Ion Exchange Regeneration Research Articles

Beneficial reuse of treated municipal wastewater and flue gas carbon dioxide via combined ion exchange

Combined ion exchange (CIX) treatment of wastewater effluent and ion-exchange regeneration using flue gas carbon dioxide (CO2) was investigated as a way of beneficially joining the water and energy sectors. CIX treatment removed calcium, magnesium, sulfate, nitrate, phosphate, and dissolved organic carbon from wastewater effluent. Regeneration of CIX using sodium chloride, sodium bicarbonate, hydrochloric acid, and CO2 was investigated. Carbon dioxide had a lower regeneration efficiency compared with the other regeneration solutions. Alternative CO2 regeneration conditions were evaluated to gain insight on the effects of increased gas pressure, increased contact time, and increased rate of CO2 dissolution on regeneration efficiency.

Integrated Coagulation-Membrane Processes with Zero Liquid Discharge (ZLD) Configuration for the Treatment of Oil Sands Produced Water

This study explores the feasibility of implementing five hybrid coagulation-membrane processes for the treatment of the boiler blow-down (BBD) water from an oil sands steam assisted gravity drainage (SAGD) operation. The processes involved (1) direct nanofiltration (NF) of the BBD water, (2) pre-treatment of the NF retentate using ion exchanger regeneration wastewater (IERW) as a chemical coagulant followed by NF, (3) pre-treatment of BBD water using IERW followed by NF, (4) dual pre-treatment of BBD water using IERW and soda ash (sodium carbonate, Na2CO3) followed by NF, and (5) forward osmosis (FO) treatment of the BBD water using IERW as a draw solution followed by NF treatment of diluted draw solution. These scenarios were compared based on total flux decline ratio (DRt), flux recovery ratio (FRR), and total dissolved solids (TDS) removal over the final NF treatment to suggest an efficient treatment technique to avoid an undesired increase in the capital and operating expenses. It was found that process-1 provided the highest selectivity toward dissolved solids (80%) with a flux decline and recovery ration of 89.6% and 97.4%, respectively. Considering the permeation flux, process-4 exhibited the lowest flux decline (86.1%) and highest recovery ratio (97.5%) compared to other processes, proving the successful role of soda ash softening, as a chemical pretreatment method, in improving the performance of membrane filtration. Process-2 presented a mediocre performance with DRt, FRR, and TDS rejection of 93.3%, 97.3%, and 74%, respectively. Finally, process-3 and process-5 showed the lowest performance among all the scenarios with low flux recovery and low permeability, respectively. In addition, process-3 was expected to be cost-efficient since it only uses an on-site generated waste as a coagulant for the chemical pretreatment of the membrane filtration unit. The optimum scenario was proposed to be the two-stage membrane process, with direct NF of BBD followed by the post-treatment of the retentate via a hybrid chemical conditioning using IERW and soda ash softening, followed by a second NF. Overall, this integrated process offered a highly efficient mean with a zero liquid discharge (ZLD) system for the treatment of high pH wastewaters into an uncontaminated stream for the boilers.

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.

Efficient treatment of oil sands produced water: Process integration using ion exchange regeneration wastewater as a chemical coagulant

The potential of ion exchange regeneration wastewater (IERW) containing magnesium ions to act as a coagulant for steam-assisted gravity drainage (SAGD) boiler blowdown (BBD) water was investigated with the aim of reducing the water consumption in a SAGD plant. Conventional techniques for the treatment of BBD water require significant operational costs as they rely on the extensive use of chemical coagulants or electric power. Since the proposed process design in this study uses a wastewater stream for the treatment of the BBD water, operational costs and energy consumption are predicted to be minimized. The effect of temperature, the mixing ratio of BBD and the IERW water, and the stirring intensity on the removal of organic matter and dissolved minerals were investigated. Usage of IERW as the coagulant enhanced the removal of impurities; removal efficiency of 81.1% and 98.6% were obtained for organic matter and silica concentration, respectively. The treatment of BBD water by IERW, however, has led to an increase in the concentration of calcium in the effluent, which was effectively mitigated by soda ash softening. Furthermore, resource recovery from the coagulated sludge was explored by SEM, EDX, FTIR, XPS, and XRD, and revealed that the precipitated compounds were mostly composed of calcium, magnesium, and silica. Additionally, the successful usage of IERW for the treatment of another BBD wastewater with a higher concentration of organic matter was demonstrated. In conclusion, the IERW water proved to be highly effective in removing contaminants from SAGD produced water.

