemical Name | Sodium hydroxide |
| Chemical Formula | NaOH |
| Appearance | White, free-flowing spherical micropearls |
| Odor | Odorless |
| Purity | ≥99% NaOH |
| Solubility In Water | 1090 g/L at 20°C |
| Melting Point | 318°C |
| Boiling Point | 1388°C |
| Density | 2.13 g/cm3 at 20°C |
| Bulk Density | Approx. 0.8-1.0 g/cm3 |
| Ph 1 Solution | Approx. 13 |
| Particle Size | Typically 0.1-0.8 mm |
As an accredited AGC Chemicals Caustic Soda Micropearls factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | AGC Chemicals Caustic Soda Micropearls are packed in 25 kg moisture-proof PE bags, palletized and shrink-wrapped for safe handling. |
| Container Loading (20′ FCL) | 20′ FCL loaded with AGC Chemicals Caustic Soda Micropearls in sealed bags on pallets, ensuring safe, secure transport. |
| Shipping | Shipping of AGC Chemicals Caustic Soda Micropearls requires UN1823 Class 8 corrosive packaging—sealed, moisture-proof bags on pallets. Keep dry and ventilated, segregated from acids, foodstuffs, and reactive metals. Ensure proper hazard labeling, transport documentation, and secure loading. Handlers must use PPE and avoid water contact to prevent hazardous reactions. |
| Storage | Store AGC Chemicals Caustic Soda Micropearls in tightly sealed original containers in a cool, dry, well-ventilated area, away from moisture, heat, and direct sunlight. Keep segregated from acids, organic materials, and reactive metals such as aluminum or zinc. Use spill containment and corrosion-resistant flooring, and elevate pallets off the ground to prevent dampness. |
| Shelf Life | Shelf life is indefinite when stored in a sealed, dry container protected from moisture and air. |
Sodium hydroxide micropearls supplied as AGC Chemicals Caustic Soda Micropearls are solid white beads manufactured by membrane electrolysis, with a NaOH mass fraction of ≥98.5%, a CAS number 1310-73-2, and a particle size distribution in which ≥90% of the material passes a 1.0 mm sieve and is retained above a 0.5 mm sieve. The spherical particle geometry reduces dusting at hopper discharge and permits gravimetric feeding into continuous dissolving skids. Because dissolution enthalpy is approximately 1.1 kJ/g, make-down vessels preparing 25–50% solutions from ambient water are designed for an adiabatic temperature rise to 80–90 °C before the addition of cooling water or heat-exchange recirculation. The downstream applications below are limited to industrial and food-grade process uses where the cited standard and the supplier certificate of analysis satisfy process qualification requirements.
Bayer-liquor caustic balance is maintained at 200–250 g/L total caustic soda expressed as Na₂O, with a free-caustic-to-alumina ratio of 0.60–0.70 in low-temperature gibbsitic bauxite digestion circuits. The micropearl form is pre-dissolved in a recirculating dissolver to 50–55% NaOH by mass and filtered through 10–20 µm leaf or cartridge filters before injection to prevent carbonate and iron fines from fouling heat-exchanger walls. In high-temperature boehmitic bauxite plants, digestion runs at 240–270 °C in tubular heaters with 10–20 min residence time; caustic make-up losses from desilication products and red mud washing are typically 60–120 kg NaOH/t Al₂O₃ depending on reactive silica content. Compliance for the refinery is assessed against the Aluminium Stewardship Initiative Performance Standard V3 and the operating permit issued under Directive 2010/75/EU where applicable. The terminal output is smelter-grade alumina, produced by precipitation of aluminium trihydroxide from supersaturated sodium aluminate liquor and calcination at 950–1050 °C.
