Properties and applications of polyacrylamide
Polyacrylamide is referred to as PAM, also known as No. 3 coagulant. The molecular formula is, and it is a linear water-soluble polymer with a molecular weight of
Between 3 million and 18 million, it appears as white powder or colorless viscous colloid, odorless, neutral, soluble in water, and easily decomposes when the temperature exceeds 120°C.
Polyacrylamide molecules have positive genes 2
2. Physical properties; This product is a colloid and powder. Colloidal products are colorless and transparent, non-toxic and non-corrosive. Powder is a white granular or fine powder solid, both of which are soluble in water. The rate of water absorption varies with the ionic properties of the derivatives. But it is almost insoluble in general solvents, and can only be dissolved by about 1 in solvents such as ethylene glycol, glycerin, glacial acetic acid, formamide, lactic acid, and acrylic acid. Products of different varieties and different molecular weights have different properties.
3. Usage: Mainly used in oil extraction, sugar refining, coal washing, mineral processing, papermaking, coating, hydrometallurgy, textile, stone cutting, chemical industry, pesticides, medicine and sewage treatment, etc. Colloidal and powder polyacrylamide can be produced with different contents, molecular weights and degrees of hydrolysis according to the product quality requirements provided by users.
PAM flocculant has a wide range of applications, and various applications require different properties. In order to meet the needs of various uses, countries around the world have developed very complex varieties and specifications. Nowadays, A relatively complete product series has been formed.
4. Instructions for use: This product is a linear polymer, especially when using powder. When preparing PAM, the following points should be achieved:
Use water that is neutral and does not contain salts and inclusions. It is advisable;
Use warm water of about 40℃ but no more than 60℃ to accelerate the dissolution of the flocculant;
When dissolving, slowly sprinkle PAM into the water. Sprinkling too much at one time will cause difficulties. Sol group; if possible, the use of step-by-step addition will be more conducive to the uniform distribution of flocculant;
When polyacrylamide is put into water, it should be stirred as soon as possible to make the agent and water quickly and fully mix. Do not stir too vigorously, and avoid strong mechanical stirring and pumps, otherwise the 3 polymer will be degraded. The stirring should be 100-300r/min;
The solubility should be controlled at 0.5-0.8 on a dry basis. , dilute to 0.08 before use;
How much is used, how much is dissolved, dilute solutions are prone to degradation.
5. Product standards are implemented in accordance with GB/T13940-92
Colloidal polyacrylamide product standards:
Project indicators
Anionic nonionic cationic
Appearance white gelatinous white gelatin white gelatinous gelatinous substance
Solid content ≥ 8—30 8—30 8—30
Molecular weight 300—900 200—900 200—500
Free monomer ≤ 0.5 0.5 0.5
Hydrolysis degree 5-30 ≤5 5-30
Polyacrylamide dry powder product standard:
Project indicators
Anionic non-ionic cationic
Appearance white or slightly yellow powder
Solid content ≥ 90 90 90
Molecular weight 300—1800 300—1000 500—1000
Free monomer ≤ 0.5 0.5 0.5
Hydrolysis degree 20—30 ≤5 Ionicity 5—30
Full dissolution time 0.5-2 2-4 0.5-1
PH value alkali medium acid
6. Storage methods and transportation
PAM should be kept sealed, dry, protected from light, and protected from high temperatures during storage to avoid moisture absorption and degradation;
PAM should not be in direct contact with metal containers When storing, it should be lined with plastic;
PAM should not be stored for too long, otherwise it will lead to aging and degradation. Generally, the thinner the concentration, the shorter the validity period.
7. Note: PAM itself is not toxic. It is only harmful when inhaled by more than 5 parts per thousand because the absorption of nutrients by the gastrointestinal mucosa is blocked by adhesion. The residual acrylamide monomer in PAM is toxic and must be strictly controlled in food applications.
8. Packaging: 25Kg/bag of colloid; 25Kg/bag of dry powder, with a three-in-one composite bag outside and a polyethylene-lined bag.
