Membranes

Research

Jump to: Review

19 pages, 4255 KiB

Open AccessArticle

Effect of TiO₂ and Al₂O₃ Addition on the Performance of Chitosan/Phosphotungstic Composite Membranes for Direct Methanol Fuel Cells

by Andrea Zaffora, Elena Giordano, Valentina Maria Volanti, Leonardo Iannucci, Sabrina Grassini, Irene Gatto and Monica Santamaria

Membranes 2023, 13(2), 210; https://doi.org/10.3390/membranes13020210 - 8 Feb 2023

Cited by 3 | Viewed by 1390

Abstract

Composite chitosan/phosphotungstic acid (CS/PTA) with the addition of TiO₂ and Al₂O₃ particles were synthesized to be used as proton exchange membranes in direct methanol fuel cells (DMFCs). The influence of fillers was assessed through X-ray diffraction, scanning electron microscopy, [...] Read more.

Composite chitosan/phosphotungstic acid (CS/PTA) with the addition of TiO₂ and Al₂O₃ particles were synthesized to be used as proton exchange membranes in direct methanol fuel cells (DMFCs). The influence of fillers was assessed through X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, liquid uptake, ion exchange capacity and methanol permeability measurements. The addition of TiO₂ particles into proton exchange membranes led to an increase in crystallinity and a decrease in liquid uptake and methanol permeability with respect to pristine CS/PTA membranes, whilst the effect of the introduction of Al₂O₃ particles on the characteristics of membranes is almost the opposite. Membranes were successfully tested as proton conductors in a single module DMFC of 1 cm² as active area, operating at 50 °C fed with 2 M methanol aqueous solution at the anode and oxygen at the cathode. Highest performance was reached by using a membrane with TiO₂ (5 wt.%) particles, i.e., a power density of 40 mW cm⁻², almost doubling the performance reached by using pristine CS/PTA membrane (i.e., 24 mW cm⁻²). Full article

(This article belongs to the Special Issue Advance in Electromembrane Technology)

► Show Figures

Figure 1

14 pages, 3149 KiB

Open AccessArticle

Separation of Hydrochloric Acid and Oxalic Acid from Rare Earth Oxalic Acid Precipitation Mother Liquor by Electrodialysis

by Hengcheng Zhou, Peihai Ju, Shaowei Hu, Lili Shi, Wenjing Yuan, Dongdong Chen, Yujie Wang and Shaoyuan Shi

Membranes 2023, 13(2), 162; https://doi.org/10.3390/membranes13020162 - 27 Jan 2023

Cited by 7 | Viewed by 2034

Abstract

In this study, the hydrochloric acid from rare earth oxalic acid precipitation mother liquor was separated by electrodialysis (ED) with different anion exchange membranes, including selective anion exchange membrane (SAEM), polymer alloy anion exchange membrane (PAAEM), and homogenous anion exchange membrane (HAEM). In [...] Read more.

In this study, the hydrochloric acid from rare earth oxalic acid precipitation mother liquor was separated by electrodialysis (ED) with different anion exchange membranes, including selective anion exchange membrane (SAEM), polymer alloy anion exchange membrane (PAAEM), and homogenous anion exchange membrane (HAEM). In addition to actual wastewater, nine types of simulated solutions with different concentrations of hydrochloric acid and oxalic acid were used in the experiments. The results indicated that the hydrochloric acid could be separated effectively by electrodialysis with SAEM from simulated and real rare earth oxalic acid precipitation mother liquor under the operating voltage 15 V and ampere 2.2 A, in which the hydrochloric acid obtained in the concentrate chamber of ED is of higher purity (>91.5%) generally. It was found that the separation effect of the two acids was related to the concentrations and molar ratios of hydrochloric acid and oxalic acid contained in their mixtures. The SEM images and ESD–mapping analyses indicated that membrane fouling appeared on the surface of ACS and CSE at the diluted side of the ED membrane stack when electrodialysis was used to treat the real rare earth oxalic acid precipitation mother liquor. Fe, Yb, Al, and Dy were found in the CSE membrane section, and organic compounds containing carbon and sulfur were attached to the surface of the ACS. The results also indicated that the real rare earth precipitation mother liquor needed to be pretreated before the separation of hydrochloric acid and oxalic acid by electrodialysis. Full article

