Characteristics and Uses of PAC (Polyaluminum Chloride)
Characteristics and Uses of PAC (Polyaluminum Chloride)
Polyaluminum chloride (PAC) is an efficient coagulant, water purifier, and phosphorus remover. Due to its outstanding advantages and wide applicability, PAC can reduce the dosage by over 30% compared to traditional water purifiers, saving more than 40% in costs. It has become a recognized excellent water purifier both domestically and internationally. Additionally, PAC can be used for purifying drinking water and special water sources such as tap water, including removing iron, cadmium, fluoride, radioactive pollutants, and floating oil.
Features of PAC (Polyaluminum Chloride):
PAC is a resin-like solid with a color ranging from yellowish to light yellow, dark brown, or dark gray. PAC is intermediate between ALCL3 and ALNCL6-NLm, where m represents the degree of polymerization and n represents the neutralization degree of PAC products. PAC, also known as polyaluminum chloride or coagulant, exhibits strong bridging and adsorption capabilities. During the hydrolysis process, physical and chemical processes such as coagulation, adsorption, and precipitation occur.
Uses of PAC (Polyaluminum Chloride):
Coagulation:
PAC is mainly used for the purification of urban water supply and drainage systems, including river water, reservoir water, and groundwater. It is also used for industrial water treatment, urban wastewater treatment, recovery of useful substances from industrial wastewater and waste residue, promoting the settlement of coal powder in coal washing wastewater, and recovering starch in starch manufacturing. PAC can purify various industrial wastewater such as dyeing wastewater, leather wastewater, fluorine-containing wastewater, heavy metal wastewater, oily wastewater, papermaking wastewater, coal washing wastewater, mining wastewater, brewing wastewater, metallurgical wastewater, and meat processing wastewater. PAC is used in sewage treatment processes such as paper sizing, sugar refining, casting molding, fabric wrinkle prevention, catalyst carrier, pharmaceutical refining, cement setting acceleration, and cosmetics production.
Phosphorus removal:
By adding chemical agents to wastewater, the phosphate ions in the water form insoluble salts, which then coagulate and separate from the water, effectively removing phosphorus. The specific reaction process involves two main reactions. Firstly, trivalent aluminum ions react with phosphate ions to form precipitates, and the precipitate compound is AlPO4.
Al3+ + PO43- → AlPO4 ↓
Secondly, trivalent aluminum ions undergo hydrolysis reactions, resulting in the presence of positive charges, mono-nuclear hydroxyl complexes, and multi-nuclear hydroxyl complexes. Through van der Waals forces and capturing in a network, the desired precipitation effect can be achieved, meeting the requirements of chemical phosphorus removal.