Countercurrent Ion Exchange Research Articles

Reduction of chloride in amine from gas sweetening unit using a continuous virtual countercurrent ion exchange setup

In this work, continuous chloride reduction was studied using a Continuous Virtual Countercurrent Ion Exchange setup (CVCIE). With this new laboratory scale setup constructed, ion exchange process which is inherently batchwise was conducted continuously. Lewatit Monoplus M800 OH and Amberjet 4500 OH resins were used for the first time for amine reclamation. According to the resins’ critical properties, Lewatit Monoplus M800 OH showed a better performance in chloride separation. The resin performance is pH-dependent. In this regard, amine-to-resin ratio at different influent chloride concentrations showed that Lewatit Monoplus M800 OH has the potential for higher chloride exchange at a pH of 10.5–11. During several experiments, the optimum amount of caustic needed for regeneration of the saturated resins was determined. Setup results showed that chloride concentration in amine tank was reduced to 50 ± 10 ppm and the pH increased to 11.85 ± 0.15 which were the averages of three different tests.

Observer Design for a Bilinear Model of a Continuous Countercurrent ION Exchange Process

The paper describes a method and proposes an algorithm for a bilinear observer design as part of a state estimation solution for a Continuous Countercurrent Ion Exchange (CCIX) process used for desalination of water. The aim of the design is to determine immeasurable process state variables using real CCIX measurement data obtained from a different study. The solution requires determination of the observer gain matrix and it is formulated on the basis of the pole placement method. The contribution of the paper is in the developed bilinear dynamic models of the process and the observer and in the extending of the pole placement method for the special matrices of the bilinear observer. An analytical procedure is developed and implemented for calculation of the characteristic equation of the observer as part of calculation of the observer gain matrix. Matlab and SIMULINK software programs for determining the estimated states are developed. Investigation of the performance of the bilinear observer and the closed loop system under various constant values of the control input and different state initial conditions is performed. The results are presented and discussed.

A novel cleaning process for industrial production of xylose in pilot scale from corncob by using screw-steam-explosive extruder.

Steam explosion is the most promising technology to replace conventional acid hydrolysis of lignocellulose for biomass pretreatment. In this paper, a new screw-steam-explosive extruder was designed and explored for xylose production and lignocellulose biorefinery at the pilot scale. We investigated the effect of different chemicals on xylose yield in the screw-steam-explosive extrusion process, and the xylose production process was optimized as followings: After pre-impregnation with sulfuric acid at 80°C for 3h, corncob was treated at 1.55MPa with 9mg sulfuric acid/g dry corncob (DC) for 5.5min, followed by countercurrent extraction (3 recycles), decoloration (activated carbon dosage 0.07g/g sugar, 75°C for 40min), and ion exchange (2 batches). Using this process, 3.575kg of crystal xylose was produced from 22kg corncob, almost 90% of hemicellulose was released as monomeric sugar, and only a small amount of by-products was released (formic acid, acetic acid, fural, 5-hydroxymethylfurfural, and phenolic compounds were 0.17, 1.14, 0.53, 0.19, and 1.75g/100g DC, respectively). All results indicated that the screw-steam-explosive extrusion provides a more effective way to convert hemicellulose into xylose and could be an alternative method to traditional sulfuric acid hydrolysis process for lignocellulose biorefinery.

Simulation and optimization of the selenium recovery process using the continuous counter-current decantation ion exchange system

A simulation and optimization process based on the electrical network model is presented to recover selenium from solutions using S 108 resins in a continuous counter-current decantation ion exchange system (CCDS). The system's performance is affected by multiple parameters, including the selenium concentration, inlet flow rate, cycle operating time, desorption solution flow rate, resin mass transferred per cycle, diffluent ratio, and so forth. In a simulation process, normally, 20 to 25 cycles are required for the electrical analogue model to reach the cyclic steady state. The average error between the experimental and modeled outlet selenium concentrations was 1.89%. After optimization, the S 108 resin initially adsorbed 856.19mg/L Se(VI) and 855.33mg/L Se(IV), which resulted in selenium concentrations of 27.4 and 21.6g/L. In addition, recovery rates were 91.45 and 88.06% following the 164mL/min Se(VI) and 128mL/min Se(IV) solution treatments, respectively.

