Poly Aluminum Chloride (PAC)
Poly Aluminum Chloride, abbreviated as PAC, is a high-efficiency inorganic polymer flocculant with the chemical general formula [Al2(OH)nCl6−n]m (where n is 1-5 and m is the degree of polymerization, usually 10-100). It is a water-soluble macromolecular compound with a three-dimensional network structure, prepared by the hydroxylation and polymerization of aluminum chloride, and is widely used in water treatment, environmental engineering and other fields.
Core Physical and Chemical Properties
Appearance: Commonly available as yellow/brown powdery solid, pale yellow liquid or colorless transparent liquid (depending on the content and basicity); solid PAC has good water solubility, and the dissolution rate in water is close to 100%.
Basicity: The key technical index, generally 40-90% (the molar ratio of hydroxyl to aluminum), which directly affects the flocculation effect; the higher the basicity, the stronger the polymerization degree and flocculation performance.
Aluminum oxide (Al2O3) content: The main effective component, solid PAC is usually divided into 26%, 28%, 30% grade (industrial grade), and drinking water grade is required to have Al2O3 ≥30% with lower heavy metal content.
Stability: Stable in normal temperature and sealed storage; avoid dampness for solid products, and the liquid products have a shelf life of 6-12 months.
pH value of aqueous solution: 3.5-5.0, showing weak acidity, no strong corrosivity (mild corrosivity to metal, need anti-corrosion equipment for storage and transportation).
Main Application Fields
Water treatment (core application): The most widely used flocculant for urban sewage treatment, industrial wastewater purification (printing and dyeing, papermaking, electroplating, coal washing wastewater, etc.) and drinking water purification. It can quickly adsorb and aggregate suspended solids, colloidal particles and organic pollutants in water to form large flocs for precipitation and separation, with high purification efficiency and fast sedimentation speed.
Papermaking industry: Used as a paper sizing agent and retention aid, which can improve the paper strength, reduce fiber loss and improve the water filtration performance of pulp, and is suitable for various papermaking processes (cultural paper, packaging paper, etc.).
Textile and printing and dyeing industry: Used for wastewater decolorization and sludge dehydration, and can also be used as a fixing agent in the dyeing process to improve the color fastness of fabrics.
Other fields: As a coagulant in the oil field water injection process, a sludge conditioning agent in environmental engineering, and an auxiliary agent in the ceramic production process to improve the molding performance of ceramic blanks.
Advantages Compared with Traditional Flocculants
High flocculation efficiency: The formed flocs are large, dense and have fast sedimentation speed, which can reduce the sedimentation time by 30-50% compared with aluminum sulfate and ferric chloride.
Wide pH adaptation range: Effective in the water pH range of 5.0-9.0, no need to adjust the water pH additionally in most cases, which simplifies the water treatment process.
Low dosage: The dosage is only 1/3-1/2 of traditional flocculants, which reduces the treatment cost and the amount of sludge produced after treatment.
Good water quality after treatment: Low residual aluminum ion content, no secondary pollution, and meets the national drinking water and industrial water discharge standards.
Strong adaptability: It still has good flocculation effect for high turbidity water, low temperature and low turbidity water, which solves the problem of poor treatment effect of traditional flocculants in special water quality.
Storage and Transportation Notes
Solid PAC: Sealed and stored in a dry, ventilated and cool warehouse, avoid dampness, rain and direct sunlight; it can be transported by ordinary freight, and avoid mixing with alkaline substances and food.
Liquid PAC: Stored in anti-corrosion containers (plastic, glass fiber reinforced plastic, etc.), avoid contact with iron and steel containers (easy to react and reduce efficacy); transported by special anti-corrosion tank trucks, and pay attention to sealing to prevent volatilization and leakage.
Operation protection: Wear rubber gloves and goggles during operation to avoid direct contact with skin and eyes; if contact occurs, rinse with plenty of clean water immediately.
Industrial Grade Classification
According to the application scenario and index requirements, PAC is mainly divided into drinking water grade and industrial grade:
Drinking water grade: Al2O3 ≥30%, low content of heavy metals (Pb, Cd, Hg, etc.), meet GB 15892-2020 standard, used for tap water, mineral water and other drinking water purification.
Industrial grade: Al2O3 26-28%, suitable for industrial wastewater treatment, sewage purification and other non-drinking water fields, with relatively loose index requirements.
