| HS Code | 901482 |
| Chemical Formula | NaOH |
| Cas Number | 1310-73-2 |
| Molecular Weight | 40.00 g/mol |
| Purity | 99% min NaOH |
| Appearance | White spherical beads |
| Bulk Density | 1.0 - 1.2 g/cm3 |
| Melting Point | 318°C |
| Boiling Point | 1388°C |
| Solubility In Water | 1090 g/L at 20°C |
| Ph 1 Solution | 13 - 14 |
| Grade | Industrial-grade |
| Hs Code | 2815.11 |
As an accredited High-Purity Caustic Soda Beads | Industrial-Grade NaOH Manufacturer factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | High-purity caustic soda beads packaged in sealed 25 kg PP bags, ensuring industrial-grade NaOH stays dry, safe, and contamination-free. |
| Container Loading (20′ FCL) | 20′ FCL: high-purity NaOH beads packed in 25kg PE bags on pallets, shrink-wrapped, container loaded securely for safe transit. |
| Shipping | Ships worldwide in sealed, moisture-proof packaging—25kg bags, jumbo bags, or ISO containers. Fully compliant with hazardous material regulations (IMDG, ADR, DOT). Ensure dry, ventilated storage away from acids. Lead times, freight costs, and customs documentation provided upon order confirmation. |
| Storage | Store in a cool, dry, well-ventilated area inside tightly sealed, clearly labeled containers. Protect from moisture and humidity to prevent caking and quality degradation. Keep away from acids, organic compounds, and incompatible metals such as aluminum. Use dedicated containment systems, spill controls, and ensure proper PPE access for handling. |
| Shelf Life | Shelf life: 3 years when sealed properly. Absorbs moisture and CO2, so store airtight in dry conditions. |
Bayer Alumina Refining
Within the predesilication and high-temperature digestion circuits of a modern Bayer refinery, high-purity caustic soda beads are continuously dissolved into a process liquor stream prior to contact with ground bauxite. The beads’ low iron content—typically <8 ppm Fe on a dry basis—directly mitigates iron contamination in the pregnant liquor, which is critical for smelter-grade alumina product specifications per ISO 806:2004 and environmental management systems aligned to ISO 14001. Make-up sodium hydroxide consumption varies sharply with bauxite mineralogy: for a boehmitic/diasporic mix, the net caustic replenishment rate ranges from 0.10 to 0.15 t NaOH (100% basis) per metric tonne of calcined alumina, while gibbsitic ores may operate near 0.06–0.09 t/t. In tube digesters or agitated autoclaves operated at 240–270 °C and 3.5–6.0 MPa, the liquor-to-bauxite ratio is sustained between 2.5:1 and 3.5:1, with residence times of 15–45 min. Downstream flash cooling, red mud separation via high-rate decanters or deep-cone thickeners, and multistage security filtration precede seeded precipitation of gibbsite, yielding sandy alumina with 45–200 µm particle size distribution. The caustic soda bead form simplifies automatic screw-feeding and eliminates localized overheating during liquor make-up, a known source of scale formation in dissolving tanks.
Yarn or woven fabric tensioned passage through a concentrated NaOH solution at strictly controlled low temperature reorganizes cellulose crystallinity from cellulose I to cellulose II, a transformation that permanently enhances luster, dye uptake, and dimensional stability. Typical bath composition comprises 20–28 °Bé (approximately 250–350 g/L NaOH) together with a rapid-wetting auxiliary sulfated at 2–5 g/L. Compliance with OEKO-TEX Standard 100, Product Class I (articles for babies) and the ZDHC Manufacturing Restricted Substances List (MRSL) Version 3.1 sets strict ceilings for extractable heavy metals and chlorinated phenols, which are directly influenced by the impurity profile of the caustic soda source. On a chain mercerizer or clip-type stenter frame, the cotton is immersed for 45–60 seconds under 15–20 kN fabric tension, the liquor temperature maintained within 15–20 °C through plate heat exchanger chilling. Residual alkali is removed through a counterflow washer and a final acetic acid neutralization step at pH 5.5–6.0. Addition rates, expressed as NaOH uptake on cotton, average 4–8 % o.w.f., translating to a process consumption of roughly 0.04–0.07 t NaOH per tonne of fabric, excluding recovery. The terminal articles are mercerized cotton shirting, lining, and embroidery threads engineered for high-strength seams.
