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Send EmailPolyaluminum Chloride, Aluminum Hydroxychloride, PAC Powder, PAC30, 1327-41-9, 101707-17-9
POLYALUMINIUM CHLORIDE (PAC) POWDER
1. Chemical Identity and Material Classification
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Chemical Name: Polyaluminium Chloride, Poly Aluminium Chloride, Basic Aluminum Chloride, Aluminum Hydroxychloride
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Synonyms: PAC, PAC Powder, PAC30, Polyaluminum Chloride, Polymeric Aluminum Chloride, Aluminum Chlorohydrate
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CAS Numbers: 1327-41-9 (primary), 101707-17-9 (alternative)
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EC Number (EINECS): 215-477-2
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General Chemical Formula: Alₙ(OH)ₘCl₍₃ₙ₋ₘ₎
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Molecular Mass: Very high due to polymeric structure (typical ~5,000–50,000 g/mol)
2. Physical Properties (Powder Form)
| Property | Value |
|---|---|
| Appearance | White to light yellow free-flowing powder |
| Odor | Odorless |
| Bulk density (20°C) | 0.65–0.85 g/cm³ |
| True density | ~2.0–2.2 g/cm³ |
| Melting point | >200°C (decomposes) |
| Hygroscopicity | Moderately hygroscopic (absorbs moisture) |
| Particle size (D50) | 10–150 µm (grade dependent) |
| Solubility in water | Fully soluble (exothermic) |
3. Chemical Specifications and Parameters
3.1 Typical Chemical Parameters (Drinking Water Grade)
| Parameter | Value |
|---|---|
| Al₂O₃ content (w/w) | 28–31% |
| Basicity | 40–90% (typical 45–75%) |
| pH (1% solution, 20°C) | 3.5–5.0 |
| Iron (Fe) | ≤ 0.01% |
| Heavy metals (Pb, Cd, Hg, Cr) | ≤ 1–5 ppm |
| Water insolubles | ≤ 0.1% |
| Chloride (Cl) | 8–12% |
| Sulfate (SO₄) | ≤ 0.05% |
| Arsenic (As) | ≤ 0.5 ppm |
3.2 Industrial Grade Specifications
| Parameter | Value |
|---|---|
| Al₂O₃ content (w/w) | 26–30% |
| Basicity | 40–85% |
| pH (1% solution) | 3.0–4.5 |
| Iron (Fe) | ≤ 0.1% |
| Heavy metals (as Pb) | ≤ 50 ppm |
| Water insolubles | ≤ 0.5% |
4. Basicity and Its Importance
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Definition: Basicity (%) = [OH⁻] / (3 × [Al³⁺]) × 100
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Low basicity (30–50%): Lower polymerization, faster hydrolysis, lower molecular weight
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Medium basicity (50–75%): Balanced performance, standard for most water treatment applications
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High basicity (75–90%): High polymerization, higher molecular weight, higher charge density
5. Polymerization and Aluminum Speciation
5.1 Aluminum Species (by Ferron Method)
| Al species | Description | Typical Ratio in PAC |
|---|---|---|
| Alₐ (monomeric) | Al³⁺, Al(OH)²⁺, Al(OH)₂⁺ | <5–10% |
| Al_b (medium polymer) | Al₁₃O₄(OH)₂₄⁷⁺ (Keggin ion) | 40–70% |
| Al_c (high polymer/colloidal) | Al(OH)₃ and high polymers | 20–50% |
5.2 Polymerization Mechanism
| Stage | Description |
|---|---|
| Hydrolysis | Al³⁺ + H₂O → Al(OH)²⁺ + H⁺ |
| Polymerization | Al(OH)²⁺ + Al(OH)²⁺ → Al₂(OH)₂⁴⁺ |
| Maturation | Formation of high polymer species (Al₁₃, Al₃₀) |
6. Coagulation Mechanism (Water Treatment)
6.1 Basic Mechanisms
| Mechanism | Description | Effectiveness in PAC |
|---|---|---|
| Charge neutralization | Cationic polymer neutralizes negatively charged particles | High |
| Bridging (flocculation) | Polymer chains bind multiple particles | Medium–High |
| Sweep flocculation | Al(OH)₃ precipitate physically entraps particles | High |
| Adsorption | Organic matter adsorbs onto polymer surface | Very high |
6.2 Comparison with Alum (Al₂(SO₄)₃)
| Property | PAC | Al₂(SO₄)₃ (Alum) |
|---|---|---|
| Al species | Pre-polymerized (Al₁₃, etc.) | Monomeric Al³⁺ |
| Rapid mix requirement | Low | High |
| Effective pH range | 5.0–9.0 | 6.0–7.5 |
| pH drop (when added to water) | Low (0.1–0.5 units) | High (0.5–1.5 units) |