Polyacrylamide
1. Product introduction:
Polyacrylamide is obtained by homopolymerization or ***polymerization of acrylamide monomer under the action of initiator The general term for polymers is one of the most widely used varieties of water-soluble polymer materials. It is mainly used in petroleum mining, water treatment, textile, papermaking, mineral processing, medicine, agriculture and other industries. It is known as additives in various industries. Polyacrylamide
Easily soluble in water and almost insoluble in organic solvents. It has the characteristics of a high polymer electrolyte in neutral and alkaline media. It is sensitive to salt electrolytes and can cross-link with high-valent metal ions. Forming an insoluble gel, due to the polar group of its molecular chain, it can adsorb suspended solid particles in sewage, bridge the particles or aggregate the particles to form large flocs through charge neutralization www.hjbuye.cn . Therefore, it can accelerate the sedimentation of particles in suspension, and has very obvious effects on accelerating solution clarification and promoting filtration. There are complete varieties of cationic, anionic and non-ionic types to meet all needs. It has good water solubility and can be completely dissolved in cold water. By adding a small amount of this series of products, you can get a great flocculation effect. Generally, you only need to add 0.01-10 m to fully exert its effect. This series of products can show greater effect when used together with inorganic flocculants.
2. Product characteristics
1) Flocculating property: PAM can neutralize suspended substances through electricity, bridge adsorption, and act as a flocculation.
2) Adhesion: It can act as an adhesive through mechanical, physical and chemical effects.
3) Resistance reduction: PAM can effectively reduce the frictional resistance of fluids. Adding a trace amount of PAM to water can reduce the resistance by 50-80%.
4) Thickening: PAM has a thickening effect under both neutral and acidic conditions. When the pH value is above 10, PAM is easily hydrolyzed and has a semi-reticular structure, and the thickening will be more obvious.
3. Introduction to the principle of PAM:
1) Principle of flocculation: When PAM is used for flocculation, it depends on the surface properties of the flocculated species, especially the dynamic potential, viscosity, and turbidity. The degree is related to the pH value of the suspension. The dynamic potential on the surface of the particles is the reason why the particles inhibit aggregation. Adding PAM with opposite surface charge can reduce the dynamic potential and cause agglomeration.
2) Adsorption bridging: PAM molecular chains are fixed on the surfaces of different particles, and polymer bridges are formed between the particles, causing the particles to form aggregates and settle.
3) Surface adsorption: various adsorptions of polar group particles on PAM molecules.
4) Netting effect: The PAM molecular chain and the dispersed phase implicate the dispersed phase together through various mechanical, physical, chemical and other effects to form a network, thus acting as a netting effect.
IV. How to use PAM:
Polyacrylamide is used through various processes of dissolution, addition and mixing.
Due to the variety and model used And the usage amount varies according to the purpose of processing. Therefore, it is necessary to conduct preliminary tests in advance to grasp the most appropriate variety, model and usage amount. The product aqueous solution should be prepared in enamel, galvanized, aluminum or plastic buckets.
Do not prepare or store it in iron containers.
1) Dissolution method
Before use, dissolve the solid to a concentration of 0.1∽0.5 so that it can take effect quickly. While dissolving, stir the water in the dissolution tank. Add the solids while adding them carefully,
so that they are evenly dispersed in the water and don't let them form lumps.
Since strong stirring for a long time will reduce its performance, it is recommended that the mixer be used for dissolution at a speed of about 20 to 200 rpm.
If the solution is left for a long time, its performance will gradually decrease depending on the water quality. Therefore, after preparing the aqueous solution, please use it within three days.
2) Addition of dissolving solution
Usually add an aqueous solution of about 0.1, but in the case of high concentration and high viscosity of the suspension, it is recommended to further dilute the aqueous solution to about 0.01 , it will be easy to mix and achieve full effect.
After adding the flocculant aqueous solution to the suspension, vigorous stirring for a long time will destroy the formed flocs. Therefore, please add it just before the flocculation treatment. of aqueous solution.
