Fast catalytic degradation of organic dye with air and MoO3:Ce nanofibers under room condition

One-dimensional Ce doped MoO₃ nanofibers with different Ce doping amount have been synthesized by a combination method of sol–gel process and electrospinning technique. X-ray diffraction (XRD), X-ray photoelectron spectrum (XPS), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) were used to characterize the resulting samples. These fibers are interesting for a number of catalytic applications. The best catalytic activity was obtained over 11.86 wt.% CeO₂-doped MoO₃ with 98% degradation effect of 0.3 g L⁻¹ Safranin-T by air under room condition towards complete degradation products such as HCO₃⁻ and NO₃⁻ within 20 min. The leaching test showed that this MoO₃:Ce nanofiber catalyst has an excellent stability and can be used as a rapid heterogeneous catalyst for about ten times by simply treatment.     

Highly stable Fe/γ‐Al2O3 catalyst for catalytic wet peroxide oxidation

BACKGROUND: A highly stable Fe/γ‐Al₂O₃ catalyst for catalytic wet peroxide oxidation has been studied using phenol as target pollutant. The catalyst was prepared by incipient wetness impregnation of γ‐Al₂O₃ with an aqueous solution of Fe(NO₃)₃· 9H₂O. The influence of pH, temperature, catalyst and H₂O₂ doses, as well as the initial phenol concentration has been analyzed. RESULTS: The reaction temperature and initial pH significantly affect both phenol conversion and total organic carbon removal. Working at 50 °C, an initial pH of 3, 100 mg L^?1 of phenol, a dose of H₂O₂ corresponding to the stoichiometric amount and 1250 mg L^?1 of catalyst, complete phenol conversion and a total organic carbon removal efficiency close to 80% were achieved. When the initial phenol concentration was increased to 1500 mg L^?1, a decreased efficiency in total organic carbon removal was observed with increased leaching of iron that can be related to a higher concentration of oxalic acid, as by‐product from catalytic wet peroxide oxidation of phenol. CONCLUSION: A laboratory synthesized γ‐Al₂O₃ supported Fe has shown potential application in catalytic wet peroxide oxidation of phenolic wastewaters. The catalyst showed remarkable stability in long‐term continuous experiments with limited Fe leaching, < 3% of the initial loading. Copyright © 2010 Society of Chemical Industry     

Effect of composition and promoters in Au/TS-1 catalysts for direct propylene epoxidation using H2 and O2

A series of Au/titanium silicalite-1 (TS-1) catalysts with different Si/Ti ratios and promoted with alkali and alkaline earth cations were prepared by deposition–precipitation (DP) and tested for direct propylene epoxidation. It was found that the gold loading and catalytic activity was highly dependent on the pH of the DP synthesis solution and the final composition of the catalyst. Addition of Group 1 metals such as K or Cs had little effect on the gold content, but increased activity, while Group 2 metals such as Mg, Ca, Sr, and Ba increased both the gold content and the catalytic activity. The highest improvement was provided by a Mg promoted catalyst, which at 443 K and 0.1 MPa with a H₂/O₂/C₃H₆/Ar = 1/1/1/7 feed mixture gave a propylene oxide (PO) formation rate of 88 gPO h⁻¹ kg_cat⁻¹, compared to 57 gPO h⁻¹ kg_cat⁻¹ for an unpromoted catalyst, corresponding to a 50% enhancement of activity. Ammonia temperature-programmed desorption (NH₃-TPD) measurements indicated little change in adsorption amount with promotion indicating that the yield increase was not due to the elimination of acidic sites on the catalyst. Instead, the improved catalytic performance was ascribed to increased Au capture efficiency and dispersion by the catalyst. The effect of Si/Ti ratio, pH of synthesis, and the promoter ions on the gold content could be understood from their effect on the surface charge of the support.     

