Acid recovery from copper metallurgical process streams polluted with arsenic by diffusion dialysis

Piperazine-functionalized porous anion exchange membranes for efficient acid recovery by diffusion dialysis

Enhanced diffusion dialysis performance of cross-linked poly(aryl piperidine) anion exchange membranes by thiol-ene click chemistry for acid recovery

In 2021, estimation shows that the worldwide annual hydrogen production is around 94 Mt. Exploitation of native hydrogen being not mature, it is obtained by its separation from other elements by different methods such as steam methane reforming, and electrolysis of water. The latter supplied by a renewable power source will take part in the development of a green hydrogen economy [1]. In this context, Proton Exchange Membrane (PEM) Electrolyzer is a promising technology due to its flexibility and very quick adaptation to load variations. However, its current development still confronts some limitations at a large industrial scale. For instance, efficiency and durability are directly impacted by the mass transport and electrical transfer within the porous materials at the anode side. Limitation of the water supply to the catalyst layer happens once there is a poor oxygen evacuation which decreases the performance of the device by inducing high overpotential. Furthermore, the PTL has an important role as an electrical conductor for charge transfer from the catalyst layer [1]. The efficiency of all the transport phenomena through the PTL and porous electrode assembly depends on their transport properties which are related to their microstructure and operating conditions. For instance, PTL with a large pore size allows good water and gas transport, while produced electrons choose a long-distance path generating an electrical resistance higher than that in the case of PTL with a small pore size [1]. So, controlled and optimum porosity and pore size could contribute to efficient water, gas, and electron transport. To define the best porous layers morphologies, a deep and accurate understanding of the phenomena is developed in this work by combining modeling and experiments.The magnetic resonance imaging (MRI) technique was used to quantify the water content within the porous layer during the two-phase flow. Instead of the real PTL made of titanium which is paramagnetic and cannot be used in the MRI, borosilicate filters with thickness, porosity, and pore size similar to the PTL were used. After positioning the sample in the 600 MHz vertical imager (Figure 1-A), a constant water flow rate is introduced while the gas flow rate is varied. The saturation profiles measured through the porous material depend on the gas flow rate and a semi-dryness of the sample occurs (Figure 1-B) with a residual quantity trapped between pores (minimum stable water content). The water flow rate variation in the channel does not affect saturation, but a higher gas flow rate is needed to reach a minimum stable water content for higher water flow rate.The gas pressure drop through the porous medium was measured and bubble formation in the channel was also analyzed. The results show that the pressure drops and types of flow (slug, annular, and bubble flow) depend on orientation of the water channel (horizontally and vertically) and flow direction (up or downward), and on the water and gas flow rates.To reach a better understanding of the dynamic characteristics of water and oxygen transport over the PTL, the phase-field model based on the Cahn-Hilliard theory was used to simulate the two-phase flow through a porous medium [2]. In this model, the modified Navier-Stokes equations for two phases are coupled with a phase-field equation for describing the diffuse interface. Numerical simulations performed in the COMSOL® multiphysics software were carried on 2D geometries composed of spherical solid grains of different sizes, having properties similar to the PTL used in the MRI experiments. Gas is injected on one side of the sample and flows through the porous medium initially saturated and evacuated on another side in contact with the water channel (Figure 1-C). Gas flow in the porous medium and bubble formation in the water channel are studied while varying the gas and water flow rates. The simulation results give information about the gas pathways within the porous medium and the saturation profiles over time, depending on the gas/water flow rates, which will be compared with experimental results.[1] J. Parra-Restrepo, “Caractérisation des hétérogénéités de fonctionnement et de dégradation au sein d’un électrolyseur à membrane échangeuse de protons (PEM),” Université de Lorraine, 2020.[2] J. W. Cahn and J. E. Hilliard, “Free Energy of a Nonuniform System. I. Interfacial Free Energy,” The Journal of Chemical Physics, vol. 28, no. 2, pp. 258–267, Feb. 1958. Figure 1

Recovery of phosphoric acid from mixed waste acids of semiconductor industry by diffusion dialysis and vacuum distillation