MATHEMATICAL MODELING SINGULARLY PERTURBED PROCESSES OF WATER SOFTENING ON SODIUM-CATIONITE FILTERS

Mathematical model of the process of water softening using ion exchange pre-treatment of waters to desalination, with a view to removal of scale forming components, such as calcium and magnesium, are formed in the paper. In this process, no additional chemicals, except for brines formed during desalination, are required for regeneration of ion-exchanger in operation cycles. An asymptotic approximation of a solution of a corresponding model problem is constructed. Theoretical description and modelling assumptions included the set of differential equations of mass balance, initial, boundary and operational conditions. The paper deals with the development of a computer model for description and prediction of the performance of ion exchange columns.

Computational and experimental study for the desalination of petrochemical industrial effluents using direct contact membrane distillation

The petrochemical, mining and power industries have reacted to the recent South African water crisis by focussing on improved brine treatment for water and salt recovery with the aim of achieving zero liquid effluent discharge. The purpose of this novel study was to compare experimentally obtained results from the treatment of synthetic NaCl solutions and petrochemical industrial brines such as spent ion exchange regenerant brines and reverse osmosis (RO) brines to the classical well-known Knudsen diffusion, molecular diffusion and transition predictive models. The predictive models were numerically solved using a developed mathematical algorithm that was coded using MATLAB® software. The impact of experimentally varying the inlet feed temperature on process performance of the system is presented here and compared to simulated results. It was found that there was good agreement between the experimentally obtained results, for both the synthetic NaCl solution and the industrial brines. The mean average percentage error (MAPE) was found to be 7.9% for the synthetic NaCl solutions when compared to the Knudsen model. The Knudsen/molecular diffusion transition theoretical model best predicted the performance of the membrane for the industrial spent ion exchange regenerant brine with a mean absolute percentage error (MAPE) of 13.3%. The Knudsen model best predicted the performance of the membrane (MAPE of 10.5%) for the industrial RO brine. Overall, the models were able to successfully predict the water flux and can be used as potential process design tools.

Silver recovery as Ag0 nanoparticles from ion-exchange regenerant solution using electrolysis

Many silver (Ag) containing consumer-products (e.g. textiles) release Ag into the environment, posing ecotoxicological risks. Ag recovery mitigates environmental hazards, recycles Ag, and leads to sustainability. In the present work, Ag has been recovered as Ag0 nanoparticles from the spent solution (thiourea (TU) ~0.5 mol/L pH ~1.1–1.2, and Ag ~550 mg/L) obtained from the regeneration of an Ag-loaded resin using a simple undivided electrolytic cell. The reclaimed regenerant solution has been recycled and reused in a closed-loop scheme over multiple cycles. The process parameters, i.e., current (0.05 A) and stirring speed (600 r/min), have been optimized for Ag recovery of ~94% and TU loss of ~2%. The reclaimed regenerant solution has been shown to regenerate Ag-loaded resin samples with >90% regeneration efficiency over 4 cycles of consecutive extraction and regeneration. The recovered Ag0 nanoparticles are monodisperse, consistently spherical in shape, and have a mean diameter of ~6 nm with standard deviation of the Gaussian fit as ~2.66 nm.