Development of Fe2O3-CeO2-TiO2/γ-Al2O3 as catalyst for catalytic wet air oxidation of methyl orange azo dye under room condition

In order to develop a catalyst with high activity and stability for catalytic wet air oxidation (CWAO) process at room temperature and atmospheric pressure, we prepared Fe₂O₃-CeO₂-TiO₂/γ-Al₂O₃ by consecutive impregnation, and determined its properties using BET, SEM, XRF, XPS and chemical analysis techniques. The degradation of an azo dye, methyl orange, in CWAO process with Fe₂O₃-CeO₂-TiO₂/γ-Al₂O₃ used as catalyst at room temperature and atmospheric pressure was also investigated, and the results show that the catalyst has an excellent catalytic activity in treating synthetic wastewater containing 500 mg/L methyl orange, and 98.09% of color and 96.08% of total organic carbon (TOC) can be removed in 2.5 h. The degradation pathway of methyl orange was analyzed by UV–vis and FT-IR spectra. The result of leaching tests shows the catalyst has an excellent stability with negligible leaching ions, and the leaching of Ce is effectively controlled by adding Ti, because Ce and Ti in the catalyst take the form of compound oxides, and the deactivation of the catalyst in successive runs is caused by the adsorption of intermediates on the surface and coverage of the active sites. The catalytic activity of the deactivated catalyst can be generally restored by rinsing it in hydrochloric acid followed by calcination.     

Decatungstate catalyst supported on silica and γ-alumina: Efficient photocatalytic oxidation of benzyl alcohols

Four supported catalysts with the same tungsten loading were prepared by depositing decatungstate species W₁₀O⁴⁻₃₂, through wet impregnation, on the surface of γ-alumina and silica at different pH values. The prepared samples were characterized using BET measurements as well as XRD, UV–vis DR, and XP spectroscopies. Higher dispersion of W(VI) oxo-species was obtained in the silica-supported catalysts compared with the corresponding alumina-supported ones. Within the same support, the dispersion was higher when the impregnation pH is lower than the point of zero charge (pzc) of the support. The decatungstate anions were present mainly on the silica surface without any modification, whereas these underwent a partial depolymerization on their deposition on the γ-alumina surface. The extent of depolymerization was less in the sample prepared at pH above pzc. These findings were explained in terms of the mode of deposition of the W(VI) species from the solution onto the support surface. The photocatalytic activity of the aforementioned catalysts, concerning the photooxidation of 1-phenylethanol, depends on the fraction of the W₁₀O⁴⁻₃₂ supported species rather than on the W(VI) dispersion. Thus, extremely high conversions have been obtained over the silica-based catalysts and also over the γ-alumina-based catalyst prepared at relatively high pH. These catalysts also are very effective in the photooxidation of a series of secondary and primary benzyl alcohols, in which benzyl ketones and benzoic acids were formed as the only or major products, respectively. The easy separation of the solid catalyst from the reaction mixture, the high activity, selectivity, and stability as well as the retained activity in subsequent catalytic cycles, make these supported catalysts suitable for a small-scale synthesis. Based on product analysis and kinetic data on the heterogeneous oxidation of benzyl alcohols, we suggest that a hydrogen abstraction transfer (HAT) mechanism predominates with respect to an electron transfer (ET) one in these reactions.     

Catalytic combustion of trichloroethene over Ru/Al2O3: Reaction mechanism and kinetic study

The performance of 0.5% Ru/Al₂O₃ for the deep oxidation of trichloroethene (1000–2500 ppmV, WHSV = 55 h⁻¹) in air was studied in this work. Experiments were carried out both at dry and wet (20,000 ppmV of H₂O) conditions. Catalytic performance was studied in terms of activity and selectivity for the different reaction products (CO₂, HCl, Cl₂, C₂Cl₄, CCl₄ and CHCl₃). Both the activity and the selectivity for total combustion are higher than other catalysts suggested in the literature for this process (especially Pd and Pt).The main organic by-products are CCl₄ and CHCl₃, whereas in all the other catalysts tested in the literature, tetrachloroethene is the main organic by-product. This fact suggests that the mechanism of the combustion reaction, involving a double-bond scission, is essentially specific for this catalyst.Kinetic data was fit to a pseudo-first order kinetic expression, providing fairly good fit.     

Selective epoxidation of styrene with air catalyzed by CoOx and CoOx/SiO2 without any reductant

Cobalt oxide (CoOx) prepared by a direct calcination of cobalt nitrate was considerably active for the epoxidation of styrene with air in DMF under mild conditions. A substrate conversion of 75.8 mol% with an epoxide selectivity of 82.1% was achieved at 353 K over 10 mg of cobalt oxide catalyst. Once CoOx was loaded on the support SiO₂ through a simple procedure consisting of wet impregnation, drying and calcination, the as-prepared catalyst presented higher catalytic activity and epoxide selectivity than cobalt oxide itself. Over the optimized catalyst CoOx/SiO₂ (1.0 wt% Co), 85.7 mol% of styrene was effectively converted at 363 K within 4 h, with a high epoxide selectivity up to 86.0%. The results showed that many factors influenced the performance of the catalyst, such as the Co loading, the support, the temperature and the atmosphere, etc. The leaching of cobalt from the catalyst CoOx/SiO₂ was negligible, indicating the applicability of the catalyst CoOx/SiO₂ as a true heterogeneous catalyst. The control test and UV–vis spectra revealed a synergic interaction among solvent, oxygen and substrate over CoOx/SiO₂.     

