Catalytic Wet Peroxide Oxidation Research Articles

Chitosan–silica nanoparticles catalyst (M@CS–SiO2) for the degradation of 1,1-dimethylhydrazine

Hybrid materials of chitosan–silica (CS–SiO2) with nonprecious-metallic ions (Cu) immobilized on (Cu–M@CS–SiO2) were developed as green catalysts for degrading 1,1-dimethyl hydrazine (UDMH) wastewater. SEM, XRD, EDX, and FT-IR were employed for characterizing the catalysts. Results indicated that metal ions were chelated with N or N and O atoms of CS–SiO2. The efficiency of UDMH degradation, chemical oxygen demand (COD) removal and the concentration of N-nitrosodimethylamine (NDMA) were used to evaluate the catalytic activity. The catalysts were firstly combined into the process of catalytic wet peroxide oxidation (CWPO) for the degradation of UDMH wastewater with H2O2. Based on the study of the effects of different metallic ions, anions and reaction factors on the catalyst activity, the optimal conditions for CWPO with M@CS–SiO2 were determined, the H2O2 dosage and temperature were 3.0 mL and 65 °C, respectively. Under these conditions, the treatable UDMH concentration was 500 mg L−1, obtaining the high efficiency of UDMH degradation and COD removal (100% in 10 min and 87.38% in 30 min, respectively) and the low concentration of NDMA (0.31 mg L−1). The catalyst activity was less affected within six reaction cycles. Meanwhile, owning a huge surface area and strong adsorption performance, this kind of hybrid material can rapidly degrade, adsorb, and separate pollution.

Catalytic Wet Peroxide Oxidation (CWPO) of 2-Hydroxybenzoic acid and contaminated industrial effluent using LnMO3(Ln= La or Pr and M= Fe or Fe-Co)

The present study involves investigation of CWPO (Catalytic Wet Peroxide Oxidation) process for the removal of 2-Hydroxybenzoic acid (2-HBA or Salicylic acid), a moderate pollutant in industrial effluent. The best experimental conditions concerning selected varied parameters viz. pH, temperature were determined using hydrogen peroxide as oxidant in process. Different B-site substituted La and Pr based perovskite catalyst were synthesised via glycine combustion method. The structural analysis of the perovskite powders was monitored by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) was performed to analyse the morphology of solids. The images of SEM show distinct pores with particle size ranging between 50-280 nm. The results demonstrated CWPO of 2-HBA was largely influenced by B- site bimetallic catalyst (M = Fe-Co) at pH = 3.5, Cat[Conc.] = 20% and T = 100 °C, degrading 85-90% of the contaminant in 120 min, meanwhile for the B-site monometallic catalyst (M = Fe), the degradation was 80-88% under same reaction conditions. The catalytic performance of LnMO3(Ln = La or Pr and M = Fe or Fe-Co) was also performed for an industrial effluent. Presence of aromatic carboxylic acid derivatives in industrial effluent were confirmed by GC-MS analysis and were successfully degraded in the range of 80-85%.

Preliminary investigation of the degradation mechanism of o, m and p-cresol using sludge-derived carbon nanosheets by catalytic oxidation based on quantum chemistry

Advanced oxidation technology is widely used to oxidize organic compounds in the liquid phase by OH conventionally. Here, we prepared a sludge-derived carbon nanosheets, which was applied in the catalytic wet air oxidation (CWAO), catalytic wet peroxide oxidation (CWPO) and catalytic wet ozone oxidation (CWOO) systems. Because of its abundant oxygen-containing functional groups, the catalytic activity of nanosheets was much higher than some conventional catalysts. It was found that the first-order reaction model did not have similar characteristics as expected. Combining with molecular descriptors calculated by the DFT method and PLS analysis, we try to explain this phenomenon for the first time and proposed possible mechanisms for the three advanced oxidation technologies.

