source:LASEN Environmental Protection release date:2025-12-15 Number of reads:110
Polyaluminum chloride (PAC) is an inorganic compound and an emerging water treatment material, classified as an inorganic polymeric coagulant—commonly abbreviated as "polyaluminum." It is a water-soluble inorganic polymer situated between AlCl₃ and Al(OH)₃, with the general chemical formula [Al₂(OH)ₙCl₆₋ₙ]ₘ, where m represents the degree of polymerization and n indicates the neutralization level of the PAC product. When n ranges from 1 to 5. the compound forms highly charged polymeric cyclic structures with a Keggin configuration, which exhibit strong charge neutralization and bridging effects toward colloids and suspended particles in water. PAC can effectively remove trace toxic substances and heavy metal ions and demonstrates excellent stability in its physical and chemical properties. Its quality can be tested according to the Chinese national standard GB 15892-2003. Due to the bridging effect of hydroxide ions and the polymerization induced by multivalent anions, the resulting polychlorinated aluminum possesses a relatively high molecular weight and elevated positive charge, making it a highly effective inorganic polymeric water treatment agent.
Polyaluminum chloride (PAC) exhibits adsorption, coagulation, and sedimentation properties. However, it has relatively poor stability and is corrosive; if accidentally splashed onto the skin, it should be immediately rinsed thoroughly with water. Operators involved in its production must wear protective work clothing, masks, gloves, and long rubber boots.
Spray-dried PAC offers several advantages, including excellent stability during spray drying, broad adaptability to various water sources, rapid hydrolysis, strong adsorption capacity, formation of large and dense flocs, fast settling, low residual turbidity in treated water, and good dewatering performance. Spray-dried PAC products ensure greater safety, help reduce water treatment incidents, and are highly safe and reliable for municipal drinking water applications.
Therefore, this form of polychlorinated aluminum is often referred to as "high-efficiency PAC," "high-performance polyaluminum chloride," or "high-grade spray-dried PAC."
PAC is suitable for treating raw water with a wide range of turbidities and operates effectively across a broad pH range. However, compared to polyacrylamide, its sedimentation performance is significantly inferior.
The basicity (or degree of hydroxylation) of polyaluminum chloride (PAC) is a relatively critical parameter, especially for PAC products intended for drinking water treatment. Generally, the lower the basicity, the higher the price. Purchasers can make decisions based on the actual production conditions of suppliers.
Moreover, PAC products manufactured from different raw materials and via different processes exhibit varying levels of basicity. This requires manufacturers to adjust their production parameters accordingly. Significantly increasing the basicity of PAC can greatly enhance both production and application efficiency. For instance, raising the basicity from 65% to 92% can reduce raw material costs by approximately 20% and lower usage costs by about 40%.
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