What Are Flocculants and Coagulants

Flocculants are mainly positive (negative) groups that neutralize some particles or particles that are difficult to separate with negative (positive) electricity in some water, reduce their potential, make them in an unstable state, and use them to polymerize. The nature makes these particles concentrated and separated by physical or chemical methods. The agents generally used to achieve this purpose are called flocculants. Flocculants are mainly used in the fields of water supply and sewage treatment.

The coagulant aid is an auxiliary agent added to improve the flocculation effect. The coagulant aid itself can have a coagulation effect or not, but it can improve the flocculation effect of the water when it is used together with the flocculating agent. According to the different roles it plays in the coagulation process, it can be divided into many categories, such as alkali used to adjust the pH value (commonly used lime); oxidant used to destroy organic matter that interferes with the flocculant, such as chlorine chemicals used to Activator that speeds up the flocculation process and increases firmness, such as silica, pac polymer chloride, activated carbon or various soils. And we collectively refer to flocculants and coagulants as coagulants.

Flocculation mechanism

The effect of eliminating or weakening the stability of the colloid is called the destabilization of the colloid. The destabilized colloid can coalesce into larger particles and quickly leave with moisture. The destabilization of the colloid is usually due to the following three aspects. 1. The compression effect of counter ions. After adding a certain electrolyte to the water, the electrolyte ionizes a large number of counter ions or hydrolyzes to form a polymer with opposite charges, which compresses the diffusion layer in the water, causing a part of the counter ions to compress to the adsorption layer and the diffusion layer becomes thinner. The electrostatic repulsive force will then weaken or disappear. At this time, when colloidal particles are in contact with each other, it is easy to coalesce into large particles through adsorption. This process is usually called agglomeration.

The bridging effect of gelatin adsorption and coagulant. Add a certain amount of macromolecular substances or high-valent salts (which can be hydrolyzed into high polymers) into the water. Such substances have a linear structure and stretch into a bond shape in the water. Suspended matter is connected together. This kind of role is called "bridging role". Because this bridging effect destroys the stability of the colloid, it gradually condenses into flocculent sediment, which is called flocculation. The destabilization of the colloid is often caused by cohesion and E at the same time, collectively called coagulation, and the added agent is called coagulant.

Net catching effect of sediment. When there are few suspended solids and colloidal impurities in the water, by increasing the amount of coagulant, they will coagulate each other to form sacrificial sediments, which will carry the particles in the water through the netting effect during the sedimentation process.