Electrodeionisation 3: The removal of nickel ions from dilute solutions

The removal of nickel ions from dilute solutions using a process that combines an ion-exchange bed with electrodialysis has been studied. The main aspects include: the concentration of nickel ions in the diluate, the voltage over the cell and the current density distribution along the ion-exchange bed. The current density distribution provides insight into the state of the bed as it is simultaneously loaded with Ni²⁺ and regenerated with an electric potential difference applied perpendicular to it. A simple model is used to describe the state of the bed and the quantity of nickel removed from it as a function of time. Under specific conditions the precipitation of metal hydroxides is observed in the compartment containing the ion-exchange bed. The results show that hydroxide precipitation is related to the nickel concentration in solution and the electric potential gradient across the bed.     

Electrodeionization 2: The migration of nickel ions absorbed in a flexible ion-exchange resin

The removal of nickel ions from a low cross-linked ion-exchange resin using an applied electrical potential gradient was studied. The potential gradient across a bed of ion-exchange particles, in which nickel ions were absorbed, was varied by two methods. One involved a change of cell voltage across beds of constant width, the other a change of bed width at constant cell voltage. In this way, various characteristics concerning the electrodialytic regeneration of a bed of ion-exchange particles in the nickel form were ascertained. The diffusion coefficient, current efficiency and migration rate of nickel in the bed are discussed. It is shown that the current efficiency for the removal of nickel is nearly one hundred percent when the bed is in the nickel form, and that the rate of regeneration is proportional to the cell voltage.     

Continuous deionization of a dilute nickel solution

This paper describes the continuous removal of nickel ions from a dilute solution using a hybrid ion-exchange/electrodialysis process. Emphasis was placed on the ionic state of the bed during the process, and the mass balance of ions in the system. Much of this information was obtained by analysing the current distribution across the cell. The effects of temperature, feed nickel concentration and feed solution flow rate were ascertained. It was found that a steady, continuous process can be achieved.     

Removal of copper ions by a cation-exchange resin in a semifluidized bed

The removal of copper ions was studied experimentally in a semifluidized bed charged with a strong cation-exchange resin, Amberlite 200C. The semifluidized bed system was formed by inserting a retaining grid in a packed bed and increasing the fluid velocity above U_mf. In this arrangement, the bed is separated into two sections; the upper packed bed section and the lower fluidized bed section. As the fluid velocity increases, the portion of the packed bed section becomes larger. As expected, the breakthrough curve obtained from the semifluidized bed lies between those from packed and fluidized beds. The breakthrough curves of copper ions were predicted reasonably well by using an axial dispersion model. In this paper, the effects of the liquid flowrate and the retaining grid height on the breakthrough behavior are extensively discussed.     

Potential and concentration gradients in a hybrid ion-exchange/electrodialysis cell

The regeneration of 2, 4 and 8% cross-linked ion-exchange resins in the nickel-form was carried out in a three-compartment hybrid ion-exchange/electrodialysis cell. During the process the potential and nickel concentration profiles in the bed were measured. The experimental results are compared to results from a one-dimensional transport model able to simulate the development of potential and concentration gradients during the process; the amount of nickel transported out of the ion-exchange bed to the cathode, or concentrate, compartment was also reasonably well predicted. Differences between the model and experimental results are also discussed. It was found that under extreme conditions (i.e., high bed voltage), the formation of metallic nickel was observed in the central ion-exchange compartment.     

