Kinetic Studies of n-Butylparaben Degradation in H2O2/UV System

This work reports the experimental results of kinetics study of n-butylparaben (BP) degradation in H₂O₂/UV systems. A pseudo–steady-state and competition kinetic approaches were used to determine the reaction rate constants between the BP and ^?OH. In competition kinetics atrazine (2.30?×?10⁹ M^?1?s^?1) was used as a reference compound. The measured rate constants for ^?OH reaction with BP ranged from (3.84 ± 0.12)?×?10⁹ M^?1?s^?1 to (8.56 ± 0.90)?×?10⁹ M^?1?s^?1 depending on solution pH and temperature. Values of the rate constant obtained using different methods were in good agreement. The calculated activation energy was equal to 19.01 ± 1.02 kJ mol^?1.     

Ultra-high creep resistant SiC ceramics prepared by rapid hot pressing

The high-temperature compression creep of additive-free β/α silicon carbide ceramics fabricated by rapid hot pressing (RHP) was investigated. The creep tests were accomplished in vacuum at temperature range 1500 °C–1750 °C and compressive loads of 200 MPa to 400 MPa. Under investigated condition the RHP ceramics possessed the lowest creep rate reported in the literature. The observed strain rates changed from 2.5 × 10^?9 s^?1 at 1500 °C and a lowest load of 275 MPa to 1.05 × 10^?7 s^?1 at 1750 °C and a highest load of 400 MPa. The average creep activation energy and the stress exponent remain essentially constant along the whole range of investigated parameters and were 315 ± 20 kJ?mol^?1, and 2.22 ± 0.17, respectively. The suggested creep mechanism involves GB sliding accommodated by GB diffusion and β?α SiC phase transformation.     

Kinetics and diffusion processes in colour removal from effluent using wood as an adsorbent

The rates of adsorption of a basic dye, Astrazone Blue, and an acidic dye, Telon Blue, on wood have been studied. The rate controlling step is mainly intraparticle diffusion, although a small resistance due to a boundary layer is experienced. The activation energies for the adsorption of Astrazone Blue and Telon Blue on wood are 16.8 kJ mol^?1 and 9.6 kJ mol^?1, respectively. The diffusion coefficients vary from 6×10^?13 cm² s^?1 to 18×10^?13 cm² s^?1 for Astrazone Blue at 18°C and from 3 × 10^?13 cm² s^?1 to 8 × 10^?13 cm² s^?1 for Telon Blue at 18°C. The variation in diffusivities is attributed to boundary layer effects.     

Metal displacement (cementation) reactions: The mercury(II)/copper system

The kinetics of the metal displacement reaction between mercury(II) ions and a rotating copper disc are reported. Since the smooth film of mercury deposited does not interfere with the rate of the reaction, the system behaves more ideally than any reported so far. With a constant volume of reactant solution, the reaction rate is found to be accurately first order in mercury(II) ions, the first order rate constant being proportional to the square root of the rotation speed and having an activation energy of 16 ± 2 kJ mol^?1. It is concluded that the reaction is diffusion controlled, the calculated diffusion coefficient being 6.4 ± 0.6 × 10^?10 m²s^?1. The results of polarization measurements for the reduction of mercury(II) ions to mercury metal on a rotating platinum disc and the oxidation of copper metal to copper(II) on a partially cemented copper disc are also presented. These results confirm that the displacement reaction is diffusion controlled, and verify the magnitude of the diffusion coefficient.     

Release of ergotamine from poly (2-hydroxyethyl Methacrylate)

The release of the alkaloid ergotamine from thin discs of poly(2-hydroxyethyl methacrylate) [PHEMA] into an aqueous buffered medium has been effected under sink conditions and monitored by fluorescence spectroscopy. The process was found to be diffusion controlled, the fraction of available drug released being linear in (time)^1/2 during the initial stages. The influences of disc thickness, drug load and temperature were investigated and yielded 2.0 (± 1.0) × 10^?13 m² s^?1 for the diffusion coefficient of ergotamine through the swollen gel at 310K and a value of 69 ± 5 kJ mol^?1 for the activation energy of diffusion. For the uptake of aqueous buffer alone into PHEMA the corresponding values were ca 100 times greater and three times smaller respectively.     