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

To determine the influence of port geometry on water and vitreous flow rates and test novel vitreous cutter tips in specific surgical situations. Custom 20-gauge and 25-gauge vitreous cutter tips with different sized ports were evaluated through porcine vitreous and water flow rates. Five cutter tips were designed and fabricated for specific surgical functionalities. Tips were compared with a normal control tip and evaluated by water and porcine vitreous flow rates, vacuum level required to cut porcine retina, time required to cut and aspirate a porcine lens, and surgical evaluation in enucleated porcine eyes. Both vitreous and water flow asymptotically approached a maximum flow as the port diameter increased. Some tips removed water faster than the normal control tip, but none removed vitreous or lens faster. Several tips required higher vacuum levels to cut retina than the normal tip. Increasing the port diameter of a vitreous cutter to increase flow becomes less effective as the port becomes larger. Furthermore, modifying the port geometry of a vitreous cutter affects its surgical interactions with tissue. In the future, combinational instruments or surgery specific instruments may allow the surgeon to use an optimal port for a specific surgical task.

An anion exchange membrane (AEM) is applied for acid recovery through the diffusion dialysis (DD) process. However, a specially designed AEM is required to achieve a high dialysis coefficient of acid (UH+) and separation factor (S). The design of our membrane for acid recovery and metal ion separation is based on the optimization of water swelling, structural stabilization (cross-linking), and introduction of cationic moieties where the delocalization of charge in a ring system (imidazole) is possible. Based on the above design, herein, preparation of a cross-linked AEM using a poly(acrylonitrile)-co-poly(vinyl imidazole) copolymer for the separation of metal ions and acid (HCl) is reported. The AEMs have been prepared by quaternization of the copolymer followed by cross-linking. The effect of a quaternizing agent (alkyl chain length) and copolymer composition on the performance of the membranes has been evaluated. The membrane (AEM2-Bu-2) prepared by the quaternization of the copolymer (AN/VIm = 75:25 mol/mol) with 1-bromobutane followed by cross-linking exhibits the highest acid recovery performance with a UH+ of 0.047 m/h and S value of 130 during the separation of the 1 M HCl + 0.18 M FeCl2 mixture. The quaternized imidazole ring provides stabilization of the cationic charge, which enhances the performance of the membrane. This work provides an insight to design a high-performance AEM for acid recovery through the DD process.

Design of tropinium-functionalized anion exchange membranes for acid recovery via diffusion dialysis process

To evaluate and compare the performance of several designs of 20-gauge dual port (DP) vitreous cutter tips with a standard 20-gauge single port tip. Custom 20-gauge pneumatic vitreous DP cutter tips with different sizes and port positions were evaluated through porcine vitreous and water flow rates. Five designed and fabricated DP cutter tips were compared with a normal single port control tip and evaluated by the measurement of water and porcine vitreous flow rates, and surgical examination in enucleated porcine eyes. Some DP tips approached a maximum vitreous and water flow rates, removing water and vitreous faster than the normal control tip. With reference to surgical evaluation, some DP tips performed better than the single port tip for bulk vitrectomy, but none shaved the vitreous base more effectively. The DP cutter system has the potential to increase the flow rates depending on the size and position of the extra port. In the future, the DP cutter may allow the surgeon to perform bulk vitrectomy more efficiently.

Augmenting acid recovery from different systems by novel Q-DAN anion exchange membranes via diffusion dialysis

GO-anchored imidazolium based cross-linked composite anion exchange membranes for the enhancement in acid recovery via diffusion dialysis

In this paper, an IoT based system that alerts the authorities about an imminent flood is introduced. The water flow rate is detected using IR Sensor and the water level is detected using Ultrasonic sensor in rivers and drains and sent over Wi-Fi to the main controller which checks these received sensor values and if the values vary beyond a particular threshold , the alarm (buzzer) and also a alert Short Message Service(SMS) is sent to mobile. A website provides the plot of the water levels and the water flow rates. Also the weather forecast information obtained from the internet is provided in the website.The controller used to process the sensor data, obtain the water level and flow rate values, and transmit the obtained values is the Node Microcontroller Unit (NodeMCU). The controller used to receive the transmitted data, interpret it, perform the actuation (buzzer and SMS) and update the website is RaspberryPi3(RPi3)