Catalytic wet peroxide oxidation of imidazolium-based ionic liquids: Catalyst stability and biodegradability enhancement

The catalytic wet peroxide oxidation (CWPO) of the imidazolium-based ionic liquids 1-butyl-3-methylimidazolium chloride (BmimCl), 1-butyl-3-methylimidazolium acetate (BmimAc), 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (BmimNTf2), 1-hexyl-3-methylimidazolium chloride (HmimCl) and 1-decyl-3-methylimidazolium chloride (DmimCl) was examined by using a Fe catalyst supported on alumina (Fe2O3/Al2O3) that was prepared by incipient wetness impregnation. Variable H2O2 doses from 0.5 to 1.5 times the stoichiometric value provided similar results in terms mg TOC removed per mg H2O2 decomposed at 80 °C (0.033 mgTOC mgH2O2−1), all allowing complete Bmim+ removal. Raising the reaction temperature to 90 °C increased the mineralization rate up to 40% TOC conversion. Differences in TOC conversion among counteranions (chloride, acetate and NTf2−) were negligible. A plausible reaction pathway is propose involving hydroxylated compounds and short-chain organic acids as reaction byproducts. CWPO markedly increased the subsequent biodegradability of the IL test solutions and led there to TOC conversions after CWPO-biodegradability assays of 55–60%. The Fe2O3/Al2O3 catalyst exhibited high long-term stability; thus, it retained most of its properties and underwent negligible Fe leaching.

Preparation of novel iron-loaded microfibers entrapped carbon-nanotube composites for catalytic wet peroxide oxidation of m-cresol in a fixed bed reactor

A novel microfibers entrapped carbon-nanotube composite catalyst with iron loaded (MF-CNT-Fe2O3) was develop followed by fixed bed catalytic wet peroxide oxidation (CWPO) of m-cresol. Firstly, the microfibers entrapped carbon-nanotube composite (MF-CNT) support was prepared by wet lay-up papermaking process and sintering process and the entrapment ratio of support was evaluated. Then active components were loaded on support by metal organic chemical vapor deposition (MOCVD) method. Characterizations were carried out including Field-Emission Scanning Electron Microscope (FE-SEM), Energy Dispersive Spectroscopy (EDS), N2 adsorption–desorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), H2-Temperature-Programmed Reduction (H2-TPR) and Thermogravimetric Analysis (TG), respectively. At last, catalytic activity was tested. Results showed that the best entrapment ratio (72.5%) occurred when stirring time was 9.5 min and the mass ratio of CNTs to stainless steel fibers was 6:3. Characterization results illustrated that advanced three-dimensional network was formed in the microfibers composites and catalysts performed high thermal stability. CNTs were successfully entrapped in the fibers and iron components were uniformly dispersed on supports. CWPO results showed that MF-CNT-Fe2O3 catalysts prepared by MOCVD performed better than by impregnation method. Additionally, MF-CNT-Fe2O3 catalysts could perform high CWPO activity (m-cresol conversion highest at 99% and TOC conversion highest at 42%, respectively). Little iron loss was observed in all treated effluents.

Photocatalytic wet peroxide oxidation process at circumneutral pH using ilmenite as catalyst

The effect of the initial pH upon Catalytic Wet Peroxide Oxidation (CWPO) and CWPO-Photoassisted (λ: 200–600 nm) has been evaluated with ilmenite (FeTiO3) as catalyst (450 mg/L) and phenol as target compound (100 mg/L). Under dark conditions, pH0 plays a key role on the mineralization degree that steeply decreased (from 50% to almost negligible) as the pH0 value rose (from 3 to 6, respectively) entailing that HO generation occurs following the classical Fenton mechanism. The irradiation with UV–vis light allows to overcome this pH-dependence, increasing the organic matter conversion above 95% within the pH range 3–6. This can be explained by considering, on the one hand, the photocatalytic properties of ilmenite, provoking H2O2 decomposition into HO radicals and, on the other hand, the effect of UV–vis light upon Fe(II)-Fe(III) cycle increasing the H2O2 decomposition rate and, consequently, HO generation at acidic pH. Therefore, under these conditions H2O2 decomposition occurs following two different mechanisms: the classical Fenton one at acidic pH and by photogenerated charges at circumneutral one. A lumped kinetic model is proposed to predict the evolution of TOC upon CWPO-Photoassisted process. Finally, ilmenite stability has been evaluated through several sequential runs.

Synthesis of coal fly ash zeolite for the catalytic wet peroxide oxidation of Orange II.