(This article belongs to the Special Issue Advance in Electromembrane Technology)

► Show Figures

Graphical abstract

13 pages, 1648 KiB

Open AccessArticle

Combined Separator Based on a Porous Ion-Exchange Membrane for Zinc–Halide Batteries

by Alexey Y. Rychagov, Yury M. Volfkovich, Valentin E. Sosenkin, Alexsandr F. Seliverstov and Marianna Y. Izmailova

Membranes 2023, 13(1), 67; https://doi.org/10.3390/membranes13010067 - 5 Jan 2023

Viewed by 2460

Abstract

In this work, we report on a comparative analysis of the bromine permeability for three separator groups under the operating conditions of a non-flow zinc–bromine battery. A new method for the synthesis of porous heterogeneous membranes based on a cation-exchange resin followed by [...] Read more.

In this work, we report on a comparative analysis of the bromine permeability for three separator groups under the operating conditions of a non-flow zinc–bromine battery. A new method for the synthesis of porous heterogeneous membranes based on a cation-exchange resin followed by treatment with tetrabutylammonium bromide is proposed. It was shown that the modified membrane significantly reduced the bromine permeability (crossover) with an acceptable increase in the ionic conductivity of the separator group. Leakage currents not exceeding 10–20 µA/cm² were achieved, and the Coulomb efficiency was over 90%. The ionic conductivity (at AC) of a membrane soaked with water was compared for different pretreatment conditions. The frequency dependence of the membrane resistance is shown. The features of the conduction mechanism of the modified membrane are discussed. Full article

(This article belongs to the Special Issue Advance in Electromembrane Technology)

► Show Figures

Figure 1

12 pages, 1583 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Technical and Environmental Feasibilities of the Commercial Production of NaOH from Brine by Means of an Integrated EDBM and Evaporation Process

by Marta Herrero-Gonzalez and Raquel Ibañez

Membranes 2022, 12(9), 885; https://doi.org/10.3390/membranes12090885 - 14 Sep 2022

Cited by 4 | Viewed by 1880

Abstract

Electrodialysis with bipolar membranes (EDBMs) is a technology that offers a great potential for the introduction of the principles of a circular economy in the desalination industry, by providing a strategy for the recovery of HCl and NaOH from brine via the process [...] Read more.

Electrodialysis with bipolar membranes (EDBMs) is a technology that offers a great potential for the introduction of the principles of a circular economy in the desalination industry, by providing a strategy for the recovery of HCl and NaOH from brine via the process of seawater reverse osmosis (SWRO). Both chemicals are widely employed in desalination facilities, however NaOH presents a special interest due to its higher requirements and cost. Nevertheless, the standard commercial concentrations that are commonly employed in the facilities cannot be obtained using the state of the art EDBM technology itself. Therefore, the aim and main purpose of this work is to prove the technical and environmental feasibilities of a new approach to produce commercial NaOH (50%wt.) from SWRO brine by means of an integrated process of EDBMs followed by a triple effect evaporation. The global process has been technically evaluated in terms of the specific energy consumption (SEC) (kWh·kg⁻¹ NaOH) and the environmental sustainability performance has been analyzed by its carbon footprint (CF) (kg CO₂-eq.·kg⁻¹ NaOH). The influence of the current density, and the power source in the EDBM stage have been evaluated on a laboratory scale while the influence of the feed stream concentration in the evaporation stage has been obtained through simulations using Aspen Plus. The lowest SEC of the integrated process (SEC_OV), 31.1 kWh·kg⁻¹ NaOH, is obtained when an average current density of 500 A·m⁻², provided by a power supply (grid mix), is applied in the EDBM stage. The environmental burdens of the integrated process have been quantified by achieving reductions in the CF by up to 54.7% when solar photovoltaic energy is employed as the power source for EDBMs, with a value of 5.38 kg CO₂-eq.·kg⁻¹ NaOH. This study presents a great potential for the introduction of the principles of a circular economy in the water industry through the recovery of NaOH from the high salinity waste stream generated in SWRO facilities and opens the possibility of the reuse of NaOH by its self-supply in the desalination plant. Full article

