A mathematical model of the cyclic operation of desalination-feedwater softening by ion-exchange with Fluidized-bed regeneration

Initial fouling rate and delay time studies of aqueous calcium sulphate sealing under sensible heating conditions

Objectives : The objectives of this study were to investigate gamma radiation induced degradation and leaching behavior of nuclide and/or organic complexing agent adsorbed ion exchange resin.Methods : Cation exchange resin (IRN 77) and anion exchange resin (IRN 78) widely used in nuclear power plants were purchased. Cobalt ion and EDTA were used to represent nuclide and organic complexing agent adsorbed to ion exchange resins. Cation and anion exchange resin adsorbed cobalt ion and/or EDTA were radiated by 60Co nuclide. The radiation dose rate was 10 kGy/hr and total doses were 0, 300, 500, and 700 kGy.Results and Discussion : The sulfone and quaternary ammonium functional groups of gamma radiated ion exchange resin were degraded, indicating nuclide/organic complexing agent would be leached from ion exchange resin. It was shown that degradation of anion exchange resin was worse than that of cation exchange resin. While the high concentrations of cobalt ion and organic matter were observed in leachate from anion exchange resin, those in leachate from cation exchange resin were very low. For mixed cation and anion exchange resin, the leaching behavior of mixed resin was improved. This shows that disposal in the form of a mixed ion exchange resin was evaluated as a safer method than that of a cation or anion exchange resin alone.Conclusion : The adsorbed nuclide and organic complexing agent were leached from ion exchange resin by gamma irradiation. The leaching behavior of cation and anion exchange resin was improved by using mixed ion exchange resin.

Studies have been made of the sorption equilibria of pyridine, picoline and lutidine in aqueous solution on ion-exchange and porous resins. The sorption behaviors of these pyridines on strong acid ion-exchange resin can be expressed by the Langmuir isotherms, and those on both weak acid ion-exchange and porous resins by the Freundlich isotherms. The sorption mechanisms followed either a neutralization reaction with the H-form ion-exchange resins, or a hydrophobic interaction with the porous resins. Methanol content of the aqueous solution as well as solution pH was found to have a significant effect on the sorption of pyridines.Furthermore, the separations of these pyridines from each other were examined for three binary solute solutions in a batch mode. The pyridines were sorbed preferentially on the resins in the following sequence:pyridine where the selectivity increased as follows:strong acid ion-exchange resin

Excerpt The use of ion exchange resins was suggested by Segal et al.2for control of gastric acidity and by Dock3for treatment of cardiac edema. The background and theory of ion exchange by resins i...

Relationships between transport and physical–mechanical properties of ion exchange membranes

I. Introduction.- Theodore Vermeulen's contributions to process design for sorption operations.- Ion Exchange: past, present, and future.- II. Chemistry of Ion Exchange Resins.- Coordination chemistry of selective ion exchange resins.- Modern research in ion exchange.- III. Chemical Engineering Aspects of Ion Exchange Processes.- Thermodynamics of ion exchange: prediction of multicomponent equilibria from binary data.- Design methods for ion-exchange processes based on the "equilibrium theory".- Fixed-bed ion exchange with formation or dissolution of precipitate.- Numerical Methods.- Modelling of multicomponent fixed bed ion exchange operations.- Fixed bed processes: a strategy for modelling.- Counter-current ion exchange.- Continuous ion exchange technology.- Efficient fractionation by ion exchange.- Parametric ion-exchange processes (parametric pumping and allied techniques).- IV. Industrial Applications.- Ion exchange in industry.- Applications of ion exchange in hydrometallurgy.- Some of the uses of ion-exchangers in hydrometallurgy.- Reaction processes involving ion-exchange resins.- Zeolites: some catalytic applications.- V. Alternative Processes.- Ion exchange membranes: principles, production and processes.- Kinetics of metal extraction: rate controlling steps and experimental techniques used to establish a design equation.- The surfactant liquid membrane: applications to metal extraction and pollution control.- Reaction reversibility in batch and continuous extractors using emulsion liquid membranes.- Fixed bed cementation experiments.- List of Participants and Lecturers.