Direct formation of H2O2 from H2 and O2 and decomposition/hydrogenation of H2O2 in aqueous acidic reaction medium over halide-containing Pd/SiO2 catalytic system

Formation of H₂O₂ from H₂ and O₂ and decomposition/hydrogenation of H₂O₂ have been studied in aqueous acidic medium over Pd/SiO₂ catalyst in presence of different halide ions (viz. F⁻, Cl⁻ and Br⁻). The halide ions were introduced in the catalytic system via incorporating them in the catalyst or by adding into the reaction medium. The nature of the halide ions present in the catalytic system showed profound influence on the H₂O₂ formation selectivity in the H₂ to H₂O₂ oxidation over the catalyst. The H₂O₂ destruction via catalytic decomposition and by hydrogenation (in presence of hydrogen) was also found to be strongly dependent upon the nature of the halide ions present in the catalytic system. Among the different halides, Br⁻ was found to selectivity promote the conversion of H₂ to H₂O₂ by significantly reducing the H₂O₂ decomposition and hydrogenation over the catalyst. The other halides, on the other hand, showed a negative influence on the H₂O₂ formation by promoting the H₂ combustion to water and/or by increasing the rate of decomposition/hydrogenation of H₂O₂ over the catalyst. An optimum concentration of Br⁻ ions in the reaction medium or in the catalyst was found to be crucial for obtaining the higher H₂O₂ yield in the direct synthesis.     

Kinetics of the catalytic destruction of cyanogen chloride

The catalytic destruction of cyanogen chloride (CNCI) in air has been investigated in a fixed-bed microreactor using a 2.15% Pt/α-alumina catalyst. If the feed stream contains water vapor, CNCl conversion as high as 98% can be achieved at 375°C and 170 000 cm³ h⁻¹ g⁻¹ space velocity. In contrast, the CNCl conversion in a dry inlet gas stream is 20% at 440°C and 46 000 cm³ h⁻¹ g⁻¹ space velocity. Water vapor in the feed stream significantly enhances the conversion of CNCl by providing an alternate hydrolysis pathway for destruction. It also promotes the complete conversion of CNCl to CO₂ and HCl with negligible selectivity to CO and Cl₂. The CNCl conversion decreases with increasing concentration in the feed stream. A kinetic model of the form r = kC_a/1(1 + K_pC_p) adequately represents the data in the presence of water vapor.     

Co/CeO2-ZrO2 catalysts prepared by impregnation and coprecipitation for ethanol steam reforming

Co/CeO₂-ZrO₂ catalysts for the ethanol steam reforming were prepared by wet incipient impregnation and coprecipitation methods. These catalysts were characterized by nitrogen adsorption, TEM-EDX, XRD, H₂-TPR, and CO chemisorption techniques. It was found that the catalyst reducibility was influenced by the preparation methods; catalysts with different reduction behaviors in the pre-reduction showed different catalytic activities toward hydrogen production. The H₂-TPR studies suggested the presence of metal–support interactions in Co/CeO₂-ZrO₂ catalysts during their hydrogen pre-reduction, a necessary treatment process for catalysts activation. These interactions were influenced by the preparation methods, and the impregnation method is a favorable method to induce a proper metal–support effect that allows only partial reduction of the cobalt species and leads to a superior catalytic activity for the hydrogen production through ethanol steam reforming. At 450 °C, the impregnated catalyst gives a hydrogen production rate of 147.3 mmol/g-s at a WHSV of 6.3 h⁻¹ (ethanol) and a steam-to-carbon ratio of 6.5.     

