How to choose PAM?

Differences between CPAM, NPAM, APAM

1、Structure difference

CPAM: A linear polymer compound, because it has a variety of active groups, can be compatible with many substances, adsorption to form hydrogen bonds. Mainly because of the flocculent, negatively charged colloids.

APAM：It is a water-soluble polymer, mainly used for the flocculation settlement of various industrial wastewater, precipitation and clarification treatment, such as steel plant wastewater, electroplating plant wastewater, metallurgical wastewater, coal washing wastewater and other sewage treatment, sludge dewatering, etc. It can also be used for drinking water clarification and purification treatment. Because its molecular chain contains a certain number of polar groups, which can adsorb solid particles suspended in water, make the bridge between particles or through charge neutralization particles to form a large flocculation, so it can accelerate the settlement of the particles in the suspension, there is very obvious to accelerate the clarification of the solution, promote filtration and other effects.

NPAM：It is a polymer or polyelectrolyte, whose molecular chain contains a certain amount of polarity gene can adsorb solid particles suspended in water, so that the particle bridge to form a large flocculation. It accelerates the settlement of particles in the suspension, has a very obvious to accelerate the clarification of the solution, promote filtration and other effects. Because the molecular chain contains amide group or ion gene, it is characterized by a high hydrophilic character, which can be dissolved in water in various proportions. Polyacrylamide aqueous solution has a good tolerance to electrolyte, such as amine chloride and sodium sulfate, which are not sensitive and are compatible with surfactants.

2、Application difference

-Application of NPAM

• Sewage treatment agent: when the suspended sewage is acidic, using nonionic polyacrylamide and flocculant is more appropriate. This is the PAM adsorption bridge role, so that the suspended particles produce flocculation precipitation, to achieve the purpose of purifying sewage. It can also be used for the purification of tap water, especially combined with inorganic flocculant, with the best effect in water treatment.
• Textile industrial additives: adding some chemicals can be allocated to chemical data, used for textile sizing.
• Sand fixation: the non-ionic polyacrylamide into 0.3% concentration and crosslinking agent, spraying on the desert can play the role of sand fixation.
• Soil moisturizer: used as a soil moisturizer and various modified polyacrylamides.

-Apllication of CPAM

• Sludge dewatering: according to the dirty nature of the product can be selected from the corresponding brand, can be effectively gravity sludge dewatering before the sludge into the pressure filtration. When dehydration, the catkins is large, does not stick the filter cloth, does not stray, the dosage is small, the dehydration efficiency is high, the moisture content of mud cake is below 80%.
• Sewage and organic wastewater treatment: this product in acidic or alkaline medium are Yang electric, the sewage suspended particles with Yin charge sewage flocculation precipitation, clarification is extremely effective, such as alcohol factory wastewater, brewery wastewater, monosodium glutamate factory wastewater, sugar factory wastewater, meat factory wastewater, beverage factory, textile dyeing factory wastewater, with cationic polyacrylamide than with anionic polyacrylamide, nonionic polyacrylamide or inorganic salt effect several times or dozens of times, because this kind of wastewater generally with Yin charge.
• Water plant water treatment flocculant: the product has the characteristics of less dosage, good effect, low cost, farewell is to match the use of inorganic flocculant effect is better.
• Oilfield chemicals: such as clay anti-expansion agent, thickening agent for oilfield acidification, etc.
• Paper aid: cationic PAM paper enhancer is a water-soluble cationic polymer containing carbamyl group, which has the functions of enhancement, retention and filtration, and can effectively improve the strength of paper. The product is also a highly effective dispersant.

-Application of APAM

Industrial wastewater treatment: for suspended particles, comparison, high concentration, particles with Yang charge, water PH value of neutral or alkaline sewage, iron and steel plant wastewater, electroplating plant wastewater, metallurgical wastewater, coal washing wastewater and other wastewater treatment, the best effect.

• Drinking water treatment: many water plants of water source from rivers, the sediment and mineral content is high, turbidity, although after precipitation filtration, still cannot meet the requirements, need to add flocculant, add amount is 1 / 50 of inorganic flocculant, but the effect is several times of inorganic flocculant, for organic pollution serious river water can use inorganic flocculant and cationic polyacrylamide use better.
• Starch factory and alcohol factory loss of starch distiller's grains recycling: now a lot of starch factory wastewater containing starch, now add anionic polyacrylamide, make starch particles flocculating precipitation, then the precipitation through the press filter into cake, can be used as feed, alcohol factory alcohol can also use anionic polyacrylamide dehydration, filter for recycling.

Technical indicators of the PAM

The technical indicators of polyacrylamide generally include molecular weight, hydrolysis degree, ionic degree, viscosity, residual monomer content, etc., so the quality of PAM can also be judged from these indicators

1、Molecular

The molecular weight of PAM is very high and has improved greatly in recent years. PAM applied in the 1970s generally had millions of molecular weights; after the 1980s, the molecular weight of most efficient PAM was above 15 million, and some reached 20 million. Each of these PAM molecules is formed by the polymerization of more than 100,000 acrylamide or acrylamide sodium acrylate (the molecular weight of acrylamide is 71, and the molecular weight of PAM containing 100,000 monomers is 7.1 million). Generally, PAM has better flocculation, with acrylamide of 71 and PAM containing 100,000 monomers of 7.1 million. The molecular weight of polyacrylamide and its derivatives ranges from hundreds of thousands to more than 10 million. According to the molecular mass, it can be divided into low molecular weight (less than 1 million), medium molecular weight (1 million ~ 10 million), high molecular weight (10 million ~ 15 million), and super molecular weight (more than 15 million).

