The use of cation exchange resin is relatively large, which is a relatively large cost item for power plants. Therefore, in the process of using ion exchange resins, we should give full play to its economic role. Pollution is inevitable in daily use. Let's take a look at the pollution forms and solutions of cation exchange resins, hoping to help everyone in their use.
Different pollution forms of cation exchange resins and their solutions
1. Pollution caused by excessive coagulant
In order to solve the problem of suspended solids in water, coagulant is usually added in the pretreatment. Once the coagulant is added in an inappropriate amount, it will pollute the subsequent cation exchange resin. If the effluent contains more than 1mg/L of coagulant, it will cause serious pollution of the cation exchange resin, and it has been found that the coagulant with a linear structure is more likely to contaminate the resin and can enter the resin particles.
When the above-mentioned pollution occurs in the resin, if the pollution degree is not very serious, it can be recovered by means such as increasing the backwash flow rate, extending the backwash time or passing compressed air. If the pollution is serious, the method of adding surfactant and dispersant can be used. The surfactant can increase the hydrophilic moth on the surface of the resin; the dispersant can ensure that the particles detached from the resin can be dispersed into the aqueous solution. In order to achieve the purpose of recovering resin.
2, the pollution of iron ions
Cation exchange resins are susceptible to iron ion pollution, especially in water treatment systems that use well water as a water source. There are three different situations in which iron ions contaminate the resin.
①If iron ions are present in a colloidal suspension, it will leak through the filter and contaminate the cation exchange resin.
②The iron is exchanged to the resin in the form of divalent iron ions, and then it is oxidized to trivalent iron ions, thereby forming a gel-like water-insoluble iron hydroxide on the resin particles.
③The divalent iron ions that may be exchanged on the resin are directly converted into trivalent iron ions on the resin exchange group, but they cannot be completely removed during the regeneration process and remain in the resin.
If the first situation occurs, backwashing can be used to remove the colloidal suspension accumulated in the resin layer. If the accumulation of iron ions occurs in the entire resin layer, an ionic surfactant and dispersant containing sodium sulfite or sodium bisulfite can be used to treat the resin, so that the trivalent iron ions can be reduced to more soluble divalent Iron ions, and the latter has less affinity for resin than the former.