At the transfer point between brownstock washing and oxygen delignification, caustic soda micropearls are mixed into a 10–12% NaOH solution and dosed directly into medium-consistency pulp at 10–12% consistency inside a high-shear mixer before the oxygen reactor. The charge is controlled between 1.5% and 3.0% NaOH on oven-dry pulp; below 1.2%, the reactor inlet pH falls below 10.5, oxygen delignification stalls, and the post-oxygen kappa number measured per ISO 302:2015 can remain 3–5 units higher than target. Above 3.5%, the extraction-stage pH exceeds 12.0, causing hemicellulose alkaline hydrolysis and a measured pulp yield loss of 1.5–2.5% on cellulosic fibre. The process is operated in two-vessel oxygen reactors, typically at 90–105 °C with 60–90 min total retention time, followed by a post-oxygen wash press that removes dissolved lignin and oxidised organic acids. Compliance is anchored to EPA 40 CFR Part 430 Subpart B for the bleached papergrade kraft and soda subcategory; EU BAT conclusions for pulp and paper set the applicable TSS and COD emission levels for the bleaching plant. Terminal product types include fully bleached eucalyptus market pulp, softwood kraft fluff pulp, and sack-paper furnish.
Batch and continuous saponification of tallow and coconut fatty acid blends uses caustic soda micropearls at a stoichiometric dose derived from the saponification value of the fat charge. For a feedstock with a saponification value of 200–210 mg KOH/g, the NaOH requirement is approximately 14.3–15.0% by weight of the oil phase; industrial soap boilers run with a deliberate 0.2–0.5% residual free alkali expressed as Na₂O in the neat soap to suppress hydrolytic rancidity. The micropearls are dissolved before entering the crutcher or continuous saponification loop because undissolved granules in the high-viscosity neat soap phase create localised alkali pockets that produce brittle, non-homogeneous bars and surface efflorescence after pressing. Continuous fatty acid neutralization is run at 70–85 °C and 2–4 bar steam-jacket pressure, with final moisture adjusted to 8–12% in the vacuum spray dryer. Compliance for the detergent product is under Regulation (EC) No 648/2004 and the REACH safety data sheet obligations of Regulation (EC) No 1907/2006. Terminal products include laundry soap noodles, toilet soap bars, and medium-titre industrial degreasers.
Neutralisation of acid mine drainage and demineralisation pH trim both require precise make-down of dry sodium hydroxide from micropearls to a 20–25% working solution, followed by metering into a flash mixer with a hydraulic retention time of 15–30 s. The dose is not fixed as a single concentration because alkalinity and dissolved carbon dioxide determine the response; a water containing 50 mg/L free CO₂ and 30 mg/L bicarbonate alkalinity will typically consume 0.04–0.09 g/L NaOH to raise pH from 6.5 to 7.5, while acid mine drainage with 800–1200 mg/L ferrous iron and 3000–5000 mg/L acidity may consume 0.7–1.2 kg NaOH/m³ once oxidation and ferric hydroxide precipitation are complete. The make-down system is equipped with a 50 µm bag filter, a magnetically coupled centrifugal pump, and a pH-controlled metering skid with a 4–20 mA signal loop; batch tank neutralization is not recommended upstream of continuous fixed-bed ion exchange because pH overshoot above 9.5 accelerates silicate scaling on downstream reverse-osmosis membranes. Compliance for drinking water additives is AWWA B501-19 and NSF/ANSI/CAN 60. Terminal product streams include clarified potable water, ion-exchange feedwater, and permitted industrial effluent.
Caustic soda micropearls for continuous mercerizing of cotton yarn and woven fabric are dissolved to 18–25°Bé (approximately 220–300 g/L NaOH) and maintained at 16–20 °C in a stainless-steel saturator; the cool temperature shifts the swelling equilibrium of cellulose I to cellulose II, increasing fibre lustre and dye uptake. The fabric is dipped under 1.0–1.5 m of lye, nipped to 80–90% wet pickup, passed through a timing cylinder providing 30–50 s dwell, and then washed in a countercurrent recuperation range where 70–80% of the caustic is recovered via vacuum slots and evaporator concentration. The addition ratio is not controlled by fibre weight alone; the lye bath is analysed every 2 hours by density and titration, with replenishment controlled to ±1°Bé because cellulose II conversion falls sharply below 17°Bé, while above 25°Bé the yarn surface becomes rough and highly swollen, causing downstream dyeing unevenness. Compliance for the textile article is evaluated against ISO 3071:2020 for pH of aqueous extract and the ZDHC Manufacturing Restricted Substances List v3.1. Terminal products are mercerized cotton poplin, sewing thread, and high-lustre knitwear fabric.