ChemInform Abstract: Decontamination of Low-Level Radioactive Wastewaters by Continuous Countercurrent Ion Exchange

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Pure Metal Chelate Solutions by Ion Exchange

Aqueous solutions of the industrially important metal chelate ferric N-(2-hydroxyethyl)ethylenediamine-N,N‘,N‘-triacetate (FeHEDTA) have been made by adsorbing an iron salt (nitrate or sulfate) on Dowex MSC-1 cation-exchange resin (Na form), flushing out the sodium salt, and eluting with Na3HEDTA. The resulting eluate contained FeHEDTA with iron concentrations approaching 2% that were free from sodium salts. Achieving industrially useful iron concentrations (>4.5%) required countercurrent ion exchange using an ISEP system. Careful manipulation of pH was required to prevent plugging due to precipitated iron oxide/hydroxide.

OPTIMAL CLOSED-LOOP CONTROLLER DESIGN FOR AN ION EXCHANGE PROCESS USED FOR DESALINATION OF WATER

A personal computer based control system for the countercurrent multistage ion exchange process for desalination of water is built. The developed control system is part of an optimization strategy of the continuous countercurrent ion exchange (CCIX) process. The paper focuses on the design of an optimal nonlinear controller as a part of a two layer control strategy with layers of optimization and direct control. The design involves two stages, nonlinear linearizing the closed loop system controller and linear quadratic controller for the linearized system. The controller is realized in LabVIEW software environment. Algorithm and programs for implementation of the design method are developed.

Novel technology: Fresh approach to countercurrent ion exchange

By reversing a commonly-used way of distributing fluids to ion-exchange cells, Belgian separations technology company PuriTech has developed a liquid adsorption separation technology, which could improve liquid-resin contact efficiency, while reducing plant operating costs and CAPEX, explains Filip Rochette.

Counter-current ion exchange for the removal of organically bound sodium from low-rank coals

South Australian low-rank coals contain high levels of water-soluble and ion-exchangeable ions that can be deleterious to coal combustion and gasification. The presence of sodium causes the formation of low melting point bonded deposits that can produce severe fouling and slagging in many processes using these coals. Approximately 70% of the sodium present in Bowmans coal is water-soluble and can therefore be removed by simple water leaching, however the remaining 30% is organically bound, predominantly to carboxyl groups. Ion exchange using sulphuric acid at pH 2 is necessary to remove this sodium, but this can generate large volumes of acidic wastewater if multiple washing stages are used with fresh water each time. Using a simple laboratory procedure, the continuous counter-current ion exchange leaching of sodium from this coal was simulated which reduced the sodium level from 1.30% on a dry basis (db) to 0.15% (db) after three stages of counter-current washing at a total coal:water ratio of 1:2. The effectiveness of interstage dewatering on the efficiency of sodium removal was highlighted. The agreement between predicted and measured values of moisture and sodium in coal was excellent.

CSA Continuous Countercurrent Ion Exchange (CCIX) Technology

Abstract The CSA-CCIX concept started at ORNL in 1951. It has been adapted to a wide variety of applications worldwide, in water and waste water treatment, fertilizers, hydrometallurgy, and general chemical processing. Unique features and how it works are described. Two extreme applications are described in detail. One is for the extraction of trace amounts of uranium from a copper leach, at 37.85m3/min (10,000 gpm) where very high throughput rates are emphasized. The other is for Acid Retardation, where a strong acid waste is purified and recovered. The feed processing rate here is much lower than the resin rate.

Studies on high density anion exchangers

Most commercially available anion exchangers are not suitable for the continuous countercurrent fluidised-bed ion-exchange technique because of their poor wet absolute densities and poor settling characteristics. A few high density anion exchangers were developed by the treatment of commercially available anion exchangers with nitric acid-potassium bromate. The effect of the temperature of chemical treatment on the ion-exchange capacity and wet absolute density of the modified anion exchangers was studied. Anion exchangers prepared under optimised conditions were characterised with respect to ion-exchange capacity, wet absolute density, rate of exchange and rinse characteristics. Of one selected product prepared under optimised conditions the elutriation velocity was determined in order to assess its utility in continuous countercurrent fluidised-bed ion exchange.