Ion Exchange Towards the Twenty First Century.- The Use of Some Coordinating Copolymers in Hydrometallurgy.- The CCS-Ion Exchange Contactor.- Outlook and Desires of Ion Exchange Resin Technology Development in the Nuclear Field.- Purification of Effluents of Acid Copper and Nickel Plating Galvanic Processes with Conventional Cation Exchange Resins. Copper and Nickel Recovery.- Anion Resin Kinetics at High Flow Rates.- Ion Exchange Desulphation of Feedwater to MSF Evaporator. Full Scale Experience.- Calculation of Economic Indexes for Desalination Plants with and Without Desulphation Pretreatment System.- Kinetic Studies on Gel and Macroporous Anion Exchangers Using the Uranyl Sulfate/Sulfate Exchange.- Salt Conservation, Selectivity Reversal and Breakthrough Detection in Ion Exchange for Nitrate Removal.- Equilibrium and Diffusion Rate Effects of Univalent and Divalent Ions in a Bifunctional Resin.- Analysis of Ion Exchange Phenomena Occurring in Silicate Glasses Immersed in a Molten Salt Bath.- The Rim-Nut Process for Recovery of N/P Fertilizer From Sewage. Start-Up of Bari's Plant.- Ion Exchange for the Recycling of Wastewater Constituents.- Cation Exchange Softening Coupled with Electrodialysis for High Recovery Desalination.- Methods of Reducing Consumption of Sulphuric Acid in Regeneration of Strong Cation Exchangers in Water Desalination.- Design Methods for Ion Exchange Equipment.- Future Criteria for the Design and Manufacturing of Water Treatment Plants.- Water Softening for Food Processing.- Ion Exchange in the Food Industry.- Ion Exchange for the Recovery of Concentrated Ammonium Sulphate from the Process Condensate of an Ammonia-Urea Factory.- The Mechanism of Ion Exchange on Microcrystals of Inorganic Oxide-Hydroxides.- A Useful Method to Summarize Data in Ion Exchange - Influence of Temperature and Ionic Size.- Reversibility and Performances in Productive Ion-Exchange Chromatography.- Mossbauer and Electron Microprobe Studies of Precipitation Phenomena in Nafion Ion Exchange Membranes.- Ion Exchange Kinetics in Zeolite A.- Kinetics of Bulk and Interfacial Ionic Motion: The Microscopic Basis and Limits for the Nernst-Planck-Poisson System.- Nernst-Planck or No?.- Application of the Stefan-Maxwell Equations to Multicomponent Ion Exchange.- Concentration Polarization and Membrane Resistance Evaluation by Current Transient and Nernst-Planck Equations.

Volatile fatty acids recovery from the effluent of an acidogenic digestion process fed with grape pomace by adsorption on ion exchange resins

Since its discovery more than a century ago, the phenomenon of ion exchange has undergone significant evolution in terms of both theory and practice, especially after the synthesis of organic (polymeric) ion exchangers. No specialty thrives in isolation. The field of ion exchange grew over decades by permeating into myriad areas from deionization to drug delivery. There have been continuous development in the synthesis of new ion exchange materials and processes that now cater to various applications in industries as diverse as power and water utilities, biotechnology, chemical purification, food and beverages, agriculture, pharmaceuticals, microelectronics, and also water treatment. Polymeric ion exchangers, viewed as a strongly ionized electrolyte with low dielectric constants, can be made suitable for various uses including trace contaminant removal in environmental separation, hydrometallurgy, catalysis, product purification, and sustainable industrial processes. Many of these specific interactions can be characterized and enhanced by making modifications to the polymer matrix, covalently attached fixed functional groups, degree of cross‐linking, porosity, and morphology. Affinity for specific ions or selectivity of the ion exchangers plays a critical role and allows one to design ion exchange processes in which complete removal of the target ion from the background of other ions is required. Selectivity of the ion exchangers also influences separation of noble metals and chemical purification operations. An understanding of the basic principles of ion exchange equilibrium and kinetics is important for the development of new materials and processes. In order for an ion exchange process to be economically viable, the ion exchangers need to be regenerable so that they may be used for tens of cycles. Such a constraint demands a tradeoff between the high selectivity of the resin and its regenerability with cost‐effective regenerants. Regulations related to the disposal of spent regenerant have also driven new advancements in the field of ion exchange.