Expanded-Bed Adsorption of Proteins Using Ion-Exchangers

Abstract

The use of expanded beds of ion-exchange adsorbents for the adsorption of proteins from feedstocks containing whole cells is described. Such feedstocks can be applied to the bed without prior removal of particulate material by centrifugation or filtration, thus showing considerable potential for this approach in simplifying downstream processing flow-sheets. Stable, expanded beds can be obtained using simple equipment adapted from that used for conventional packed bed adsorption and chromatography processes. Ion-exchange adsorbents are likely to be chosen for such separations as a result of the robustness of the ion-exchange groups to cleaning and sanitization protocols. Frontal analysis involving the measurement of breakthrough curves indicates that the adsorption performance of an expanded bed is similar to that achieved when the same amount of adsorbent is used in a packed configuration at the same volumetric flow-rate. In addition, the adsorption performance of an expanded bed of a cation exchanger was not diminished when adsorption was carried out in the presence of high concentrations of cells. However, the performance of similar beds of anion exchangers was found to be reduced under some conditions depending on the type of cells, their concentration, and their age. The results from the expanded bed adsorption experiments were consistent with those from batch adsorption which showed that the adsorption characteristics of the anion exchangers were diminished in the presence of cells in contrast to results with a cation-exchanger system where little deterioration in performance was noted. The results suggest that cation exchangers might be expected to be of more use for expanded bed adsorption in the presence of cells.     

碳毡基体电活性铁氰化镍电极电控离子交换连续分离Cs~+(英文)

Nickel hexacyanoferrate (NiHCF) film was synthesized on porous three-dimensional carbon felt (PTCF) substrate by repetitious batch chemical depositions, and the NiHCF/PTCF electrode was used as electrochemically switched ion exchange (ESIX) electrode in a packed bed for continuous separation for cesium ions. The morphologies of the prepared electrodes were characterized by scanning electron microscopy and the effects of solution concentration on the ion-exchange capacity of the electrodes were investigated by cyclic voltammetry technique. Cycling stability and long-term storage stability of NiHCF/PTCF electrodes were also studied. The NiHCF/PTCF electrodes with excellent ion-exchange ability were used to assemble a diaphragm-isolated ESIX reactor for cesium separation. Continuous separation of cesium and regeneration of NiHCF/PTCF electrode based on the diaphragm-isolated reactor were performed in a laboratory-scale two-electrode system.     

Transport phenomena in the electrodeionization of cesium from AMP-PAN

Electrodeionization (EDI) of cesium from cesium-sorbed ammonium molybdophosphate-polyacrylonitrile (AMP-PAN) was investigated by passing eluant through the packed bed of ion-exchange resin in an electrodialysis cell. The deionized cesium from the packed bed was recovered in catholyte by migration and in the eluant by convection. Recovery percentage of Cs by migration increased while the recovery by convection decreased with increase in current density from 20 to 40 mA/cm². Increased eluant concentration resulted in low migration percentage of cesium. Increased catholyte concentration had a negligible effect on total recovery. Apparent diffusion coefficients evaluated using the Nernst–Plank relation increased with increase in current density and catholyte concentration while a decreasing trend was observed with increase in eluant concentration.     

Removal and recovery of heavy metal ions in fixed and semi-fluidized beds

Uptakes of heavy metal ions such as Pb²⁺ and Ni²⁺ were studied experimentally in fixed and semifluidized beds packed with a strong cation exchange resin, Amberlite 200. Single and binary aqueous solutions of lead and nickel ions were passed through ion exchange columns, and the exit concentrations were measured to get the breakthrough behavior of the ions. From the exit concentration profiles, the breakthrough time and the ion exchange capacity were evaluated. After removal of heavy metal ions from binary solution of lead and nickel ions until the breakthrough time, two metal ions were recovered by precipitation and resolubilization of lead. In this paper, the recovery yield and separation efficiency are rigorously discussed.     

Removal of zinc ions from aqueous solution using a cation exchange resin

The present study is concerned with the mass transfer and kinetics study of zinc ions removal from aqueous solution using a cation exchange resin packed in a rotating cylindrical basket reactor. The effect of various experimental parameters on the rate of zinc ion removal, such as initial zinc ion concentration, packed bed rotation speed and temperature has been investigated. In addition to find a suitable equilibrium isotherm and kinetic model for the zinc ion removal in a batch reactor. The experimental isotherm data were analyzed using the Langmuir, Freundlich and D–R equations. The equilibrium data fit well in the Langmuir isotherm. The experimental data were analyzed using four sorption kinetic models, pseudo-first and second-order equations, the Elovich and the intraparticle diffusion model equation, to determine the best fit equation for the biosorption of zinc ions onto purolite C-100 MH resin. Results show that the Elovich equation provides the best correlation for the biosorption process.     