Effect of sintering on the catalytic activity of a Pt based catalyst for CO oxidation: Experiments and modeling

The goal of this paper was to make the link between sintering of a 1.6% Pt/Al₂O₃ catalyst and its activity for CO oxidation reaction. Thermal aging of this catalyst for different durations ranging from 15 min to 16 h, at 600 and 700 °C, under 7% O₂, led to a shift of the platinum particle size distributions towards larger diameters, due to sintering. These distributions were studied by transmission electron microscopy. The number and the surface average diameters of platinum particles increase from 1.3 to 8.9 nm and 2.1 to 12.8 nm, respectively, after 16 h aging at 600 °C. The catalytic activity for CO oxidation under different CO and O₂ inlet concentrations decreases after aging the catalyst. The light-off temperature increased by 48 °C when the catalyst was aged for 16 h at 600 °C. The CO oxidation reaction is structure sensitive with a catalytic activity increasing with the platinum particle size. To account for this size effect, two intrinsic kinetic constants, related either to platinum atoms on planar faces or atoms on edges and corners were defined. A platinum site located on a planar face was found to be 2.5 more active than a platinum site on edges or corners, whatever the temperature. The global kinetic law {r (mol m⁻² s⁻¹) = 103 × exp(−64,500/RT)[O₂]^0.74[CO]^−0.5)} related to a reaction occurring on a platinum atom located on planar faces allows a simulation of the CO conversion curves during a temperature ramp. Modeling of the catalytic CO conversion during a temperature ramp, using the different aged catalysts, allows prediction of the CO conversion curves over a wide range of experimental conditions.     

Synthesis of a highly active carbon-supported Ir–V/C catalyst for the hydrogen oxidation reaction in PEMFC

The active, carbon-supported Ir and Ir–V nanoclusters with well-controlled particle size, dispersity, and composition uniformity, have been synthesized via an ethylene glycol method using IrCl₃ and NH₄VO₃ as the Ir and V precursors. The nanostructured catalysts were characterized by X-ray diffraction and high-resolution transmission electron microscopy. The catalytic activities of these carbon-supported nanoclusters were screened by applying on-line cyclic voltammetry and electrochemical impedance spectroscopy techniques, which were used to characterize the electrochemical properties of fuel cells using several anode Ir/C and Ir–V/C catalysts. It was found that Ir/C and Ir–V/C catalysts affect the performance of electrocatalysts significantly based on the discharge characteristics of the fuel cell. The catalyst Ir–V/C at 40 wt.% displayed the highest catalytic activity to hydrogen oxidation reaction and, therefore, high cell performance is achieved which results in a maximum power density of 563 mW cm⁻² at 0.512 V and 70 °C in a real H₂/air fuel cell. This performance is 20% higher as compared to the commercial available Pt/C catalyst. Fuel cell life test at a constant current density of 1000 mA cm⁻² in a H₂/O₂ condition shows good stability of anode Ir–V/C after 100 h of continuous operation.     

Sulphide-induced deactivation of Pd/Al2O3 as hydrodechlorination catalyst and its oxidative regeneration with permanganate

Pd-based catalysts have become important in environmental catalysis for their ability to hydrodechlorinate a wide range of chlorinated organic contaminants in water under ambient conditions. The success of their application in the remediation practice, e.g. for groundwater treatment, is often hindered by the sensitivity of Pd to poisoning by sulphur compounds. In this study, the stability and sulphide-induced deactivation behaviour of a highly active Pd/Al₂O₃ catalyst was investigated. The specific activity of Pd for the hydrodechlorination of chlorobenzene corresponds to rate coefficients up to k_Pd = 350 L g⁻¹ min⁻¹. The totally deactivated catalyst, resultant of sulphide poisoning, was regenerated with potassium permanganate. The pH value, as a key parameter which may influence the degree of deactivation as well as the efficiency of catalyst regeneration, was evaluated. Results show that in clean water the Pd/Al₂O₃ catalyst showed no inherent deactivation regardless of the ageing time and the pH value of the catalyst suspension. The degree of catalyst poisoning effected by 1.8–5.4 μM sulphide, corresponding to molar ratios of S:Pd_surface = 1.5–8.5, was observed to be higher under neutral and alkaline than under acidic conditions. The exposure of the catalyst to higher sulphide concentration of 14.2 μM resulted in complete catalyst deactivation regardless of the pH conditions. However, the efficacy of permanganate as oxidative regenerant for the fouled catalyst showed strong pH-dependence. A regeneration time of 10–30 min at low pH was sufficient to recover completely the high catalytic activity of Pd/Al₂O₃ for the hydrodechlorination reaction.     

