Rocking-chair capacitive deionization (RCDI) attracts increasing attention with its capability of semi-continuous desalination. However, there is a potential concern for pH fluctuation of the effluent, which deteriorated water quality. In this work, we addressed the effect of the pH fluctuation on desalination behavior of RCDI and disclosed the underlying mechanism for pH evolution. The desalted stream in RCDI revealed high acidity, and oppositely the brine stream became basic. As the intensive pH initiates, those pH-related species distort the conductivity profiles with deteriorated adsorption capacity. By further analyzing dissolved oxygen and potential distribution variation, we will clarify the cause of pH-variation and distorted conductivity profile. The effect of the charging voltage and the flowrates on desalination performance and pH-variation will be carefully studied. With better understanding of RCDI, strategies for enhancing pH stability and water recovery will further be presented.

Comprehensive study on desalination performance and pH-related behavior in rocking-chair capacitive deionization

ACS Spring Meeting 2021

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