Continuous Countercurrent Ion Exchange for Desalination and Tertiary Treatment of Effluents and Other Brackish Waters

A continuous countercurrent ion exchange (CCIX) process has been developed for desalination of mineralized effluents and brackish water. The process utilizes macroporous resins in a strong cation/weak anion sequence. Removal of organic matter by the anion resin results in colour and odour removal and approximately 70% reduction of the COD of humus tank effluent. No pretreatment is required and resin has been in use over the equivalent of more than two years of continuous operation without significant fouling or loss of capacity. Any required degree of desalination is attinable. The basic four-colunn system (cation load and regeneration pair and anion load and regeneration pair) of countercurrent fluidized bed multistage contactors attains greater than 80% water recovery using up to 1,0 N sulphuric acid and 0,2 N lime slurry as regenerants. Low solubility of CaSO4, in the cation waste liquid and column operating problems if high lime concentrations are used set limits on the water recovery. Calcium content of the feed water affects water recovery. New techniques using five-column systems permit byproduct recovery and/or reuse of spent regenerants and result in over 90% water recovery. The capital cost estimate for a 10 000 kℓ/day plant is R5 million while unit costs of water are 30 to 40 c/kℓ. for removal of 500 mg/ℓ TDS. Present work involves lime contacting improvements and evaluation of carbon adsorption polishing of the ion exchange product to produce potable water.

Continuous Inuous Countercurrent Ion Exchange Recovery of Catalase from Beef Liver Extract

Abstract When the ion exchange cellulose “Protion1” was used on a pilot plant scale to produce a re-usable water from a proteinaceous treated meatworks effluent2, it withstood such industrial handling without excessive degradation. A desire to exploit this characteristic of “Protion”, coupled with a wish to overcome problems like the blockage of downflow resin beds by fine suspended solids encountered in the meatworks effluent project, suggested using “Protion” in fluidised beds. However, since the introduction of batch fluidised bed processes seemed reasonably straightforward, it was decided instead to develop a truly continuous process in which “Protion” might have an even greater advantage over more fragile sorbents. Since continuous systems require a greater level of instrumentation and engineering skill than batch processes, it was later decided to apply the technique, not for effluent treatment but for the extraction of enzymes from protein broths It was thought that the greater product value in thi...

Note on a continuous counter current ion exchange with two step regeneration for zinc recovery from synthetic fibre plant waste water

Note on a continuous counter current ion exchange with two step regeneration for zinc recovery from synthetic fibre plant waste water

Separation of stable isotopes by chemical and ion-exchange methods

Methods of separating stable isotopes by the use of various types of molecular compounds. The use of molecular compounds for separating isotopes of boron, sulphur and oxygen. Isotopic exchange reactions in the electric discharges. Calculation of single stage separation factors for exchange reactions. Potentialities of the isotope separation process using ion exchange. The use of ion exchange for separating lithium isotopes. Combination of ion chromatography with electromigration of ion. Synthetic zeolites (molecular sieves) used as ion exchangers. Principles and applications of the continuous countercurrent ion exchange method.

Studies on Continuous Countercurrent Ion Exchange of the System of Magnesium and Hydrogen Ion

Continuous countercurrent ion exchange was studied with the cationic system of magnesium and hydrogen ion, using an exchange column, 2cm in internal diameter and 5 to 30cm in height, where the bed of resin particles moved downward.The data were correlated by an equation so as to relate the overall volumetric coefficient of mass transfer based on fluid film to operating variables and the properties of the ionic system.The results indicated that film resistance of each phase was of the same order of magnitude. Overall volumetric coefficient based on the fluid film was found to be about 0.03 [1/sec].Non-dimensional constants, α and β, appearing in the correlation equation, and related to film resistance of each phase, were 2.4 and 0.2, respectively. These values were smaller than those, 4.7 and 0.9, respcctively, obtained by Hiester et al., for the monovalent system of lithium, potassium and hydrogen ion. These differences may be attributable to the colum diameter differences, i.e., 9cm diameter in the Hiester's equipment and 2cm diameter in the authors'. More studies will be required, however, to know what factors participate in this phenomenon. Some considerations were made on the mutual relation between the degree of the exchange adsorption of magnesium in the solution and the ratio of the fluid flow rate to the resin particles flow rate.

Analytical methods used in studies on continuous separation of ions by countercurrent ion exchange

The hydrogen ion concentration exhibited a pronounced effect on the apparent alkali ion concentrations as determined with a Beckman DU spectrophotometer with a flame attachment. Lithium and potassium ions showed a mutual interference, which appeared small, but was sufficient to affect the theoretical evaluation of exchange systems, especially under trace conditions. Control of slit widths eliminated some of the interferences, but further corrective measures had to be applied by the use of prepared calibration curves. Several methods for removing ions quantitatively from the resins were explored. While copper salts were effective elutants, they could not be used in routine analysis because of interference with the lithium and potassium ions analyses and elution with hydrochloric acid was finally chosen. A simple and economical method was found for determining the ultimate capacity of the resin.