5. PAM product classification:
Nonionic polyacrylamide:
Nonionic polyacrylamide series products are synthesized through special processes and have High molecular weight linear polymer with low ionicity. Due to its special group,
poop gives it the functions of flocculation, dispersion, thickening, adhesion, film formation, gel, and stable colloid. Nonionic polyacrylamide can be divided into ultra-high molecular weight polyacrylamide, high molecular weight polyacrylamide, medium molecular weight polyacrylamide and low molecular weight polyacrylamide according to molecular weight. Ultra-high molecular weight polyacrylamide is mainly used for tertiary oil recovery in oil fields. High molecular weight polyacrylamide is mainly used as a flocculant. Medium molecular weight polyacrylamide is mainly used as a dry strength agent for paper. Low molecular weight polyacrylamide is mainly used as a dry strength agent for paper. Make dispersant.
1) Technical indicators:
Appearance: white particles or powder
Molecular weight: tens to 20 million
2) Usage:
1. In the mining industry, a large amount of water is usually used, and in the end it is often necessary to recover useful solids in the water and purify and recycle the wastewater. The application of non-ionic polyacrylamide flocculant can promote the sinking of solids,
liquid clarification and mud cake dehydration, thereby improving production efficiency, reducing tailings loss and water consumption, and reducing equipment investment. and processing costs, and avoid environmental pollution.
For example: leaching of molybdenum,
precipitation and separation of gold, recovery of uranium ore;
2. In the process of coal washing,
pulverized coal and coal Sedimentation and filtration of mud are major economic and pollution control issues. Non-ionic polyacrylamide series products can reduce soil coloration, pipeline blockage, pump maintenance and river water pollution, improve production capacity,
recover coal powder and increase filtration rate, and can also completely clarify water;
3. In the electrolytic refining process, it can homogenize the metal precipitation, make the coating brighter, and improve the current efficiency;
4. In the inorganic fiber slurry, the formed asbestos- The drainage of cement products is improved, which increases the strength of asbestos board blanks; in insulating boards,
can improve the binding ability of additives and fibers;
5. Can be used as plastic wrap and additives for agricultural films;
6. Nonionic polyacrylamide composite materials can be used as grouting materials for mineral deposits, ponds, dams, and foundations;
7. Can be used in soil improvement Enhance the solidity of the soil aggregate structure, increase the soil moisture content and the load-bearing load of the soil structure;
8. Polyacrylamide gel can be used to separate substances that maintain biological activity, control the release of drugs and enzymes. Gel electrolytes for embedding, protein electrophoresis, and batteries.
9. Used for sewage treatment. When the sewage is acidic, this product has special effects. It can also be used in conjunction with polyaluminum, polyferric sulfate, etc.
3) Notes:
1. Ionic PAM uses its long polymer chain to absorb many small particles or oil beads in the sewage and then entangle them together to form a framework. bridge. It is a flocculant with very strong flocculation ability
, and its flocculation speed is faster than that of anionic PAM. In the treatment of oily wastewater in oil fields, it is usually used in conjunction with aluminum salt.
2. Before use, the optimal dosage must be determined through experiments. If the dosage is too low, it will not work, and if the dosage is too high, it will have the opposite effect. This is because beyond a certain concentration, PAM not only has no flocculation effect, but also plays a dispersion and stabilizing effect.
3. A lower concentration should be used when adding medicine to ensure uniform mixing.
Cationic polyacrylamide
Cationic polyacrylamide is a linear polymer compound. Because it has a variety of active groups, it can be affinity and adsorbed with many substances to form hydrogen. key. It is mainly used to flocculate negatively charged colloids.
It has functions such as turbidity removal, decolorization, adsorption, and adhesion. It is suitable for dyeing, papermaking, food, construction, metallurgy, mineral processing, coal powder, oil fields, and aquatic product processing. It is especially suitable for the dehydration treatment of urban sewage, urban sludge, papermaking sludge and other industrial sludge in the treatment of wastewater with high organic colloid content in fermentation and other industries.
