Can Polyaluminum Chloride Be Used After Getting Damp? Here's the Answer

Can Polyaluminum Chloride Be Used After Getting Damp? Here's the Answer

Polyaluminum Chloride (PAC) is a commonly used flocculant in Water Treatment. It is prone to dampness and caking during storage and transportation. Whether it can still be used depends on the degree of dampness, the state of caking, and whether it has deteriorated.

1. Why Is It Prone to Dampness?

PAC is an inorganic polymer compound with strong hydrophilicity. Its molecules contain a large number of hydroxyl groups, which easily absorb moisture from the air. Caking is more likely to occur, especially in humid environments, when the packaging is damaged, or when ventilation is poor.

2. What Changes Happen After Dampness?

1. Physical Changes: When slightly damp, only the surface of the particles softens and adheres, while the interior remains dry. There is no peculiar smell or discoloration, and the chemical composition remains unchanged. Only the dissolution rate is affected.
2. Chemical Changes: When severely damp, the caking becomes hard. Mold may grow, there may be a peculiar smell, and the color may darken. PAC undergoes hydrolysis and decomposition, leading to a decrease in the content of effective aluminum, and the flocculation effect is greatly reduced or even lost.

3. How to Judge Whether It Can Be Used?

1. Check the Appearance: If the caking is loose and can be crushed into powder by hand without abnormalities, it can be used. If the caking is hard, discolored, moldy, or has a peculiar smell, it has deteriorated and is not recommended for use.
2. Test the Component Content: If conditions permit, test the content of effective aluminum. If it meets the standard (e.g., 28%, 30%), it can be used; if it is lower than 25%, appropriate measures need to be taken.
3. Conduct a Small-Scale Test: After dissolution, if the solution is uniform without a large amount of insoluble substances and the flocculation effect is normal, it can be used; otherwise, it should be discarded.

4. Precautions for Use (If Usable)

1. Extend the stirring time (30-60 minutes) to ensure full dissolution.
2. According to the results of the small-scale test, appropriately increase the dosage by 10%-20%.
3. Seal it in time and store it in a dry and ventilated place to avoid secondary dampness.

5. How to Prevent Dampness?

Choose a dry and ventilated warehouse with humidity controlled below 60%; ensure the packaging is intact; follow the "first-in, first-out" principle to avoid long-term storage (shelf life is 12 months); do not store it with hygroscopic items.

Summary

Slightly damp PAC that has not deteriorated can be used after proper treatment; severely caked and deteriorated PAC should be replaced. The key is to judge its state through "appearance inspection + small-scale test" and do a good job in moisture prevention during storage to reduce problems from the source.