Polyacrylamide (PAM) is a generic term for homopolymers of acrylamide or polymers copolymerized with other monomers. It is one of the most widely used varieties of water-soluble polymers.

Because the polyacrylamide structural unit contains amide groups, it is easy to form hydrogen bonds, so that it has good water solubility and high chemical activity, and it is easy to obtain various modifications of branched or network structure through grafting or crosslinking. It has a wide range of applications in industries such as oil mining, water treatment, textile, papermaking, mineral processing, medicine, agriculture and other industries.

Precautions

Cautions for the use of cationic polyacrylamide:

  1. The size of the floc: Too small floc will affect the speed of drainage. Too large floc will make the floc restrain more water and reduce the degree of mud crackers. After selecting the molecular weight of polyacrylamide, the size of the floc can be adjusted.
  2. Sludge characteristics: The first point is to understand the source, characteristics and composition of sludge, and the proportion of sludge. According to different properties, sludge can be divided into organic and inorganic sludge. Cationic polyacrylamide is used to dispose of organic sludge, the relative anionic polyacrylamide flocculant is used for inorganic sludge, anionic polyacrylamide is used when the alkalinity is strong, and anionic polyacrylamide is not suitable when the acidity is strong, solid content In high-time sludge, the amount of polyacrylamide is usually large.
  3. Flocculation strength: The flocculation should be stable and not broken under the action of shear. Increasing the molecular weight of polyacrylamide or choosing a suitable molecular structure can help improve the stability of the floc.
  4. Ionicity of polyacrylamide: For dewatered sludge, the flocculants of different ionicities can be selected after a small trial, and the best suitable polyacrylamide is selected, so that the best effect of the flocculant can be obtained. Minimize the amount of medicine added and save costs.
  5. Dissolution of polyacrylamide: Only when it is well dissolved can the flocculation effect be fully exerted. Sometimes it is necessary to speed up the dissolution rate, at this time it can be considered to increase the concentration of the polyacrylamide solution.

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Sequential method of mixing and using polyacrylamide and other flocculants:

When using the composite flocculant, it is necessary to pay attention to the order of addition and the interval of addition. The combined use of PAC and PAM is to allow PAC to complete the neutralization charge/colloids destabilization to form fine flocs, and then further increase the volume of flocs to facilitate full precipitation.

Since the reaction time of polyaluminum chloride PAC is very short, strong mixing is required after addition, and the PAM action time is long. Mixing should be strong first and then weak-the first strong is to mix uniformly and then weak to avoid damage to the flocs.

Polyacrylamide is a flocculant, and polyaluminum chloride is a coagulant. Generally, the coagulant is added before polyacrylamide, but for safety reasons, it is recommended that you determine the order of addition through the experimental effect.

Dosing point, dosing amount, dosing time and mixing intensity need to be determined by experiment. Remember that they must not be used together, otherwise it will affect the effect and increase the cost of use.

Method for judging the failure of polyacrylamide flocculant:

The failure of polyacrylamide can be judged from two aspects, one is the decrease in viscosity, and the other is the poor flocculation effect

Use characteristics

  1. Flocculation: PAM can neutralize suspended substances through electric neutralization, bridge adsorption, and play a role in flocculation.
  2. Adhesion: It can play the role of adhesion through mechanical, physical and chemical effects.
  3. Resistance reduction: PAM can effectively reduce the frictional resistance of the fluid. Adding a small amount of PAM to the water can reduce the resistance by 50-80%.
  4. Thickening: PAM has a thickening effect under neutral and acid conditions. When the PH value is above 10, PAM is easy to hydrolyze. The thickening will be more obvious when it has a semi-network structure.