Diffusion Dialysis Process Research Articles

Recovery of sulfuric acid from a stone coal acid leaching solution by diffusion dialysis

Diffusion dialysis was employed to recover sulfuric acid from a stone coal acid leaching solution. The dialysis coefficients of H+, V, Al, Fe, Mg, K, F, P, and S ions in a stone coal acid leaching solution for an anion exchange membrane were determined. The effects of the flow rate, flow rate ratio, and water osmosis rate as well as ion rejection on sulfuric acid recovery were investigated. The results demonstrated that the DF120-III anion exchange membrane showed a good separation performance for separating sulfuric acid from the stone coal acid leaching solution. In the diffusion dialysis process, the water osmosis rate, sulfuric acid recovery, ion rejection, water equilibrium and processing ability were taken into consideration. Controlling water osmosis was more important than obtaining a higher acid recovery. Under the optimum operating conditions of a feed flow rate of 12mL/min and flow rate ratio of water to feed of 1–1.1, sulfuric acid recovery reached 71.12%, the water osmosis rate was controlled at approximately 14.95%, and vanadium rejection was approximately 95.50%. The rejection of impurity ions, such as Al, Fe, Mg, K, F, P, and S was approximately 99.04%, 97.37%, 98.01%, 85.12%, 98.33%, 91.16%, and 69.96%, respectively. The high rejections of F in the form of complexes and P in the form of incompletely dissociated acid were disadvantageous to the recovery of sulfuric acid. The recovered acid was able to be reused in the acid leaching process by the addition of fresh acid.

Preparation and properties of cation-exchange membranes based on commercial chlorosulfonated polyethylene (CSM) for diffusion dialysis

Cation-exchange membranes for diffusion dialysis (DD) were prepared by selecting chlorosulfonated polyethylene (CSM) and methacrylic acid (MAA) as framework and functional monomer, respectively. An interpenetrating network structure (IPN) was formed by free radical polymerization and consequent crosslinking reaction. The membranes possessed ion exchange capacities (IECs) of 1.98–3.12 mmol/g, water uptake (WR) of 12.7–34.8%, swelling degree of 72.7–170% as well as favorable thermal stability and alkali resistance (almost zero mass loss in hot alkali solution). The membranes were applied for DD process to recover alkali from NaOH/Na2WO4 system at 25 °C and 65 °C. Results indicated that coefficients for OH− (UOH) were in the range of 0.0015–0.018 m/h and separation factors (S) were in the range of 9–33 at 25 and 65 °C, respectively.

Selective removal of halides from spent zinc sulfate electrolyte by diffusion dialysis

Zinc metal is mainly produced by a hydrometallurgical process, in which zinc electrolyte is recirculated, and impurities especially halides are accumulated then, which have dreadful impacts on the process and product. Until now numerous efforts have been made to remove halides from the electrolyte, but none of them are fully satisfying, and it is still a big issue for the industry. As a conventional membrane technology, diffusion dialysis (DD) is originally designed to recover free acid from acid-salt mixture by concentration gradient. In this work, we proposed a novel process to selectively remove these halide impurities from the spent zinc electrolyte by DD directly. Significant Cl- and F- permselectivities over HSO4- are observed in this process. The removal efficiencies are as high as 50–70% and 30–42% for chloride and fluoride, respectively, while the zinc loss is less than 1%. The flow intensity in the current work is much higher than that in conventional DD, which reduces the overall cost immensely. The mechanism of this selective mass transfer is also studied intensively to understand influence of flow intensity, charge number and hydrated radii of ions on the permselectivity. The results here are not confined to provide a superior method to remove halide impurities for the zinc industry, but also extend new applications and deepen understandings for the well-established DD process in selective ion separation. This capability is very likely to become a new growth point and future direction for the DD process besides acid/alkali recovery.

Crosslinked PVA-based hybrid membranes containing di-sulfonic acid groups for alkali recovery

