Research and analysis on layer state distribution of EDI membrane block ion exchange resin

In order to master the distribution law of each layer state of the ion exchange resin in the EDI membrane block, this paper firstly analyzed the working principles and characteristics of the migration failure layer, exchange stability layer and hydrolysis protection layer of EDI ion exchange resin. Then, the effects of influent conductivity and operating current on the layer state distribution were tested through experiments. The results showed that the thickness of the hydrolytic protection layer was negatively correlated with the influent conductivity and positively correlated with the operating current. The hydrolysis protection layer was the key point to ensure the quality of product water from EDI membrane block. When the influent conductivity was less than 10 µS/cm (25 ℃), the ratio of the hydrolytic protective layer thickness to the thickness of the whole resin layer was ≥11.43%, which could well ensure that the conductivity of product water from EDI membrane block was <0.1 µS/cm (25 ℃). When the conductivity of influent was 5 µS/cm and the conductivity of product water was <0.1 µS/cm (25 ℃), the thickness of the hydrolytic protective layer could be increased by increasing the operating current, and the thickness of the hydrolytic protective layer was linear with the operating current.