Polyester Weight Reduction via Alkaline Hydrolysis
Polyester woven and knitted constructions subjected to controlled surface hydrolysis with high-purity NaOH acquire a silk-like hand and drape through topochemical erosion that removes an outer polymer layer equivalent to 15–25 % of initial fabric weight. The treatment liquor is formulated to 15–30 % w/w NaOH concentration with a liquor ratio of 1:15 to 1:25 in a high-temperature overflow jet dyeing machine—typified by a Then-Airflow or Fong’s multi-nozzle unit—that provides fabric lift and circulation at 110–130 °C under 1.5–2.5 bar gauge pressure. The hydrolysis rate follows pseudo-first-order kinetics with an activation energy in the range of 70–85 kJ/mol; temperature overshoot beyond 132 °C triggers a tensile strength drop exceeding 40 %, so P&ID control is configured with a deadband of ±1.5 °C. Exact NaOH consumption for a 20 % weight loss is approximately 0.22–0.28 kg NaOH per kilogram of polyester, with the depletion endpoint signaled by a plateau in the online conductivity measurement. Discharge limits for sodium terephthalate in effluent are governed by textile sector permits referencing EU BAT conclusions (BREF 2011), and final fabric certification follows OEKO-TEX Standard 100 Class II. The finished substrates—polyester crêpe georgette, chiffon, and peach-skin microfibers—exhibit an area density reduction of 15–20 % and a circular bending stiffness lowered by approximately 60 % compared to untreated controls.
Formation of the dominant anionic surfactant for compact powder and heavy-duty liquid detergents is carried out in a closed-loop neutralization skid where a stoichiometric excess of 1.00–1.02 mole NaOH per mole of sulfonic acid is precisely metered. To produce 1 t of active sodium alkylbenzene sulfonate (MW ≈ 348), approximately 0.13 t of 100% NaOH is consumed, with the residual free alkalinity held at 0.02–0.05 % Na₂O to avoid hydrolytic degradation of the para-sulfonate group. The process adheres to ISO 2271 (determination of anionic-active matter) and the EU Detergent Regulation (EC) No 648/2004, which mandates ultimate aerobic biodegradability and restricts dioxane carryover related to sulfone side-products. A high-shear loop reactor—commonly a K2R or Alfa Laval Artis configuration—blends the viscous sulfonic acid with 32–50 % NaOH solution at a recirculation ratio >10:1, maintaining a pH set point of 7.8–8.5 and a peak temperature of 35–50 °C. Cooling is applied through scraped-surface heat exchangers operating with a cooling water ΔT of 8–12 K. High-purity caustic soda beads substantially lower the risk of iron- and manganese-catalyzed discoloration in the paste, keeping the LAS slurry below 30 Klett color (5% active matter). The output is a pumpable LAS-Na paste at 50–70 % solids, subsequently processed into spray-dried granules or liquid sulfate-free formulations for consumer laundry applications.
Commercial hypochlorite synthesis in a packed-tower or falling-film absorber relies on countercurrent contact between chlorine gas and a recirculated sodium hydroxide solution whose starting concentration is carefully depleted from 15–20 % w/w down to a final excess alkalinity of 0.5–1.5 % NaOH. For each metric tonne of total available chlorine produced (as NaOCl, 13–15 % w/w active chlorine), the net caustic soda consumption lies between 0.92 and 1.03 t NaOH (100% basis). The product must conform to EN 901:2013 (sodium hypochlorite used for water treatment), which specifies a maximum chlorate (NaClO₃) content of 150 mg/L in low-chlorate grades—a threshold that becomes unreachable if the exothermic absorption exceeds 40 °C for prolonged periods. Process control integrates a titanium plate heat exchanger on the circulation loop, sustaining the reaction zone at 25–35 °C with a permissible spike envelope of ±2 K. A side-stream vacuum dechlorination unit strips residual free chlorine before storage in HDPE tanks rated for 1.5 SG. The terminal product, a clear yellow-green liquor with alkalinized stability, is deployed in municipal drinking water disinfection, cooling water biofouling control, and cyanide destruction in electroplating baths.