Hybrid cation exchange membranes (CEMs) are prepared from polyvinyl alcohol (PVA), 3-mercaptopropyltriethoxysilane (MPTES) and benzaldehyde disulfonic acid disodium salt (BADSANa), which contains several functional groups like –OH, –SH/ –Si(OC2H5)3 and –SO3Na/ –CHO, etc. The availability of –CHO and –Si(OC2H5)3 groups are of immense importance as they can be easily cross-linked with PVA–OH groups through the acetal and sol-gel reaction. The -SH groups are further oxidized into the –SO3H groups in the presence of Fenton’s reagent or ozone to make the membrane matrix charged. It has been observed that membrane hydrophilicity and ion exchange capacities gradually increase with the dosage of BADSANa and MPTES. The tensile strength of prepared membranes is in the range of 5.8–30.9 MPa while the elongation at break (Eb) of 118.9–447.2%. The short-term thermal stability is ranged between 165 and 275 °C. The alkali resistance is acceptable at room temperature. Diffusion dialysis (DD) process shows that if the prepared membranes are oxidized by Fenton’s reagent, the dialysis coefficients of NaOH (UOH) in NaOH /NaAlO2 solution are in the range of 2.8–23.4 mm/h along with the separation factors (S) in between 4.6 and 20.0. The optimized membrane (M6B2-F) has both the highest S value of 20.0 and UOH as 23.4 mm/h. The similar separation performance can be achieved if the membranes are oxidized by ozone instead of Fenton’s reagent. The ozone oxidation, the organic solvent free preparation, and the favorable DD performances may provide new clues for designing new cation exchange hybrid membranes for alkali recovery.

Fabrication of cation exchange membrane from polyvinyl alcohol using lignin sulfonic acid: Applications in diffusion dialysis process for alkali recovery

ABSTRACTWe report polyvinyl alcohol (PVA)-based hybrid membranes composed of salt of lignin sulfonic acid (LSA) and tetraethyl orthosilicate. The concentration of LSA with respect to PVA varied from 10% to 40%. The hybrid membranes showed water uptake (WU) in the range of 122–210%, ion exchange capacities in the range of 0.32–0.75 mmol g−1, dialysis coefficient (UOH) from 0.0068 to 0.0119 m h−1, and selectivity (S) from 15 to 26. The hybrid membranes also showed thermal and mechanical stability.

Development of novel PVA-QUDAP based anion exchange membranes for diffusion dialysis and theoretical analysis therein

Abstract Anion exchange membrane is a key component that determines the performance of diffusion dialysis process for acid recovery. This study reports a novel anion exchange membrane composed of poly vinyl alcohol (PVA), quaternized 1-hydroxy-N, N-dimethyl-N-(pyridine-2-ylmethyl) methanaminium (QUDAP) and tetraethyl orthosilicate (TEOS) prepared by classical sol–gel process. The anion exchange membranes were characterized by scanning electron microscopy (SEM), dynamic mechanical analysis (DMA), Fourier transform infra-red (FTIR) and thermo gravimetric analysis (TGA). The QUDAP contents were varied with respect to PVA, and were found to influence the electrochemical performance and physiochemical properties of prepared membranes. These hybrid membranes showed ion exchange capacity (IEC) values ranging from 0.23 to 0.75 mmol/g with water uptake of 68.76–131.42%, and excellent tensile strength and elongation at break of 42.04–50.66 MPa and 76.35–163.63%, respectively. Good proton dialysis coefficients (UH) values of 0.0222 m/h with high separation factor (S) of 54.28 at 25 °C were achieved. These obtained values are much greater than commercial membrane DF-120 (0.009 m/h for UH, 18.8 for S). A lumped parameter model was developed to predict the performance of acid recovery via diffusion dialysis in terms of diffusion coefficient and variation in feed volume. The experimental results were compared with model predications, the consequences of predications suggest that the model can give a reasonable agreement with experimental results.

Improved acid recovery performance by novel Poly(DMAEM-co-γ-MPS) anion exchange membrane via diffusion dialysis

Rapid development of diffusion dialysis based on anion exchange membranes (AEMs) established its prominent significance as a leading candidate in the field of separation science and technology. AEM-based diffusion dialysis (DD) processes intended to acid recovery have generated much interest due to their exclusive selectivity. Here, we report the effects of novel Poly(DMAEM-co-γ-MPS)-based AEMs for DD applications (acid recovery). Free radical polymerization was successfully done with the initiator azobisisobutyronitrile (AIBN) to achieve the desired polymer Poly(DMAEM-co-γ-MPS). Finally, quaternization with EPTAC and methyl iodide was done to make the membrane matrix charged. The dosage of Poly(DMAEM-co-γ-MPS) inside membrane matrix plays a crucial role to determine the physiochemical and electrochemical properties of the prepared membranes. The influence of Poly(DMAEM-co-γ-MPS) on the acid recovery behavior of the membranes was explored in detail. The prepared membranes displayed high thermo-mechanical stability. At 25°C, the acid dialysis coefficient (UH) values were between 0.016–0.029m/h, while the separation factors (S) ranged from 23.3 to 87.7. Both the acid recovery (7.25 times) and separation factors (~3.6 times) are much higher than the commercial fiber supported anion exchange membrane DF-120B (UH and S=0.004m/h and 24.3, respectively). Prepared AEMs are the potent candidate for acid recovery via diffusion dialysis. The highlight of this work is the fabrication of new AEMs, which shows high acid dialysis performance and selectivity.