| Low temperature performance (~5°C) | Excellent | Poor |
| Residual aluminum (effluent) | Low (<0.1 mg/L Al) | Medium–High |
| Sludge volume | Low (50–70% of alum) | High |
| Dosage requirement (as Al₂O₃) | Low (30–50% of alum) | High |
7. Usage and Dosing Guidelines
7.1 Solution Preparation (From Powder)
| Step | Description |
|---|---|
| 1 | Prepare clean water (preferably drinking water quality) |
| 2 | Add PAC powder slowly to water with continuous medium-speed mixing |
| 3 | Mix for 30–60 minutes until completely dissolved |
| 4 | Typical storage concentration: 5–10% (w/w) |
| 5 | Use immediately after mixing stops (before particles settle) |
7.2 Dosage Table (As Product, Not as Al₂O₃)
| Application | Typical Dosage (mg/L product) | Typical Al₂O₃ Dosage (mg/L) |
|---|---|---|
| Drinking water (low turbidity) | 5–15 | 1.5–4.5 |
| Drinking water (medium turbidity) | 15–40 | 4.5–12 |
| Drinking water (high turbidity) | 40–100 | 12–30 |
| Municipal wastewater (P removal) | 50–150 | 15–45 |
| Industrial wastewater | 50–200 | 15–60 |
| Paper industry | 100–500 g/ton paper | 30–150 g/ton |
| Textile wastewater | 30–150 | 9–45 |
7.3 Optimum Operating Conditions
| Parameter | Value |
|---|---|
| Optimum pH range | 6.0–7.5 |
| Effective pH range | 5.0–9.0 |
| Rapid mixing time | 1–3 minutes |
| Slow mixing time | 10–20 minutes |
| Settling time | 30–60 minutes |
| Temperature range | 2–40°C |
8. Sectoral Applications – Drinking Water Treatment
8.1 Application Details
| Parameter | Value |
|---|---|
| Purpose | Turbidity, color, organic matter removal |
| Typical dosage | 5–50 mg/L (product) |
| Turbidity removal | 95–99% (inlet <500 NTU) |
| Color removal | 80–95% |
| COD removal | 40–70% |
| Residual aluminum | <0.1 mg/L (WHO limit 0.2 mg/L) |
| Standard compliance | NSF/ANSI 60 certified (drinking water grade) |
8.2 Advantages Over Alum
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Lower dosage (30–50% of alum)
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Less sludge (50–70% of alum)
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Lower residual aluminum
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Wider effective pH range
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Better low temperature performance
9. Sectoral Applications – Municipal and Industrial Wastewater Treatment
9.1 Application Details
| Parameter | Value |
|---|---|
| Purpose | TSS, COD, BOD, phosphorus, heavy metal removal |
| Typical dosage | 50–200 mg/L (product) |
| TSS removal | 85–95% |
| COD removal | 40–70% |
| Phosphorus removal | 80–95% |
| Heavy metal removal (Pb, Cu, Cd, Ni) | 70–95% |
9.2 Industrial Wastewater Applications by Sector
| Sector | Pollutants | Typical Dosage (mg/L) |
|---|---|---|
| Textile | Dyes, color, COD | 30–150 |
| Pulp & Paper | COD, TSS, color | 20–100 |
| Leather | Chromium, COD, color | 50–200 |
| Metal finishing | Heavy metals (Ni, Cu, Zn) | 30–150 |
| Food processing | Oil, COD, TSS | 20–100 |
| Petrochemical | Emulsified oils, COD | 50–250 |
10. Sectoral Applications – Paper Industry
10.1 Application Details
| Parameter | Value |
|---|---|
| Purpose | Retention of fillers (calcium carbonate, clay) and dyes |
| Typical dosage | 100–500 g/ton paper (product) |
| Retention efficiency increase | 10–30% |
| Cationic demand | High (neutralizes negative charge of pulp) |
| Synergists | Cationic starch, polyacrylamide |
11. Sectoral Applications – Textile Industry
11.1 Application Details
| Parameter | Value |
|---|---|
| Purpose | Removal of dyes, surfactants, finishing chemicals |
| Typical dosage | 30–150 mg/L (product) |
| Color removal | 80–95% |
| COD removal | 40–70% |
| Polymer combination | Often used with cationic or anionic polyacrylamide |
12. Sectoral Applications – Construction and Concrete Industry
12.1 Indirect Uses
| Application | Description |
|---|---|
| Concrete plant process water | Clarification and recycling of water |
| Aggregate wash water | Suspended solids removal |