Fly ash, a coal combustion residue produced by Termotasajero in Colombia, has been hydrothermally treated after an alkaline fusion to produce zeolite without addition of silicon or aluminum. The starting material was thoroughly mixed with NaOH, in a 1:1.2 mass ratio, to obtain a homogeneous mixture that was heated to 100°C during different times (6, 8, and 10h) and three zeolite samples were produced. The samples were characterized by XRD, SEM, XRF, Mössbauer spectroscopy, and N2 physisorption. According to characterization results (high surface area and appropriate morphological properties including crystallinity) and synthesis time, zeolitic catalyst synthesized with 8h of hydrothermal treatment was selected to perform further analysis. This sample consisted of a mixture of zeolite X and zeolite A of high surface area (301m2g-1) and a Fe content of 6% wt/wt. The zeolite was used as a catalyst for the Fenton oxidation of Orange II. Experiments were performed in a laboratory batch reactor at 70°C and constant pH = 3, using different concentrations of H2O2. When the stoichiometric amount of H2O2 was used, good mineralization (XTOC = 45%), complete discoloration, and oxidant consumption were obtained after 240min of reaction. The sample retained activity after 16h of usage. The presence of Fe in the reaction media was always detected and a homogeneous Fenton mechanism induced by surface-leached iron is suggested.

Stability of carbon-supported iron catalysts for catalytic wet peroxide oxidation of ionic liquids

The stability of two carbon-supported Fe catalysts in the catalytic wet peroxide oxidation (CWPO) of 1-Butyl-3-methylimidazolium acetate (BmimAc) was examined. One catalyst (Fe/AS) was obtained by chemical activation of dried sewage sludge with iron chloride at a FeCl3:sewage sludge mass ratio of 3 and the other (Fe/HTCS) by hydrothermal carbonization of the sludge in the presence of FeCl3 at a mass ratio of also 3. Fe/AS catalyst exhibited a well-developed porosity, whereas Fe/HTCS one did not show porosity. The carbon content was high in both catalysts, with a total Fe content of 5.2 and 6.6% (w/w) for Fe/AS and Fe/HTCS catalysts, respectively. An aditional Fe catalyst prepared by incipient wetness impregnation on a commercial active carbon support (Fe/AC) was used for comparison with the previous two. All catalysts were active in experiments of H2O2 decomposition and long-term CWPO runs (0.133 kgFe h molBmimAc–1 at 80 °C). Whereas Fe/AC catalyst lost activity largely due to Fe leaching (90% of FeBulk), Fe/AS and Fe/HTCS catalysts exhibited virtually no Fe leaching and hence fairly good stability. Fe/AS catalyst, which afforded complete removal of Bmim+ and TOC conversion values around 30%, proved the most efficient catalyst.

Relationship of Crystals Shape, Aggregation Mode and Surface Purity in Catalytic Wet Peroxide Oxidation of Phenol in Dark with Titania Anatase Nanocrystals

A series of TiO2 anatase materials with a thickness to width ratio of 0.22–0.62 in their primary nanocrystals, 1.03–1.27 nanocrystals aggregation ratio and 38–68% exposure of (001) facets were tested in phenol CWPO in a fixed-bed reactor in dark. Inactive oxyfluoride phase that covers the as-synthesized nanocrystals should be removed in order to get the highest catalytic activity. Catalytic activity was proportional to the value of surface area related to the exposed (001) facets at the TiO2 nanocrystals surface excluding any synergistic effects between (001) and (101) facets in catalysis. The linear regression of experimental data for studied reaction revealed that the specific catalytic activity per 1 m2 of (001) facets at the surface of TiO2 nanocrystals is at least four times higher compared with that of (101) facets. This is in agreement with theoretical predictions attributing the catalytic activity to surface titanols as active sites and formation of titanols mainly at the surface of (001) facets due to dissociative adsorption of water.

