Regeneration Of Ion Exchange Resins Research Articles

Biochar derived from watermelon rinds as regenerable adsorbent for efficient removal of thallium(I) from wastewater

Discarded watermelon rinds were used to prepare porous biochars, which act as regenerable adsorbents for treating both synthetic and real Tl-containing wastewater. The primary biochar prepared under pyrolysis temperature of 500 °C was found to be the most effective for Tl(I) removal. The primary biochar had the best Tl(I) removal efficacy over a wide pH range (4–12), followed by the KOH-modified and HCl-modified biochar. Maximum Tl(I) adsorption capacity reached 178.4 mg/g, which is superior to that of other biochar. Strong resistance to the interference from co-existing cations and organics on Tl(I) removal was also observed during treatment of complex synthetic and real industrial wastewater. Characterization techniques such as X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectra, high resolution transmission electron microscope (HRTEM), and X-ray photoelectron spectroscopy (XPS) reveal that the K- and Cl-rich primary biochar acts as regenerable amphibious ion exchange resins to perform reversible adsorption and desorption of Tl(I). The biochar derived from watermelon rinds exhibits effective Tl(I) removal performance and strong regenerability, and is a promising adsorbent for Tl(I) removal with excellent application prospects.

Techno-economic assessment of multi-effect distillation process for the treatment and recycling of ion exchange resin spent brines

A treatment chain including nanofiltration, crystallization and multi-effect distillation (MED) is for the first time proposed for the treatment of an effluent produced during the regeneration of Ion Exchange resins employed for water softening. The goal is to recover the minerals and to restore the regenerant solution to be reused in the next regeneration cycle. MED is the most crucial unit of the treatment chain from an economic point of view. A techno-economic analysis on the MED unit was performed and a novel performance indicator, named Levelized Brine Cost, was introduced as a measure of the economic feasibility of the process. Different scenarios were analysed, assuming different thermal energy sources and configurations (plane-MED or MED-TVC). It was found that the plane-MED fed by waste-heat at 1 bar is very competitive, leading to a reduction of 50% of the fresh regenerant current cost. Moreover, the thermal energy cost of 20US$/MWhth was identified as the threshold value below which producing regenerant solution in the MED is economically more advantageous than buying a fresh one. Overall, MED allows reducing the environmental impact of the industrial process and it results competitive with the state of the art for a wide range of operating conditions.

Development of macroporous Magnéli phase Ti4O7 ceramic materials: As an efficient anode for mineralization of poly- and perfluoroalkyl substances

Magnéli phase Ti4O7 ceramic materials having extensive interconnecting macropores with an average pore size of 2.6 μm and 21.6% porosity were fabricated using a high-temperature sintering method, and then tested as an anode in a batch mode for electrooxidative mineralization of environmentally persistent poly- and perfluoroalkyl substances (PFASs) such as perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS). Tests were also conducted with other “non-active” electrodes for comparison, including Ce-doped PbO2 and Ti/BDD electrodes. The results showed that the porous Ti4O7 ceramic anode exhibited greater PFOA/PFOS oxidation rates than those of the other electrodes. Only trace amounts of perfluorocarboxylic acid (PFCAs) with shortened chain lengths were observed as intermediates during PFOA mineralization. SO42− and F− were recovered as the mineralization products of PFOS electrooxidation, while no organofluorine compounds such as shorter-chain PFCAs were detected in the solution by high-resolution mass spectrometry (HRMS). Possible mechanisms for PFOA/PFOS mineralization over porous Ti4O7 ceramic electrode were proposed on the basis of reaction products analysis. In addition, the developed porous Ti4O7 ceramic anode was successfully applied to treatment of the still bottom liquid waste containing high concentrations of poly- and perfluoroalkyl substances (PFASs) as well as high chloride and organic content concentrations from the regeneration of ion-exchange resin that had been used for remediation of PFASs-impacted groundwater. The results illustrate the promise of the macroporous Magnéli phase Ti4O7 ceramic materials for electrochemical treatment of PFASs in water.

