Pulp & Paper Chemicals — NaOH, H2O2, PAC, ClO2 for Kraft Pulping & ECF Bleaching | Lộc Thiên
Pulp & Paper Chemicals — NaOH, H2O2, PAC, ClO2
TL;DR: The pulp & paper industry relies on four key chemical groups: NaOH (CAS 1310-73-2) for Kraft pulping at 155–175°C, H₂O₂ (CAS 7722-84-1) for dioxin-free ECF/TCF bleaching, PAC (CAS 1327-41-9) for wastewater coagulation meeting QCVN 12-MT:2015, and ClO₂ for disinfection. Lộc Thiên supplies all four groups, delivering to 6 warehouses across 3 regions with batch-specific CoA/MSDS.
Table of Contents
- What chemicals does the pulp & paper industry use?
- NaOH — Kraft pulping chemical
- H₂O₂ — chlorine-free pulp bleaching
- PAC — paper mill wastewater coagulation
- ClO₂ — final-stage bleaching and disinfection
- Technical specification comparison table
- Reference dosage by process stage
- QCVN 12-MT:2015 standard and documentation
- Buy pulp & paper chemicals from Lộc Thiên
- Frequently asked questions
What chemicals does the pulp & paper industry use?
Chemicals used in paper and pulp production are divided into four main groups by process stage:
Group 1 — Pulping chemicals: NaOH (caustic soda), Na₂S (sodium sulfide). Breaks down lignin from cellulose fibers in the Kraft process.
Group 2 — Bleaching chemicals: H₂O₂ (hydrogen peroxide), ClO₂ (chlorine dioxide), NaOCl (sodium hypochlorite). Removes residual lignin and chromophores, raising ISO brightness.
Group 3 — Wastewater coagulants: PAC (polyaluminium chloride), PAM polymer. Treats paper mill wastewater to QCVN 12-MT:2015 compliance.
Group 4 — pH adjustment and auxiliary chemicals: H₂SO₄ (sulfuric acid), Na₂CO₃ (soda ash), CaCO₃ (calcium carbonate), dyes, sizing agents.
According to the Vietnam Pulp & Paper Association (VPPA), the paper industry consumes over 200,000 tons of chemicals annually, with NaOH accounting for ~35%, H₂O₂ ~15%, and PAC plus coagulants ~12%.
NaOH — Kraft pulping chemical
NaOH (Sodium Hydroxide, CAS 1310-73-2) is the foundational chemical in the Kraft process — which accounts for 90% of global pulp production. NaOH combines with Na₂S to form “white liquor,” hydrolyzing lignin-carbohydrate bonds at 155–175°C and 700–1000 kPa pressure.
Mechanism: OH⁻ ions break ether bonds in lignin, releasing long cellulose fibers → increased mechanical strength of finished paper.
Technical specifications — NaOH for pulp & paper:
| Parameter | NaOH Flakes | NaOH Liquid 32% | NaOH Liquid 50% |
|---|---|---|---|
| NaOH content | ≥99.0% | 32.0 ± 0.5% | 50.0 ± 0.5% |
| Na₂CO₃ | ≤0.5% | ≤0.2% | ≤0.3% |
| NaCl | ≤0.03% | ≤0.01% | ≤0.02% |
| Fe₂O₃ | ≤0.005% | ≤0.001% | ≤0.002% |
| Packaging | 25kg/bag, 1 MT pallet | IBC 1000L, 20 MT tanker | IBC 1000L, 20 MT tanker |
Reference dosage — Kraft pulping:
- Softwood: 16–20% Active Alkali (AA) based on oven-dry wood weight
- Hardwood: 12–16% AA
- Bamboo, straw: 10–14% AA
- Cooking temperature: 155–175°C, retention time 2–4 hours
- Target H-factor: 800–1200 depending on raw material
“Controlling Active Alkali (AA%) and H-factor are the two parameters that determine Kraft pulp quality. A 1% deviation in AA can change paper tear strength by 5–8%.” — KTV Phan Cẩm Thùy, Technical Lead, HCLT
H₂O₂ — chlorine-free pulp bleaching
H₂O₂ (Hydrogen Peroxide, CAS 7722-84-1) is a next-generation bleaching agent replacing Cl₂, recommended by the WHO and EU for ECF/TCF processes. H₂O₂ generates no dioxins or furans (AOX), meeting export standards for the EU and Japan.