Food-grade caustic soda micropearls are diluted to 2–4% NaOH for tomato peeling and 5–8% NaOH for potato peeling, with bath temperatures of 75–85 °C and immersion periods of 30–90 s. The peel detachment mechanism is methyl-ester saponification in the pectin-rich middle lamella; insufficient caustic leaves residual peel, while overdosing above 10% NaOH causes rapid flesh hydrolysis and increases raw fruit mass loss by 3–5%. The line typically uses a rotary drum peeler with internal steam sparging, followed by a high-pressure water spray at 3–5 bar and a citric-acid neutralization rinse at 0.5–1.0% to bring surface pH below 8.0. Compliance is restricted to the food-grade product governed by 21 CFR 184.1763 and the Food Chemicals Codex sodium hydroxide monograph; technical grades are not permitted in this application. Terminal product types include canned whole peeled tomatoes, diced potatoes for industrial freezing, and peeled baby carrots.
Transesterification of low-moisture vegetable oil with methanol uses sodium hydroxide micropearls to generate sodium methoxide in situ, but only when the oil free fatty acid content is below 0.1% by mass and moisture is below 500 mg/kg. The catalyst is prepared by dissolving micropearls in anhydrous methanol at 0.3–0.6% NaOH by oil mass; water introduced by hydrated or carbonate-contaminated caustic increases soap formation via saponification, raising the kinematic viscosity of the crude methyl ester beyond the 6.0 mm²/s upper limit of the finished B100 specification and potentially causing free glycerol or flash point failures. The reaction proceeds in a continuous stirred-tank reactor at 50–60 °C with a 6:1 methanol-to-oil molar ratio and a residence time of 60–90 min; the crude glycerol phase is separated by gravity in a decanter, and the methyl ester is washed with acidified water at 0.5% of ester volume. Compliance of the final fuel is evaluated against ASTM D6751-23 and EN 14214:2012+A2:2019. Terminal products include fatty acid methyl esters for distillate blending and crude glycerol for refining.
Competitive AGC Chemicals Caustic Soda Micropearls prices that fit your budget—flexible terms and customized quotes for every order.
For samples, pricing, or more information, please contact us at +8615365186327 or mail to sales3@liwei-chem.com.
We will respond to you as soon as possible.
Tel: +8615365186327
Email: sales3@liwei-chem.com
Flexible payment, competitive price, premium service - Inquire now!
AGC Chemicals Caustic Soda Micropearls is anhydrous sodium hydroxide supplied as a white, free-flowing solid with the molecular formula NaOH. The product is manufactured by concentrating membrane-electrolysis caustic liquor and solidifying the melt into near-spherical micropearls. Substance identity is fixed by CAS number 1310-73-2 and EC number 215-185-5. Molar mass is 39.997 g mol⁻¹. The micropearl form is controlled to a representative particle-size distribution of 0.6–1.2 mm. True solid density is 2.13 g/cm³; poured bulk density typically ranges from 1.2 g/cm³ to 1.3 g/cm³. The material is hygroscopic and deliquescent, absorbing water vapour and carbon dioxide from ambient air; open exposure above 60–70% RH can produce surface wetting and sodium carbonate crusting. Commercial packaging commonly includes 25 kg moisture-barrier bags and intermediate bulk containers; the specific package format and fill weight vary by regional supply chain. The product designation identifies the dry micropearl solid, distinct from flake, pellet, and solution grades.