Modelling the transport of ions and electrochemical regeneration of the resin in a hybrid ion exchange/electrodialysis process for As(V) removal

This paper presents the 2D modeling of a laboratory scale ion exchange/electrodialysis (IXED) flow cell for removal of As(V) ions from water. The cell consists of a central compartment (DS) delimited by two anion membranes and packed with anion exchange resin, one compartment on each side of the central compartment (CC and AC compartment) lined with a cation exchange membrane and a rinse compartment at each end of the cell. The developed model comprises: the anion exchange in the resin bed in a process controlled by the mass transport rate; the ion transport in the solutions of resin-free compartments, in the membranes and resin, based on Nernst–Planck equation; and enhanced water dissociation at the anion membrane/solution interface. The obtained results show the potential profiles, Donnan potential, concentration polarization and the contribution of each mechanism (diffusion and migration) to ion transport rate as well as the effect of the potential difference on water dissociation rate along the membrane surface. The results show that, at typically low arsenic concentrations in arsenic removal processes, water dissociation plays a key role in ion exchange resin regeneration, process whose intensity grows as the cell potential rises. Moreover, the non-homogeneous distribution of current produces uneven resin regeneration that depends on design and operating parameters. The ion exchange/electrodialysis model is applied to the IXED cell operating in recirculation mode by using individual tanks connected to each cell compartment to describe the experimental batch behavior where arsenic concentration varied from (initial) 13.3 ppm to (final concentration) less than 0.01, 8.9 and 21.3 ppm in DS, CC and AC compartments, respectively, at an operating current density of 8.4 A m−2 removing 99.9% of arsenic in DS compartment with 18.9% of total current efficiency. The model results of As(V) concentration decline in the solution flowing over the ion exchange bed agree very closely with experimental data; however, the As(V) concentration results in the resin-free compartments show deviations from experimental data during the process with 6 and 16% deviations at the end of the batch. These deviations are attributed to model assumptions, in particular to the effect of diverse, non-considered, As(V) ion species.

Performance of continuous electrodeionization technique during the purification of the nonaqueous organic solvent N,N-dimethylformamide

Abstract This work focused on the use of a continuous electrodeionization (CEDI) device for the purification of the nonaqueous organic solvent N,N-dimethylformamide (DMF). CEDI is mainly used to purify, separate and concentrate hydrous solutions. Its main characteristic is the regeneration of ion-exchange resins by H+ and OH− generated by water splitting. However, for the DMF system, the resins act as channels for ion transfer. DMF cannot be regenerated because it is an anhydrous solution. In this study, the CEDI technique was adopted to remove formic acid (FA), dimethylamine (DMA) and inorganic salts from industrial-grade DMF. Experimental results demonstrated that DMA, FA and salts can be easily removed. Meanwhile, the effects of the voltages and flow rates on the CEDI performance were investigated systematically. This technique is a useful and effective process for the purification of the nonaqueous organic solvent DMF and can be used for the continuous production of high purity DMF.

Application of the bipolar electrodialysis technique for the production of hydrochloric acid from wastewater regeneration of ion exchange resins

This research had as a goal to determine how the application of bipolar electrodialysis technique influences the production of hydrochloric acid, regeneration of ion exchange resins from wastewater in the urbanization Enace – Carabayllo, Lima, Peru. The technique used was electrodialysis bipolar. For this, the bipolar electrodialysis module was constructed at laboratory scale with the purpose of recovering the chlorine ion (Cl-) for the production of hydrochloric acid and the recovery of the sodium ion (Na +) to obtain a sub product as is the sodium hydroxide from residual regeneration water of ion exchange resins. The controllable factors were considered as: voltage applied to the electrodialysis cell (6, 12, 18 V), and feed flow (300 mL/min, 600 mL/min). A recovery after of 200 minutes, 18 volts and a flow of 600mL/min was achieved a percentage of 84.91% of chlorine ion for the production of hydrochloric acid and 39.02% of sodium ion for a by-product of sodium hydroxide.

Electrochemical separation of copper and zinc in the process of ion-exchange water treatment

The publication presents the results of the study on determination of the effectiveness of ion-exchange extraction of copper and zinc from the solution of the mixture of zinc and copper sulfates with the cation exchanger KU-2-8, as well as the effectiveness of regeneration of ion exchange resins in the Cu2+, Zn2+ form with the sulfuric acid solution. It is shown that the total sorption capacity of the resin is rather high. Desorption with the KU-2-8 cation exchanger took place effectively. The conditions of the electrochemical separation of copper and zinc in the anode are considered depending on the current density and the solution acidity. The results reveal that the solution acidity has little effect on the effectiveness of extraction of copper ions. The study has shown that it is possible not only to extract these metals on strongly acidic cations from aquatic media with repeated use of the resins, but also to restore processed regeneration solutions with the help of electrolysis to obtain pure metals — copper and zinc. At that, the solutions are suitable for reuse.