2、Hydrolysis&ionicity

The ionicity of PAM has a great impact on its use effect, but its appropriate value depends on the type and nature of the material treated, and there will be different best values in different cases. If the ionic strength of the treated material is higher (including more inorganic matter), the ionic degree of the PAM used should be higher, otherwise it should be lower. Usually, aniicity is called hydrolysis. And the ionicity generally refers to the cation.

Degree of inonicity=n/(m+n)*100%

3、Residual monomer

The residual monomer content of PAM refers to the acrylamide monomer content with no complete reaction and finally remaining in the polyacrylamide products in the process of polymerization of acrylamide into polyacrylamide, which is an important parameter to measure whether it is applicable to the food industry. Polyacrylamide is nontoxic, but acrylamide has some toxicity. In the industrial polyacrylamide, it is inevitable to leave a trace amount of unpolymerized acrylamide monomer. Therefore, the residual monomer content in the PAM product must be strictly controlled. International regulation, the content of residual monomer in PAM used in drinking water and food industry shall not exceed 0.05%. This value of the foreign famous products is less than 0.03%.

4、Viscosity

The PAM solution is very thick. Higher molecular weight of PAM has greater solution viscosity. This is because PAM macro-molecules are long, thin chains with great resistance to movement in solution. The essence of viscosity is the size of the friction force in the solution, also known as the internal friction coefficient. The viscosity of solutions of various polymer organic matter is higher and increases with increasing molecular weight. A method to determine the molecular weight of polymer organic matter is to determine the viscosity of a certain concentration of solution under certain conditions, and then calculate its molecular weight according to a certain formula, which is called "sticky average molecular weigh.

The selection of PAM

Polyacrylamide can be divided into non-ionic, anionic and cationic polyacrylamide types according to its ionic characteristics. According to the molecular weight of different specifications of molecular weight, ionomicity derived many models, in the face of the market disorderly specifications system, for their own sewage system preferred the best polyacrylamide model is really very difficult. As that, getting sewage or sludge polyacrylicyl selection of common problems makes a big difference.

1、Understand the source of the sludge

Sludge is an inevitable product of sewage treatment. First of all, we should understand the source, nature, composition and solid content of sludge. According to the different main components of sludge, sludge can be divided into organic sludge and inorganic sludge. Generally speaking, cationic polyacrylamide is used for the treatment of organic sludge, anionic polyacrylamide is used for the treatment of inorganic sludge, cationic polyacrylamide is not easy when the alkaline is strong, and anionic polyacrylamide should not be used when the acid is strong, the solid content of sludge is high, usually the amount of polyacrylamide is large.

2、The molecular weight selection of the polyacrylamide

Polyacrylamide molecular weight refers to the length of molecular chain, polyacrylamide molecular weight between 500-18 million, in general, the higher the molecular weight of polyacrylamide products, viscosity, however, when in use, not the higher the molecular weight products, the better the effect, specific in use, according to the actual application industry, water quality, processing equipment conditions, to decide the appropriate polyacrylamide molecular weight. Polyacrylamide is a polymer coagulant, which can be divided into low molecular weight (<1 million), medium molecular weight (2-4 million) and high molecular weight (> 7 million). Polyacrylamide is used in wastewater treatment, with a molecular weight ranging from millions to tens of millions of polymer water-soluble organic polymers. Domestic polymeric polyacrylamide are: non-ionic polyacrylamide (NPAM, molecular weight 8-15 million), anionic polyacrylamide (APAM, molecular weight 8-20 million), cationic polyacrylamide (CPAM, molecular weight 8-12 million, ionicity 10% -80%).If the coagulant is used, the higher the molecular weight, the closer the catkins, the less the drug, but the molecular weight of anionic polyacrylamide is recommended not to exceed 20 million. If in terms of sludge dewatering. Using the belt filter press, the general molecular weight can not be too high, if the molecular weight is very high, it may cause the filter cloth blockage, affect the dehydration effect; for example, you use the centrifugal filter press, the molecular weight requirements should be higher, because the centrifugal filter press requires the catkins to shear as far as possible, so we should choose a relatively high molecular weight products.

3.Ionomicity selection of the polyacrylamide species

For the dehydrated sludge, flocculants with different ion degrees can be screened through small experiments to select the best and appropriate polyacrylamide, so that the best flocculant effect can be achieved, and the minimum amount of dosage can be added and save the cost. Key to ionic selection:

• The size of the flocculant
• Catculent strength (moisture content）
• Mix of the polyacrylamide with the sludge sludge
• The dissolution of the polyacrylamide solution