Supercritical water oxidation of quinoline in a continuous plug flow reactor—part 2: kinetics

The results of a detailed investigation into the kinetics of quinoline oxidation in supercritical water are presented. The novel kinetic data presented were obtained in a continuously operated, plug flow reactor where parameters such as temperature, pressure, residence time and stoichiometric ratio of oxidant to quinoline were investigated and detailed in the companion paper (Pinto LDS, Freitas dos Santos LMF, Al‐Duri B and Santos RCD, Supercritical water oxidation of quinoline in a continuous plug flow reactor—part 1: effect of key operating parameters. J Chem Technol Biotechnol). An induction time was experimentally observed, ranging from 1.5 to 3.5 s, with longer times observed in experiments carried out at lower temperatures. A pseudo‐first‐order rate expression with respect to quinoline concentration (with oxygen excess) was first adopted and the activation energy of 234 kJ mol^?1 and a pre‐exponential factor of 2.1 × 10¹⁴ s^?1 were estimated. Furthermore, an integral power rate model expression was established, attributing a reaction order for quinoline as 1 and for oxygen as 0.36. An activation energy and pre‐exponential factor for this model were determined as 224 kJ mol^?1 and 3.68 × 10¹⁴ M^?0.36 s^?1, respectively. A global rate expression was then regressed for the quinoline reaction rate from the complete set of data. The resulting activation energy was 226 ± 19 kJ mol^?1 and the pre‐exponential factor was 2.7 × 10^{13 ± 2} M^?0.1 s^?1. The reaction orders for quinoline and oxygen were 0.8 ± 0.1 and 0.3 ± 0.1, respectively. It was shown that the least‐squares regression method provided the best‐fit model for experimental results investigated in this study. Copyright © 2006 Society of Chemical Industry     

Modeling the PAAc‐AN‐TV surface using 134Cs and 152+154Eu sorption

A novel composite, composed of poly (acrylic acid (AAc), acrylonitrile, and titanium vanadate, was prepared by induced gamma irradiation route at 20 kGy to be used as a hybrid organic‐inorganic sorbent. 5–200 μm particle diameters of the composite were obtained. An average particle size of 75 μm of crystalline (17‐20) composite was used; it was thermally stable to 486°C. The distribution coefficients of Cs⁺ and Eu³⁺ were studied as a function of pH; 2350 mL·g^?1 and 645 mL·g^?1 were obtained in case of ^152+154Eu and ¹³⁴Cs at pH 6. 1.55 mmol·g^?1 and 1.85 mmol·g^?1 maximum loadings were accommodated for the same ions at the same pH. Different models were used to scan the surface of the exchanger, so that the topography of the surface was studied as a function of surface active site types, concentrations, and heterogeneity. Langmuir, Freundlich and D‐R models were used. Also, different kinetic models, as Lagergren pseudo first‐order, pseudo second‐order and Morris‐Weber intraparticle diffusion models were applied to study the possible mechanism of the sorption process; pseudo first‐order was exempted to investigate the mechanism. They proved that chemisorption and ion exchange mechanism with controlled diffusion are predominant, with their characteristic mean energies (8.731 kJ·mol^?1 and 9.310 kJ·mol^?1 for Cs⁺ and Eu³⁺, respectively). Double Shell Model was finally adopted to explain the suggested mechanism. Negative values of ΔG°, ?2.15 kJ·mol^?1 to ?7.92 kJ·mol^?1 in case of Cs⁺ and ?3.35 kJ·mol^?1 to ?9.67 kJ·mol^?1 in case of Eu³⁺adsorption at different temperatures, indicate the spontaneous nature of the reactions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

STUDIES OF THE HYDROUS NIOBIUM(V) OXIDE ION EXCHANGER. VII.RATE OF THE ISOTOPIC EXCHANGE OF CESIUM IONS BETWEEN THE EXCHANGER IN THE Cs+ FORM AND AQUEOUS SOLUTION

ABSTRACT

The isotopic exchange rate of Cs⁺ between hydrous niobium(V) oxide in the Cs⁺ form and aqueous solutions was determined radiochemically. The rate was controlled by the diffusion of Cs⁺ in the exchanger particle at varying pH. The diffusion coefficients at 10°C increased with pH up to pH7; from 3.0x10^?11 m²s^?1 at pH6 to 4.0×10^?11 m²s^?1 at pH7, and became constant above pH8 (5.0x10^?11 m²s^?1). While the diffusion coefficients of Na⁺ monotonously decrease with increasing pH; from 7.9×l0^?11 m²s^?1 at pH6.5 to 2.8×l0^?11 m²s^?1 at pHll. The difference in the dependence of diffusion coefficients on pH between Cs⁺ and Na⁺ was interpreted in terms of strength of interaction between counterions and ion-exchange sites since hydrous niobium(V) oxide has selectivity higher for Cs⁺ than for Na⁺.     