Double cross-linking PVA-SiO2 hybrid membranes for alkali recovery

Abstract Non-charged PVA-SiO2 hybrid membranes are prepared through sol-gel process among polyvinyl alcohol (PVA) and double cross-linking agents, which are selected from four types of alkoxysilanes including tetraethoxysilane (TEOS), tetramethoxysilane (TMOS), γ-aminopropyl triethoxysilane (APTEOS) and methacryloxypropyl trimethoxy silane (MPS). The double cross-linking agent can combine their advantages including different hydrolysis rates of OC2H5 and OCH3 groups, high compatibility of NH2, and polymerizable C C bonds. The NH2 group from APTEOS can enhance membrane homogeneity, thermal stability and flexibility due to its compatibility with PVA–OH groups. The membranes have high selectivity (62–101) but low permeability in diffusion dialysis process for separating NaOH/Na2WO4 solution. Single type of Si(OCH3) groups produces large silica particles (1.5–5μm), which reduce membrane stability but enhance permeability. The membrane has low strength and flexibility, and high swelling degrees in 65 °C water (373–408%) and weight loss percentage in 65 °C NaOH solution (25.8–28.7%). The permeability can reach up to 0.0076–0.0092 m/h but the selectivity is only 23.7–25.0 at 20–40 °C. The combination of Si(OCH3) and Si(OC2H5) groups (TEOS and MPS) can obtain high strength and flexibility (20.3 MPa, 571%), acceptable swelling degrees (232–279%) and balanced permeability and selectivity (0.0043–0.0071 m/h, 45–110). Hence, double cross-linking agents can be combined to prepare optimized neutral membranes for diffusion dialysis.

Diffusion dialysis for NaCl and NaAc recovery using polyelectrolyte complexes/PVA membranes

Abstract Diffusion dialysis (DD) technique is nowadays mainly utilized for recovering acid or alkali solutions, but the recovery of salts such as sodium chloride (NaCl) and sodium acetate (NaAc) is much more difficult due to their low diffusivity. Polyelectrolyte complexes (PECs)/polyvinyl alcohol (PVA) membranes containing functional groups of C OH, Si OH, N+(CH3)3 and SO3Na are pioneered for DD process of salts. The membranes have improved stability in water and salt solution. The dialysis coefficients of NaCl (UNaCl) are in the range of 0.00196–0.00290 m/h, which are 6–30 times higher than the values of commercial DF-9010 and CJMCDD-1 membranes. The dialysis coefficients of NaAc (UNaAc) are in the range of 0.00108–0.00503 m/h, which are 30–143 times higher than the value of CJMCDD-1 membrane, whereas DF-9010 membrane has poor stability in NaAc solution. Finally, PECs/PVA membranes are applied to NaCl/threonine (Thr) mixture and NaAc waste residue solution, showing their outstanding advantages for DD process of salts. The membranes show both high permeability and selectivity for NaCl/Thr mixture, with separation factor (SNaCl/Thr) as high as 6.495 (DF-9010: 1.25; CJMCDD-1: 0.224). The UNaAc values for NaAc waste residue solution are 0.000602–0.00120 m/h, higher than that of commercial CJMCDD-1 membrane.

Preparation of pyrrolidinium-based anion-exchange membranes for acid recovery via diffusion dialysis

ABSTRACTIn this manuscript, the preparation of pyrrolidinium-based anion-exchange membranes (AEMs) from brominated poly(2,6-dimethyl-1,4-phenyleneoxide) (BPPO) is reported. Prepared membranes were completely characterized in terms of Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), atomic force microscopy (AFM), ion-exchange capacity (IEC), water uptake (WR), linear expansion ratios (LER), mechanical stability, acid stability, etc. Excellent thermal, mechanical and acid stability can be observed for prepared membranes. Prepared membranes were used in diffusion dialysis (DD) process for acid recovery from model waste HCl/FeCl2 solution. The dialysis coefficient of HCl (UH) is found to be in the range of 0.018–0.049 m/h, whereas the separation factor (S) was obtained as 36.24–66.39. Prepared membranes show much better DD performance than that of commercial fibre–supported DF-120B membrane (0.004 m/h for UH, 24.3 for S at 25°C). Prepared membranes got the potential to be used as a promising candidate for acid recovery via DD.