Treatment of wastewater containing copper,zinc, nickel and cobalt using Duolite ES‐467

Duolite ES‐467 was used to treat wastewater containing heavy metal ions. Sorption experiments were carried out at varying pH values, agitation speeds, reaction times, and metal ion and sorbent concentrations. Each of the parameters affects the sorption behaviour of individual metal ions. Copper sorption was greater compared with other metal ions such as zinc, nickel and cobalt. The presence of other metal ions affects copper sorption. Equilibrium isotherm curves were developed. These were used to predict that the metal ion concentration would be reduced from 100 to less than 1 mg dm^?3. Fixed bed tests were conducted to investigate the efficiency of Duolite ES‐467 for the selective removal of copper ions from multi‐metal solutions. Breakthrough curves were obtained using Duolite ES‐467 for solutions containing copper, nickel and copper, zinc, nickel and cobalt. Elution studies were also carried out using sulfuric acid. © 2002 Society of Chemical Industry     

Use of electrodialysis to remove silver ions frommodel solutions and wastewater

The feasibility of the removal of Ag⁺ ions in a model solution and a sample of rinse water provided from an industrial plating plantwas investigated in a batch electrodialysis system. The experiments were carried out using two different types of ion-exchange membranes. The effects of applied potential, pH value and initial silver concentration on the duration of electrodialysis and energy consumption were examined. Full removal of Ag+ ions was achieved from model solutions and the sample of rinse water. The most convenient applied voltage and energy consumption values to remove silver ions are reported. These results will be useful for designing and operating different capacities of electrodialysis plants for recovering Ag⁺ ions.     

炭粒床高效工业除尘装置的设计与开发

The new dust removal technical route using the carbon-granular bed filter,packed of carbon particles with appropriate grade derive from an online-process vibration sieve,to replace the traditional baggy filter had been developed successfully for capturing the micro-carbon dusts produced from pulverization of petroleum coke,and the green close loop of carbon materials is thus completed in the combined pulverizing and classifying system and pulverized carbon dust removal process.The high dust removal efficiency greater than 99%,low outlet dust concentration less than 100 mg.m-3,low pressure drop through dust filtration chamber less than 980 Pa,simple and easy design,and flexible and stable operation were achieved also with the carbon-granular bed filter in both bench and industrial scale operations.     

Removal of Lead and Nickel Ions Using Zeolite Tuff

The capacity of Jordanian zeolite tuff for the removal of lead and nickel ions from aqueous solutions has been investigated under different conditions, namely zeolite particle size, initial solution pH, initial metal ion concentration, slurry concentration and solution temperature. Equilibrium data obtained have been found to fit both the Langmuir and Freundlich adsorption isotherms. It has been found that this zeolite (phillipsite) tuff is an efficient ion exchanger for removing both lead and nickel ions. Its removal capability is considerably higher for lead ions than for nickel ions under all conditions tested; however, the actual exchange capacities are far below the theoretical values. The finer the zeolite particles used, the higher the metal exchange capacity. An initial solution pH of 4·0 is favourable for obtaining high metal removal. © 1997 SCI.     

炭粒床高效工业除尘装置的设计与开发

The new dust removal technical route using the carbon-granular bed filter, packed of carbon particles with appropriate grade derive from an online-process vibration sieve, to replace the traditional baggy filter had been developed successfully for capturing the micro-carbon dusts produced from pulverization of petroleum coke,and the green close loop of carbon materials is thus completed in the combined pulverizing and classifying system and pulverized carbon dust removal process. The high dust removal efficiency greater than 99%, low outlet dust concentration less than 100 mg-m-S, low pressure drop through dust filtration chamber less than 980 Pa, simple and easy design, and flexible and stable operation were achieved also with the carbon-granular bed filter in both bench and industrial scale operations.     

