Polyacrylamide PAM is a widely used synthetic organic polymer flocculant, sometimes also used as a coagulant aid. The raw material for the production of polyacrylamide is polyacrylonitrile CH2=CHCN. Under certain conditions, acrylonitrile hydrolyzes to produce acrylamide, which is then suspended and polymerized to obtain polyacrylamide. Polyacrylamide belongs to water-soluble resins, and there are two types of products: granular solids and viscous aqueous solutions of certain concentrations.

The actual form of polyacrylamide in water is random coil, which has a certain particle size and some amide groups on its surface. Therefore, it can play a corresponding bridging and adsorption role, that is, it has a certain flocculation ability. However, due to the curling of long chains of polyacrylamide into coils, the bridging range is limited. After the formation of two amide groups, their interactions cancel each other out, resulting in the loss of two adsorption sites. In addition, some amide groups are trapped inside the coil structure and cannot come into contact with and adsorb impurity particles in water, so their adsorption capacity cannot be fully utilized.

In order to separate the amide groups that are bound together again and expose the hidden amide groups on the surface, people have tried to extend and expand the random coil appropriately, and even tried to add some cationic or anionic groups on the long molecular chain, while improving the adsorption bridging ability and the effect of electrically neutralizing and compressing the double layer. In this way, a series of polyacrylamide coagulants or coagulants with different properties have been derived on the basis of PAM.

For example, adding alkali to a polyacrylamide solution can convert some of the amide groups on the chain links into sodium carboxylate, which can easily dissociate into sodium ions in water, leaving the COO - groups on the branches, thus generating partially hydrolyzed anionic polyacrylamide. The COO - groups on the molecular structure of anionic polyacrylamide give negative charges to the molecular chains, which repel each other and open the amide chains that were originally bound together, causing the molecular chains to gradually extend from a linear shape to a long chain shape, thereby expanding the bridging range and improving the flocculation ability. As a coagulant aid, its advantages are even more outstanding.

The effectiveness of using anionic polyacrylamide is related to its degree of hydrolysis. A low degree of hydrolysis can lead to poor coagulation or coagulation aid effects, while a high degree of hydrolysis can increase production costs.

Compared with other coagulants, polyaluminum chloride has the following advantages:

Widely applicable and adaptable to a wide range of water properties. Easy to quickly form large alum flowers, with good precipitation performance. The suitable pH range is wide (between 5-9), and the pH and alkalinity of the treated water decrease little. When the water temperature is low, a stable sedimentation effect can still be maintained. The alkalinity is higher than other aluminum salts and iron salts, and it has less corrosive effect on equipment.

Main features

This product is an inorganic polymer coagulant. Mainly through mechanisms such as double-layer compression, adsorption electro neutralization, adsorption bridging, and sediment net capture, fine suspended particles and colloidal ions in water are destabilized, aggregated, flocculated, coagulated, and precipitated to achieve purification treatment effects.

Physical and chemical properties

Liquid products are colorless, light yellow, light gray, or brown transparent or semi transparent liquids without precipitation. Solid products are white, light gray, light yellow, or brown grains or powders. Aluminum oxide content in the product: liquid product>8%, solid product 20% -40%, alkalinity 70% -75%.

usage method

Add the product (solid) to room temperature water in a weight ratio of 1/3 while stirring until completely dissolved, and then dilute with water to the desired concentration. When the raw water concentration is 100-500mg/, the dosage should be 3-6mg/I. When adding, a water test should be conducted based on the water quality to select the optimal dosage before use.

Packaging and Storage

The solid is packaged in 25KG bags, with an inner layer of plastic film and an outer layer of plastic woven bags. The product should be stored indoors in a dry, ventilated, and cool place, and should not be damp.

Main applications

PAC is an important coagulant in the field of water purification, which has efficient purification effects on low temperature, low turbidity, and high turbidity water. However, due to the reaction between its monomers and organic matter, substances harmful to human health can be generated. Therefore, ensuring its purity is crucial in water purification.

Safety, Health, and Protection

Water treatment agent polyaluminum chloride products are corrosive. If accidentally splashed on the skin, rinse immediately with water. Personnel producing and using this product should wear work clothes, masks, gloves, and long rubber boots. Production equipment should be sealed, and workshop ventilation should be good.

The water treatment agent polyaluminum chloride product has no combustion or explosion hazards. When using polyaluminum chloride as a coagulant in urban water supply processes, it may lead to high levels of aluminum salts in the water, which is one of the factors causing dementia in the elderly.

Ferrous sulfate, a traditional iron salt, is often used as a coagulant in wastewater treatment. It has a good removal effect on suspended solids, fluoride, arsenic, and some heavy metal ions in water. The dosage of coagulants varies for wastewater with different pollutant contents. Generally speaking, when the amount of ferrous sulfate added to the wastewater is insufficient, the pollutants in the water cannot reach the settling point, the coagulation effect is weakened, and the removal rate is not high. So, on the contrary, what are the effects of excessive addition of ferrous sulfate?

The impact of excessive addition of ferrous sulfate

1. Enhanced acidity. Ferrous sulfate belongs to strongly acidic chemical agents, and excessive addition can increase the acidity of water. For wastewater that needs to lower the pH value, acidic neutralizing agents can be saved. However, for other wastewater, it can cause a decrease in water pH value, enhance the overall acidity of water quality, and affect the effectiveness of the action.

2. The amount of sludge increases. For most chemical agents, the larger the dosage, the greater the amount of sludge produced. This is due to the increase in metal salts generated by the reaction between ferrous sulfate and wastewater compared to microbial treatment.

3. The cost increases and the processing effect weakens. There is a saying in the folk that goes, 'When the extreme is reversed,' when ferrous sulfate is added in excess, not only does the cost of the agent used increase, but also the cost of other auxiliary agents (such as neutralizing agents), sludge treatment fees, labor costs, etc. At the same time, it also affects its coagulation effect, causing the formed flocs to disintegrate.

Excessive addition of ferrous sulfate leads to precipitation of iron ions, resulting in water color reversal after wastewater coagulation. Ferrous sulfate can cause the water to turn red and yellow due to the yellow color of iron ions. Therefore, when processing, the dosage of coagulant should be strictly controlled through beaker trials or addition methods.