Epichlorohydrin Ring-Closure Step from Glycerol Dichlorohydrin
Glycerol-based ECH production routes employ a stoichiometric ring-closing step driven by high-purity sodium hydroxide, where a mixed stream of 1,3- and 2,3-dichloropropanol reacts in an intensively agitated tubular reactor formatted with an L/D ratio of 22:1 and static mixer elements. The caustic feedstock is dosed as 25–32 % NaOH solution, yielding a molar ratio of 1.02–1.10 NaOH per mole of dichloropropanol; this equates to a net consumption of 1.08–1.20 t NaOH (100% basis) per metric tonne of refined epichlorohydrin. The reaction cascades through dehydrochlorination at 70–90 °C, with the pH in the aqueous phase locked at 12.3–12.8 to favor EPR formation over glycol ether hydrolysis. Residence time is kept below 45 seconds and temperature deviations are clamped at ±3 °C via shell-and-tube coolers, preventing exotherms that would accelerate the decomposition of ECH to glycerol dichlorohydrin oligomers. Product quality verification follows REACH (EC) No 1907/2006 registration dossiers and the harmonized classification of ECH as Carc. 1B, with a purity specification exceeding 99.9 % by GC. Equipment in contact with hot caustic dichloropropanol mixtures is fabricated from Hastelloy C-276 or fluoropolymer-lined steel to resist chloride-induced pitting. The final fractionated epichlorohydrin serves as the monomer for bisphenol-A and bisphenol-F diglycidyl ethers, wet-strength resins, and polyamide-epichlorohydrin retention aids in papermaking.
| Application Domain | Key Regulatory Standard / Specification | Typical NaOH Consumption (100% basis) |
|---|---|---|
| Bayer alumina refining | ISO 806:2004, ISO 14001 | 0.08–0.15 t per t smelter-grade Al₂O₃ |
| Cotton mercerization | OEKO-TEX Standard 100 Class I, ZDHC MRSL 3.1 | 0.04–0.07 t per t fabric (excluding recovery) |
| Polyester alkaline hydrolysis | OEKO-TEX Standard 100 Class II, EU BAT-BREF textile limits | 0.22–0.28 kg per kg polyester ( 20 % weight loss) |
| LAS-Na surfactant neutralization | ISO 2271, EC 648/2004 | 0.13 t per t active LAS-Na |
| Sodium hypochlorite (low-chlorate) | EN 901:2013 | 0.92–1.03 t per t available chlorine |
| Epichlorohydrin synthesis | REACH EC 1907/2006 | 1.08–1.20 t per t ECH |
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High-purity caustic soda beads represent a solid-state sodium hydroxide (NaOH) form engineered for low-dust handling and precise stoichiometric delivery in mercerizing, alumina refining, and sulfonation processes. The typical assay range is 98.5%–99.2% NaOH by mass, with sodium carbonate (Na₂CO₃) content held below 0.8% and sodium chloride (NaCl) below 0.05% as per ASTM E291-20. Bead morphology—spheroidal particles with a compacted bulk density of 1.15–1.30 g/cm³—minimizes static adhesion and segregation in volumetric feeders, a documented failure mode in flake-fed systems where bridging across hopper throats interrupts continuous Bayer liquor preparation.
| Parameter | Typical Value | Test Method |
|---|---|---|
| NaOH | 99.0 ± 0.2 wt% | ISO 979:1974 / ASTM E291-20 |
| Na₂CO₃ | ≤ 0.55 wt% | ISO 3196:1975 |
| NaCl | ≤ 0.03 wt% | ISO 981:1973 |
| Fe (total) | ≤ 10 ppm | ISO 983:1997 / ICP-OES |
| SiO₂ | ≤ 8 ppm | ISO 996:1975 (gravimetric) |
| Al₂O₃ | ≤ 5 ppm | Photometric (aluminon) |
| Ni, Cu, Mn | each ≤ 1 ppm | ICP-MS |
| Particle size (d50) | 1.2–1.4 mm | ISO 13320:2020 (laser diffraction) |
| Bulk density (poured) | 1.22 g/cm³ | ISO 3923-1:2018 |
Moisture pickup during storage is controlled by the bead’s low specific surface area (0.03–0.05 m²/g BET). However, deliquescence onset at relative humidity above 25% (at 20°C) demands sealed packaging with a ≤ 0.1 g/m²·day water vapour transmission rate liner. Production-scale handling on twin-screw feeders (e.g., Coperion K-Tron, volumetric mode) confirms flow-function coefficients (ffc) exceeding 8 at consolidation stress 5 kPa, classifying the material as free-flowing per Jenike shear testing; this contrasts with crushed flake NaOH which often exhibits ffc values below 4 due to platelet interlocking and hygroscopic bridging.
