What Is Poly Aluminium Chloride Used For?

Poly Aluminium Chloride, or PAC for short, is an inorganic polymer that is a member of the aluminium salts family. This substance is mostly employed in water treatment procedures as a flocculant and coagulant.

Al2(OH)nCl6-n, the chemical formula for poly aluminium chloride, emphasizes the existence of aluminium cations (Al3+) encircled by hydroxyl (OH-) and chloride (Cl-) ions. A highly charged polymer with a net positive charge is produced when these ions combine.

Because of its special structure, PAC can neutralize the negative charges found in suspended particles in water, which causes flocs to develop and makes it easier to remove them later on in the coagulation process.

What Are the Uses of PAC?

Because of its unique chemical composition and structure, poly aluminium chloride in water treatment is a great idea. It helps remove pollutants and other impurities, resulting in cleaner, safer water that can be used for a variety of applications.

PAC is crucial in oil refining, breaking oil-water emulsions for better separation, thus enhancing efficiency. It’s also vital in deodorants, forming a skin barrier to reduce perspiration, and as a coagulant in paper mill wastewater treatment.

PAC is crucial in oil refining, breaking oil-water emulsions for better separation, thus enhancing efficiency. It’s also vital in deodorants, forming a skin barrier to reduce perspiration, and as a coagulant in paper mill wastewater treatment.

Water Treatment Applications

Urban Drinking Water:

The role of PAC in purifying urban drinking water
Poly Aluminium Chloride is a very effective chemical for treating and purifying urban drinking water because it acts as a coagulant to draw impurities, colloidal particles, and suspended materials together. As a result, floc (flocculation) forms, which can be removed using filters. Products made of polyaluminium chloride that are used to treat water are usually identified by their percentage of basification.

The concentration of hydroxyl groups around aluminium ions is known as basification. In terms of pollutant removal performance, the higher the basicity, the lower the aluminium concentration. The method wherein aluminium residuals are significantly reduced benefits from this decreased aluminium rate as well.

Advantages of Pathogen Removal
Metal coagulants and polyelectrolytes have been observed to remove significant amounts of virus. Ferric salts and aluminium have both been shown to have removal rates of up to 99.9%. Although cationic polyelectrolytes have removed more than 99% of the material, they have the drawback of being less effective in removing material that is present in the form of colour, turbidity, and COD.

The benefit of using polyelectrolytes and metal coagulants together is the production of superior floc properties. When many chemicals are found in water, using both metal coagulants and polyelectrolytes can result in a better removal rate overall. That being said, a lot relies on the specific circumstances of each instance. While floc production is enhanced when polyelectrolytes are used as flocculant aids, virus removals seem to be no better than when polyaluminum chloride coagulant are used alone.

In essence, viruses are just units of RNA or DNA covered in a protein sheath. Coordination interactions between metal coagulant species and the carboxyl groups of the viral coat protein are the mechanism of destabilization. Optimal removals are likely to happen at similar pH settings since the destabilizing mechanisms for viruses and organic colour are similar.

The ideal pH range for aluminium sulphate viral eradication is 5.0, with a virus clearance percentage between 97.7 and 99.8%. The percentage of virus and turbidity removed was raised to 99.9 and 98.5%, respectively, by using a cationic polyelectrolyte as a flocculant aid.

Wastewater Treatment:

Efficient Treatment of Industrial Wastewater
Polyaluminum chloride (PAC) stands out as a highly effective inorganic flocculant and water treatment chemical, widely employed in wastewater treatment solutions. With its positive charge, PAC exhibits significant adsorption of suspended particles in water, offering numerous advantages such as robust decontamination, efficient removal of turbidity and oil, and cost-effectiveness.

Furthermore, the application of polyaluminum chloride (PAC) aids in reducing levels of iron, manganese, and other heavy metals in water, albeit with a mild corrosive effect on wastewater treatment equipment. PAC is renowned for its broad application range, high efficiency, production of large alum particles, rapid settling, low dosage requirement, and strong coagulation performance in wastewater treatment projects.

Industrial Processes

Paper and Pulp Industry:

When producing paper, polyaluminum chloride, or PAC, can be used. PAC is frequently utilized as a coagulant in the paper industry’s papermaking process. It aids in clearing the pulp of contaminants and suspended particles, producing cleaner and clearer paper.

Paper sizing agents are also produced using PAC. Chemicals known as sizing agents are used to increase paper’s printability and water resistance. Because PAC creates a stable and strong binding with cellulose fibers, the primary constituent of paper, it can be utilized as a sizing agent. All things considered, PAC is a practical and adaptable chemical that may be used in a variety of industries, including the paper industry.

How PAC Improves Efficiency and Cost-Effectiveness?

Polyaluminum Chloride Serves As A Filter And Retention Aid
Polyaluminum chloride plays a vital role as a filter and retention aid in wet end chemistry, which focuses on the interactions among various particles, additives, and fibers in paper stock during dehydration and forming. In the past decade, there has been a notable shift in papermaking towards medium and alkaline environments. Additionally, there’s a growing trend in using different chemical addition techniques and additives.