Decontamination of spent ion-exchangers contaminated with cesium radionuclides using resorcinol-formaldehyde resins

The origin of the emergence of radioactive contamination not removable in the process of acid-base regeneration of ion-exchange resins used in treatment of technological media and liquid radioactive waste streams has been determined. It has been shown that a majority of cesium radionuclides not removable by regeneration are bound to inorganic deposits on the surface and inside the ion-exchange resin beads. The nature of the above inorganic inclusions has been investigated by means of the methods of electron microscopy, IR spectrometry and X-ray diffraction. The method of decontamination of spent ion-exchange resins and zeolites contaminated with cesium radionuclides employing selective resorcinol-formaldehyde resins has been suggested. Good prospects of such an approach in deep decontamination of spent ion exchangers have been demonstrated.

(Invited) Electrospun Nanofiber Composite Bipolar Membranes

Bipolar membranes, typically a laminate of an anion-exchange and cation-exchange membrane, have the unique capability to split water at a potential as low as 0.8 V while conventional electrolysis requires at least 1.2 V. Such membranes are employed in a number of important industrial processes, including the production of mineral acids, the recovery of organic acids from fermentation processes, pH control, and ion-exchange resin regeneration. The use of bipolar membranes in electrodialysis separations eliminates unwanted salt efflux and disposal problems and offers significant savings in electrical energy consumption. Recently, bipolar membranes have also been examined for use in self-humidifying hydrogen/air fuel cells, where the recombination of electrochemically generated hydroxide ions and protons at the bipolar junction produces water that improves membrane hydration, with higher power output at reduced feed gas humidity conditions. We report here for the first time on the design, fabrication, and testing of a new bipolar membrane that was made by polymer nanofiber electrospinning, where the anion-exchange polymer is quaternized poly(phenylene oxide) and the cation-exchange polymer is sulfonated poly(ether ether ketone). This new membrane has a 3-D nanofiber bipolar junction with a very high interfacial area, unlike the typical 2D planar junction. This extended junction morphology is important for two reasons: (1) it improves the attachment (adhesion) of the two ion-exchange layers so that ballooning/delamination is minimized or eliminated and (2) the increased bipolar junction surface area will lead to a better distribution of the water splitting reaction and lower membrane voltage drop for the same operating current density. The procedure for membrane fabrication will be described and the performance of electrospun films will be compared to bipolar membranes in the literature.

The Effect of Water Quality on the Formation of the Deposits Composition in the Hot-Water System, Closed Type

There are discusses the problems associated with the formation of the chemical composition and the formation of deposits in the hot-water systems of closed type in some areas of Krasnodar Kray. There is analyzed the relationship between the processed formation elemental and phase composition of deposits, corrosion of construction equipment materials to the composition of natural water and the methods of its treatment. There were identified the main phases included in the deposit, which are based on calcium carbonate represented by calcite, aragonite and vaterite, and a mixture of the iron oxides in the form of wustite, magnetite and hematite. There was demonstrated the possibility of corrosion prevention of system’s construction materials, reducing the discharge of concentrated salt solutions resulting from the regeneration of ion exchange resins.

Decontamination of spent ion-exchange resins contaminated with cesium radionuclides

Possible causes of the occurrence of radioactive contamination irremovable by acid–base regeneration of ion-exchange resins used in treatment of process media and liquid radioactive waste have been studied. It has been found that most of the irremovable cesium radionuclides are bound to inorganic deposits on the surface and in the bulk of ion-exchange resin granules. The nature of inorganic inclusions has been investigated on real and model spent ion-exchange resins (SIER). A method has been proposed for decontaminating SIER using resorcinol–formaldehyde resins selective to cesium radionuclides. Such an approach has been shown to be promising for deep decontamination of SIER.

Study of a new process for the efficient regeneration of ion exchange resins

Mixed bead resins comprising weakly acidic (carboxylic acid) and weakly basic (tertiary amine) groups were produced with properties similar to the thermally regenerable Sirotherm resin. This resin typically had a capacity of about 0.5mmol NaCl per gram and the sorption isotherm was found to be consistent with the Langmuir equation. The resin could be partially regenerated by heat (80%) and water washing (40%) as the ion sorption capacity was much reduced on heating to 80°C. However, the resin could be completely regenerated by a combination of heat and pre-washing with concentrated ammonium bicarbonate solution. On heating to 60°C or more the bicarbonate salt completely decomposes and can be removed from the resin as carbon dioxide and ammonia gases. These initial results suggest that this type of ion exchange resin could be used in a continuous process where the regeneration salt (ammonium bicarbonate) is thermally decomposed, collected and re-used to improve the efficiency of regeneration.

