BPPO-Based Anion Exchange Membranes for Acid Recovery via Diffusion Dialysis

Abstract

To reduce the environmental impact of acids present in various industrial wastes, improved and robust anion exchange membranes (AEMs) are highly desired. Moreover, they should exhibit high retention of salts, fast acid permeation and they should be able to operate with low energy input. In this work, AEMs are prepared using a facile solution-casting from brominated poly-(2,6-dimethyl-1,4-phenylene oxide) (BPPO) and increasing amounts of 2-phenylimidazole (PI). Neither quaternary ammonium salts, nor ionic liquids and silica-containing compounds are involved in the synthesis. The prepared membranes showed an ion exchange capacity of 1.1–1.8 mmol/g, a water uptake of 22%–47%, a linear expansion ratio of 1%–6% and a tensile strength of 0.83–10.20 MPa. These membranes have potential for recovering waste acid via diffusion dialysis, as the acid dialysis coefficient (UH) at room temperature for HCl is in the range of 0.006–0.018 m/h while the separation factor (S) is in the range of 16–28, which are higher than commercial DF-120B membranes (UH = 0.004 m/h, S = 24).

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

“…Figure 7 b depicts the separation factor of the fabricated functionalized inorganic/organic composite AEMs at ambient temperature. The obtained value of separation factor was increased from 139 to 260 with increasing the amount of inorganic filler from 2.5% to 7.5% into the QPPO, which surpassed the evaluated commercial membrane DF-120B (24.3) [ 32 , 42 ]. With increasing the amount of inorganic filler, water uptake, linear swelling ratio (dimensional stability), and IEC were increased.…”

“…The second weight loss was noted in the range of 180 to 240 °C. It was due to the degradation quaternary ammonium group into the polymeric material [ 32 , 33 ]. The final weight loss was found around 470 °C.…”

“…Moreover, the AEMs with higher IEC represented higher swelling degree and modest mechanical stability. To date, several polymeric materials namely polysulfone [ 27 ], poly(tetrafluoroethylene) [ 28 ], polyvinyl alcohol (PVA) [ 29 ], chitosan [ 30 ], polybenzimidazole [ 31 ], and bromo-methylated poly (phenylene oxide) (BPPO) [ 32 , 33 , 34 ], etc. were utilized for the development of the AEMs.…”

Diffusion Dialysis for Acid Recovery from Acidic Waste Solutions: Anion Exchange Membranes and Technology Integration

“…Compared to the PPO-based porous membrane functionalized with quaternary ammonium groups ( Figure 7 e) without aromatic groups ( T d = 164.2 °C) [ 78 ], the membrane exhibited a higher thermal stability (thermal degradation temperature ( T d = 179 °C)). Besides, Khan [ 101 ] prepared a series of PPO-based AEMs modified by phenylimidazole groups ( Figure 7 f). The results showed that these AEMs exhibited excellent acid stability.…”

“… The structure of ( a ) quaternizated poly(VBC-co-γ-MPS), ( b ) Q-DAN, ( c ) glycidyl trimethyl ammonium chloride, ( d ) quaternary aromatic amine groups, ( e ) quaternary ammonium, ( f ) phenyl imidazole, ( g ) AESP ( h ) QUDAP [ 49 , 78 , 83 , 84 , 99 , 100 , 101 , 102 ]. …”