Polyacrylamide (PAM) is a linear water-soluble polymer. It is the most commonly used water treatment agent in our sewage treatment. There is no one! In our practical application, PAM is divided into three types: cationic, anionic and non-ionic. How to choose these three types of PAM should start from the differences among them!

1、 Structural differences

Cationic polyacrylamide (CPAM): it is a linear polymer compound. Because it has a variety of active groups, it can form hydrogen bonds by affinity and adsorption with many substances. It mainly flocculates negatively charged colloids.

Anionic polyacrylamide (APAM): it is a water-soluble polymer, which is mainly used for flocculation, sedimentation and clarification of various industrial wastewater, such as wastewater treatment of iron and steel plant, electroplating plant, metallurgical wastewater, coal washing wastewater and sludge dewatering. It can also be used for drinking water clarification and purification. Because its molecular chain contains a certain number of polar groups, it can bridge the particles by adsorbing the solid particles suspended in the water or condense the particles to form large flocs through charge neutralization. Therefore, it can accelerate the sedimentation of particles in the suspension, significantly accelerate the clarification of solution and promote filtration.

Non ionic polyacrylamide (NPAM): it is a high molecular polymer or polyelectrolyte. Its molecular chain contains a certain amount of polar genes, which can adsorb solid particles suspended in water and bridge between particles to form large flocs. It accelerates the sedimentation of particles in the suspension, has a very obvious effect of accelerating the clarification of the solution and promoting filtration. Because the molecular chain contains amide groups or ionic genes, it is characterized by high hydrophilicity and can be dissolved in water in various proportions. Polyacrylamide aqueous solution has good tolerance to electrolytes, such as amine chloride and sodium sulfate. It is also compatible with surfactants.

2、 Different uses

1. Application of nonionic polyacrylamide

Sewage treatment agent: when the suspended sewage is acidic, it is more appropriate to use non-ionic polyacrylamide as flocculant. This is that PAM plays the role of adsorption and bridging, so that suspended particles produce flocculation and sedimentation, so as to achieve the purpose of purifying sewage. It can also be used for the purification of tap water, especially in combination with inorganic flocculant, which has the best effect in water treatment.

Textile industry auxiliaries: chemical materials can be prepared by adding some chemicals for textile sizing.

Sand prevention and fixation: dissolve the non-ionic polyacrylamide into 0.3% concentration, add crosslinking agent, and spray it on the desert to prevent and fix sand.

Soil humectant: used as the basic raw material of soil humectant and various modified polyacrylamide.

2. Application of cationic polyacrylamide

Sludge dewatering: the corresponding brand of this product can be selected according to the nature of the sludge, which can effectively carry out gravity sludge dewatering before the sludge enters the pressure filtration. During dehydration, the floc is large, does not stick to the filter cloth, does not flow away during pressure filtration, the dosage is small, the dehydration efficiency is high, and the moisture content of mud cake is less than 80%.

Treatment of sewage and organic wastewater: This product shows positive electricity in acidic or alkaline medium, so it is very effective to flocculate, precipitate and clarify the sewage with negative charge of suspended particles in the sewage, such as alcohol factory wastewater, brewery wastewater, monosodium glutamate factory wastewater, sugar factory wastewater, meat and food factory wastewater, beverage factory wastewater, textile printing and dyeing factory wastewater, etc, The effect of cationic polyacrylamide is several times or tens of times higher than that of anionic polyacrylamide, non-ionic polyacrylamide or inorganic salt, because this kind of wastewater generally has negative charge.

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

Oilfield chemicals: such as clay anti swelling agent, thickener for oilfield acidification, etc.

Papermaking AIDS: Cationic PAM paper enhancer is a water-soluble cationic polymer containing carbamoyl group. It has the functions of reinforcement, retention and filtration, and can effectively improve the strength of paper. At the same time, the product is also a highly efficient dispersant.

3. Application of anionic polyacrylamide

Industrial wastewater treatment: for suspended particles, sewage with relatively high concentration, particles with positive charge, neutral or alkaline pH value of water, steel plant wastewater, electroplating plant wastewater, metallurgical wastewater, coal washing wastewater and other wastewater treatment, the effect is the best.

Drinking water treatment: the water source of many Waterworks in China comes from rivers. The content of sediment and minerals is high and relatively turbid. Although it can not meet the requirements after sedimentation and filtration, it needs to add flocculant. The dosage is 1 / 50 of inorganic flocculant, but the effect is several times that of inorganic flocculant, For rivers with serious organic pollution, inorganic flocculant and cationic polyacrylamide can be used together, and the effect is better.

Recovery of lost starch distiller's grains in starch factories and alcohol factories: at present, the wastewater of many starch factories contains a lot of starch. Now anionic polyacrylamide is added to flocculate and precipitate the starch particles, and then the precipitate is pressed and filtered into cake shape by filter press, which can be used as feed. The alcohol in alcohol factories can also be dehydrated by anionic polyacrylamide and recycled by filter press.

3、 How to distinguish three PAM?

1. Use pH value for judgment

Firstly, the polyacrylamide reagent that is in use and has good effect is configured into an appropriate proportion of aqueous solution, and the pH test paper is prepared. The pH of polyacrylamide reagent with different ionic types will be different, and the polyacrylamide production process will also affect the pH. this can be consulted with regular polyacrylamide manufacturers.

2. The mixed exclusion method is used for judgment

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

3. Judging by the sewage treatment in the laboratory

First of all, we need to understand the water quality characteristics of the sewage to be treated. Anionic polyacrylamide is mainly used to flocculate the sewage with high alkaline or inorganic content or more negative charge; Cationic polyacrylamide is mainly used to flocculate sewage with high acid or organic content or more positive charge. Make a simple judgment by the effect of the agent.