The reclamation of brine generated from desalination process by bipolar membrane electrodialysis

Some techno-economical analyses and environmental impact evaluation have proved that bipolar membrane electrodialysis (BMED) is feasible for the reclamation of industrial saline water. However, to date, the technology cannot be put into practice due to some unsolved application-oriented problems, such as the requirements of BMED for feed solution, the availability of the produced acid and base, relatively high salt concentration of the effluent, and relatively low desalinating efficiency and capacity. In this work, a novel hybrid process, which coupled conventional electrodialysis installed with monovalent selective cation-exchange membranes with BMED running in a constant-voltage mode, was designed to reclaim brine generated from surface water desalination by the ion-exchange process. Subsequently, the response surface methodology was employed to establish the empirical models for understanding the influences of some initial operating conditions on BMED performance. Finally, the BMED-based reclamation scheme was confirmed again by a continuous BMED experiment on real solution. Specially, the effects of product concentration on current efficiency and energy consumption were investigated. In this case, an acceptable current efficiency and energy consumption were obtained on the basis of the conventional membranes and spacers when the product concentration was set as 0.9M, which is adequate for the regeneration of ion-exchange resins.

A comparison of silver‐ and copper‐charged polypropylene feed spacers for biofouling control

AbstractImplementation of nanofiltration (NF) and reverse osmosis (RO) processes in treating traditional water sources can provide a steady‐state level of removal that eliminates the need for regeneration of ion exchange resins or granular activated carbon. Moreover, RO can help meet future potable water demands through desalination of seawater and brackish waters. The productivity of membrane filtration is severely lowered by fouling, which is caused by the accumulation of foreign substances on the surface and/or within pores of membranes. Microbial fouling, or biofouling, is the growth of microorganisms on the membrane surface and on the feed spacer as present between the envelopes. The fouling of membranes has demanded and continues to demand considerable attention from industry and research communities. Many of these applications use membranes in a spiral wound configuration that contains a feed spacer. The goal of this project was to develop low‐biofouling polypropylene (PP) spacers through the functionalization of PP by a spacer arm with metal chelating ligands charged with biocidal metal ions, investigate the use of this metal‐charged polypropylene (PP) feed spacers that target biofouling control, and to use some traditional and one novel techniques to autopsy the membranes after filtration to gain a better understanding of the biofouling mechanism and how the modified spacers are affecting it. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Carbon Dioxide Regeneration of Ion Exchange Resins and Fibers: A Review

Alternative chemicals for the regenerant of ion exchangers have been the subject of research for the past sixty years. The advances spanning this time period have been significant and demonstrated at the laboratory, pilot, and commercial scale. The use of carbon dioxide as a regenerant has several significant benefits including cost savings, waste minimization, and carbon dioxide sequestration, with applications including: chemical synthesis, desalination, demineralization, metals removal and hardness removal. Having originally been pursued as a means of reducing costs of regenerant chemicals, regeneration with carbon dioxide has also been described as a non-polluting separation process and has shown significant environmental benefits. Its use as a regenerant circumvents the use of brines, strong acids, or other aggressive chemicals and with the advent of new materials such as ion exchange fibers, the list of potential applications will continue to grow. This review discusses some of the significant advances during the history of this environmentally benign regeneration process.

Waste Water Remediation Using Electrochemically Cycled Extractants in Room Temperature Ionic Liquids

This project involved preliminary development of an electrochemically activated, regenerable anion-exchange system for nitrate removal from waste water. The goal was to combine desirable features of liquid-liquid extraction, e.g., fast kinetics and process simplicity, with those of anion-exchange processes using resins. At the same time, volatile organic solvents would be eliminated and replaced with a regenerative medium. We developed a liquid-liquid extraction system using a non-volatile, water insoluble room temperature ionic liquid (RTIL) in place of the organic phase. Because RTILs are intrinsic electrolytes, they provide a ready method of in situ electrochemical activation and deactivation of redox-active extractants, such as ferrocenes. The redox-active extractant made nitrate recovery in a small volume possible, while avoiding consumable chemical oxidants and reductants and without generating large secondary waste streams, such as are obtained during regeneration of ion-exchange resins.