| Ready-mix concrete plants | Treatment of muddy water for reuse |
| Outcome | Cleaner process water, reduced discharge, regulatory compliance |
13. Sectoral Applications – Other Industries
| Sector | Application |
|---|---|
| Food | Sugar refining, process water treatment |
| Mining / Metallurgy | Heavy metal and suspended solids removal |
| Chemical | Process water pre-treatment, equipment protection |
| Oil & Gas | Injection water treatment, produced water treatment |
14. Comparison with Conventional Coagulants
| Property | PAC (Powder) | Alum (Al₂(SO₄)₃) | FeCl₃ | Poly-DADMAC |
|---|---|---|---|---|
| Al/Fe content | Medium (15–17% Al) | High (8–9% Al) | High (20% Fe) | Very low (organic) |
| Effective pH range | 5.0–9.0 | 6.0–7.5 | 5.0–8.0 | 4.0–9.0 |
| Basicity | 40–90% | 0% | 0% | Organic |
| Sludge volume | Low | High | Medium | Low |
| Residual aluminum | Very low | High | None | None |
| Low temperature performance | Excellent | Poor | Good | Good |
| Color removal | Excellent | Medium | Good | Poor |
| Phosphate removal | Excellent | Good | Excellent | None |
| Heavy metal removal | Good | Medium | Excellent | None |
| Cost | Medium | Low | Low | Medium |
15. Advantages and Reasons for Preference (Technical Summary)
| Advantage | Description |
|---|---|
| High coagulation efficiency | Pre-polymerized Al species (>40% Al₁₃) – rapid floc formation |
| Effective over wide pH range | Effective at pH 5–9 (alum requires pH 6–7.5) |
| Minimizes pH change | High basicity → pH drop <0.5 units when added to water |
| Low sludge production | 30–50% less sludge volume compared to alum |
| Low residual aluminum | Effluent Al <0.1 mg/L (WHO limit 0.2 mg/L) |
| Excellent low temperature performance | Effective even at ~5°C (alum is poor) |
| Easy dosing | Dilution not required – prepare 5–10% solution |
| Low dosage requirement | 30–50% less Al₂O₃ requirement compared to alum |
| Nitrogen and phosphorus removal | Effective for eutrophication control |
| Heavy metal removal | 70–95% removal for Pb, Cu, Cd, Ni |
| Long shelf life (powder form) | 24 months in sealed packaging |
| Lower transportation cost | More concentrated than liquid forms |
16. Limitations and Precautions
| Limitation | Description / Solution |
|---|---|
| Powder handling difficulty | Protect from moisture; use appropriate dust control measures |
| Hygroscopic | Store in sealed containers; do not expose to air for prolonged periods |
| Dissolution is exothermic | Temperature may rise – use wide-mouth vessels, avoid overheating |
| High alkalinity (>200 mg/L CaCO₃) | Higher dosage may be required (to prevent pH rise) |
| Very low temperature (<2°C) | Increased viscosity – mixing optimization may be required |
| Metal equipment | Corrosive – use plastic or lined equipment |
| Dilution stability | Diluted solutions (<5%) are not stable – use immediately |
17. Safety and Toxicology
| Parameter | Value |
|---|---|
| Oral LD₅₀ (rat) | >5,000 mg/kg (low toxicity) |
| Dermal LD₅₀ (rabbit) | >2,000 mg/kg |
| Skin irritation | Mild irritant |
| Eye irritation | Irritant |
| Skin sensitization | Non-sensitizer |
| Mutagenicity | Negative |
| Carcinogenicity | Not classified |
| Aluminum toxicity | Neurotoxicity potential at high doses (drinking water residual regulated) |
| Drinking water Al limit (WHO) | 0.1–0.2 mg/L |
| Drinking water Al limit (EU) | 0.2 mg/L |
18. Safety Precautions and Personal Protective Equipment (PPE)
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Hazards:
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Acidic – causes skin and eye irritation
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May be harmful if swallowed
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Dust inhalation may cause respiratory irritation
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Reactivity:
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Neutralization with strong alkalis (exothermic)
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May generate hydrogen gas upon contact with many metals