Molecular transport characteristics of a chlorosulfonated polyethylene geomembrane in the presence of aromatic esters

Results of a study on sorption and diffusion of chlorosulfonated polyethylene geomembrane with methyl benzoate, ethyl benzoate, methyl salicylate, iso-butyl salicylate, phenyl acetate, and diethyl phthalate in the temperature range 25–60°C are presented. A gravimetric sorption method is used to calculate the diffusion and permeation coefficients from the Fickian relationship. The diffusion results are dependent on penetrant–membrane interactions, temperature, and on penetrant concentration. The values of diffusion coefficients range from 0·02 × 10^?7 cm² s^?1 for diethyl phthalate at 25°C to 1·81 × 10^?7 cm² s^?1 for ethyl benzoate at 60°C. The activation energies for diffusion range from 21 to 50 kJ mol^?1. The values of heat of sorption ranged between 2·2 and 6·4 kJ mol^?1. Sorption results are also analyzed using a first-order sorption kinetic equation. Experimental results and calculated parameters are used to discuss the transport behavior. None of the esters used have shown any chemical attack toward the geomembrane.     

Sorption of caesium by complex hexacyanoferrates iv. ion exchange kinetics and mechanism of sorption by potassium copper ferrocyanide

The kinetics of caesium sorption by potassium copper ferrocyanide have been studied. Liquid film diffusion is rate controlling in very dilute solutions of caesium (3.8 × 10^?6m). The average film diffusion coefficient was found to be 1.465 × 10^?9 m² s^?1 at 20°C and the activation energy for the corresponding process was found to be 15.14 kJ mol^?1. Chemical reaction rate controls the caesium-potassium ion exchange process at a higher caesium concentration of 3.8 × 10^?3m. The shell progressive reaction model was found applicable to the sorption process. The activation energy for the caesium-potassium ion exchange reaction was measured to be 74.85 kJ mol^?1. Finally, a comparison between the theoretical and the experimental sorption profile has been made to demonstrate the validity of the theory.     

Hydride Transfer: A Dominating Reaction of Ozone with Tertiary Butanol and Formate Ion in Aqueous Solution

This article provides evidences that hydride transfer is an important primary step in ozone reactions of formate and tertiary butanol in aqueous media. In both systems, one argument is the fact that the free hydroxyl radical yields are relative low ((40 ± 4)% and (7 ± 0.8)% for formate and tertiary butanol, respectively). Another hint is the high exergonicity of these reactions: ΔG = –249 kJ mol^?1 for formate/ozone system and ΔG = –114 kJ mol^?1 for hydride transfer followed by a methyl shift in the reaction between tertiary butanol and ozone. In addition, the main product of tertiary butanol ozonolysis is butan-2-one [(89 ± 3)%], a compound that is formed only via hydride transfer. For the reaction of ozone with formate an activation energy of (54.6 ± 1.2) kJ mol^?1 and a pre-exponential term of (2.5 ± 1.2) × 10¹¹ were determined (in the presence of tertiary butanol as ^?OH scavenger) whereas for tertiary butanol the two activation parameters were (68.7 ± 1.9) kJ mol^?1 and (2.0 ± 1.5) × 10⁹, respectively.     

Kinetics of Estrone Ozone/Hydrogen Peroxide Advanced Oxidation Treatment

Ozone/hydrogen peroxide batch treatment was utilized to study the degradation of the steroidal hormone estrone (E1). The competition kinetics method was used to determine the rate constants of reaction for direct ozone and E1, and for hydroxyl radicals and E1 at three pH levels (4, 7, and 8.5), three different molar O₃/H₂O₂ ratios (1:2, 2:1, and 4:1) and a temperature about 20°C. The average second-order rate constants for direct ozone-E1 reaction were determined as 6.2?×?10³?±?3.2?×?10³ M^?1s^?1, 9.4?×?10⁵?±?2.7?×?10⁵ M^?1s^?1, and 2.1?×?10⁷?±?3.1?×?10⁶ M^?1s^?1 at pH 4, 7, and 8.5, respectively. It was found that pH had the greatest influence on the reaction rate, whereas O₃/H₂O₂ ratio was found to be slightly statistically significant. For the hydroxyl radical-E1 reaction, apparent rate constants ranged from 1.1?×?10¹⁰ M^?1s^?1 to 7.0?×?10¹⁰ M^?1s^?1 with an average value of 2.6?×?10¹⁰ M^?1s^?1. Overall, O₃/H₂O₂ is shown to be an effective treatment for E1.     