Facile synthesis of pyridinium functionalized anion exchange membranes for diffusion dialysis application

Abstract Pyridinium functionalized anion exchange membranes are prepared for diffusion dialysis using polyvinyl alcohol (PVA) as base material. Four membranes have been prepared by varying the content of pyridinium salt. The ion exchange (IEC), water uptake (WU), thickness and linear expansion ratio have been measured or calculated. These membranes have shown excellent thermal and chemical stabilities. When applied in diffusion dialysis with a simulated solution mixture of HCl and FeCl2, the membranes show successfully good acid recovery and separation factor. The acid dialysis coefficients are in the range of 1.74–2.48 (10−2 m/h) and separation factors in the range of 30.49–57.51. The obtained acid dialysis coefficients and separation factors are greater than that of the widely used commercial membrane DF-120 with (UH = 0.9 × 10−2 m/h) and (S = 18.5). Hence, the results of this study suggest that the pyridinium functionalized AEMs can be potentially applied in diffusion dialysis process for acid recovery.

Acidic Recovery from Wastewater of Automotive Battery Plant Using Membrane Technology

Diffusion dialysis (DD) equipped with anion exchange membranes (AEMs) is used as an effective tool to recover acidfrom various types of waste acid solutions. The aim of this study was to investigate the possibility of using the DD process to recover sulfuric acid (HsSO4) from the acidic wastewater from an automotive battery plant. A numbers of experimental runs was conducted to optimize the equipment’s operating conditions, particularly variations in feed flow and flow rate ratios . The results showed that H2SO4 permeated well through the AEM, while metal ions were efficiently rejected. The recovery of H2SO4 increased as flow rate decreased. Approximately 84.5% of H2SO4 could be recovered at 9 .38 × 10 -5 m3 h-1 m-2. Pb2+ rejection was 69.5%. In addition, recovery efficiency could be improved by increasing the flow rate ratio. At the highest flow rate ratio, DD could recover up to 90% of H2SO4 while the lowest rejection of Pb2+ (61%) was obtained. Also, the investigation of the effect of variation of flow rate ratio on recovery efficiency revealed that the optimum flow rate ratio should be controlled at around 1 to 1.2.

Acidic Recovery from Wastewater of Automotive Battery Plant Using Membrane Technology

Diffusion dialysis (DD) equipped with anion exchange membranes (AEMs) is effectively used as a tool to recover acid (H + ) from various type of wasted acid solution. The aim of this study was to investigate the possibility of using DD process to recover sulfuric acid (H 2 SO 4 ) from the acidic wastewater of automotive battery plant. Numbers of experimental runs were conducted to optimize the operating conditions of such equipment, for example variation of feed flow and flow rate ratio (Q water /Q feed ). The results showed that H 2 SO 4 permeated well through the AEM, while metal ions were efficiently rejected. The recovery of H 2 SO 4 increased as the flow rate decreased. Approximately 84.5% of H 2 SO 4 could be recovered at 9.38 × 10 - 5 m 3 /h m 2 . Pb 2+ ion rejection was 69.5%. In addition, H 2 SO 4 recovery efficiency could be improved by increasing the flow rate ratio. At the highest flow rate ratio, DD could recover up to 90% of H 2 SO 4 while the lowest rejection of Pb 2+ ion (61%) was obtained. Also, the results from variation of flow rate ratio revealed that the optimum Q water /Q feed should be controlled around 1 to 1.2

Novel silica-functionalized aminoisophthalic acid-based membranes for base recovery via diffusion dialysis