Room-Temperature Atomic Layer Deposition of Aluminum Silicate for Molecule Sorption

A room-temperature atomic layer deposition (RT-ALD) of aluminum silicate for molecule sorption is developed using trimethylaluminum (TMA) and trismethylaminosilane (TDMAS) using a plasma excited humidified argon. The aluminum-silicate is a main material of zeolites that is used for cation sorption. If we achieved the aluminum silicate deposition on flexible films, we could expect the film used as a regenerable ion exchange filter. The schematic of ALD system is shown in Fig.1. TMA and TDMAS were introduced with mass flow controllers. A remote plasma system generating excited humidified argon was installed to the ALD chamber. The source gas for the oxidizing gas is a mixture of water vapor and argon. The plasma was generated in a glass tube with an induction coil with a frequency of 13.56 MHz and a RF power of 100 W. For the deposition, we repeated the cycle of TDMAS and TMA saturation and oxidizing gas treatment at RT. To control the aluminum to Si atomic ratio in the aluminum silicate, we adjusted the initial exposure of TDMAS. To confirm the Na sorption ability of the aluminum silicate film deposited by the present technology, we immersed the aluminum silicate coated Si sample in a 100 mM NaCl solution for 3h. The dried sample was evaluated by X-ray photoelectron spectroscopy. As shown in Fig. 2, the enhanced Na adsorption is confirmed. In the conference, we discuss the mechanism of Na sorption on the RT deposited aluminum silicate. Acknowledgements This work was partly supported by JSPS KAKENHI Grant Numbers 15H03536. It was also partly supported by JST-CREST Grant Number JPMJCR14F3, Japan. Figure 1

Perspectives of integration the technology of ion-exchanging ammonium extraction from the system of municipal drain water purification

The exchange capacity and the selectivity of different ion-exchange products regarding the ammonium ions in purification processeswere measured; the regenerative preparation compounds’ influence on efficiency of conduction of ion-exchange products regeneration was learnt. The adsorption processes were adapted to known technological schemes of sewage and polluted surface water purification, that was polluted with ammonium ions. There were measured the technological aspects of water purification by using adsorption on natural dispersed sorbents. The technological schemes of drain water purification from ammonium ions were developed.

Sulfur-based denitrification treating regeneration water from ion exchange at high performance and low cost

Autotrophic denitrification with sulfur is an underexplored alternative to heterotrophic denitrification to remove nitrate from wastewater poor in organics. The application on ion exchange regeneration water (19.4–32.1 mS cm−1) is novel. Three fixed bed reactors were tested at 15 °C for >4 months, inoculated with activated sludge from sewage treatment. All were fast in start-up (<10 days) with high performance (94 ± 2% removal efficiency). pH control with NaOH rendered higher nitrate removal rates than limestone addition to the bed (211 ± 13 vs. 102 ± 13 mg N L−1 d−1), related to higher pH (6.64 vs. 6.24) and sulfur surface area. Bacterial communities were strongly enriched in Sulfurimonas (63–67%) and Thiobacillus (24–26%). In an economic comparison, sulfur-based denitrification (€5.3 kg−1 N) was 15% cheaper than methanol-based denitrification (€6.22 kg−1 N) and both treatments were opex dominated (85.9 vs. 86.5%). Overall, the technological and economic feasibility should boost further implementation of sulfurotrophic denitrification.

Efficiency estimation of cation-exchange recovery of heavy metals from solutions containing their mixtures

The object of research is the washing waste water of galvanic plants containing heavy metal cations. The most common reagent methods for purification of galvanic drains do not provide the required degree of water purification, are accompanied by the loss of valuable components and the formation of significant amounts of toxic sludge. Ion exchange is promising in development of wastewater treatment of galvanic productions. One of the most important problems of ion-exchange technology is the processes of regeneration of ion exchangers, and, in particular, the recycling of spent regeneration solutions. The most promising in the recovery of regeneration solutions is the electrochemical method. However, electroextraction of zinc and nickel is practically impossible from acidic solutions without separation of the electrode space by the membrane. In addition, effluents from the galvanic industry contain mixtures of heavy metal ions. This complicates the process of wastewater treatment and the return of valuable components to production. In the course of the study, a strongly acidic cation exchanger KU-2-8 in the Na + -form is used to study the processes of combined sorption of heavy metal ions. Regeneration of the cation exchanger is carried out with solutions of sulfuric and hydrochloric acids. Electroextraction of zinc and nickel from acid regeneration solutions is carried out in a two-cell electrolyzer with an anion-exchange membrane MA 41. The obtained results indicate that under conditions of the concentration of heavy metals on cation exchanger KU-2-8, efficient separation can’t be achieved. It is established that ions of heavy metals are sorbed individually and in mixtures with other ions of heavy metals are effectively desorbed by solutions of sulfuric and hydrochloric acids. The use of a two-cell electrolyzer, in contrast to carrying out electrolysis processes without separation of the electrode space, almost completely eliminates zinc and nickel ions from acidic regenerative rods. And to obtain a solution of sulfuric acid in the anode chamber at a concentration of 239–651 meq/dm 3 .

