What happens when ion exchange resins are contaminated?

When polluted, the following phenomena usually occur: in the same city,

　　The colour of the resin changes from yellow to dark brown or black. The exchange capacity of resin decreased significantly, which was manifested by the decrease of water production in the "soul bed" cycle. The quality of sewage is deteriorating. The results show that the effluent pH value decreases, the conductivity increases, and the effluent volume of "sodium leak", "hard leak" and "silicon leak" increases significantly. The unit consumption of regeneration increased. The cleaning time is prolonged and the cleaning water is increased.

　　How to prevent ion exchange resin from being polluted?

　　In order to prevent ion exchange resin from being polluted, the following aspects should be done well:

　　Do a good job of pretreatment. Ion exchange resins can be divided into styrene resin and acrylic resin according to their matrix types. The main properties and types of resins are determined by the types of chemical active groups in resins. Firstly, it can be divided into cationic resins and anionic resins, which can exchange ions with cations and anions in solution respectively. Cationic resins can be divided into strong acidity and weak acidity. Anionic resins can be divided into strong alkalinity and weak alkalinity. This is one of the important measures to prevent ion exchange resin from being polluted. It is very important to select and use coagulant correctly for its pretreatment. Aluminum salt as coagulant is better than iron salt as coagulant in removing organic matter in water quality. The optimum technological conditions of coagulant were determined by experiments, and strict operation was carried out to prevent iron and aluminium ions from "moving backward" in coagulant, resulting in the pollution of resin, especially cation exchange resin. The residual chlorine and turbidity entering the normal bed water must be strictly controlled. Residual chlorinated oxidized resins are prevented. Strengthen regenerant management. In addition to strict procurement quality inspection, transportation, warehousing work, but also to do a good job in management. For example, the transportation pipeline and storage tank of regenerant should be made of anticorrosive material, and the filtration and clarification of regenerant in bed should be done well. For possible contact with resin compressed air, purification measures should be taken, requiring no oil, water and oil-free compressors as far as possible.

　　There are two kinds of "iron pollution" in ion exchange resins: one is that iron compounds enter the exchange bed in the form of suspended solids or colloids; because of the adsorption of resin, iron compounds will be firmly deposited on the inside and surface of the resin, thus affecting the "pore diffusion" of ions, thereby increasing the pressure drop of the resin layer or leading to "bias". Another form of iron pollution

　　It enters the exchange bed in the form of Fe2+ and exchanges with Fe2+. Fe2+ is adsorbed by resin and partly oxidized by Fe3+. Ion exchange resin is composed of classification name, skeleton (or gene) name and basic name. The pore structure is divided into two types: gel type and large pore type. All macroporous resins with physical pore structure are added "big hole" before the full name. If the classification is acidic, the word "yang" should be added before the name, while the classification is alkaline, and the word "yin" should be added before the name. Such as: macroporous strong acidic styrene cation exchange resin. Ion exchange resins can be divided into styrene resin and acrylic resin according to their matrix types. The main properties and types of resins are determined by the types of chemical active groups in resins. Firstly, it can be divided into cationic resins and anionic resins, which can exchange ions with cations and anions in solution respectively. Cationic resins can be divided into strong acidity and weak acidity. Anionic resins can be divided into strong alkalinity and weak alkalinity. These iron ions can not be completely exchanged by H + in the regeneration process, so that Fe ~ (3+) occupies the exchange position and oxidizes into iron compounds, resulting in iron pollution. The longer the iron sticks to the resin, the more difficult it is to remove it.