The progress in diffusion dialysis (DD)-based separations provides an effective platform for the development of suitable materials for cation exchange membranes (CEM), as CEM-based DD processes aimed at alkali recovery have generated much interest due to their unique ion transport phenomena. Here, for the first time, we report the use of novel silica-functionalized aminoisophthalic acid (AIPA)-based CEMs with polyvinylalcohol (PVA) used as a binder for DD applications (base recovery). The synthesis of the active material AIPA involved a classic nucleophilic reaction between 5-aminoisophthalic acid and 3-glycidoxypropyltrimethoxysilane. By varying the amount of AIPA inside the membrane matrix, the properties of the prepared membranes can be altered. The prepared AIPA membranes were investigated systematically in terms of water uptake (WR), ion exchange capacity (IEC) and thermomechanical measurements, such as DMA and TGA. The influence of AIPA on the base recovery behaviour of the membranes was investigated in detail. The prepared AIPA membranes displayed water uptake values (WR) within 44.2–47.5%, ion exchange capacity (IEC) values between 0.48 and 0.93mmol/g, initial decomposition temperatures (IDTs) of 193 to 219°C, tensile strength (TS) values of 50.1 to 58.4MPa and elongation at break (Eb) values of 6.6 to 224.9%. At 25°C, the dialysis coefficient (UOH) values were between 0.0068 and 0.0097m/h, whereas the separation factors (S) ranged from 17.86 to 31.79. The membranes have great potential for base recovery via diffusion dialysis.

Porous diffusion dialysis membranes for rapid acid recovery

To enhance the proton permeability of the anion exchange membranes used in diffusion dialysis, porous ultrafiltration membrane with a thin skin layer rather than the dense membrane was utilized for the preparation of diffusion dialysis membrane. In particular, brominated poly (phenylene oxide) (BPPO) ultrafiltration membrane was fabricated via a phase inversion method and then modified by crosslinking with polyethyleneimine (PEI) and subsequent quaternization with trimethylamine (TMA) via nucleophilic substitution reaction. Diffusion dialysis related properties of the membranes such as water uptake, ion exchange capacity, and thermal and swelling stabilities were investigated. Due to the special structure of the membranes (i.e., high porosity and low thickness of the top layer (sub-1μm), as confirmed by scanning electron microscopy) the optimal membrane exhibited 6.4 times higher acid dialysis coefficient for HCl recovery from HCl/FeCl2 solution than the commercial DF-120 (thickness=320μm) membrane at the similar separation factor. The calculated acid recovery capacity can increase from 11.3 up to 83.7Lm−2d−1 by replacing DF-120 with our optimal membrane. Our findings show the porous membranes developed here have great potential for high-efficiency acid recovery through diffusion dialysis process.

Combination of OH– ions and –OH groups within QPPO/PVA hybrid membranes for acid recovery

Hybrid membranes are prepared from quaternized poly(2,6-dimethyl-1,4-phenylene oxide) (QPPO), polyvinyl alcohol (PVA), monophenyl triethoxysilane, and tetraethoxysilane through sol–gel process. QPPO contains the anion-exchange groups which can be in the form of –N+(CH3)3OH−, –N+(CH3)3Cl−, or –N+(CH3)3Br−. The OH− ions can combine with PVA–OH groups to form weak interactions such as hydrogen bonds, and thus enhance the compatibility between QPPO and PVA phases and membrane stability. Hybrid membranes with the combination of OH−/−OH are generally homogenous and compact, with the lower water uptake of 57.6–67.4%, methanol content of 38.3–40.2%, and swelling degrees of 223–500% in 65°C water. The ion-exchange capacities are similar in the range of 1.04–1.08 mmol/g. Diffusion dialysis (DD) of HCl/FeCl2 solution shows that as the temperature increases from 15 to 55°C, the dialysis coefficients of HCl (UH) increase from 0.008 m/h to 0.014–0.018 m/h, while the separation factors decrease from 61–67 to 41–50. The UH values are similar to that of commercial membrane DF-120 (0.009 m/h at 25°C), and the separation factors are higher than those of reported membranes (lower than 48). The UH values can remain 87–95% after the erosion of HCl/FeCl2 system, with no significant reduction of selectivity. Hence, the combination of OH− ions and PVA–OH groups is effective to elevate membrane stability and selectivity, and the QPPO/PVA hybrid membranes can be potentially applied in DD process for acid recovery.

Hybrid membranes from sulphonated poly (2, 6-dimethyl-1, 4-phenylene oxide) and sulphonated nano silica for alkali recovery

Hybrid membranes for diffusion dialysis were prepared by incorporating sulphonated nano silica particles into sulphonated poly (2, 6-dimethyl-1, 4-phenylene oxide) (SPPO) matrix. The membranes with ion exchange capacities (IECs) of 1.87–2.00mmol/g possessed favorable thermal stability and alkali resistance. They were tested in NaOH/Na2WO4 feed solution via diffusion dialysis (DD) process. Results showed that as-prepared hybrid membranes exhibited better separation performance under the temperature higher than 35°C. The highest hydroxide flux (UOH) reached 0.015m/h at 55°C with a separation factor around 34. The pure SPPO (as control) exhibited much lower UOH values at the investigated temperature range though its separation factor was higher. The structure and physico-chemical properties of the hybrid membranes were investigated to better understand the DD results. Sulfonic groups at the surface of nano silica particles were believed to enhance the transport of Na+ and i.e., promoted the diffusion of OH−.