Dissolution rate is governed by the accessible particle surface-to-volume ratio. A bed of micropearls presents a larger and more uniform liquid-contact interface than an equivalent bed of larger pellets, while avoiding the stacked lamellar geometry of flake caustic soda that can blind a dissolving grate or form slow-wetting pockets. The heat of solution of anhydrous NaOH is approximately −44.5 kJ/mol. Sodium hydroxide solubility in water is 1110 g/L at 20 °C; the resulting exotherm can raise local interface temperature above 80 °C if water feed is not cooled. Production-scale make-up skids therefore use 10–25 °C softened water, a recirculation loop, and a venturi eductor with motive water at 2.5–3.5 bar to prevent surface boiling and caustic aerosol release. In gravimetric dosing, a loss-in-weight feeder with 10 mm flighted auger and delivery capacity near 1.5 m³/h can maintain batch-weight repeatability of approximately ±2% for micropearls. Irregular flake often requires vibratory tray feeders, multiple stroke corrections, and hopper vibrators to control bridging and variable screw fill. Dust generation is lower than flake handling, but dilute-phase pneumatic conveying can create fines below 250 µm through attrition. Those fines carry electrostatic charge and adhere to bin walls, so transfer lines are fitted with dust extraction, polypropylene filter bags rated below 80 °C, and grounding of metallic spout sections.
Commercial caustic soda micropearls are specified primarily by total alkalinity as NaOH, with additional limits for carbonate, chloride, iron, and sulfate. Analytical methods for industrial solid caustic soda are given under ASTM E291-20; NaOH assay may also be verified by ISO 979:2022. For drinking-water service, the product is assessed against the purity criteria of EN 896:2012. The table below is a representative compliance matrix, not a substitute for the lot certificate of analysis.
| Parameter | Representative limit | Analytical basis |
|---|---|---|
| NaOH assay | ≥99.0 wt% | ASTM E291-20 / ISO 979:2022 acidimetric titration |
| Na2CO3 | ≤0.5 wt% | ASTM E291-20 carbonate evolution |
| NaCl | ≤0.03 wt% | ASTM E291-20 or ion chromatography |
| Fe2O3 | ≤0.001 wt% | ICP-OES after acid digestion |
| Na2SO4 | ≤0.01 wt% | Ion chromatography |
Trace-metal limits for arsenic, lead, cadmium, mercury, and antimony become relevant when the product is used for potable-water pH adjustment under EN 896:2012. Dry micropearls provide only hydroxide alkalinity; they are not dispersants, scale inhibitors, or disinfectants. Because the solid is hygroscopic, sample increments are taken using a rapid thief sampler under dry-air or nitrogen cover and transported in sealed polypropylene containers. Published data for the specific AGC micropearl grade in pharmacopoeial buffer production and high-purity analytical reagent applications are limited; such services normally require a dedicated pharmaceutical-grade or reagent-grade liquid sodium hydroxide rather than an industrial solid.
Substitution economics are governed by water content, transport temperature, and receiving-system configuration. Sodium hydroxide liquor at 50 wt% has a solution density of approximately 1.53 g/cm³ and a freezing point near 12 °C; heated storage and recirculation are required in unheated outdoor tanks. The viscosity of 50% NaOH liquor at 20 °C is near 75 cP, while a dilute 30 wt% solution is approximately 10 cP, which restricts concentrated-liquid pumping through small-diameter lines. Anhydrous micropearls eliminate water weight and freeze risk but require a dry-solids screw feeder, dust-control hood, and dissolution tank with exotherm management. Compared with flake caustic soda, micropearls have a narrower particle-size band, more uniform bulk density, and reduced hopper bridging. Compared with pellets, micropearls respond faster to feed changes because the average diffusion path within each particle is shorter. The table summarises form-dependent handling behaviour.
| Form | Representative geometry | Water content | Main handling constraint |
|---|---|---|---|
| Micropearl | 0.6–1.2 mm near-spherical | Anhydrous | Hygroscopic; closed storage required |
| Flake | 2–5 mm irregular lamella | Anhydrous | Bridging and dusting in screw feed |
| Pellet | 2–4 mm compact granule | Anhydrous | Slower dissolution; uniform size |
| Liquid 50 wt% | Bulk solution | Approximately 50 wt% water | Freezes near 12 °C |
In chemical synthesis, anhydrous micropearls are preferred where water introduction must be controlled. Dry feed reduces the water load on downstream distillation when sodium hydroxide is used as a moisture-sensitive reagent. For batch sodium hypochlorite generation, micropearls are first dissolved to a 15–20 wt% caustic solution, then chlorinated under pH control in the range 9.0–10.5 and reaction temperature below 20 °C. In water treatment, substitution of solid for 50% NaOH is often driven by freight cost and remote storage; the solid is diluted to 30 wt% before day-tank supply because that solution remains liquid above 4 °C. The pH-trim loop then uses a positive-displacement pump with stroke adjustment rather than on-off contactor switching.