A new thermal-reduction-based approach for producing Mg from seawater

A new process is presented for producing metallic magnesium from seawater. Ion exchange is used to selectively extract Mg2+ from seawater, without introducing Na+ and K+ impurities into the product Mg. The magnesium extracted from the resin is reacted with CaO and precipitates on the surface of fine ferrosilicon suspension to produce a Mg(OH)2-Ca(OH)2-FeSi solids cake, which, after further wash and decantation, yields raw material at a quality similar to that used in the classical dolomite-based Pidgeon silicothermic reduction technique. The filtrate of the raw cake decantation step, comprising predominantly of CaCl2, is used as the ion-exchange regeneration solution. Ca2+ ions are adsorbed on the resin and thereafter replenished through CaO dosage, applied for the Mg(OH)2 precipitation. The close contact between the Mg(OH)2 and the FeSi in the dry cake enables direct usage of the cake in ~1150°C retort which is applied for single-step dehydration and thermal reduction of the Mg2+, thereby minimizing the problem of heat and mass transfer through the briquettes and eliminating the need for separate calcination, briquetting and reduction. Feasibility dehydration and reduction tests yielded 99.0–99.5% pure Mg. Materials and energy cost assessment revealed that the proposed process is ~$0.75 more expensive per kg of magnesium than the dolomite-based process, assuming equal thermal reduction yields. The cost estimation stimulates further optimization and parametric study of the proposed process and suggests that production of Mg in places where dolomite is not available, requiring seawater as the sole raw resource, is feasible.

Integrated bicarbonate-form ion exchange treatment and regeneration for DOC removal: Model development and pilot plant study

The application of bicarbonate-form anion exchange resin and sodium bicarbonate salt for resin regeneration was investigated in this research is to reduce chloride ion release during treatment and the disposal burden of sodium chloride regeneration solution when using traditional chloride-form ion exchange (IX). The target contaminant in this research was dissolved organic carbon (DOC). The performance evaluation was conducted in a completely mixed flow reactor (CMFR) IX configuration. A process model that integrated treatment and regeneration was investigated based on the characteristics of configuration. The kinetic and equilibrium experiments were performed to obtain required parameters for the process model. The pilot plant tests were conducted to validate the model as well as provide practical understanding on operation. The DOC concentration predicted by the process model responded to the change of salt concentration in the solution, and showed a good agreement with pilot plant data with less than 10% difference in terms of percentage removal. Both model predictions and pilot plant tests showed over 60% DOC removal by bicarbonate-form resin for treatment and sodium bicarbonate for regeneration, which was comparable to chloride-form resin for treatment and sodium chloride for regeneration. Lastly, the DOC removal was improved by using higher salt concentration for regeneration.

Production of Acids and Bases for Ion Exchange Regeneration from Dilute Salt Solutions Using Bipolar Membrane Electrodialysis

The acids and bases used for ion exchange regeneration contribute significantly to the increasing salinity of potable water supplies. This research investigated the use of bipolar membrane electrodialysis (BMED) for producing acids and bases from dilute salt solutions that are produced during reverse osmosis or evaporative cooling. Using single pass BMED, acids and bases were produced with concentrations equal to ∼75% of the feed salt concentration with current utilizations >75%. Current utilization increased with increasing feed salt concentrations due to decreased leakage current through the monopolar membranes. The maximum current density at which the BMED stack could be operated depended on the feed salt concentration and the flow velocity and was limited by water dissociation at the interface between the diluate solutions and the monopolar membranes. The stack resistance was dominated by the bipolar membranes, even for the most dilute feed solutions. The energy required per mole of acid or base produ...

