Evaluation of Electrodialysis Desalination Performance of Novel Bioinspired and Conventional Ion Exchange Membranes with Sodium Chloride Feed Solutions

Abstract

Electrodialysis (ED) desalination performance of different conventional and laboratory-scale ion exchange membranes (IEMs) has been evaluated by many researchers, but most of these studies used their own sets of experimental parameters such as feed solution compositions and concentrations, superficial velocities of the process streams (diluate, concentrate, and electrode rinse), applied electrical voltages, and types of IEMs. Thus, direct comparison of ED desalination performance of different IEMs is virtually impossible. While the use of different conventional IEMs in ED has been reported, the use of bioinspired ion exchange membrane has not been reported yet. The goal of this study was to evaluate the ED desalination performance differences between novel laboratory‑scale bioinspired IEM and conventional IEMs by determining (i) limiting current density, (ii) current density, (iii) current efficiency, (iv) salinity reduction in diluate stream, (v) normalized specific energy consumption, and (vi) water flux by osmosis as a function of (a) initial concentration of NaCl feed solution (diluate and concentrate streams), (b) superficial velocity of feed solution, and (c) applied stack voltage per cell-pair of membranes. A laboratory‑scale single stage batch-recycle electrodialysis experimental apparatus was assembled with five cell‑pairs of IEMs with an active cross-sectional area of 7.84 cm2. In this study, seven combinations of IEMs (commercial and laboratory-made) were compared: (i) Neosepta AMX/CMX, (ii) PCA PCSA/PCSK, (iii) Fujifilm Type 1 AEM/CEM, (iv) SUEZ AR204SZRA/CR67HMR, (v) Ralex AMH-PES/CMH-PES, (vi) Neosepta AMX/Bare Polycarbonate membrane (Polycarb), and (vii) Neosepta AMX/Sandia novel bioinspired cation exchange membrane (SandiaCEM). ED desalination performance with the Sandia novel bioinspired cation exchange membrane (SandiaCEM) was found to be competitive with commercial Neosepta CMX cation exchange membrane.

Improved Performance of Cation Exchange Membranes Coated with Chitosan

“…12 In contrast, a lower current efficiency (∼5%) than for commercial membranes has also been reported for synthesized bioinspired membranes with aquaporin channels. 28 In our case, coating 50%DD chitosan coating on a commercial membrane has led to ∼16% higher current efficiency compared to the uncoated control membrane.…”

“…The ionic flux of our membranes was estimated as J N a C l = Δ m N a C l false( 2 N normalc normalp A normalm normale normalm false) Δ t exp where Δ m NaCl is the change in mass of NaCl in the diluate solution in grams over the duration of the experiment in hours, Δ t exp , N cp is the number of cell pairs in the electrodialysis stack, and A mem is the active area of the membrane in m 2 . The flux was recorded over six runs for each membrane set, and the results are shown in Figure .…”

Recovery of the N,N-Dibutylimidazolium Chloride Ionic Liquid from Aqueous Solutions by Electrodialysis Method

“…Current efficiency is defined as the ratio between the current used in the ED stack for effective ion recovery from diluate solution to concentrate and the amount of the total current applied in the ED stack. Current efficiency defines how much of the electric current is effectively used in ion transport across ion-exchange membranes [ 38 , 39 ]. In Figure 2 d, the effect of [C 4 C 4 IM]Cl concentration in the initial diluate on the electrodialysis current efficiency is shown.…”

Recovery of Biologically Treated Textile Wastewater by Ozonation and Subsequent Bipolar Membrane Electrodialysis Process

“…Centrifugal pumps with flow rates in the range of 4-8 L/h were utilized to supply wastewater and electrolytes to the BPMED system. Hyder et al [36] recommended keeping the transmembrane pressure between all compartments lower than 1.4 kPa to stabilize the electrodialysis system. Similarly, the manufacturer recommended the transmembrane pressure should be kept as zero during the BPMED process run to prevent water transfer through ion-exchange membranes.…”

“…where; C 0 is the initial conductivity of the BTTWW and C t is the conductivity value of BTTWW at time t. The ion separation rate in an ideal BPMED process is proportional to the current density through the BPMED stack. Current density (i) of the BPMED process was calculated by using the following formula [36]:…”