Effect of particle size on thermal decomposition and devolatilization kinetics of melon seed shell

Thermogravimetric analysis (TGA) and devolatilization kinetics of melon seed shell (MSS) at different particle sizes (150?µm and 500?µm) and at different heating rates (10, 15, 20, and 25?°C/min) were investigated with the aid of TGA. The results of the TGA analysis show that the TGA curves corresponding to the first and third stages for 150?µm particle sizes exhibited some bumps that developed at the first and third stages of pyrolysis. It was also observed that at constant heating rate, the maximum peak temperature increases as the particle sizes increase from 150 to 500?µm, whereas 500?µm particle sizes exhibited higher peak temperatures compared to 150?µm particle sizes. The resulting TGA data were applied to the Kissinger (K), Kissinger–Akahira–Sunose (KAS) and Flynn–Wall–Ozawa (FWO) methods and kinetic parameters (activation energy, E and frequency factor, A) were determined. The E and A obtained using K method were 74.27?kJ mol^?1 and 3.84?×?10⁵?min^?1 for 150?µm particle size, whereas for 500?µm particle size were 97.12?kJ mol^?1 and 3.74?×?10⁷?min^?1, respectively. However, the average E and A obtained using KAS and FWO methods were 82.35?kJ mol^?1, 1.29?×?10⁷?min^?1, and 88.50?kJ mol^?1, 1.32?×?10⁷?min^?1 for 150?µm particle sizes. While for 500?µm particle sizes, the E and A were 108.46?kJ mol^?1, 3.14?×?10⁹?min^?1, and 113.05?kJ mol^?1, 7.56?×?10⁹?min^?1, respectively. It was observed that E and A calculated from FWO and KAS methods were very close and higher than that obtained by K method. It was observed that the minimum heat required for the cracking of MSS particles into products is reached later at higher peak temperatures since the heat transfer is less effective as they are at lower peak temperatures.     

Heavy Metal Removal and Neutralization of Acid Mine Waste Water ‐ Kinetic Study

The influence of the apatite on the efficiency of neutralization and on heavy metal removal of acid mine waste water has been studied. The analysis of the treated waste water samples with apatite has shown an advanced purification, the concentration of the heavy metals after the treatment of the waste water with apatite being 25 to 1000 times less than the Maximum Concentration Limits admitted by European Norms (NTPA 001/2005). In order to establish the macro‐kinetic mechanism in the neutralization process, the activation energy, Ea, and the kinetic parameters, rate coefficient of reaction, k_r, and k_t were determined from the experimental results obtained in “ceramic ball‐mill” reactor. The obtained values of the activation energy Ea >> 42 kJ mol^?1 (e.g. Ea = 115.50 ± 7.50 kJ mol^?1 for a conversion of sulphuric acid η_H2SO4 = 0.05, Ea = 60.90 ± 9.50 kJ mol^?1 for η ^H2SO4 = 0.10 and Ea = 55.75 ± 10.45 kJ mol^‐1 for η ^H2SO4 = 0.15) suggest that up to a conversion of H2SO4 equal 0.15 the global process is controlled by the transformation process, adsorption followed by reaction, which means surface‐controlled reactions. At a conversion of sulphuric acid η ^H2SO4 > 0.15, the obtained values of activation energy Ea < 42 kJ mol^‐1 (e.g. Ea = 37.55 ± 4.05 kJ mol^‐1 for η ^H2SO4 = 0.2, Ea = 37.54 ± 2.54 kJ mol^‐1 for η ^H2SO4 = 0.3 and Ea = 37.44 ± 2.90 kJ mol^‐1 for η ^H2SO4 = 0.4) indicate diffusion‐controlled processes. This means a combined process model, which involves the transfer in the liquid phase followed by the chemical reaction at the surface of the solid. Kinetic parameters as rate coefficient of reaction, kr with values ranging from (5.02 ± 1.62) 10‐4 to (8.00 ± 1.55) 10‐4 (s^‐1) and transfer coefficient, kt, ranging from (8.40 ± 0.50) 10‐5 to (10.42 ± 0.65) 10‐5 (m s^‐1) were determined.     