Development and validation of a novel modeling framework integrating ion exchange and resin regeneration for water treatment

Models have been developed to simulate the process of ion exchange for water treatment. However the modeling of resin regeneration process, which can predict regeneration efficiency and residual stream for determining technology sustainability, was not incorporated into previous models. Therefore a model integrating both ion exchange and resin regeneration considering regeneration efficiency is needed for evaluating and improving ion exchange technology. This study developed an integrated model aiming to simulate ion exchange and resin regeneration in different configurations (fixed bed, fluidized bed) for the first time. The integrated model has been validated via comparing model predictions with experimental data. The impacts of dimensionless groups (i.e. the Péclet number, the diffusion modulus, and the Biot number) on ion exchange breakthrough curve have been analyzed using this model. In addition, this integrated model has been used to optimize the regeneration frequency to improve the overall performance of ion exchange. It demonstrated this integrated model could be a useful tool for further studies in ion exchange technology.

Efficiency and life cycle environmental impacts of ion-exchange regeneration using sodium, potassium, chloride, and bicarbonate salts

The goal of this research was to investigate the efficiency and life cycle environmental impacts of ion exchange (IX) regeneration using conventional NaCl and the alternative salts KCl, NaHCO3, and KHCO3. The regeneration efficiency was evaluated by considering anion exchange resin (AER) exhausted with nitrate and cation exchange resin (CER) exhausted with calcium. The regeneration efficiency of chloride was higher than bicarbonate for polystyrene AER, while the regeneration efficiency of bicarbonate was higher than chloride for polyacrylic AER. The regeneration efficiency of potassium was higher than sodium for all CERs. Because all salts showed high regeneration efficiency, assessing the environmental impacts of the salts from upstream and downstream phases was deemed key to improving the sustainability of the IX unit process. The increasing environmental burden of the salts was NaCl < KCl < KHCO3, while the impacts of NaHCO3 were greater or less than KCl depending on the impact category. The environmental burden was based on a comparative life cycle assessment (LCA) of mining and processing, and did not include disposal of the waste regeneration solution. A literature study regarding the environmental impacts of the regeneration ions indicated the potential benefit of the alternative salts over NaCl was due to disposal applications. For instance, disposal of KCl waste regeneration solution to soils can offset the demand for potassium fertilizer inputs and is not harmful to soil structure, and disposal of KHCO3 and NaHCO3 waste regeneration solution can offset the chemicals needed during wastewater treatment when nitrification is limited by low alkalinity.

The Experimental Research on Performance of the Composite Ion-Exchange Regenerant FH-30

The composite ion-exchange regenerant FH-30 was made using the own patent technology. The effect of softened water quality and running cycle, after the use of FH-30, was studied under simulation of industrial boiler softened water preparation process conditions. The dynamic simulation experimental results showed that at room temperature, the flow speed of 35 cm/min, the running cycle would not change when the dosage of regenerant was changed, the sodium and ammonium ion content would decrease with the increase of the running time in the softened water preparation process, the sodium ion content would decrease a bit faster at the later running cycle when the dosage of regenerant was greater, the molar ratio of sodium and ammonium almost not changed in the softened water preparation process when the regenerant dosage was 2.1 gram per milliliter resin, composite regenerant can completely replace single sodium salt regenerant. Through the measurement of sodium and ammonium ion in the regeneration resin and failure resin, proved that sodium and ammonium ion were not accumulated in the resin layer.