Metallic ions recovery from membrane separation processes concentrate: A special look onto ion exchange resins

Excerpt HISTORICAL ASPECTS The presence of substances in the soil capable of fixing cation constituents of fertilizers as a result of ion exchanging processes was first recognized by chemists more ...

The condition of sources and central water supply systems does not guarantee the required quality of drinking water. A large part of the population of Ukraine uses drinking water that does not meet hygienic requirements according to various indicators. Manganese compounds are quite often present in natural waters. Their quantitative content can vary in a wide range, depending on the region, it can be 5-6 mg/dm3. Manganese in underground waters is presented as ion Mn2+, salts of which are soluble. To remove manganese from water one should transfer it to insoluble state by oxidation. Today, there are a number of typical technologies of demagnetization of water. Many works have also been published which describe the purification of water from manganese ion. It is worth noting that with a high content of manganese compounds in water, their removal is a rather difficult task. Removal of manganese compounds from water can be implemented using the ion exchange method, which consists of filtering water through loading in salt or acidic form. At the same time, softening and desalination of water can occur simultaneously. Therefore, the ion exchange method should be used for comprehensive water purification, softening, and removal of manganese compounds. In order to study the oxidizing capacity of catalytic loading with respect to manganese compounds in water were used as a catalytic load KU-2-8 cationite modified with magnetite and manganese oxide in H+, Na+, and Ca2+ forms. To modify cationite with magnetite under static conditions, it was treated with a solution containing a mixture of Fe2+ and Fe3+ ions in a ratio of 1:2. The research was also carried out on the preparation of catalysts based on cationites by modifying them with manganese compounds. The purpose of this article is to evaluate the efficiency of manganese removal from water when using a catalyst sorbent. The article presents the results of research on water purification from manganese compounds using sorbents-catalysts modified with iron and manganese compounds. It was established that in static and dynamic conditions, complete extraction of manganese ions can be achieved using sorbents based on polymer resin and magnetite. When using cation exchange resin modified with magnetite, the removal of Mn2+ ions from aqueous solutions occurs both due to ion exchange, regardless of the form of the ion exchanger, and due to oxidation on the catalyst (magnetite) in the presence of dissolved oxygen. Modified cation exchange resin in Na+ form leads to the extraction of manganese due to sorption and oxidation of Mn2+. In this case, sorption of calcium and magnesium ions, which is known to be accompanied by an increase in pH. The pH of the medium increased, which increased the efficiency of oxidation of manganese ions on magnetite. Under these conditions, the sorbent catalyst provides complete removal of manganese ions due to catalytic oxidation and sorption of manganese ions on magnetite.

Oilfield "produced" waters usually contain high hardness, and high dissolved solids along with some alkalinity. The problem of disposing of these waters and the need for huge volumes of water for alkaline water flooding and steam generation for steam floods, necessitate the softening and reinjection of softened produced water. Water for alkaline and steam flooding needs to be softened to almost zero hardness to prevent plugging during injection and to prevent scaling on boiler tubes. Softening of high TDS and high hardness waters requires a very selective resin with high operating capacity such as a weak carboxylic acid-type ion exchange resin. Conventional softening with strong acid resins would not work under these conditions. This paper discusses the different processes in softening oilfield produced water. Data obtained in softening varieties of produced waters from different oilfields in California will be presented. Performance characteristics of weak cation exchange resins and their chemical regenerant requirements will also be discussed.

A combined ion exchange–nanofiltration process for water desalination: I. sulphate–chloride ion-exchange in saline solutions

Desalination of whey by electrodialysis and ion exchange resins: analysis of both processes with regard to sustainability by calculating their cumulative energy demand