(This article belongs to the Special Issue Advance in Electromembrane Technology)

► Show Figures

Graphical abstract

12 pages, 4250 KiB

Open AccessArticle

Membrane Fouling and Electrochemical Regeneration at a PbO₂-Reactive Electrochemical Membrane: Study on Experiment and Mechanism

by Liankai Gu, Yonghao Zhang, Weiqing Han and Kajia Wei

Membranes 2022, 12(8), 814; https://doi.org/10.3390/membranes12080814 - 22 Aug 2022

Cited by 1 | Viewed by 1519

Abstract

Membrane fouling and regeneration are the key issues for the application of membrane separation (MS) technology. Reactive electrochemical membranes (REMs) exhibited high, stable permeate flux and the function of chemical-free electrochemical regeneration. This study fabricated a micro-filtration REM characterized by a PbO₂ [...] Read more.

Membrane fouling and regeneration are the key issues for the application of membrane separation (MS) technology. Reactive electrochemical membranes (REMs) exhibited high, stable permeate flux and the function of chemical-free electrochemical regeneration. This study fabricated a micro-filtration REM characterized by a PbO₂ layer (PbO₂-REM) to investigate the electro-triggered anti-fouling and regeneration progress within REMs. The PbO₂-REM exhibited a three-dimensional porous structure with a few branch-like micro-pores. The PbO₂-REM could alleviate Humic acid (HA) and Bisphenol A (BPA) fouling through electrochemical degradation combined with bubble migration, which achieved the best anti-fouling performance at current density of 4 mA cm⁻² with 99.2% BPA removal. Regeneration in the electro-backwash (e-BW) mode was found as eight times that in the forward wash and full flux recovery was achieved at a current density of 3 mA cm⁻². EIS and simulation study also confirmed complete regeneration by e-BW, which was ascribed to the air–water wash formed by bubble migration and flow. Repeated regeneration tests showed that PbO₂-REM was stable for more than five cycles, indicating its high durability for practical uses. Mechanism analysis assisted by finite element simulation illustrated that the high catalytic PbO₂ layer plays an important role in antifouling and regeneration. Full article

(This article belongs to the Special Issue Advance in Electromembrane Technology)

► Show Figures

Figure 1

11 pages, 1832 KiB

Open AccessArticle

Electromembrane Extraction of Posaconazole for Matrix-Assisted Laser Desorption/Ionization Mass Spectrometric Detection

by Chi-Sheng Chen, Wen-Chi Chen and Sarah Y. Chang

Membranes 2022, 12(6), 620; https://doi.org/10.3390/membranes12060620 - 14 Jun 2022

Cited by 1 | Viewed by 1497

Abstract

A new mode of electromembrane extraction (EME) has been developed for detection via matrix-assisted laser desorption/ionization mass spectrometry (MALDI/MS). Posaconazole, extracted from 8 mL of a 10 mM trifluoroacetic acid solution onto a thin polyvinylidene difluoride (PVDF) membrane, was used as a model [...] Read more.

A new mode of electromembrane extraction (EME) has been developed for detection via matrix-assisted laser desorption/ionization mass spectrometry (MALDI/MS). Posaconazole, extracted from 8 mL of a 10 mM trifluoroacetic acid solution onto a thin polyvinylidene difluoride (PVDF) membrane, was used as a model analyte. The transport was forced by an electrical potential difference between two electrodes inside the lumen of a hollow fiber and glass tube. Under an application of 80 V, cationic posaconazole in the sample solution moved toward the negative electrode inside the glass tube and was trapped by the PVDF membrane on the side. After 15 min of extraction, 3 μL of α-cyano-4-hydroxycinnamic acid (CHCA) solution was applied on top of the membrane, which was then analyzed by MALDI/MS. Under optimal extraction conditions, the calibration curve of posaconazole was linear over a concentration range of 0.10–100.00 nM. The limit of detection (LOD) at a signal-to-noise ratio of 3 was 0.03 nM with an enhancement factor of 138 for posaconazole. The application of this method to the determination of posaconazole in human serum samples was also successfully demonstrated. Full article

