Cationic polymers used for wastewater treatment are mainly the following: polydimethyl diallylammonium chloride (PDADMAC),  cationic polyacrylamide (CPAM), cationic polyaluminum (PAC), cationic starch and polyethyleneimine (PEI). They each have different performance characteristics and scope of application. The following is an introduction and comparison of their performance characteristics and scope of application.

1. Poly(dimethyl diallylammonium chloride) (PDADMAC)

Performance Characteristics

High charge density: high cationic charge density, can quickly neutralize negatively charged suspended particles.

PDADMAC is not sensitive to pH changes and is chlorine resistant.

Through electric neutralization and adsorption and bridging, it can destabilize and flocculate the suspended particles in water and water-soluble substances containing negatively charged genes, and it has obvious effect in decolorization, sterilization and removal of organic matter.

As a flocculant, polydimethyl diallylammonium chloride has the characteristics of low dosage, large floc, fast settling speed, low residual turbidity and low sludge production.

Scope of application

It can be used for decolorization, flocculation and purification in water treatment process;

As cationic coagulant in sewage treatment, mining and mineral processing;

In textile dyeing and finishing auxiliaries it can be used as a non-formaldehyde color fixing agent to form a film on fabrics and improve dyeing fastness;

Commonly used in the papermaking industry to improve the hanging rate of pulp, in papermaking auxiliaries can be used as retention filtering agent, paper coating antistatic;

In papermaking process, used as anionic waste capture agent, AKD ripening promoter;

In oilfield chemicals, it is used as clay stabilizer for drilling, cationic modifier for acidification and fracturing in water injection, flocculant, water plugging agent, drilling fluid treatment agent and so on.

2. Cationic polyacrylamide (CPAM)

Performance characteristics

Electric neutralization: CPAM has a large number of cationic groups, which can neutralize the negative charge of suspended particles in water.

Strong adsorption and bridging effect: through adsorption and bridging effect, the fine particles will be gathered into large flocs to accelerate the settlement.

Fast flocculation: fast flocculation and settling speed.

Good solubility: easy to dissolve, easy to use.

Scope of application

Municipal wastewater treatment: for removing suspended solids and organic pollutants.

Industrial wastewater treatment: for chemical, pharmaceutical, food, textile and other industries.

Sludge dewatering: improve the dewatering efficiency of sludge.

3. Cationic polyaluminum (PAC)

Performance characteristics

Compound polymer: compounded by a variety of cations and aluminum ions, high charge density.

Good flocculation performance: can effectively remove suspended matter and colloid at low dose.

Good stability: insensitive to changes in water quality.

Scope of application

Sewage treatment: suitable for industrial wastewater and municipal sewage treatment.

Drinking water treatment: purify drinking water, remove suspended particles and organic matter.

Mineral treatment: flocculation and sedimentation of mineral slurry and improvement of mineral recovery rate.

4. Cationic starch

Performance characteristics

Natural polymer: modified from natural starch.

Good adsorption: strong adsorption capacity for suspended particles and colloidal substances.

Biodegradability: environmentally friendly.

Scope of application

Paper industry: Improve pulp strength and surface smoothness.

Textile industry: improve yarn strength and softness.

Food processing: clarification of fruit juices and beverages, removal of suspended particles and impurities.

5. Polyethyleneimine (PEI)

Performance Characteristics

High charge density: with a high density of cationic groups, strong electrical neutralization ability.

Good adsorption capacity: strong adsorption of organic matter and heavy metals.

Acid and alkali resistance: stable under strong acid and alkali conditions.

Scope of application

Industrial wastewater treatment: especially suitable for heavy metal-containing wastewater and high concentration organic wastewater treatment.

Paper industry: used as pulp reinforcing agent and paper dry and wet strength agent.

Chemical industry: used as flocculant and stabilizer.

Summary

Polydimethyl diallylammonium chloride: suitable for drinking water treatment, sewage treatment, paper making and petroleum industry, adapt to a wide range of pH, the use of a small amount but the effect is obvious.

Cationic polyacrylamide: widely used in sewage treatment and paper industry, suitable for a variety of wastewater treatment, flocculation and sedimentation effect.

Cationic polyaluminum: widely used in sewage and drinking water treatment, good stability, adapt to water quality changes.

Cationic starch: mainly used in paper making, textile and food processing, with good biodegradability.

Polyethyleneimine: outstanding performance in the treatment of heavy metal-containing wastewater and high concentration of organic wastewater, strong acid and alkali resistance, narrower application range but obvious effect.

Various types of cationic polymers have their own advantages and scope of application, the selection should be based on the specific water quality and treatment needs, taking into account the performance and cost of the agent, in order to achieve good treatment results.