Preparation of diffusion dialysis membrane for acid recovery via a phase-inversion method

Herein, the preparation of anion exchange membrane (AEM) from brominated poly(2,6-dimethyl 1,6-phenylene oxide) BPPO and dimethylaniline (DMA) by phase-inversion process is reported. Anion exchange membranes (AEMs) are prepared by varying the DMA contents. Prepared AEMs show high thermal stability, water uptake (WR) around 202% to 226%, dimensional change ratios of 1.5% to 2.6% and ion exchange capacities (IECs) of 0.34 mmol/g to 0.82 mmol/g with contact angle of 59.18° to 65.15°. These membranes are porous in nature as confirmed by SEM observation. The porous property of membranes are important as it could reduce the resistance of transportation of ions across the membranes. They have been used in diffusion dialysis (DD) process for recovery of hydrochloric acid (HCl) from the mixture of HCl and ferrous chloride (FeCl2). Presence of ¯N+(CH3)2C6H5Br &$175;as a functional group in membrane matrix facilitates its applications in DD process. The dialysis coefficients of hydrochloric acid (UH) of the membranes are in range of 0.0016 m/h to 0.14 m/h and the separation factors (S) are in range of 2.09 to 7.32 in the HCl/FeCl2 system at room temperature. The porous membrane structure and presence of amine functional group are responsible for the mechanism of diffusion dialysis (DD).

Imidazolium functionalized anion exchange membrane blended with PVA for acid recovery via diffusion dialysis process

Anion exchange silica precursor (AESP) was prepared by alkylation of 3-chloropropyltriethoxysilane (CPTS) to 1-methyl imidazole and then the corresponding anion exchange membranes were obtained through sol–gel process of AESP with polyvinyl alcohol (PVA) in the presence of tetraethoxysilane (TEOS). The obtained anion-exchange membranes showed water uptakes (WU) in the range of 44.11–118.86% and ion-exchange capacities (IEC) of 1.34–1.86mmol/g. The presence of alkoxy-silane groups influenced the membrane properties as they exhibited moderate thermal stability and excellent mechanical properties. When applied for acid recovery through diffusion dialysis process, the membranes exhibited excellent acid flux. The H+ dialysis coefficients (UH) are in the range of 1.87–4.83×10−2m/h greater than commercial membrane DF-120 (9×10−3m/h). The obtained separation factors (S) 12.72–52.5 are also greater than that of commercial membrane DF-120 (18.5). Hence, the results of this study suggest that the imidazolium functionalized AEMs can be potentially applied in diffusion dialysis process for acid recovery.

Removal and recovery of sodium hydroxide (NaOH) from industrial wastewater by two-stage diffusion dialysis (DD) and electrodialysis (ED) processes

In this study, a two-stage diffusion dialysis (DD) and electrodialysis (ED) system for the removal and recovery of sodium hydroxide from industrial wastewater were investigated. The study was carried out at laboratory scale using food industry wastewater. Sodium hydroxide is commonly used as principal strong base by various chemical industries. The processed wastewater therefore enhances the pH levels of receiving water bodies that affects the physiological functions of aquatic organisms, plants, and makes the water inappropriate for human consumption. 1.0-μm PTFE (Advantec, USA), forward osmosis (FO) (Hydration Technology Innovation) membranes, platinum coated over titanium anode, and graphite cathode were used in this study. In the first stage of the DD process, NaOH from the feed solution (FS) i.e. wastewater to draw solution (DS) i.e. deionized water (DI) was carried out through PTFE membrane in a diffusion cell. The initial concentration of NaOH in the FS was from 1 to 3M and in the first step, 60 to 62% of NaOH was diffused from the FS to DS. In the second step of the DD process, further 48 to 50% NaOH was transferred from the FS to DS and overall 80 to 83% NaOH was removed from the FS. In the second stage, the DS collected from diffusion cell was transferred to the ED cell as the FS for further treatment and recovery of caustic soda. During the ED process, 15.0 V was applied for 5.0 h batch time. Sodium cations were transported from the FS to DS under the influence of electric potential through FO membrane and up to 44% of NaOH was recovered.