전기투석과 이온교환수지를 이용한 스테인레스 산업의 산세폐수 내 질산성 질소의 제거

Lab-scale Electrodialysis(ED) system with different membranes combined with before or after pyroma process were carried out to remove nitrate from two pickling acid wastewater containing high concentrations of <TEX>$NO_3\;^-$</TEX>(<TEX>${\approx}$</TEX>150,000 mg/L) and F(<TEX>$({\approx}$</TEX> 160,000 mg/L) and some heavy metals(Fe, Ti, and Cr). The ED system before Pyroma process(Sample A) was not successful in <TEX>$NO_3\;^-$</TEX> removal due to cation membrane fouling by the heavy metals, whereas, in the ED system after Pyroma process(Sample B), about 98% of nitrate was removed because of relatively low <TEX>$NO_3\;^-$</TEX> concentration (about 30,000 mg/L) and no heavy metals. Mono-selective membranes(CIMS/ACS) in ED system have no selectivity for nitrate compared to divalent-selective membranes(CMX/AMX). The operation time for nitrate removal time decreased with increasing the applied voltage from 10V to 15V with no difference in the nitrate removal rate between both voltages. Nitrate adsorption of a strong-base anion exchange resin of <TEX>$Cl\;^-$</TEX> type was also conducted. The Freundlich model(<TEX>$R^2$</TEX> > 0.996) was fitted better than Langmuir mode(<TEX>$R^2$</TEX> > 0.984) to the adsorption data. The maximum adsorption capacity (<TEX>$Q^0$</TEX>) was 492 mg/g for Sample A and 111 mg/g for Sample B due to the difference in initial nitrate concentrations between the two wastewater samples. In the regeneration of ion exchange resins, the nitrate removal rate in the pickling acid wastewater decreased as the adsorption step was repeated because certain amount of adsorbed <TEX>$NO_3\;^-$</TEX> remained in the resins in spite of several desorption steps for regeneration. In conclusion, the optimum system configuration to treat pickling acid wastewater from stainless-steel industry is the multi-processes of the Pyroma-Electrodialysis-Ion exchange.

Electro-assisted regeneration of ion exchange resins

Electro-assisted regeneration (EAR) for the mixed bed of strongly acidic cation and weakly basic anion exchange resins with the Al(OH)3 suspension in a three-compartment cell was investigated. The desalination experiments were carried out to evaluate the characteristic of the regenerated mixed resins. Experimental results showed that the efficiency of resin regeneration was strictly dependent on the voltage, regeneration time, and feed regenerant flow rate. The amount of the effluent reached 50 times the volume of the resins bed, and the conductivity was less than 1.0 μs/cm. Compared to the conventional ER, the total effluent volume of EAR was about 1000 mL more than that of ER under the same conditions, and the outlet conductivity was significantly lower. The desalination and regeneration reaction mechanisms of the mixed resins indicated the regeneration efficiency of resin with Al(OH)3 as the regenerant was much higher than that with H2O.

Achieving environmental compliance via ion exchange resin regeneration: ACM Technologies turns industrial wastewater into a revenue stream

Achieving environmental compliance via ion exchange resin regeneration: ACM Technologies turns industrial wastewater into a revenue stream

Continuous capacitive deionization–electrodialysis reversal through electrostatic shielding for desalination and deionization of water

We report a new concept for capacitive deionization with simple and cheap porous bipolar intermediate graphite electrodes which is operated continuously by constant or alternating polarity without any down time for electrode saturation, regeneration and rinsing steps and certainly without any permselective ion exchange membranes. The proposed process utilizes the advantages of the classical electrodeionization technologies combining them all to a unified continuous capacitive deionization–continuous electrodeionization–electrodialysis–electrodialysis reversal process. Separate and unchanged diluate and concentrate compartments are created in two modes, first by periodical charging/discharging the bipolar intermediate electrodes through a pulsating electric field and second by simultaneous charging/discharging them through a constant or pulsating electric field and electrostatic shielding. Because of coion permeation and the convenience of alternating the polarity without any negative impact on the deionization process, the new technique is less affected by the known membrane associated limitation, such as concentration polarization, limiting current density or scaling. The new electrochemical deionization technique is suitable for regeneration of ion exchange resins and production of high purity deionized water, removal of heavy metal ions from industrial effluents and desalination of brackish or seawater.