Gold catalysts supported on titanium oxide for catalytic wet air oxidation of succinic acid

Catalytic wet air oxidation of a representative organic compound (aqueous solution of 5 g l⁻¹ succinic acid at 190 °C and 50 bar total air pressure) was investigated over gold on titania prepared from the deposition–precipitation method (with urea or NaOH) and compared to experiments performed over a Ru/TiO₂ catalyst. These preliminary results demonstrate that gold catalysts are efficient for the degradation of this organic acid. The catalytic activity is strongly dependent on the gold particle size characterized by transmission electron microscopy (TEM) with smaller particles producing higher turnover frequencies. Modification of metal dispersion occurs during reaction, leading to minor activity.     

新型高性能Ziegler-Natta催化剂用于乙烯淤浆聚合

A novel high performance MgCl2/TiCl4 catalyst with tetrabutyloxsilicane as electron donor was prepared for ethylene slurry polymerization process. The properties of the catalyst such as particle size distribution, catalytic activity, hydrogen responsibility and copolymerization performance were investigated and compared with commercial catalyst (imported catalyst). Copolymerization of ethylene and 1-butylene using the catalyst was stud-ied in a pilot plant. The composition, structure and property of the copolymer were characterized by 13C nuclear magnetic resonance (13C NMR) and gel permeation chromatography-Infrared (GPC-IR), and compared with those of the copolymer obtained from a commercial catalyst. In comparison with the commercial catalyst, the novel cata-lyst had a higher activity (up to 34.6 kg&#8226;g－1) and a better particle size distribution (PSD), and produced polymers having higher bulk density (up to 0.37 g&#8226;cm－3) with less fine resin. Meanwhile, the novel catalyst showed a higher hydrogen responsibility and better copolymerization performance. The results indicated that the copolymer obtained from the novel catalyst has a higher branch in the high molecular weight fraction and lower branch in the low mo-lecular weight fraction.     

Effect of sulphur poisoning on perovskite catalysts prepared by flame-pyrolysis

ABO₃ perovskite-like catalysts are known to be sensitive to sulphur-containing compounds. Possible solutions to increase resistance to sulphur are represented by either catalyst bed protection with basic guards or catalyst doping with different transition or noble metals. In the present work La_(1−x)A^′_xCoO₃, La_(1−x)A^′_xMnO₃ and La_(1−x)A^′_xFeO₃, with A′ = Ce, Sr and x = 0, 0.1, 0.2, either pure or doped with noble metals (0.5 wt% Pt or Pd), were prepared in nano-powder form by flame-pyrolysis. All the catalysts were tested for the catalytic flameless combustion of methane, monitoring the activity by on-line mass spectrometry. The catalysts were then progressively deactivated in operando with a new procedure, consisting of repeated injection of some doses of tetrahydrothiophene (THT), usually employed as odorant in the natural gas grid, with continuous analysis of the transient response of the catalyst. The activity tests were then repeated on the poisoned catalyst. Different regenerative treatments were also tried, either in oxidising or reducing atmosphere.Among the unsubstituted samples, higher activity and better resistance to poisoning have been observed in general with manganites with respect to the corresponding formulations containing Co or Fe at the B-site. The worst catalyst showed LaFeO₃, from both the points of view of activity and of resistance to sulphur poisoning. La_0.9Sr_0.1MnO₃ showed, the best results, exhibiting very high activity and good resistance even after the addition of up to 8.4 mg of THT/g of catalyst. Interesting results were attained also by adding Sr to Co-based perovskites. Sr showed a first action by forcing Mn or Co in their highest oxidation state, but, in addition, it could also act as a sulphur guard, likely forming stable sulphates due to its basicity. Among noble metals, Pt doping proved beneficial in improving the activity of both the fresh and the poisoned catalyst.     

Deep desulphurization of diesel fuels on bifunctional monolithic nanostructured Pt-zeolite catalysts

