Ten minutes to distinguish and use cationic, anionic, and non-ionic PAM!

Polyacrylamide (PAM) is a linear water-soluble polymer and the most commonly used water treatment agent in our wastewater treatment industry, without exception! In our practical applications, PAM is divided into three types: cationic, anionic, and non-ionic. How to choose these three types of PAM should start with the differences between them!

1、 Structural differences

Cationic Polyacrylamide (CPAM): It is a linear polymer compound that, due to its various active functional groups, can form hydrogen bonds by affinity and adsorption with many substances. Mainly flocculation of negatively charged colloids.

Anionic Polyacrylamide (APAM): It is a water-soluble polymer mainly used for flocculation, sedimentation, and clarification treatment of various industrial wastewater, such as steel plant wastewater, electroplating plant wastewater, metallurgical wastewater, coal washing wastewater, and sludge dewatering. It can also be used for clarifying and purifying drinking water. Due to the presence of a certain number of polar groups in its molecular chain, it can adsorb solid particles suspended in water, bridging between particles or aggregating particles to form large flocs through charge neutralization. Therefore, it can accelerate the settling of particles in suspension, significantly improve solution clarification, and promote filtration.

Non ionic polyacrylamide (NPAM): It is a polymer or polyelectrolyte with a certain amount of polar genes in its molecular chain that can adsorb suspended solid particles in water, bridging particles to form large flocs. It accelerates the settling of particles in the suspension, significantly improves the clarification of the solution, and promotes filtration. Due to the presence of amide groups or ion genes in the molecular chain, its significant feature is high hydrophilicity, which can be dissolved in water in various proportions. Polyacrylamide aqueous solution has good tolerance for electrolytes, such as amine chloride and sodium sulfate, and is also compatible with surfactants.

2、 Difference in usage

1) Application of non-ionic polyacrylamide

Wastewater treatment agent: When suspended wastewater is acidic, non-ionic polyacrylamide and flocculant are more suitable. This is the adsorption bridging effect of PAM, which causes suspended particles to flocculate and precipitate, achieving the goal of purifying wastewater. It can also be used for purifying tap water, especially when combined with inorganic flocculants, which has the best effect in water treatment.

Textile industry additives: Adding some chemicals can be formulated into chemical materials for textile sizing.

Sand prevention and stabilization: Dissolve non-ionic polyacrylamide into a 0.3% concentration and add it to a crosslinking agent. Spray it on the desert to achieve sand prevention and stabilization.

Soil Moisturizing Agent: Used as a basic raw material for soil moisturizing agents and various modified polyacrylamides.

2) Application of cationic polyacrylamide

Sludge dewatering: Depending on the nature of the sludge, the corresponding brand of this product can be selected, which can effectively perform gravity sludge dewatering before the sludge enters the filter press. During dehydration, large flocs are produced, which do not stick to the filter cloth and do not disperse during pressure filtration. The amount used is small, and the dehydration efficiency is high. The moisture content of the mud cake is below 80%.

The treatment of sewage and organic wastewater: This product exhibits cationic properties in acidic or alkaline media, which is extremely effective in flocculation and precipitation of negatively charged suspended particles in sewage, such as alcohol factory wastewater, beer factory wastewater, monosodium glutamate factory wastewater, sugar factory wastewater, meat factory wastewater, beverage factory wastewater, textile printing and dyeing factory wastewater, etc. The use of cationic polyacrylamide is several times or tens of times more effective than using anionic polyacrylamide, nonionic polyacrylamide or inorganic salts because such wastewater generally carries negative charges.

Water treatment flocculant for waterworks: This product has the characteristics of low dosage, good effect, and low cost. It is better to use it in combination with inorganic flocculants for better results.

Oilfield chemicals: such as clay anti swelling agents, thickening agents for oilfield acidification, etc.

Paper making additive: Cationic PAM paper enhancer is a water-soluble cationic polymer containing amino formyl groups, which has functions such as reinforcement, retention aid, and filtration aid, and can effectively improve the strength of paper. At the same time, this product is also an efficient dispersant.

3) Application of anionic polyacrylamide

Industrial wastewater treatment: For wastewater with suspended particles, high concentration, positively charged particles, neutral or alkaline pH value, steel plant wastewater, electroplating plant wastewater, metallurgical wastewater, coal washing wastewater, etc., the best effect is achieved.

Drinking water treatment: Many water plants in China source water from rivers, which have high sediment and mineral content and are relatively turbid. Although they have been filtered through sedimentation, they still cannot meet the requirements. Therefore, coagulants need to be added, with a dosage of 1/50 of inorganic coagulants, but the effect is several times that of inorganic coagulants. For rivers with severe organic pollution, the combination of inorganic coagulants and cationic polyacrylamide can be used for better results.

The recovery of lost starch distiller's grains from starch and alcohol factories: Nowadays, many starch factories' wastewater contains a lot of starch. Anionic polyacrylamide is added to flocculate and precipitate starch particles, and then the precipitate is filtered by a filter press into a cake shape, which can be used as feed. Alcohol from alcohol factories can also be dehydrated by anionic polyacrylamide and filtered for recovery.

3、How to distinguish the three types of PAM?

1) Using pH value for judgment

Firstly, prepare an appropriate proportion of aqueous solution of the polyacrylamide reagent that is currently in use and has good effects, and prepare pH test strips. The acidity and alkalinity of polyacrylamide reagents with different ion types may vary, and the production process of polyacrylamide may also affect the acidity and alkalinity. This can be consulted with a reputable polyacrylamide manufacturer.

2) Using mixed exclusion method for judgment

Friends with a basic foundation in chemistry will know that in chemistry, anions and cations undergo chemical reactions when they are together. We can make a simple judgment from this point.

3) Judging by the laboratory sewage treatment situation

Firstly, we need to understand the water quality characteristics of the wastewater to be treated. Anionic polyacrylamide agents mainly have good flocculation effects on wastewater with high alkaline or inorganic content or high negative charge; Cationic polyacrylamide agents mainly have good flocculation effects on wastewater with high acidity or organic content, or with a high positive charge. Simple judgments can be made based on the effectiveness of the medication.