Description of Polyaluminum chloride
Polyaluminum chloride (PAC) is an advanced coagulant widely used in water treatment and industrial processes for its superior efficiency in removing impurities from water. It is a polymerized aluminum-based chemical with a formula typically represented as
𝐴𝑙𝑛(𝑂𝐻)𝑚𝐶𝑙3𝑛−𝑚Aln(OH)mCl3n−m, where the degree of polymerization and hydrolysis varies based on the manufacturing process.
Key Characteristics:
- Form: PAC is available in both liquid and solid forms. The liquid is clear to pale yellow, while the solid form ranges from white to light yellow powder or granules.
- Basicity: PAC has a higher degree of basicity (i.e., the percentage of hydroxide ions present relative to aluminum ions), which allows it to work more efficiently across a broader pH range than traditional coagulants like alum (aluminum sulfate).
- Solubility: It is highly soluble in water and rapidly dissolves to form a solution that is ready for use in treatment processes.
Applications of Polyaluminum chloride
Polyaluminum chloride (PAC) has a wide range of applications across different industries due to its efficiency as a coagulant and flocculant. Here are the primary applications:
- Drinking Water Treatment
PAC is extensively used in municipal water treatment plants to purify drinking water. It effectively coagulates and removes: Suspended solids
Organic matter
Microorganisms (such as bacteria and viruses)
Color and turbidity
PAC works efficiently across a broader pH range and produces less residual aluminum in treated water compared to traditional coagulants like aluminum sulfate (alum). - Wastewater Treatment
In industrial and municipal wastewater treatment, PAC is used to: Clarify wastewater by removing suspended particles and colloids
Eliminate heavy metals, oils, and fats
Reduce turbidity and chemical oxygen demand (COD)
Aid in the dewatering process by creating larger, more easily filterable flocs
It is especially useful in treating wastewater from industries like mining, oil refining, and metal processing. - Paper and Pulp Industry
PAC is utilized in the paper manufacturing process to: Improve the retention of fillers and fine particles, enhancing paper strength and quality
Optimize water drainage during the papermaking process, leading to faster production and reduced water consumption
Reduce the need for additional chemicals and improve the efficiency of production
It also helps in treating wastewater generated during the papermaking process. - Textile Industry
PAC is widely used in the treatment of textile dye wastewater, which is known for its high coloration and pollutant load. It helps: Decolorize wastewater by binding and precipitating dye molecules
Remove suspended solids, oils, and heavy metals
Improve the overall water clarity, reducing environmental pollution from textile effluents
Its effectiveness in treating a variety of dye types (such as reactive, direct, and acid dyes) makes it a preferred coagulant in the textile sector. - Cosmetics and Deodorants
In cosmetics, especially in antiperspirants and deodorants, PAC is sometimes used as an active ingredient because of its astringent properties, which help reduce perspiration by temporarily blocking sweat glands. - Mining and Metallurgy
PAC is used in mineral processing and metal refining operations to: Clarify water used in the extraction of minerals and metals
Remove heavy metals and other impurities from process water
Help in separating valuable minerals from ores by enhancing the sedimentation and filtration processes - Food Industry
In the food industry, PAC is used in the treatment of water that comes into direct contact with food products. It ensures that water is free from contaminants, meeting the stringent quality standards required for food production processes. - Swimming Pool Treatment
PAC is used in swimming pools to maintain water clarity by coagulating and removing fine particles, oils, and other impurities. This improves filtration efficiency and ensures clean and safe swimming conditions. - Oil and Gas Industry
PAC is used in the oil and gas sector for: Treating produced water, which contains oil, grease, and suspended solids
Clarifying water used in hydraulic fracturing operations
Reducing the overall pollutant load in effluents released from oil refineries - Sugar and Beverage Industries
In sugar production and the beverage industry, PAC is employed to purify process water and remove impurities, improving the quality and safety of the final product.
Polyaluminum chloride Advantages
Polyaluminum chloride (PAC) offers several advantages over traditional coagulants, making it a popular choice in various industries, particularly in water and wastewater treatment. Here are its main advantages:
- Higher Coagulation Efficiency
PAC has a higher coagulation efficiency compared to traditional coagulants like aluminum sulfate (alum). This means it can remove suspended particles, organic matter, and impurities more effectively, leading to cleaner water and better filtration. - Effective Across a Wide pH Range
PAC is effective in a broader pH range, typically between 5 and 9. This flexibility allows it to be used in different types of water and under various conditions, without needing significant pH adjustments. - Lower Dosage Requirements
Compared to alum or other coagulants, PAC requires lower dosages to achieve the same or even better results. This reduces chemical consumption, leading to cost savings in large-scale operations. - Produces Less Sludge
One of PAC’s key advantages is its ability to produce less sludge compared to other coagulants. This reduces the costs and environmental impact associated with sludge disposal, making the treatment process more efficient and sustainable. - Faster Reaction Time
PAC coagulates faster than traditional coagulants, which speeds up the water treatment process. This leads to quicker sedimentation and filtration, improving the overall efficiency of the treatment systems. - Reduced Residual Aluminum
PAC leaves lower residual aluminum levels in treated water compared to aluminum sulfate, which is beneficial for human health and the environment. This makes it a preferred choice in drinking water treatment processes. - Improved Turbidity Removal
PAC is highly effective in reducing turbidity in water, making it clearer and safer for consumption or industrial use. It can handle highly turbid water better than conventional coagulants. - Lower Corrosion Potential
The reduced presence of free aluminum ions in the water after treatment with PAC helps lower the risk of corrosion in pipes and equipment, extending the life of water distribution systems and reducing maintenance costs. - Better Filtration and Finer Flocs
PAC produces denser and more uniform flocs (aggregated particles), which improves filtration efficiency and makes it easier to remove contaminants. This results in clearer water and less wear and tear on filtration systems. - Suitable for Cold Water
PAC remains effective even in cold water, where some coagulants, such as alum, tend to lose efficiency. This makes it a versatile option for regions with varying seasonal temperatures or colder climates. - Versatility in Applications
PAC can be used in a wide range of industries, including drinking water treatment, wastewater treatment, the paper and pulp industry, the textile industry, and the food and beverage sector. Its wide applicability makes it a multi-purpose coagulant for various industrial processes. - Reduced Need for pH Adjustments
Unlike traditional coagulants, PAC does not require significant pH adjustments prior to or during treatment. This simplifies the process and reduces the need for additional chemicals like lime, further cutting costs.