Selective separation of Cr(III) and Fe(III) from liquid effluents using a chelating resin

This study aimed to assess the selective separation of Cr(III) from Fe(III) from liquid solutions by using a chelating ion exchange resin, Diaion CR 11, from Mitsubishi Chemical Corporation, in the H(+) form. Equilibrium experiments with synthetic solutions of iron and chromium were carried out in batch mode. For both metals favorable adsorption isotherms were obtained, and the experimental data were well described by the Langmuir model. However, the resin exhibited higher affinity for iron than for chromium. The regeneration experiments revealed that, for both metals, HCl provided higher removal efficiencies than H(2)SO(4) and HNO(3). Moreover, precipitation with NaOH allows selectively separate chromium and iron to be stripped from the resin. Experiments in fixed bed operation were carried out to assess the dynamic behavior of the sorption of Cr(III) and Fe(III) into the tested resin by using synthetic and industrial solutions. The experiments with industrial effluent showed that the resin can remove low levels of contaminant transition metal ions, and thus the effluent can be purified for reuse of chromium during periods of 20-25 min. The resin regeneration was achieved with a sequential treatment with HCl and NaOH/H(2)O(2). High efficiencies were observed for both monocomponent and multicomponent systems. A global strategy for separating and recovering Cr(III) from an effluent that also contains Fe(III) is presented, involving the integration of ion exchange (saturation and regeneration phases) and precipitation processes. In conclusion, our approach demonstrates that efficient separation of chromium and iron is possible if ion exchange operation in a fixed bed configuration is optimized and combined with conventional processes such as precipitation.

Sustainable Electrochemical Regeneration of Copper-Loaded Ion Exchange Media

An electrochemical method for regenerating copper-loaded ion exchange media was investigated. The method involved circulating a moderate pH regenerant solution between a bed of ion exchange media and an electrochemical cell. The electrochemical regeneration process eliminates more than 99% of the acid and base use associated with conventional regeneration, consumes no water, produces metallic copper, and eliminates the production of a copper-laden sludge. Experiments were performed measuring copper plating rates as a function of the aqueous copper concentration, cell current, and flow rate. Experiments were also performed to determine the equilibrium partitioning of copper ions between the solution and the ion exchange media under loading and regeneration conditions. A mathematical model was developed and calibrated using experimental data, to provide guidance for the design of electrochemical ion exchange regeneration systems. The model incorporates the plating kinetics, the stripping of copper from the resin, and the equilibrium isotherm and predicts aqueous and adsorbed copper concentrations during the regeneration process. The model indicates that, in 789 min, 90% of copper can be removed from a resin loaded with 50 mg(Cu)/g(resin). An economic analysis indicates that energy costs for plating are less than 1% of chemical costs for conventional ion exchange regeneration.

Application of a Re–Pd bimetallic catalyst for treatment of perchlorate in waste ion-exchange regenerant brine

Concentrated sodium chloride (NaCl) brines are often used to regenerate ion-exchange (IX) resins applied to treat drinking water sources contaminated with perchlorate (ClO4−), generating large volumes of contaminated waste brine. Chemical and biological processes for ClO4− reduction are often inhibited severely by high salt levels, making it difficult to recycle waste brines. Recent work demonstrated that novel rhenium–palladium bimetallic catalysts on activated carbon support (Re–Pd/C) can efficiently reduce ClO4− to chloride (Cl−) under acidic conditions, and here the applicability of the process for treating waste IX brines was examined. Experiments conducted in synthetic NaCl-only brine (6–12 wt%) showed higher Re–Pd/C catalyst activity than in comparable freshwater solutions, but the rate constant for ClO4− reduction measured in a real IX waste brine was found to be 65 times lower than in the synthetic NaCl brine. Through a series of experiments, co-contamination of the IX waste brine by excess NO3− (which the catalyst reduces principally to NH4+) was found to be the primary cause for deactivation of the Re–Pd/C catalyst, most likely by altering the immobilized Re component. Pre-treatment of NO3− using a different bimetallic catalyst (In–Pd/Al2O3) improved selectivity for N2 over NH4+ and enabled facile ClO4− reduction by the Re–Pd/C catalyst. Thus, sequential catalytic treatment may be a promising strategy for enabling reuse of waste IX brine containing NO3− and ClO4−.