The preparation of Pt-zeolite catalysts, including choice of the noble metal precursor and loading (1.0–1.8 wt.%), was optimized for maximizing the catalytic activity in thiophene hydrodesulphurization (HDS) and benzene hydrogenation (HYD). According to data obtained by HRTEM, XPS, EXAFS and FTIR spectroscopy of adsorbed CO, the catalysts contained finely dispersed Pt nanoparticles (2–5 nm) located on montmorillonite and zeolite surfaces as: Pt⁰ (main, ν_CO = 2070–2095 cm⁻¹), Pt^δ+ (ν_CO = 2128 cm⁻¹) and Pt²⁺ (ν_CO = 2149–2155 cm⁻¹). It was shown that the state of Pt depended on the Si/Al zeolite ratio, montmorillonite presence and Pt precursor. The use of H₂PtCl₆ as the precursor (impregnation) promoted stabilization of an oxidized Pt state, most likely Pt(OH)_xCl_y. When Pt(NH₃)₄Cl₂ (ion-exchange) was used, the Pt⁰ and hydroxo- or oxy-complexes Pt(OH)₆²⁻ or PtO₂ were formed. The addition of the Ca-montmorillonite favoured stabilization of Pt^+δ. The Cl⁻ ions inhibit reduction of oxidized Pt state to Pt particles. The Pt-zeolite catalyst demonstrated high efficiency in ultra-deep desulphurization of DLCO. The good catalyst performance in hydrogenation activity and sulphur resistance can be explained by the favourable pore space architecture and the location and the state of the Pt clusters. The bimodal texture of the developed zeolite substrates allows realizing a concept for design of sulphur-resistant noble metal hydrotreating catalyst proposed by Song [C. Song, Shape-Selective Catalysis, Chemicals Synthesis and Hydrocarbon Processing (ACS Symposium Series 738), Washington, 1999, p. 381; Chemtech 29(3) (1999) 26].     

Decomposition of ozone on Ag/SiO2 catalyst for abatement of waste gases emissions

A silica-supported Ag system made by the incipient wetness impregnation method was investigated in the reaction of heterogeneous catalytic decomposition of ozone. It was established that the catalytic ozone decomposition on Ag/SiO₂ proceeded in the temperature interval −40 °C to 25 °C as a first order reaction with activation energy of 65 kJ/mol (pre-exponential factor 5.0 × 10¹⁴ s⁻¹). Based on the results from the instrumental methods (SEM, XRD, XPS, EPR, TPD) it can be concluded that in presence of ozone the silver is oxidized to a complicated mixture of Ag₂O₃ and AgO. Due to the high activity and stability of the Ag/SiO₂ catalyst, it is promising for neutralization of waste gases containing ozone.     

Study on the catalytic synthesis of diethyl carbonate from CO and ethyl nitrite over supported Pd catalysts

A vapor phase synthesis of diethyl carbonate (DEC) from carbon monoxide and ethyl nitrite (EN) was studied in a continuous flow micro fixed-bed reactor at atmospheric pressure. PdCl₂–CuCl₂/AC (activated carbon) catalyst exhibited better catalytic activity compared with other binary catalyst systems. The suitable Pd-loading is about 2.0 wt%, and some additives (LaCl₃, CeCl₃, PrCl₃) are benefit for the DEC yield and selectivity. Influences of various reaction parameters on the DEC yield and selectivity were tested. The optimum reaction temperature lies in 378–388 K and the suitable gas hourly space velocity (GHSV) range is 2500–3000 h⁻¹ considering both factors of DEC production and CO conversion. An optimum CO/C₂H₅ONO mole ratio exists for catalytic activity, which is about 1/1. The stability of PdCl₂–CuCl₂/AC catalyst and PdCl₂–CuCl₂–CeCl₃/AC catalyst was also investigated. The possible reason of the deactivation behavior of catalysts was discussed with the help of XRD.     

Studies on the activation of hydrogen peroxide for color removal in the presence of a new Cu(II)-polyampholyte heterogeneous catalyst

In this work we describe the application of a new non-soluble and non-porous complex with copper ion based on ethylene glycol diglycidyl ether (EGDE), methacrylic acid (MAA) and 2-methylimidazole (2MI) in the decolorization of an azo dye Methyl Orange (MO) as a model pollutant at room temperature.The complex with copper ion was studied by ESR and SEM and was tested as a heterogeneous catalyst for H₂O₂ activation. A possible mechanism of interaction involves the production of hydroxyl radicals (confirmed by ESR), dioxygen and water.The Cu(II)-polyampholyte/H₂O₂ system acted efficiently in the color removal of MO. The adsorption and oxidative degradation of the azo-based dye followed pseudo-first-order kinetic profiles, and the rate constant for degradation had a second-order dependence on copper ion content in the mixture.A removal of MO higher than 90% was achieved in 20 min at pH 7.0, combining 0.8 mM of complexed copper ions in the mixture with 24 mM hydrogen peroxide.The dye adsorbed on the polyampholyte following a L4-type isotherm with 4.9 μmol g⁻¹ maximum loading capacity and 3.1 μM dissociation constant for the first monolayer.