Bleaching mechanism: At pH 10–11, H₂O₂ dissociates into perhydroxyl anion (HO₂⁻):
H₂O₂ + OH⁻ → HO₂⁻ + H₂O
HO₂⁻ + chromophores (lignin) → colorless productsOptimal operating parameters:
- pH: 10.0–11.0 (adjust with NaOH)
- Temperature: 60–70°C
- Retention time: 2–3 hours
- Dosage: 15–40 kg H₂O₂/ton oven-dry pulp (depending on target brightness)
- Stabilizer: MgSO₄ 0.5–1.0 kg/ton pulp
Typical results with OQP process (Ozone-Quebracho-Peroxide):
- Inlet ISO brightness: 50–60%
- Outlet ISO brightness: 80–90%
- AOX: ≤0.1 mg/L (QCVN compliant)
Technical specifications — Industrial H₂O₂:
| Parameter | H₂O₂ 27.5% | H₂O₂ 50% |
|---|---|---|
| Content | 27.5 ± 0.5% | 50.0 ± 1.0% |
| Active oxygen | ≥13.0% | ≥23.5% |
| Fe | ≤0.5 ppm | ≤1.0 ppm |
| Stability | ≥97% | ≥97% |
| Packaging | IBC 1000L, 25 MT tanker | IBC 1000L, 25 MT tanker |
PAC — paper mill wastewater coagulation
Paper mill wastewater has COD 800–2000 mg/L and TSS 500–1500 mg/L, primarily from dissolved lignin, fine cellulose, and residual bleaching chemicals. PAC (Poly Aluminium Chloride, CAS 1327-41-9) with its Al₁₃ polycation structure neutralizes the negative charge of these colloidal particles, producing fast-settling flocs.
Coagulation mechanism:
- Neutralizes negative charge of cellulose and lignin → loss of dispersion stability
- Forms bridges between particles → Al(OH)₃ floc precipitation
- Mechanical entrapment of suspended solids during settling
PAC operating parameters — paper mill wastewater treatment:
| Parameter | PAC 10% | PAC 17% |
|---|---|---|
| Al₂O₃ content | 10 ± 1% | 17 ± 1% |
| Basicity | 45–65% | 45–65% |
| Solution pH | 3.5–5.0 | 3.5–5.0 |
| Dosage | 150–300 mg/L | 100–250 mg/L |
| Optimal pH range | 6.5–7.5 | 6.5–7.5 |
| Packaging | IBC 1000L | 25 kg bag, 25 L pail |
Typical treatment efficiency:
- TSS reduction: 85–95%
- COD reduction: 40–60%
- Color reduction: 60–80%
- Settling time: 20–30 minutes
PAC note: Unlike conventional alum, PAC 10% and 17% feature pre-hydrolyzed Al₁₃ polycation structure, enabling effective coagulation even at low temperatures (5–15°C) without dosage increase. This is a significant advantage for paper mills operating in cold seasons or using surface water from rivers and lakes.
When combined with aerobic biological treatment after coagulation, treated water meets QCVN 12-MT:2015 Column A: COD ≤75 mg/L, TSS ≤50 mg/L, AOX ≤0.1 mg/L.
ClO₂ — final-stage bleaching and disinfection
ClO₂ (Chlorine Dioxide, CAS 10049-04-4) is a selective strong oxidizer used in final-stage ECF bleaching and feed water disinfection in paper mills. ClO₂ has an oxidation potential E° = 0.95V (reduction to Cl⁻) and selectively attacks the lignin aromatic ring while preserving cellulose fiber structure.
Mechanism: ClO₂ oxidizes lignin aromatic rings into colorless carboxylic acids, preserving cellulose fiber structure. Unlike Cl₂, ClO₂ does not undergo substitution halogenation, producing extremely low AOX levels.
