Boron Removal from Lithium Pentaborate (Li₂B₁₀O₁₆·10H₂O) Solution Using Ion Exchange Resin

Abstract

Recovery of deuterium oxide (D₂O) e.g., heavy water from lithium pentaborate, Li₂B₁₀O₁₆·10H₂O (represented as LiPB), solution in heavy water is achieved by using a mixed bed (MB) ion exchanger. Boron removal capacity for the strong base anion exchange resin was found to increase with an increasing concentration of boron in the inlet solution of ion exchange column. With 0.2 M LiPB (i.e., 2 M Boron) the anion resin in the mixed bed showed four to five times the boron removal capacity observed with 0.001 M LiPB. This increased capacity is attributed to the existence of polymeric borate species at higher boron concentration. A similar high capacity for the strong base anion exchanger could be obtained in batch equilibration of the resin with 0.2 M LiPB. However, column experiments with simple anion exchanger yielded boron slip from the beginning of the run but, nevertheless, nearly realized the LiPB concentration–dependent higher boron removal capacities mentioned previously. The mixed ion exchange method of D₂O recovery appears to be a better alternative to the distillation method.

Keywords:

• Lithium pentaborate
• ion exchange
• heavy water
• polymeric boron species

Acknowledgments

The authors thank Mr. R. G. Khandelwal, Chemistry Advisor and Head, Heavy Water Manager Kakarapara Atomic Power Station for posing the task. The authors also thank Dr. N. M.Gupta, Head, ApCD, for his interest in this study, Dr. A. K. Tyagi Head, SSCS, ApCD, for useful discussions on XRD data, and Dr. M. Sudersanan, Head, ACD, for analytical support. Thanks are due to Ms. Sudha Shenoy for Li analysis. Help in getting XRD, TG‐DTA, and IR data through the services of Ms. Aruna Sonawane (XRD), Mr. A. Sirsat (TG/DTA), and Dr. V. S. Kamble and Mr. Dharmesh Kumar (IR) is duly acknowledged.