There are several elements that affect the flow rate of water. One of the most convincing factors that resist the flow of water is the salinity. When the salinity takes place in a pipe the minerals of calcium and magnesium carbonates stick to the surfaces of pipes, which restricts water flow in the pipe. The main goal of this project is to investigate the effect of salinity on the flow rate of water. To achieve project aims, this project includes two experiments, the effect of salinity on the flow rate of water experiment and the effect of salt size on water flow rate experiment. The design of two experiments components is same but the type of salt will be changed. In general, the investigation of salinity influence on water flow rate is observed under fixed temperature and initial flow rate. At the end of the experiments, the results are mentioned in tables and in the line graphs to describe the effect of salinity on the flow rate of water. In the effect of salinity on the flow rate of water experiment, the results show inversely proportional relation between salinity and flow rate of water.To illustrate, when the amount of salinity increase the flow rate will decrease because the salt will restrict the flow of water. On the other hand, the results of the influence of salt size on the flow rate of water experiment show the big size salt restricts the flow of water more than small size salt. So, the using different size of salt will change the flow rate of water that flows in the piping system.

This study presents the possibility of using diffusion dialysis for the separation of inorganic acids (hydrochloric, nitric, and hydrofluoric) and their ferric salts whose composition corresponds to that of real spent pickling solutions. At a steady state, the transport properties of three different anion-exchange membranes (Fumasep-FAD, Neosepta-AFN, and Neosepta-AHA) are compared using a continuous counter-current dialyzer. At a constant composition of the solutions (acid concentration 3 mol L−1 and iron concentration 30–40 g L−1), the effects of volumetric liquid flow rates on the transport rate of H+ and Fe3+ ions through the membrane are studied. The dialysis process is characterized by the recovery of acids and the rejection of salts. Furthermore, the values of the dialysis coefficients of acids, iron, and the acid/iron separation factors are calculated and compared. The volumetric flow rates of the inlet streams change in limits from 3 × 10−8 to 6 × 10−8 m3 s−1 (from 3 to 6 L h−1 m−2, relative to the membrane area). A comparison of the tested membranes shows slightly better results for acid recovery, iron rejection, and acid/iron separation factors for the Fumasep-FAD membrane than for the Neosepta-AFN membrane. However, the results obtained show that both of these anion-exchange membranes can be considered good separators for tested mixtures that simulate real spent pickling solutions, and there is a good precondition for using diffusion dialysis for processing these solutions in industrial practice. On the contrary, very low values of acid recovery and the overall dialysis coefficient of acid are found for the Neosepta-AHA membrane in the test range of the volumetric flow rate, and, thus, this membrane is insufficient for the adequate separation of these acids and iron salts.

In this study, a novel poly(AMIM‐co‐AC) (PAMIMAC) copolymer was successfully synthesized through copolymerization of 1‐allyl‐3‐methylimidazolium chloride (AMIM) and acrolein (AC); a series of anion exchange membranes (AEMs) with network structures were fabricated through an efficient solvent casting method by blending varying proportions of PAMIMAC with polyvinyl alcohol (PVA) and ethylene‐vinyl alcohol copolymer (EVOH) in dimethyl sulfoxide (DMSO). The resulting membranes underwent comprehensive characterization employing 1 H NMR, FTIR, XPS, SEM, and AFM techniques to elucidate their chemical composition and morphological features. Systematic evaluation revealed excellent dimensional stability, acid resistance, mechanical stability, and thermal stability, along with favorable water absorption rates and competitive ion exchange capacities. Notably, in diffusion dialysis (DD) performance tests, the optimized membranes demonstrated superior proton permeability coefficients (U H + ) (U H + = 14.2–42.3 × 10 −3 m/h) and separation factors (S = 63–27) compared to the commercial DF‐120 membrane (U H + = 9 × 10 −3 m/h, S = 18). This remarkable enhancement in both permeability‐selectivity and operational stability positions these PAMIMAC‐based AEMs as promising candidates for practical separation applications. The combination of straightforward fabrication methodology, stable physicochemical properties, and exceptional DD performance suggests significant potential for industrial implementation in acid recovery processes and related membrane‐based separation technologies.