(This article belongs to the Special Issue Advance in Electromembrane Technology)

► Show Figures

Figure 1

12 pages, 2459 KiB

Open AccessArticle

Importance of Hydroxide Ion Conductivity Measurement for Alkaline Water Electrolysis Membranes

by Jun Hyun Lim, Jian Hou, Jaehong Chun, Rae Duk Lee, Jaehan Yun, Jinwoo Jung and Chang Hyun Lee

Membranes 2022, 12(6), 556; https://doi.org/10.3390/membranes12060556 - 26 May 2022

Cited by 3 | Viewed by 3182

Abstract

Alkaline water electrolysis (AWE) refers to a representative water electrolysis technology that applies electricity to synthesize hydrogen gas without the production of carbon dioxide. The ideal polymer electrolyte membranes for AWE should be capable of transporting hydroxide ions (OH⁻) quickly in [...] Read more.

Alkaline water electrolysis (AWE) refers to a representative water electrolysis technology that applies electricity to synthesize hydrogen gas without the production of carbon dioxide. The ideal polymer electrolyte membranes for AWE should be capable of transporting hydroxide ions (OH⁻) quickly in harsh alkaline environments at increased temperatures. However, there has not yet been any desirable impedance measurement method for estimating hydroxide ions’ conduction behavior across the membranes, since their impedance spectra are significantly affected by connection modes between electrodes and membranes in the test cells and the impedance evaluation environments. Accordingly, the measurement method suitable for obtaining precise hydroxide ion conductivity values through the membranes should be determined. For this purpose, Zirfon^®, a state-of-the-art AWE membrane, was adopted as the standard membrane sample to perform the impedance measurement. The impedance spectra were acquired using homemade test cells with different electrode configurations in alkaline environments, and the corresponding hydroxide ion conductivity values were determined based on the electrochemical spectra. Furthermore, a modified four-probe method was found as an optimal measurement method by comparing the conductivity obtained under alkaline conditions. Full article

(This article belongs to the Special Issue Advance in Electromembrane Technology)

► Show Figures

Figure 1

Review

Jump to: Research

22 pages, 6962 KiB

Open AccessReview

Application of Bipolar Membrane Electrodialysis in Environmental Protection and Resource Recovery: A Review

by Yu Luo, Yaoxing Liu, Jiangnan Shen and Bart Van der Bruggen

Membranes 2022, 12(9), 829; https://doi.org/10.3390/membranes12090829 - 24 Aug 2022

Cited by 22 | Viewed by 4586

Abstract

Bipolar membrane electrodialysis (BMED) is a new membrane separation technology composed of electrodialysis (ED) through a bipolar membrane (BPM). Under the action of an electric field, H₂O can be dissociated to H⁺ and OH⁻, and the anions and [...] Read more.

Bipolar membrane electrodialysis (BMED) is a new membrane separation technology composed of electrodialysis (ED) through a bipolar membrane (BPM). Under the action of an electric field, H₂O can be dissociated to H⁺ and OH⁻, and the anions and cations in the solution can be recovered as acids and bases, respectively, without adding chemical reagents, which reduces the application cost and carbon footprint, and leads to simple operation and high efficiency. Its application is becoming more widespread and promising, and it has become a research hotspot. This review mainly introduces the application of BMED to recovering salts in the form of acids and bases, CO₂ capture, ammonia nitrogen recovery, and ion removal and recovery from wastewater. Finally, BMED is summarized, and future prospects are discussed. Full article

(This article belongs to the Special Issue Advance in Electromembrane Technology)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Advance in Electromembrane Technology

Share This Special Issue

Special Issue Editor

Special Issue Information

Published Papers (8 papers)

Research

Review

Further Information

Guidelines

MDPI Initiatives

Follow MDPI