Reduction of metal ions in dilute solutions using a GBC-reactor: Part I: Experimental study on the laboratory scale reduction of ferric ions

To reduce metal ions in dilute solutions a new type of electrochemical reactor has been developed: the GBC-reactor. This reactor consists of a gas diffusion electrode coupled with a packed bed electrode. The working principle of the reactor is based upon two main reactions: the catalytic oxidation of hydrogen gas in the gas diffusion electrode and the simultaneous reduction of metal ions on the packed bed electrode. This process occurs spontaneously without the need for an external power supply when the Gibbs free energy of the total reaction is negative. To study the behaviour of the reactor the reduction of ferric ions was used as a model system. The experimental results, obtained from varying a number of key process parameters, could be described using a very simple macroscopic rate equation. It is concluded that the reduction of ferric ions in a GBC-reactor is controlled by both mass transfer and electrochemical kinetics. To carry out scale-up and optimization studies a reactor model incorporating the potential distribution in the packed bed electrode is, however, necessary.     

Reduction of metal ions in dilute solutions using a GBC-reactor: Part I: Experimental study on the laboratory scale reduction of ferric ions

To reduce metal ions in dilute solutions a new type of electrochemical reactor has been developed: the GBC-reactor. This reactor consists of a gas diffusion electrode coupled with a packed bed electrode. The working principle of the reactor is based upon two main reactions: the catalytic oxidation of hydrogen gas in the gas diffusion electrode and the simultaneous reduction of metal ions on the packed bed electrode. This process occurs spontaneously without the need for an external power supply when the Gibbs free energy of the total reaction is negative. To study the behaviour of the reactor the reduction of ferric ions was used as a model system. The experimental results, obtained from varying a number of key process parameters, could be described using a very simple macroscopic rate equation. It is concluded that the reduction of ferric ions in a GBC-reactor is controlled by both mass transfer and electrochemical kinetics. To carry out scale-up and optimization studies a reactor model incorporating the potential distribution in the packed bed electrode is, however, necessary.     

三维电极法去除配位电镀废水中的镍离子和铜离子

将颗粒状活性炭作为三维电极的粒子,采用三维电极法去除配位电镀废水中的镍离子和铜离子。考察了pH值、电流、极板间距、炭水比(粒子电极活性炭与处理水量的体积比)对镍离子和铜离子去除率的影响。在设定的范围内,镍离子和铜离子的去除率随pH值的升高呈现先升后降的变化趋势,随电流和炭水比的增大而升高,随极板间距的增大而降低。当废水中镍离子和铜离子的初始质量浓度分别为82.309 3mg/L和52.761 5mg/L、活性炭的体积为1 000mL、处理时间为2.0h时,最佳的处理工艺条件为:pH值4、电流0.6A,极板间距20cm,炭水比10∶9。此时,镍离子和铜离子的去除率分别为83.40%和86.20%。出水经过混凝沉淀后,镍离子和铜离子的去除率分别达到99.87%和99.68%,在出水中的质量浓度分别为0.107 2mg/L和0.169 3mg/L,出水水质达到《电镀污染物排放标准》(GB 21900—2008)中表2的排放限值。     

Packed bed electrodes. I. The electrochemical extraction of copper ions from dilute aqueous solutions

A study has been made of the cathodic deposition of copper ions from flowing dilute aqueous solutions onto a packed bed of graphite. The electrodeposition reaction is mass transfer controlled and expressions are presented for the cathodic current as a function of time, solution flow rate and bed characteristics. These have been verified from potentiostatic experiments. The cathode current efficiency is shown to approach 100% and packed bed electrodes are shown to be an effective means of extracting or removing metal ions from dilute solutions.     

Investigation of transport phenomena in a hybrid ion exchange-electrodialysis system for the removal of copper ions

Hybrid ion exchange electrodialysis processes allow the removal of metal ions from dilute waste liquids and the recovery of more concentrated solutions. The work reported here was aimed at investigating the two steps in the treatment process, namely, adsorption of metal ions onto the packed bed of resin and electromigration (i.e., the transport of these ions in the complex system under the applied electrical field). The case of copper sulfate was investigated. Dowex resins with a cross-linking degree of 2 and 8% were used. The flux of copper through the resin bed and the current efficiency for ion transfer to the cathode compartment were determined as a function of potential gradient and copper ionic fraction in the bed. Apparent diffusion coefficients of Cu²⁺ in the overall system were deduced from the experimental data.