In Bayer-process alumina digestion, sodium hydroxide is introduced into recirculating spent liquor to maintain the Na₂O-to-Al₂O₃ molar ratio required for bauxite extraction. Digestion temperatures range from 145 °C for gibbsitic bauxite to 240–265 °C for boehmitic and diasporic feeds. Dry micropearl addition into a mix tank upstream of the digestion heaters is controlled by conductivity and total alkali titration. The narrow particle-size distribution reduces local supersaturation near the feed point, which can otherwise cause sodium aluminate precipitation on cooler tank walls. In kraft pulp mills, caustic soda is dissolved in weak white liquor or water to produce a 10–20 wt% caustic solution before injection into the causticizing or bleach-plant extraction stage. For water treatment, pH correction of low-alkalinity source water is based on Langelier Saturation Index targets between +0.5 and +1.5 in distribution systems; sodium hydroxide is selected over sodium carbonate where calcium hardness is not removed. In saponification of fats and oils, the stoichiometric requirement is 3 mol NaOH per mole triglyceride. Industrial soap kettles typically add a 15–25 wt% caustic solution with temperature control near 80–100 °C; direct dry-particle contact can otherwise hydrolyse fatty acid esters unevenly. In flue-gas scrubbing, caustic soda neutralises acid gases when system pH is maintained between 6.5 and 7.5, but its higher alkalinity can strip CO₂ and increase calcium sulfite scaling if hardness is present. It is therefore not automatically interchangeable with lime or sodium carbonate slurry in all scrubber circuits.
Closed storage is the primary moisture-exclusion barrier. Sodium hydroxide deliquesces above 60–70% RH, forming a surface film that reacts with atmospheric CO₂ to produce sodium carbonate crust. Silos for micropearls are typically carbon steel with an alkali-resistant lining or stainless steel. Bare carbon steel can be used only where temperature and stress-corrosion cracking are managed; sustained hot caustic service requires stress-relieved steel or nickel-alloy materials. Aluminium, magnesium, zinc, and tin are prohibited in caustic contact. The reaction with aluminium is:
2Al + 2NaOH + 6H₂O → 2Na[Al(OH)₄] + 3H₂
Hydrogen evolution creates an explosive confined-space hazard. Rotary valves, hopper cones, and transfer lances must therefore be free of aluminium bronze and hot-dip galvanized surfaces. Silica dissolves in strong alkali; glass and ceramic packings should not be used in continuous caustic lines above 40 °C. Dilute-phase pneumatic transfer with air velocities from 18 m/s to 25 m/s is used for bulk movement, but higher air speed increases micropearl breakage and dust generation. A cyclone and baghouse with polypropylene filter bags rated below 80 °C control emissions; bin vents must be grounded because fines can carry electrostatic charge. Thermal limits are fixed by the melting point of 318 °C and boiling point of 1388 °C. The product is classified under EU CLP as Skin Corr. 1A H314. Transport classification for solid sodium hydroxide is UN1823, Class 8, Packing Group II; the corresponding 50% solution is UN1824. Neutralisation with strong acid releases approximately −57.1 kJ/mol; uncontrolled mixing can cause violent splattering. Mixing with acid should be conducted with continuous agitation and local ventilation. Any batching or sampling area requires an eye-wash station, corrosion-resistant gloves, and face-shield protection. The product should not be discharged to sanitary sewer until the solution is neutralised and meets the local discharge permit pH and sodium limits.
Committed to quality, innovation, and reliable chemical solutions for a sustainable future.
