Fabrication of doubly charged anion-exchange membranes for enhancing hydroxide conductivity

Adsorption of Eosin B from Wastewater onto the Prepared Porous Anion Exchange Membrane

This research describes the fabrication of the porous trimethylamine (TMA)-grafted anion exchange membrane (AEM) over a phase inversion process. The synthesis of the generated AEM was verified using Fourier transform infrared (FTIR) spectroscopy. The fabricated porous AEM showed 240% water uptake (WR), 1.45 mg/g ion exchange capacity (IEC), and a 9.0% linear expansion ratio (LER) at 25 °C. It exhibited a porous structure and higher thermal stability. It was utilized to remove eosin B (EB) from wastewater via the process of adsorption. The adsorption capacity of EB increased with time and the starting concentration of EB while decreasing with temperature and the AEM dosage. Adsorption isotherm investigation results showed that EB adsorption onto the porous AEM followed the Langmuir isotherm because the value of correlation coefficient (R2 = 0.992) was close to unity. Because the correlation coefficient was close to one, it was determined through adsorption kinetic experiments that the adsorption of EB on the produced porous AEM was suitable for a pseudo-second-order model. Thermodynamic study about process of EB adsorption on the porous AEM revealed that there was an exothermic (ΔH° = -16.60 kJ/mol) and spontaneous process.

SPEEK and SPPO Blended Membranes for Proton Exchange Membrane Fuel Cells

In fuel cell applications, the proton exchange membrane (PEM) is the major component where the balance among dimensional stability, proton conductivity, and durability is a long-term trail. In this research, a series of blended SPEEK/SPPO membranes were designed by varying the amounts of sulfonated poly(ether ether ketone) (SPEEK) into sulfonated poly(phenylene) oxide (SPPO) for fuel cell application. Fourier transform infrared spectroscopy (FTIR) was used to confirm the successful synthesis of the blended membranes. Morphological features of the fabricated membranes were characterized by using scanning electron microscopy (SEM). Results showed that these membranes exhibited homogeneous structures. The fabricated blended membranes SPEEK/SPPO showed ion exchange capacity (IEC) of 1.23 to 2.0 mmol/g, water uptake (W_R) of 22.92 to 64.57% and membrane swelling (MS) of 7.53 to 25.49%. The proton conductivity of these blended membranes was measured at different temperature. The proton conductivity and chemical stability of the prepared membranes were compared with commercial membrane Nafion 117 (Sigma-Aldrich, St. Louis, Missouri, United States) under same experimental conditions. The proton conductivity of the fabricated membranes increased by enhancing the amount of SPPO into the membrane matrix. Moreover, the proton conductivity of the fabricated membranes was investigated as a function of temperature. Results demonstrated that these membranes are good for applications in proton exchange membrane fuel cell (PEMFC).

Effect of Different Quaternary Ammonium Groups on the Hydroxide Conductivity and Stability of Anion Exchange Membranes

Anion exchange membrane fuel cells (AEMFCs) are encouraging electrochemical structures for the competent and complaisant conversion of energy. Herein, the development of brominated poly(2,6-dimethyl phenylene oxide) (BPPO)-based anion exchange membranes (AEMs) with different quaternary ammonium groups for AEMFCs was reported. The successful preparation of AEMs was proved by utilizing proton nuclear magnetic resonance and Fourier transform infrared spectroscopy. They were explored in terms of water uptake (W _R), ion exchange capacity (IEC), hydration number (λ), linear swelling ratio (LSR), morphology, tensile strength (TS), and elongation at break (E _b). The alkaline stability of the prepared AEMs was assessed and compared with each other. The experimental outcomes demonstrated that the N-methylpyrrolidinium-based membrane (MPyPPO) exhibited higher alkaline stability, whereas the N-methylimidazolium-based membrane (MImPPO) showed the lowest alkaline stability among the prepared AEMs. Similarly, the hydroxide conductivity of the prepared AEMs was measured and compared with each other. The pyrrolidinium-based membrane (MPyPPO) exhibited higher hydroxide conductivity among the prepared AEMs.

Synthesis of DMEA-Grafted Anion Exchange Membrane for Adsorptive Discharge of Methyl Orange from Wastewaters

This manuscript describes the synthesis of dimethylethanolamine (DMEA)-grafted anion exchange membrane (AEM) by incorporating dimethylethanolamine as ion-exchange content into the polymer matrix via the solution casting method. The synthesis of the DMEA-grafted AEM was demonstrated by Fourier transform infrared (FTIR) spectroscopy. The prepared DMEA-grafted AEM exhibited higher thermal stability, homogeneous morphology, water uptake (W_R) of 115%, and an ion exchange capacity (IEC) of 2.70 meq/g. It was used for the adsorptive removal of methyl orange (MO) from an aqueous solution via batch processing. The effect of several operating factors, including contact time, membrane dosage, initial concentration of aqueous dye solution, and temperature on the percentage discharge of MO and adsorption capacity, was evaluated. Experimental data for adsorption of MO onto the DMEA-grafted AEM was analyzed with two parameter and three parameter nonlinear adsorption isotherm models but fitted best using a nonlinear Freundlich isotherm. Adsorption kinetics were studied by using several models, and attained results showed that experimental data fitted well to pseudo-second-order kinetics. A thermodynamic study showed that adsorption of MO onto the prepared DMEA-grafted AEM was an endothermic process. Moreover, it was a feasible and spontaneous process.

Higher Acid Recovery Efficiency of Novel Functionalized Inorganic/Organic Composite Anion Exchange Membranes from Acidic Wastewater

In this work, the synthesis of a series of the functionalized inorganic/organic composite anion exchange membranes (AEMs) was carried out by employing the varying amount of inorganic filler consist of N-(trimethoxysilylpropyl)-N,N,N-trimethylammonium chloride (TMSP-TMA⁺Cl^-) into the quaternized poly (2, 6-dimethyl-1, 4-phenylene oxide) (QPPO) matrix for acid recovery via diffusion dialysis (DD) process. Fourier transform infrared (FTIR) spectroscopy clearly demonstrated the fabrication of the functionalized inorganic/organic composite AEMs and the subsequent membrane characteristic measurements such as ion exchange capacity (IEC), linear swelling ratio (LSR), and water uptake (W_R) gave us the optimum loading condition of the filler without undesirable filler particle aggregation. These composite AEMs exhibited IEC of 2.18 to 2.29 meq/g, LSR of 13.33 to 18.52%, and W_R of 46.11 to 81.66% with sufficient thermal, chemical, and mechanical stability. The diffusion dialysis (DD) test for acid recovery from artificial acid wastewater of HCl/FeCl₂ showed high acid DD coefficient (U_H⁺) (0.022 to 0.025 m/h) and high separation factor (S) (139-260) compared with the commercial membrane. Furthermore, the developed AEMs was acceptably stable (weight loss < 20%) in the acid wastewater at 60 °C as an accelerated severe condition for 2 weeks. These results clearly indicated that the developed AEMs have sufficient potential for acid recovery application by DD process.