Enhanced performance of cobalt ferrite encapsulated in graphitic shell by means of AC magnetically activated catalytic wet peroxide oxidation of 4-nitrophenol

Here we report preliminary catalytic wet peroxide oxidation (CWPO) experiments performed in the presence of an alternating current (AC) magnetic field. One ferromagnetic graphitic nanocomposite – composed by a cobalt ferrite core and a graphitic shell (CoFe2O4/MGNC), was employed in the process, here named magnetically activated catalytic wet peroxide oxidation (MA-CWPO). An aqueous solution containing 5.0 g L−1 of 4-nitrophenol (4-NP) to simulate a high strength polluted stream was used as model system. The experiments were performed at room temperature and atmospheric pressure, with stoichiometric amount of hydrogen peroxide (H2O2), pH = 3 and CoFe2O4/MGNC catalyst load = 5.0 g L−1 (corresponding to a 4-NP/CoFe2O4 mass ratio of 6.9, as CoFe2O4 accounts for 14.4 wt% of CoFe2O4/MGNC). It was shown that the performance of CWPO is enhanced upon application of an AC magnetic field (frequency of 533.9 kHz and magnitude of 240 G). As a result, high 4-NP mineralization was obtained by MA-CWPO (as reflected by a total organic carbon abatement of 79% after 4 h of reaction, instead of 39% in the absence of a magnetic field). This positive effect was ascribed to the localised increase of CoFe2O4/MGNC surface temperature resulting from heat release upon exposure of the nanoparticulated catalyst to an AC magnetic field, which accelerates the catalytic decomposition of H2O2 via hydroxyl radicals (HO) formation.

Preparation and properties of Cu-Ni bimetallic oxide catalyst supported on activated carbon for microwave assisted catalytic wet hydrogen peroxide oxidation for biologically pretreated coal chemical industry wastewater treatment

A microwave (MW)-assisted catalytic wet hydrogen peroxide oxidation (CWHPO) process was investigated to treat biologically pretreated coal chemical industry wastewater (CCIW) in this study. The activated carbon (AC) supported Cu-Ni bimetallic oxide catalyst was prepared by impregnation and precipitation method for MWCWHPO. The catalytic performance of the catalyst was investigated, and the main influencing factors were discussed. The results showed that the removal efficiencies of quinoline and total organic carbon (TOC) with catalyst prepared by impregnation method were 85% and 70%, respectively, and the removal efficiencies of quinoline and TOC with catalyst prepared by precipitation method were up to 95% and 76%, respectively. The utilization rate of hydrogen peroxide (H2O2) and the generation quantity of hydroxyl radicals were higher in the reaction process with the catalyst prepared by precipitation method than those with the catalyst prepared by impregnation method. The characterization of the catalyst showed that the smaller active component grains size, larger surface area and higher proportion of chemical adsorption oxygen were the main reason for the high catalytic efficiency. Furthermore, the optimized reaction conditions were: reaction temperature of 60 °C, microwave power of 500 W, and H2O2 initial concentration of 0.066 M. Moreover, the Cu-Ni bimetallic oxide catalyst is an efficient and stable catalyst in the degradation and mineralization of pollutants in the MWCWHPO process. The synthesized catalyst was verified to be attractive for use in the heterogeneous wet peroxide oxidation system under microwave irradiation.

Mineralization of quinoline in aqueous solution by microwave-assisted catalytic wet peroxide oxidation system: process optimization, products analysis and degradation route research.

The experimental design methodology was used to optimize the experimental parameters of quinoline mineralization by microwave-enhanced catalytic wet peroxide oxidation (CWPO). Initial pH value, temperature, H2O2 dosage, and microwave power were selected as independent variables. The mineralization efficiency approached 83.82% under the optimized conditions: initial pH 6.00, temperature 60 °C, H2O2 dosage 0.09 mol/L, and microwave power 565.10 W. Regression analysis with an R2 value of 0.9867 showed a good agreement between the experimental results and the predicted values. Furthermore, based on the detection and identification of products by gas chromatography mass spectrometry, the oxidation degradation pathways of quinoline were proposed. The energy balance and costs analysis indicated that the total cost of the microwave-enhanced CWPO process for wastewater treatment was 40.60 yuan/m3.

