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Polyacrylamide Precautions
Aug 24, 2017

Polyacrylamide Category Polyacrylamide Introduction: Polyacrylamide (PAM) is a water-soluble polymer, insoluble in most organic solvents, has good flocculation, can reduce the friction between the liquid resistance, according to ion characteristics Can be divided into non-ionic, anionic, cationic and amphoteric four types.

PAM polyacrylamide is a water-soluble linear polymer composed of acrylamide (AM) monomer initiated by free radicals. It has good flocculation property and can reduce the frictional resistance between liquids. For non-ionic, anionic, cationic and amphoteric four types. Polyacrylamide (PAM) is insoluble in most organic solvents such as methanol, ethanol, acetone, ether, aliphatic and aromatic hydrocarbons, except for a few polar organic solvents such as acetic acid, acrylic acid, chloroacetic acid, ethylene glycol, Molten urea and formamide. But the solubility of these organic solvents is limited, often need to heat, or no much application value.

At the appropriate low concentration, the polyacrylamide solution can be regarded as a network structure, intertrochanical entanglement and hydrogen bonding to form a mesh node; when the concentration is high, because the solution contains many chain-linked contacts, The solution is gelatinous. PAM aqueous solution and a lot of water and miscible organic compounds have good compatibility, the electrolyte has a good compatibility, the amine chloride, calcium sulfate, copper sulfate, potassium hydroxide, sodium carbonate, sodium borate, nitric acid Sodium, sodium phosphate, sodium sulfate, zinc chloride, boric acid and phosphoric acid and other substances are not sensitive. [1] 

Polyacrylamide mesh: mesh refers to the size of the material or roughness, mesh number is the number of square meters per unit area. General definition is 1 inch * 1 inch area of the number of mesh, Number of mesh mesh. Such as 600 mesh is 600 square feet per square inch mesh, polyacrylamide mesh head 20 mesh to 80 mesh, that is, between 0.85mm ~ 0.2mm, which is the granular polyacrylamide mesh size, powder The size of polyacrylamide can be controlled at about 100 mesh, the greater the number of polyacrylamide easier to dissolve, the size of polyacrylamide alone can not measure the size of the product is good or bad!

Polyacrylamide is white powder or small particles, the density of 1.32g / cm3 (23 degrees), glass transition temperature of 188 degrees, softening temperature of nearly 210 degrees, the general method of drying contains a small amount of water, dry The homopolymer, which is separated from the environment by the freeze-drying process, is a white, soft, non-crystalline solid, but is a glassy partially transparent solid, completely dry polyacrylamide PAM when precipitated from the solution and dried Is a brittle white solid, commercial polyacrylamide drying is usually dry under moderate conditions, the general water content of 5% to 15%, cast on the glass plate prepared by the polymer film, it is transparent, hard, fragile s solid type

Polyacrylamide Use Precautions:

1, the size of the floc: flocculation is too small will affect the speed of drainage, floc too will make the flock more water and reduce the mud cake dryness. The size of the floc can be adjusted by selecting the molecular weight of the polyacrylamide.

2, sludge characteristics: the first point to understand the source of sludge, characteristics and composition, the proportion. According to the nature of the different sludge can be divided into two kinds of organic and inorganic sludge. Cationic polyacrylamide for the disposal of organic sludge, the relative anionic polyacrylamide flocculant for inorganic sludge, alkaline strong with anionic polyacrylamide, and acidity is not strong with anionic polyacrylamide, solid content High sludge usually polyacrylamide is also used in large quantities.

3, floc strength: flocs in the shear under the action should be stable and not broken. Increasing the molecular weight of polyacrylamide or selecting the appropriate molecular structure contributes to the progress of floc stability.

4, polyacrylamide ion degree: for the dewatered sludge, can be used to different degrees of flocculant after a small test to be selected to select the best suitable polyacrylamide, so that can get the best flocculant effect, But also to minimize the amount of drugs, saving costs.

5, polyacrylamide dissolved: dissolved in order to fully play the role of flocculation. Sometimes the need to speed up the dissolution rate, then consider the progress of polyacrylamide solution concentration.

Polyacrylamide and polyaluminium chloride can be used at the same time

In fact, when the sewage treatment time, some sewage, the use of a single flocculant is not achieve the effect, must be used in combination with two, in the use of inorganic flocculant PAC and polyacrylamide composite flocculant treatment of sewage will achieve better Of the effect, but when adding drugs to pay attention to the order, the order is not correct, but also achieve the effect.

Polyacrylamide and other flocculants are mixed using the sequential method of addition:

When using the complex flocculant must pay attention to the order of addition and the time interval! PAC and PAM is used in combination with PAC first to complete the charge / colloid decay to form a small floc, the further increase in floc volume is conducive to full precipitation. As the polymerization of aluminum chloride PAC reaction time is very short, so after the need to join the strong mixing, PAM role of time to long, mixed attention to the first strong after the weak - first strong is to mix even after the weak is to avoid damage to floc! Polyacrylamide is a flocculant, poly aluminum chloride is a coagulant, under normal circumstances is the first plus coagulant plus polyacrylamide, but for the sake of insurance, it is recommended that you through the experimental results to determine the order of addition! Dosing point, dosage, dosing time and mixing strength need to determine the experiment, remember that they can not put two of their drugs together, otherwise it will affect the effect, increase the use of cost.

Judgment of failure of polyacrylamide flocculant

Often encountered a lot of sewage treatment plants, especially in the southern region, due to the humid climate, some of the sewage plant polyacrylamide due to a long time or the packing port is not tightened lead to moisture absorption agglomeration, for polyacrylamide flocculant agglomeration , Many people have questions, is not a failure, but also can not be used, in fact, as this situation as long as you can dissolve it, the aqueous solution has a viscosity, is not a failure, but after the agglomeration of polyacrylamide is difficult to dissolve Open, in fact, also means that the waste of resources. In fact, the shelf life of different types of polyacrylamide is very different, this and its structure is related, relatively speaking, anionic polyacrylamide effective period of time to long, cationic polyacrylamide generally our state warranty period of 1 year The Beyond this period, are regarded as more than the shelf life. There is a risk of failure,

Polyacrylamide failure can be judged from two aspects, one is the viscosity reduction, the second is the flocculation effect worse.