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Acidic solution when mixed with water (exothermic)
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PPE (recommended):
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Chemical-resistant gloves (nitrile or neoprene)
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Safety goggles (EN 166)
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Dust mask (FFP1 or N95) – during powder handling
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Protective clothing (acid-resistant)
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Engineering controls:
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Local exhaust ventilation (LEV) for powder handling
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Dust collection systems
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Eyewash stations
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First aid:
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Inhalation: Move to fresh air
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Skin contact: Wash with plenty of water
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Eye contact: Rinse with water for 15 minutes
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Ingestion: Drink plenty of water; seek medical attention
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19. Storage and Shelf Life
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Storage conditions:
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Cool, dry, well-ventilated area (5–30°C)
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Keep in original sealed containers
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Protect from moisture and direct sunlight
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Use acid-resistant plastic containers (HDPE, PP, PVC) – DO NOT use metal containers
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Store separately from other chemicals (especially alkalis)
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Shelf life:
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Original sealed container: 12–24 months
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Diluted solution: 24–48 hours (use immediately)
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Degradation indicators:
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Caking (moisture absorption)
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Darkening of color (partial hydrolysis)
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Decreased solubility
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20. Sectoral Suitability Summary Table
| Sector | Application | Typical Dosage (mg/L product) | Notes |
|---|---|---|---|
| Drinking Water | Turbidity, color, organic removal | 5–50 | Must be NSF/ANSI 60 compliant |
| Municipal Wastewater | Phosphorus removal, COD reduction | 50–150 | Chemical precipitation |
| Textile Wastewater | Color removal, COD reduction | 30–150 | Effective for azo dyes |
| Paper Industry | Retention aid, dry strength | 100–500 g/ton paper | Synergy with cationic starch |
| Metal Finishing WW | Heavy metal removal (Ni, Cu, Zn) | 30–150 | Precipitate at pH 7–9 |
| Leather Wastewater | Chromium removal, COD reduction | 50–200 | pH optimization required |
| Food Process Water | TSS and organic removal | 20–100 | Food-grade equipment required |
| Mining | Suspended solids removal | 50–200 | Tailings ponds |
| Oil & Gas | Injection water treatment | 50–250 | High salinity tolerance |
| Construction | Process water treatment (aggregate washing) | 50–200 | Closed-loop water systems |
This TDS is prepared in compliance with ISO 11014-1 format and is intended for water treatment engineers, wastewater plant operators, process engineers, paper and textile chemists, and procurement professionals. Certificates of Analysis (CoA), Safety Data Sheets (SDS), jar test protocols, and sample validation reports are available upon request.
