Abstract

Weakly charged elements, or elements that are not well dissociated in water, are not removed efficiently by conventional water-purification technologies. In the production of high-purity water, silica and boron are generally the first ions to breakthrough into purified water when the ion-exchange resin approaches depletion. In this study, the behavior of these two elements was studied through various steps in a water-purification chain. An optimized system configuration is proposed that combines reverse osmosis and electrodeionization technologies in the pre-treatment phase, and results in the efficient removal of boron. These initial purification steps produce high-resistivity water, presenting a low ionic challenge to ultrapure polishing resins. In addition, a specific chelating adsorbent enhances the retention capacity of boron. Typical values achieved for the most important parameters assessed while producing ultrapure water are described.