In the molecular structure of polyacrylamide, in addition to the amide group, negatively charged carboxylic acid groups, sulfonic acid groups, hydroxamic acid groups, positively charged quaternary ammonium salt groups, etc., are introduced according to different applications, which determine the flocculation, thickening and drag reduction effects of polyacrylamide products.

1. Flocculation

The flocculation process is actually completed in two steps: coagulation and flocculation.

Coagulation: The coagulation mechanism of suspended particles in raw water or wastewater is through the addition of cationic coagulants and the 

negative charge carried by colloidal particles, forming sponge-like flocs that become unstable. Inorganic coagulants are mainly aluminum and iron 

salts and their polymers. Organic coagulants are mainly PolyDADMAC.

Flocculation: Flocculation refers to the process by which suspended particles in water aggregate and settle due to adsorption bridging or charge 

neutralization with groups on polymer molecular chains.

The charge properties of flocculants are selected based on the type of particles in the wastewater. Generally, negatively charged flocculants are 

used to capture inorganic particles, and positively charged flocculants are used to capture organic particles. However, the type of flocculant must 

be determined through on-site experiments.

2. Thickening Effect

Polyacrylamide's thickening properties manifest in two ways. First, the presence of hydrophilic groups in the polymer molecules forms a "water sheath" through hydrogen bonds, increasing the internal frictional force of relative movement. Second, the carboxyl groups in the polyacrylamide molecules dissociate in water, producing many like-charged chain segments. These chain segments repel each other, allowing the polymer molecular coils to unfurl more freely in water, resulting in better thickening ability.

3. Drag Reduction Effect

When drag-reducing agents are added to an aqueous medium, the linear macromolecules rapidly unfold, reducing turbulent resistance within the fluid and suppressing radial turbulent disturbances. This prevents or mitigates turbulence, thus reducing drag.