Contents lists available at ScienceDirect Desalination journal homepage: www.elsevier.com/locate/desal Effect of process conditions on recovery of lithium and boron from water using bipolar membrane electrodialysis (BMED) Samuel Bunani a,b,d , Muserref Arda b , Nalan Kabay a,⁎ , Kazuharu Yoshizuka c , Syouhei Nishihama c a Department of Chemical Engineering, Ege University, Izmir, Turkey b Department of Chemistry, Ege University, Izmir, Turkey c Department of Chemical Engineering, The University of Kitakyushu, Japan d Department of Chemistry, Burundi University, Bujumbura, Burundi ARTICLE INFO Keywords: Bipolar membrane electrodialysis (BMED) Boron Lithium Recovery Separation ABSTRACT Electrodialysis (ED) combined with bipolar membrane, a new system known as bipolar membrane electrodialysis (BMED) has been developed to separate ions from aqueous saline solutions and recover them in their corresponding acids and bases. In this study, separation and recovery of lithium and boron from aqueous solution by BMED method was investigated. Lithium and boron were recovered as LiOH and H 3 BO 3 with BMED, respectively. The influence of process conditions such as applied potential, initial sample volume and pH on BMED performance was monitored. The performance of BMED method increased with an increase in applied voltage but decreased with an increase in initial sample volume. At optimum conditions of 15 V and 0.5 L as initial sample volume, separation and recovery of lithium were 99.6% and 88.3%, respectively, while the respective values for boron were 72.3% and 70.8%. An increase in pH improved separation and recovery of boron more than those of lithium. At pH 12.25, separation and recovery of boron were 95.6% and 78.8%, respectively. The BMED method was found to be effective for simultaneous separation and recovery of lithium and boron from same aqueous solution at optimum operating conditions. 1. Introduction Lithium and boron are trace elements usually found in geothermal waters [17]. Both are very important elements because of their various industrial applications. Lithium based compounds have been used in glass, ceramics, carbon dioxide absorbent systems, Li ion based batteries and antidepressant agent production. Lithium hydroxide constitutes a raw material in the process for various types of industries. During the industrial production process, the need of lowering melting points and reducing coefficient of thermal expansion may be achieved by an addition of lithium [11]. Boron is also one of the useful elements for different type of industries. Boron is especially used in glass, ceramics, detergents and semiconductors manufacturing industries. Therefore, recovering such important elements from their natural sources is one of the strategies to face the demand for lithium and boron that has increased in recent decades. Recent literature has reported various methods for removal or/and recovery of lithium and boron. The separation methods for trace elements are mostly adsorption, membrane filtration (NF and RO) and electromembranes processes such electrodialysis (ED), electrodialysis reversal (EDR) and bipolar mem- brane electrodialysis (BMED). Although the separation of lithium from solutions by solvent extraction is possible, the extractants should be highly selective for lithium [2]. The main drawback of solvent extraction is the use of large amount of organic solvent in the whole process, and solvent extraction becomes costly and energy-consuming since recycling the waste solvent for later reuse is very difficult. To escape from the problem of the large amount of contaminated solvents, alternative methods for lithium separation and recovery rather than solvent extraction should be investigated. Parsa et al. [13] has investigated conventional ED process and their results have proven ED process as promising method for lithium recovery from contami- nated solution of lithium bromide. Jiang et al., [3] reported the possibility to produce LiOH with a purity of 95% from a solution of Li 2 CO 3 by using electro-electrodialysis bipolar membrane (EEDBM) process. The technology commonly used for the removal of boron from aqueous solutions is the application of chelating resin and seems to be one of the most effective methods [15]. In addition to ion exchange method by chelating resin, membrane processes form another group of preferred technologies for boron removal from water. Recently, adsorp- tion-membrane filtration hybrid process was suggested as an alternative method for boron removal from geothermal water [5]. Electrodialysis http://dx.doi.org/10.1016/j.desal.2017.04.017 Received 15 January 2017; Received in revised form 7 March 2017; Accepted 19 April 2017 ⁎ Corresponding author. E-mail address: nalan.kabay@ege.edu.tr (N. Kabay). Desalination 416 (2017) 10–15 0011-9164/ © 2017 Elsevier B.V. All rights reserved. MARK