Effect of Temperature on Kinetics and Adsorption Profile of Endothermic Chemisorption Process: –Tm(III)–PAN Loaded PUF System

Abstract

The sorption behavior of 3.18×10^?6 mol l^?1 solution of Tm(III) metal ions onto 7.25 mg l^?1 of 1‐(2‐pyridylazo)‐2‐naphthol (PAN) loaded polyurethane foam (PUF) has been investigated at different temperatures i.e. 303 K, 313 K, and 323 K. The maximum equilibration time of sorption was 30 minutes from pH 7.5 buffer solution at all temperatures. The various rate parameters of adsorption process have been investigated. The diffusional activation energy (ΔE_ads) and activation entropy (ΔS_ads) of the system were found to be 22.1±2.6 kJ mol^?1 and 52.7±6.2 J mol^?1 K^?1, respectively. The thermodynamic parameters such as enthalpy (ΔH), entropy (ΔS), and Gibbs free energy (ΔG) were calculated and interpreted. The positive value of ΔH and negative value of ΔG indicate that sorption is endothermic and spontaneous in nature, respectively. The adsorption isotherms such as Freundlich, Langmuir, and Dubinin–Radushkevich isotherm were tested experimentally at different temperatures. The changes in adsorption isotherm constants were discussed. The binding energy constant (b) of Langmuir isotherm increases with temperature. The differential heat of adsorption (ΔH_diff), entropy of adsorption (ΔS_diff) and adsorption free energy (ΔG_ads) at 313 K were determined and found to be 38±2 kJ mol^?1, 249±3 J mol^?1 K^?1 and –40.1±1.1 kJ mol^?1, respectively. The stability of sorbed complex and mechanism involved in adsorption process has been discussed using different thermodynamic parameters and sorption free energy.     

Kinetic study of anionic polymerization of butadiene in a polar solvent

The kinetics of the propagation reaction for the polymerization of butadiene initiated by cumyl potassium in tetrahydrofuran solution at several temperatures have been studied. Kinetic data and electrolytic behaviour indicate that polybutadienyl free ions assume the whole of the propagation reaction. At 0°C, the respective rate constants for ion-pairs and free ions are 1 l mol^?1 s^?1 and 4.8 × 10⁴ l mol^?1 s^?1 respectively. The ionic dissociation constant is 7.8 × 10^?9 mol/l. The activation energy of the propagation reaction for free ions is 6.5 kcal/mol.     

Interpreting the Activated Rate Theory for Solid-Phase Crystallization: Comparing Lactose and Sucrose

The activated rate theory (ART) for solid-phase crystallization has been interpreted to assess its key features with previous data for spray-dried lactose and new data for spray-dried sucrose. The theory implies that the kinetic parameters for the two sugars should be different due to the differences in their structural configurations. The activation enthalpy for solid-phase crystal growth has been found to be 39 ± 2 kJ/mol for lactose and 68 ± 4 kJ/mol for sucrose. These activation enthalpies are close to the values for liquid-phase crystallization (40 kJ mol^?1 for lactose; 66–75 kJ mol^?1 for sucrose) from previous literature, suggesting that the theory might apply to both liquid- and solid-phase crystallization. There are also physical arguments for suggesting that the activated state in the new theory has features of both solid- and liquid-phase crystallization. For lactose and sucrose, the crystal growth rate constants at 25°C have been found to be 1.4 × 10^?4 s^?1and 2.5 × 10^?5 s^?1, respectively, similar to the literature values of 1.3 × 10^?4 s^?1and 3 × 10^?5 s^?1, respectively. The difference in the thermodynamic parameters between the two sugars has been found to be significant, as expected from the differences in their structures. Interpreting the sucrose data in terms of the Williams-Landel-Ferry equation and the Avrami equation has shown their limitations and inconsistencies for the new sucrose data, as found previously for lactose. Key features of the ART are highlighted and discussed. These features include minimum activation enthalpies and maximum activation entropies at particular moisture contents for each sugar and minimum and maximum moisture contents below which crystallization is predicted to occur very slowly.     