1) Technical indicators:
Appearance: white particles or powder;
Molecular weight: 3-15 million
Cation degree: 3 --100
2) Usage:
1. As a flocculant, it is mainly used in industrial solid-liquid separation processes, including sedimentation, clarification, concentration and sludge dehydration. , the main industries used are: urban sewage treatment, paper industry, food processing industry, petrochemical industry, metallurgical industry, mineral processing industry, dyeing industry, sugar industry and wastewater treatment in various industries. It is used for sludge sedimentation and sludge dehydration in the treatment of urban sewage and meat, poultry, and food processing wastewater. The positively charged groups it contains electrically neutralize the negatively charged organic colloids in the sludge and The excellent bridging and cohesion function of polymers promotes the colloidal particles to aggregate into large flocs and separate them from their suspension. www.hjbuye.cn The effect is obvious and the dosage is small.
2. It can be used as paper dry strength agent, retention agent and filter aid in the paper industry. It can greatly improve the quality of paper, save costs and improve the production capacity of paper mills.
It can directly form electrostatic bridges with inorganic salt ions, fibers and other organic polymers to enhance the physical strength of paper, reduce the loss of fibers or fillers, speed up water filtration, and enhance, retain, and assist It has a filtration effect and can also be used to treat white water. At the same time, it can have an obvious flocculation effect during the deinking process.
3. The fiber slurry can improve the drainage of formed asbestos-cement products and increase the strength of asbestos board blanks; in insulation boards, it can improve the binding ability of additives and fibers.
4. It can be used as a clarifier for mine wastewater and coal washing wastewater in the mining and coal preparation industries.
5. It can be used to treat dyeing wastewater, leather wastewater, and oily wastewater to remove turbidity and decolorize them to meet discharge standards.
6. In phosphoric acid purification, it helps to separate gypsum in wet phosphoric acid process.
7. Used as water treatment flocculant in water plants using river water. Less dosage, good effect and low cost. Especially when used in combination with inorganic flocculants, the effect is better. It will become an efficient flocculant for water plants along the Yangtze River, Yellow River and other river basins.
3) Notes:
Preparation and storage of aqueous solutions should be carried out in enamel, galvanized, or plastic barrels, and should not be in contact with iron products;
When dissolving, the product should be added evenly and slowly into a dissolver with stirring and heating measures. Large clumps and long-term severe mechanical shearing should be avoided.
Anionic polyacrylamide
Anionic polyacrylamide series products are water-soluble linear polymers synthesized with a high degree of polymerization. Supplied in a dust-free and free-flowing microgranular state or colloidal form, it is completely soluble in water,
and due to its microgranular form, dissolves quickly. Different types of polyacrylamide have different active groups, which can flocculate different suspended particles and facilitate filtration and separation. This series of products is almost insoluble in any organic solvent and largely soluble in water.
It is widely used in many industries for flocculation, thickening, bonding, scale inhibition, stable colloid, drag reduction, film formation, gel and biological materials, etc.
1) Technical indicators:
Appearance: white particles or powder
Molecular weight: 5 to 25 million
2) Usage:
1. Exploration and development of oil fields, exploration of geology, water conservancy and coal. Used as an additive for drilling mud materials, it can reduce the friction of the drill bit, extend the service life of the drill bit, increase the drilling speed and footage, reduce clogging when changing drills, and have an obvious effect on preventing well collapse. In addition, it also It is used in thickened water oil displacement, fracturing fluid and selective water plugging, and has a significant effect on improving oil recovery;
2. Used for purification of drinking water, river water, urban sludge, Treatment of urban domestic wastewater and industrial wastewater;
3. In the papermaking industry, it is used as a clarification of caustic soda liquid, a fiber dispersant to improve the beating degree, a filler retention aid, and a paper enhancer to improve water filtration. rate and white water recovery;
4. Used in sizing in the textile and carpet industries, cement quick-setting, and synthetic resin coatings. Photosensitive polymers, adhesives, dispersants, as well as agricultural soil gels, mud stabilizers,
Soil conditioners;
5. Sugar making in the sugar industry Juice clarifier;
6. Can be used as aquatic feed additives and binders;
7. Recovery of treated oil in refinery water treatment fields.