Technical specifications:
- Form: dissolved gas solution (unstable above 9%, must be used same day)
- pH: 2–4
- Bleaching dosage: 5–15 kg ClO₂/ton pulp
- Temperature: 50–70°C
- Retention time: 60–120 minutes
Comparison of ClO₂ with other bleaching agents:
| Parameter | H₂O₂ | ClO₂ | NaOCl |
|---|---|---|---|
| AOX generated | None | Very low | Yes |
| Maximum brightness | ≤88 ISO | ≤92 ISO | ≤85 ISO |
| Equipment corrosion | Low | Medium | High |
| Cost/kg | Low | High | Low |
Technical specification comparison table
| Chemical | CAS | Specific Gravity | Solution pH | Common Packaging | Main Application |
|---|---|---|---|---|---|
| NaOH flakes | 1310-73-2 | 2.13 | 13–14 | 25kg/bag | Kraft pulping |
| NaOH liquid 32% | 1310-73-2 | 1.328 | 13–14 | IBC 1000L | Pulping, pH adjustment |
| H₂O₂ 50% | 7722-84-1 | 1.195 | 3–4 | IBC 1000L | ECF/TCF bleaching |
| PAC 17% | 1327-41-9 | 1.32 | 3.5–5.0 | IBC 1000L | Wastewater coagulation |
| ClO₂ (solution) | 10049-04-4 | — | 2–4 | On-site generation | Bleaching + disinfection |
Reference dosage by process stage
| Process Stage | Chemical | Dosage | Conditions |
|---|---|---|---|
| Kraft pulping | NaOH + Na₂S | 12–20% AA/ton wood | 155–175°C, 2–4h |
| Pulp washing | H₂SO₄ | 5–10 kg/ton pulp | pH 5.5–6.5 |
| ECF bleaching | H₂O₂ | 15–40 kg/ton pulp | pH 10–11, 60–70°C |
| Final bleaching | ClO₂ | 5–15 kg/ton pulp | pH 2–4, 50–70°C |
| Wastewater treatment | PAC 17% | 150–300 mg/L | pH 6.5–7.5 |
| Flocculant aid | Anionic polymer | 1–5 mg/L | After PAC |
QCVN 12-MT:2015 standard and documentation
Paper mill wastewater must meet QCVN 12-MT:2015/BTNMT (Column A for environmentally sensitive areas):
| Parameter | Column A | Column B |
|---|---|---|
| COD | ≤75 mg/L | ≤150 mg/L |
| TSS | ≤50 mg/L | ≤100 mg/L |
| AOX | ≤0.1 mg/L | ≤0.3 mg/L |
| pH | 6.0–8.5 | 5.5–9.0 |
| Color | ≤20 Pt-Co | ≤70 Pt-Co |
Lộc Thiên supplies full legal documentation for ISO 14001 audits and periodic environmental inspections: batch-specific CoA (batch code, production date, expiry date), MSDS/SDS GHS 16-section bilingual English-Vietnamese, CO/CQ certificates of origin for imported goods, chemical business license (Decree 113/2017/ND-CP), and fire safety inspection certificate.
Buy pulp & paper chemicals from Lộc Thiên
Lộc Thiên supplies all four pulp & paper chemical groups — from pulping and bleaching chemicals through to wastewater coagulants. 6 strategic warehouses in Ho Chi Minh City, Binh Duong, Dong Nai, Ba Ria-Vung Tau, Can Tho, Da Nang, and Bac Ninh. Tanker trucks 5–30 tons, same-day delivery to industrial parks (HCMC 4h, southern IPs 24h).
🛒 Need bulk pulp & paper chemicals? Request a quote — NaOH, H₂O₂, PAC, ClO₂ with batch CoA/MSDS, nationwide industrial park delivery. Hotline 0979 891 929.
Frequently asked questions
What types of chemicals are used in the pulp & paper industry?
4 groups: (1) NaOH for Kraft pulping, (2) H₂O₂ and ClO₂ for bleaching, (3) PAC for wastewater coagulation, (4) H₂SO₄, Na₂CO₃ for pH adjustment and auxiliaries.
What concentration of NaOH is used for pulp cooking?
NaOH flakes ≥99% or liquid 32–50%. Dosage calculated as AA%: softwood 16–20%, hardwood 12–16%, bamboo/straw 10–14%. Cooking temperature 155–175°C.
What advantages does H₂O₂ have over chlorine for pulp bleaching?
Zero dioxin and AOX generation, achieves ISO brightness 80–90%, environmentally friendly. Meets EU and Japanese standards for paper export.
What dosage of PAC is used for paper mill wastewater treatment?
PAC 17% at 100–300 mg/L at pH 6.5–7.5, reduces TSS by 85–95%, COD by 40–60%. Combined with biological treatment meets QCVN 12-MT:2015 Column A.
How does ClO₂ differ from H₂O₂ in paper bleaching?
ClO₂ achieves higher brightness (≤92 ISO) and is more selective, but costs more and requires on-site generation equipment. H₂O₂ is more common for ECF/TCF bleaching.
What documentation is provided with pulp & paper chemicals?
Batch-specific CoA, GHS 16-section MSDS, CO/CQ of origin, chemical license (Decree 113), fire safety certificate. Sufficient for ISO 14001 audits.
Can I order pulp & paper chemicals for same-day delivery to Binh Duong IPs?
Yes — warehouses in Binh Duong, Dong Nai, and HCMC. Order before 10am for same-day afternoon delivery to VSIP, Amata, Nhon Trach, My Phuoc. Hazardous-material certified trucks.
Hotline 0979 891 929 — quote within 15 minutes, nationwide delivery from 200 kg to 20 tons per shipment.