Yellow smoke occurs because a kind of catalyst is needed in the production process of PFS. After PFS is produced, the reaction has disappeared. During the loading and transportation of finished products, due to the long-term transportation of chemicals by some transport vehicles, some chemical substances, some reducing chemical substances (for example, this vehicle is loading PFS) may still remain in the vehicle Iron has just been active before, and ferrous sulfate has strong reducibility.

In the presence of iron ions, yellow smoke will be released during unloading (nitrate ions are reduced to form no and NO2 gases, which are discharged into the air to form yellow smoke).

The appearance of yellow smoke has no influence on the use effect of products. However, yellow smoke can not appear when unloading at the customer's site. Therefore, when transporting PFS, the vehicle must be cleaned to avoid the existence of residual substances, especially reducing chemical residues.

How to solve the problem of water blackening after the use of polymerized ferric sulfate?

The reason of blackening after adding PFS is mainly due to the anaerobic section of some wastewater treatment processes, because PFS has both sulfate and iron ions. During anaerobic process, some sulfate reducing bacteria will reduce sulfate to sulfur ion, and sulfur ion will react with iron ion to form iron sulfide precipitation. And iron sulfide is black. If there is a biochemical system (an aeration tank of activated sludge) after anaerobic treatment, if the aeration rate is enough, the black matter will be oxidized again soon and return to the normal color of activated sludge.