Kinetics of phenylurea herbicides oxidation by Fenton and photo‐Fenton processes

The chemical oxidation of four selected phenylurea herbicides (linuron, chlortoluron, diuron, and isoproturon) was studied by means of the Fenton system. The influence of the initial concentrations of hydrogen peroxide and ferrous ions, the pH and the type of buffer (perchloric acid/perchlorate, acetic acid/acetate, or phosphoric acid/phosphate) was established according to the degradation levels obtained. In the kinetic study, the general decomposition reaction was divided into two stages with different reaction rates, which was justified by considering the whole reaction mechanism for this system. In this kinetic study, a competition kinetics model, which used p‐chlorobenzoic acid as a reference compound, was applied for the evaluation of the rate constants for each reaction between the herbicides and the hydroxyl radical. The proposed values for these rate constants are: 7.5 × 10⁹ L mol^?1 s^?1 for chlortoluron, 5.6 × 10⁹ L mol^?1 s^?1 for linuron, 7.1 × 10⁹ L mol^?1 s^?1 for diuron and 5.7 × 10⁹ L mol^?1 s^?1 for isoproturon. Finally, some experiments with the photo‐Fenton system reveal increases in the decomposition levels of the herbicides, due to additional generation reactions of hydroxyl radicals. Copyright © 2007 Society of Chemical Industry     

Treatment of dyehouse waste‐water by supercritical water oxidation: a case study

BACKGROUND: Supercritical water oxidation (SCWO) of dyehouse waste‐water containing several organic pollutants has been studied. The removal of these organic components with unknown proportions is considered in terms of total organic carbon concentration (TOC), with an initial value of 856.9 mg L^?1. Oxidation reactions were performed using diluted hydrogen peroxide. The reaction conditions ranged between temperatures of 400–600 °C and residence times of 8–16 s under 25 MPa of pressure. RESULTS: TOC removal efficiencies using SCWO and hydrothermal decomposition were between 92.0 and 100% and 6.6 and 93.8%, respectively. An overall reaction rate, which consists of hydrothermal decomposition and the oxidation reaction, was determined for the hydrothermal decomposition of the waste‐water with an activation energy of 104.12 ( ± 2.6) kJ mol^?1 and a pre‐exponential factor of 1.59( ± 0.5) × 10⁵ s^?1. The oxidation reaction rate orders for the TOC and the oxidant were 1.169 ( ± 0.3) and 0.075 ( ± 0.04) with activation energies of 18.194 ( ± 1.09) kJ mol^?1, and pre‐exponential factor of 5.181 ( ± 1.3) L^0.244 mmol^?0.244 s^?1 at the 95% confidence level. CONCLUSION: Results demonstrate that the SCWO process decreased TOC content by up to 100% in residence times between 8 and 16 s under various reaction conditions. The treatment efficiency increased remarkably with increasing temperature and the presence of excess oxygen in the reaction medium. Color of the waste‐water was removed completely at temperatures of 450 °C and above. Copyright © 2010 Society of Chemical Industry     

ELECTRO-DEIONIZATION OF Cr (VI)-CONTAINING SOLUTION. PART II: CHROMIUM TRANSPORT THROUGH INORGANIC ION-EXCHANGER AND COMPOSITE CERAMIC MEMBRANE

Cr (VI) transport through a composite ceramic membrane containing an ion-exchange component, namely xerogel of hydrated zirconium dioxide, was investigated. The diffusion coefficient of Cr (VI) species through the membrane, which has been determined under open circuit conditions, is 1.80 × 10^?10 m² s^?1. The transport number of Cr (VI) species through the ceramic membrane was found to rise with increasing voltage and reached 0.17 under “over-limiting current” conditions. On the other hand, the transport of chromate ions through hydrogel of hydrated zirconium dioxide becomes more intensive with a decrease in potential drop through the system involving ion-exchanger bed and ceramic membrane due to decrease in the membrane resistance. The diffusion coefficient of Cr (VI) ions in hydrogel of the inorganic ion exchanger was estimated as 4.36 × 10^?12 m² s^?1. A possibility of Cr (VI) removal from a weakly acidic diluted solution using an electro-deionization method was shown: the degree of solution purification was found to reach 50%. The transport of species is realized through both the solution and the ion exchanger.