Why do we use polyaluminum chloride?
Polyaluminum chloride (PAC) is widely used because of its effectiveness and efficiency in water treatment and other industrial processes. Here are the primary reasons why PAC is commonly chosen:
- Efficient Coagulation and Flocculation
PAC is highly effective at coagulating and flocculating suspended solids, organic matter, and other impurities in water. This leads to better removal of contaminants, making it ideal for:Drinking water purification: To ensure safe, clean water by removing particulates, turbidity, and pathogens.
Wastewater treatment: To remove pollutants like oils, heavy metals, and organic compounds from industrial effluents. - Lower Chemical Dosage
PAC requires a smaller dosage compared to other coagulants such as aluminum sulfate (alum) to achieve the same or better results. This reduces the overall chemical usage and operational costs in water treatment facilities. - Reduced Sludge Production
One of the major benefits of using PAC is that it produces less sludge than traditional coagulants. This leads to: Lower sludge disposal costs
Reduced environmental impact
Easier sludge management and treatment - Effective Over a Wide pH Range
PAC works efficiently across a broader pH range (typically 5 to 9) without the need for significant pH adjustments. This makes it adaptable to different water conditions, both in drinking water treatment and industrial wastewater. - Faster Sedimentation and Filtration
PAC has a faster reaction time compared to other coagulants, which speeds up the sedimentation and filtration processes. This allows for quicker treatment cycles, enhancing the efficiency of water treatment plants. - Improved Water Quality
PAC results in cleaner and clearer water by forming denser, more compact flocs that are easier to filter out. This significantly reduces turbidity and ensures high water quality for: Municipal drinking water
Industrial water processes (e.g., in food, beverage, and paper industries) - Lower Residual Aluminum
PAC typically leaves lower levels of residual aluminum in treated water compared to aluminum sulfate. This is important for: Health: Reducing aluminum exposure in drinking water.
Environment: Lower risk of aluminum contamination in water bodies. - Cost-Effectiveness
PAC is more cost-effective than other coagulants because of its: Lower chemical dosage
Reduced sludge production
Faster reaction times These factors help lower overall operational costs in water treatment and industrial processes. - Versatility
PAC can be used in a wide range of applications, including: Drinking water treatment
Industrial wastewater treatment
Paper and pulp production
Textile industry for dye wastewater treatment
Swimming pools for water clarity - Environmental Benefits
Using PAC in water treatment results in lower residual chemical by-products and less sludge, which reduces the environmental burden of waste disposal. The smaller volumes of chemicals required also mean a reduced carbon footprint in chemical production and transportation.
Packing of Polyaluminum chloride
- Liquid Form: Available in 200-liter drums, 1000-liter IBC containers, or bulk tankers.
- Solid Form: Packed in 25 kg or 50 kg polypropylene bags with inner polyethylene liners, or jumbo bags of 500 kg or 1000 kg.
Environmental and Health Considerations:
While PAC is highly efficient, proper dosing is important to avoid excessive aluminum residue in treated water, which can pose environmental and health risks if not carefully controlled.
Storage and Handling:
- Storage: Store in a cool, dry place away from direct sunlight and extreme temperatures. Ensure the packaging is tightly sealed to avoid moisture absorption (for solid PAC).
- Shelf Life: Liquid PAC has a shelf life of approximately 6 months, while solid PAC can last up to 12 months if stored properly.
- Handling: Handle with care, using appropriate personal protective equipment (PPE), including gloves and goggles. Avoid contact with skin and eyes.
Safety Information:
- Hazard Classification: PAC is classified as non-hazardous under normal usage conditions but is corrosive in concentrated form.
- Precautionary Statements: Avoid inhalation, ingestion, and skin contact. In case of contact with skin or eyes, rinse thoroughly with water.
First Aid Measures:
- Skin Contact: Wash with plenty of soap and water.
- Eye Contact: Rinse cautiously with water for several minutes.
- Inhalation: Move to fresh air and seek medical attention if symptoms persist.
Technical Data Sheet of Polyaluminum chloride
| Parameter | Specification |
| Appearance | Yellow to pale yellow powder (solid) or clear, light yellow liquid |
| Al₂O₃ Content (Aluminum Oxide) | 28-30% (for solid) / 10-18% (for liquid) |
| Basicity | 40-85% |
| pH (1% Aqueous Solution) | 3.5 – 5.0 |
| Insoluble Substances | ≤ 1.5% (solid) / ≤ 0.5% (liquid) |
| Density (Liquid PAC) | 1.15 – 1.25 g/cm³ |
| Viscosity (Liquid PAC) | 10-40 mPa.s (at 20°C) |
| Chloride (Cl) | 10 – 16% |
| Sulfate (SO₄) | ≤ 3.5% |
| Iron (Fe) Content | ≤ 0.005% |
| Heavy Metals (As, Pb, Hg) | ≤ 0.0005% |
| Water Insoluble Substances | ≤ 0.5% (liquid PAC) |
| Alkalinity | ≥ 0.1% (solid PAC) |