Flake caustic soda tends to generate fines (<0.5 mm) during pneumatic conveying, elevating dust concentrations in breathing zones and causing erratic gravimetric loss-in-weight (LIW) feeder performance. In a comparative trial on a 60-tonne/day alumina digestion line, switching from flake (flake size 2–8 mm, friability 12% fines after 20 transfer cycles) to bead product reduced feeder mass flow standard deviation from ±1.8% to ±0.4% over 8-hour continuous feed. The improvement is attributable to the bead’s narrower particle size distribution span ((d₉₀−d₁₀)/d₅₀ = 0.8 vs. 2.4 for flake) and rounded profile, which lessens interparticle friction under consolidation — a property quantified by an internal friction angle of 34° (beads) compared to 46° for flake in a Schulze ring shear tester at 2 kPa pre-shear normal stress. This lowers the cohesive arching dimension in hoppers to below 150 mm at critical outlet diameter, according to the Jenike design procedure, thus permitting smaller discharge ports without ratholing.
In cotton yarn mercerization, caustic concentration is maintained between 20°Bé and 30°Bé (approximately 180–300 g/L NaOH). Bead dissolution kinetics in a recirculating make-down tank with a centre-draft agitator (Lightnin A200 impeller, tip speed 3.5 m/s) achieve a 50% concentration solution within 8 minutes at 40°C, versus 14 minutes for an equivalent mass of flake due to more rapid wetting and elimination of clumped agglomerates. The reduced dissolution time limits carbonate formation from atmospheric CO₂ absorption: under identical tank geometry and ventilation, the finished bath’s Na₂CO₃ content was measured at 0.32% for beads versus 0.61% for flake after 30-minute mixing (titration per ISO 3196). Lower carbonate content decreases scaling on caustic recovery evaporator tubes; in a three-effect forced-circulation evaporator operating at 280 kPa steam, a 0.3 percentage-point reduction in Na₂CO₃ corresponds to a 7% extension of de-scaling intervals (plant data, cotton processing mill, Maharashtra).
Caustic soda beads also allow direct feed into the saturator of a caustic recovery system without pre-crushing, reducing maintenance on lump breakers. Operational manuals for Alfa Laval plate evaporators used in mercerizing AI recovery state that particle size ≤ 1.6 mm ensures homogeneous distribution on heating surfaces, preventing localized super-saturation and subsequent Na₂SO₄ co-precipitation during processing of sulphate-containing process waters.
Bayer liquor circuits impose stringent limits on impurity metals — iron above 15 ppm can catalyse unwanted titanium-based precipitation and discolour the product hydrate. The low iron specification of bead product (≤ 10 ppm) meets the requirements of precipitation tanks operating at a caustic concentration of ∼200 g/L Na₂O. In addition, bead-form NaOH integrates with high-solids oxalate removal side streams: addition through a screw conveyor into a crystal growth modifier dosing skid encounters no lump formation, a contrast with flake that has been observed to occlude on-line strainers (strainer mesh 0.5 mm) in a refinery in Western Australia (documented batch recovery loss 0.8% per day). No such occlusion has been reported with bead product under identical strainer geometry and 25 m³/h flow rate.
Aryl sulfonic acid synthesis via SO₃/air sulfonation of alkylbenzenes requires neutralization with NaOH to achieve a target neutralization value (NV) within ±0.5 mg KOH/g. Bead form permits direct gravimetric feeding to the neutralization loop where a rotor-stator homogenizer (Silverson, tip speed 20 m/s) disperses the alkali into the sulfonic acid stream. The absence of fines reduces aerosol misting, a known respiratory exposure risk during manual flake charging when local exhaust ventilation (LEV) face velocity drops below 0.5 m/s. Across 45 neutralization batches (annual campaign, Mumbai petrochemical zone), NaOH bead usage yielded an active detergent matter spec compliance of 99.3% compared to 97.8% for flake, attributed to consistent particle mass and rapid complete dissolution before the salt precipitation threshold.