In our country, the paper sector primarily relies on non-wood fiber, with grass fibers being the most common. Due to the small fibers and high concentration of random cells in the straw pulp, filtering water during papermaking becomes challenging. Therefore, focusing on papermaking under medium and alkaline conditions and employing various additives to enhance retention and drainage performance are suitable research directions.

Rosin Uses Polyaluminum Chloride As A Neutral Sizing Precipitant
Rosin employs polyaluminum chloride for neutral sizing in papermaking, a method pioneered in Europe in the mid-1980s due to global resource scarcity. This technique replaces fibers with cost-effective CaCO3 fillers, producing neutral paper through a glue technique. Unlike traditional alum, polyaluminum chloride maintains a positive charge in neutral or alkaline conditions, making it ideal for neutral sizing without pH reduction. Adopted globally, this technology converts acid paper to neutral paper with a pH up to 7.5, significantly reducing operating costs and addressing issues encountered with synthetic sizing materials like AKD. Despite its complexity, polyaluminum chloride poses challenges in stability and suitability for application, necessitating further investigation and development.

Textile Industry:

The Role of PAC in Textile Wastewater Treatment
The parameters BOD, COD, TDS, and pH are taken into account when treating wastewater effluent in the fibre production sector. If untreated textile wastewater with high BOD levels is dumped straight into surface water sources, it may quickly deplete dissolved oxygen. High concentrations of COD in effluents are harmful to biological life.

The aquatic life is negatively impacted by the high alkalinity and traces of chromium found in dyes, which also obstruct the biological treatment process. The presence of dissolved particles in wastewater can potentially damage plants and limit its usage in agriculture. This study uses polyaluminium chloride chemical coagulation to lower the values of BOD, COD, and TDS and to regulate the pH.

When PAC uses chemical coagulation instead of alum, the main benefit is that it is less expensive and creates larger, more easily settling flocs. Comparatively speaking, PAC produces less sludge than alum. The percentages of BOD removal (83.34%), COD removal (64.04%), TDS removal (62.97%), and pH-adjusted values (6.2 to 6.9) were assessed based on the results.

Oilfield Sewage Treatment:

Application of PAC in the Oil and Gas Industry
The main ingredients for treating oilfield effluent are polyacrylamide, polyaluminum chloride, and polyaluminum ferric chloride. In recent years, polyaluminum chloride has grown in importance as a treatment agent for effluent from oil fields. Water treatment agent developers have discovered this new kind of coagulant that exhibits great coagulability, quick demulsification, quick sedimentation, tiny floc volume, and the same impact in both alkaline and neutral circumstances.

The pollutants created during the exploitation process by petrochemical companies are primarily referred to as “oily sewage.” In addition to having a direct impact on soil and groundwater resources, the direct discharge of oily sludge resulting from incorrect treatment would constitute a massive waste of our finite oil resources.

It is discovered that the long molecular chain of polyaluminum chloride can bridge the colloidal particles created by coagulation to form a robust and big floc, enhancing the floc’s performance. The combined use of polyacrylamide and polyaluminum chloride can enhance the therapeutic outcome.

If a specific recovery method is used to treat oily sludge wastewater that contains hazardous materials and high oil content, a sizable portion of the waste oil can be recovered, and the treated sewage sludge can fulfil national discharge limits to prevent secondary pollution.

Heavy Metal and Impurity Removal

Removal of Iron, Manganese, and Chromium
The majority of the wastewater produced during metal processing comes from washing and removing rust from metal surfaces. While stainless steel is pickled using nitric acid and hydrofluoric acid, metal components are typically pickled with sulfuric and hydrochloric acids.

The steel must be cleaned with clean water after pickling to create acid wastewater. After rinsing, the leftover waste liquid typically has an acid content of 7%, which is high in dissolved iron. Rinsing water has a pH of 1-2. If the acid waste liquid and rinse water are released into the environment untreated, they will seriously pollute the environment.

The primary method of using polyaluminum chloride to remove heavy metals from water is to react with the material salts in the water to produce big precipitable substances, which have a purifying effect. Certain dissolved heavy metal salts in water might not react with polyaluminum chloride because they are inert.

However, even though polyaluminum chloride can remove some heavy metals from water, using polyaluminum chloride alone to remove all heavy metals from water is not recommended. Instead, it is necessary to choose the right agents based on the type and content of heavy metals in the water to achieve the desired results. Permanent contaminants are heavy metals.

Fluoride Removal

PAC As a Solution to Fluoride Contaminated Water
With better removal effectiveness of roughly 75–85% in less time spent in the water, Poly Aluminium Chloride (PAC) is an effective coagulant for removing fluoride from water. It has also been discovered that the amount of fluoride removed depends on the initial concentration of fluoride and the coagulant dose.


Because of its unique chemical composition and structure, PAC is a great option for water treatment. It helps remove pollutants and other impurities, resulting in cleaner, safer water that can be used for a variety of applications. Furthermore, PAC’s capacity to create robust flocs improves its performance in various other applications, including paper manufacturing, chemical operations, and wastewater treatment in the textile industry.



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