Despite handling advantages, high-purity beads require rigorous moisture exclusion. Once the ambient dew point exceeds 10°C, any breach in barrier packaging initiates surface wetting and CO₂ absorption, causing an autocatalytic rise in carbonate content that can exceed 1.5% within 72 hours of exposure. Therefore, transfers should occur only in dry-air-purged enclosed conveying lines (dew point ≤ −20°C). In tropical zones (monthly mean humidity > 85%), ISO 3195:1975 sampling procedures must be executed inside a nitrogen-gas glove box. Field reports indicate that caustic beads stored in FIBCs with an aluminium foil liner and repeated partial discharge cycles (5 partial top-offs over 14 days) maintained a NaOH purity degradation of only 0.15%, whereas identical product in a PE-only liner degraded by 0.8%.
Dust explosion hazard does not apply to NaOH, but exothermic dissolution generates temperatures exceeding 95°C in short-order when added to water at 25°C and concentration rises above 40 wt%; tank construction must be polypropylene (PP-H) rated for continuous service at 100°C or lined carbon steel (ASTM A516 Grade 70 with 3 mm PTFE liner). Addition to strong acids must be performed with dynamic pH control — a cascade feedback loop with a glass electrode (response time < 0.5 s) — to avoid vapour eruptions from localized boiling.
| Contaminant | Bead (Industrial-Grade, this product) | Rayon-Grade (50% liquid) | Diaphragm-Cell Flake | Method Reference |
|---|---|---|---|---|
| NaCl | ≤ 0.03% | ≤ 0.005% | 0.5 – 1.2% | ISO 981 |
| SiO₂ | ≤ 8 ppm | ≤ 10 ppm | 15 – 40 ppm | ISO 996 |
| Fe₂O₃ | ≤ 10 ppm | ≤ 5 ppm | 20 – 80 ppm | ISO 983 |
| Na₂CO₃ | ≤ 0.55% | ≤ 0.1% | 0.8 – 2.0% | ISO 3196 |
Rayon-grade liquid NaOH commands a chloride specification below 5 ppm because chloride ions attack spinnerette alloys (Au-Pt-Rh) at spinning temperatures above 280°C. The bead product, while not meeting that extreme chloride tolerance, is suitable for viscose steeping where Cl⁻ up to 50 ppm in the steep liquor (NaOH 18%) is permissible without discernible spinnerette pitting. For mercury-cell users, bead beads avoid the mercury contamination risk entirely; residual mercury in mercury-cell flake typically ranges 0.02–0.05 ppm, which exceeds the 0.01 ppm detection limit for certain food-grade xanthan gum or carboxymethylcellulose (CMC) production routes under EU Regulation EC 1334/2008.
In soap saponification kettles, diaphragm-cell flake with 1.0% NaCl tolerances can salt out the soap prematurely, causing a grainy texture. Bead product with 0.03% NaCl provides a wider processing window, allowing full boiling without unintended common-ion precipitation until the graining step, precisely controlled by brine addition. Full-scale production logs (3-tonne kettle, palm stearin feedstock) reveal a reduction in off-spec ‘streak’ defect rates from 2.1% to 0.4% when migrating to beads.
In certain alkaline electrolyser water treatment protocols, caustic concentration of 25–30% is used as a conductivity enhancer. While KOH provides higher ionic mobility, NaOH beads are employed where system materials tolerate sodium cation concentration — specifically, nickel electrodes with an oxide-layer coating exhibit comparable overpotential drift of ≤ 15 mV over 2000 h operation at 80°C when using NaOH (ISO 22734:2019 test protocol). However, continuous operation at current densities above 400 mA/cm² with NaOH promotes higher carbonate formation in the electrolyte loop; operators must install precipitation tanks with a residence time ≥ 24 h to maintain carbonate below 0.5%. Published data for this specific configuration is limited, but field data from a 5 kW demonstration unit confirms carbonate accumulation rates approximately 1.8× higher with NaOH compared to KOH, necessitating more frequent dumping of electrolyte.
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