Continuous removal of Cr(VI) and Orange II over a novel Fe0-NaA zeolite membrane catalyst

A novel Fe0-NaA zeolite membrane catalyst was prepared for continuous removal of Cr(VI) and Orange II (OII) in a fixed bed reactor. Firstly, the NaA zeolite membrane on the paper-like sintered stainless steel fibers support was prepared by wet lay-up papermaking technique and secondary growth method. Then, Fe0-NaA zeolite membrane catalyst was synthesized by traditional liquid-phase technique and characterized by using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Finally, catalytic activity of Fe0-NaA zeolite membrane catalysts was studied by investigating the breakthrough time of Cr(VI) and conversion of OII as well as the iron leaching concentration in the effluent based on the reduction reaction and catalytic wet peroxide oxidation (CWPO) processes in a fixed bed reactor. The results showed that nanoscale Fe0 particles were uniformly loaded on the surface of the NaA zeolite membrane. An acidic environment was more favorable to the reduction of Cr(VI) and the breakthrough time reached 300 min for 4.7% breakthrough at pH 2. Both Yoon-Nelson and Bed Depth Service Time (BDST) models were found to agree well with the experimental results of Cr(VI) removal. The catalyst for CWPO of OII achieved the highest activity (OII conversion > 97%, COD removal ratio about 86.0%, respectively) after continuously ran for 240 min. Meanwhile, low iron leaching concentration (<3.5 mg/L) was detected in the treated effluent.

Efficient degradation of sulfamethoxazole by catalytic wet peroxide oxidation with sludge-derived carbon as catalysts

ABSTRACTSulfamethoxazole (SMX) is a commonly used antibiotic for both human and animals. The frequent detection of SMX in natural water bodies and sediment has become an issue of great environmental concern due to its potential risk to induce antibiotic resistance in pathogenic bacteria. In the present work, the catalytic wet peroxide oxidation (CWPO) was investigated to remove SMX with sludge-derived carbon (SC) as a cheap alternative catalyst. Different acids were used to modify SC. It was found that SC modified with sulphuric acid (SC-H2SO4) demonstrated the best catalytic activity. The removal efficiency of SMX and TOC was 97.7% and 65.7%, respectively, after 260 min, at pH 5 with a dosage of 220 mg/L H2O2. The effects of temperature, initial pH and H2O2 dosage were also investigated. The study demonstrated that the increase of temperature could significantly improve the degradation of SMX from 10.0% at 20°C to 94.7% at 60°C.

Treatment of methyl orange by the catalytic wet peroxide oxidation process in batch and continuous fixed bed reactors using Fe-impregnated 13X as catalyst.

Fe-impregnated 13X (Fe-13X) catalysts were prepared for catalytic wet peroxide oxidation (CWPO) of methyl orange (MO) solution in batch and continuous fixed bed reactors. A systematical study was carried out to investigate the influence of the main operating parameters on the batch reactor performance. The kinetic curves were analyzed by using a pseudo-first-order kinetic equation over the 30-70 °C temperature range. In addition, the effects of catalysts filling amount and feed flow rate on the catalytic performance of Fe-13X catalysts in a fixed bed reactor were studied. The experimental results showed that the Fe-13X catalysts achieved the highest activity (100% MO conversion and 74.5% chemical oxygen demand (COD) elimination ratio, respectively) at 25 min with trace mount of Fe leaching concentration (<2.1 mg/L) at the optimized reaction conditions (namely 1.0 g/L catalyst concentration, pH 2.0, 17.6 mM H2O2, 70 °C) in a batch reactor. Kinetic studies showed that two different reaction regions existed, and an activation energy of 51.9 kJ/mol for the second region was found. Under the optimal operating conditions found (namely, catalysts filling amount of 3.5 g, feed flow rate of 4 mL/min), the Fe-13X catalysts displayed high MO conversion (99.4%) and COD elimination ratio (77.1%) after continuously ran for 200 min in a fixed bed reactor.

Cover Image, Volume 93, Issue 9

The cover image, by Yi Yang et al., is based on the Research Article Catalytic wet peroxide oxidation of m‐cresol over novel Fe2O3 loaded microfibrous entrapped CNT composite catalyst in a fixed‐bed reactor, DOI: 10.1002/jctb.5609. image

Ferrosilicate-Based Heterogeneous Fenton Catalysts: Influence of Crystallinity, Porosity, and Iron Speciation

Different ferrosilicate samples have been prepared with varying degrees of crystallinity, porous texture, and speciation of the Fe sites by both hydrothermal and sol–gel procedures: Fe-silicalite-1 with microcrystals (2–10 µm) and nanocrystals (180 nm), Fe-containing composite material consisting of silicalite-1 and amorphous silica, and two samples of mesoporous Fe-containing amorphous silica Fe–SiO2. The resulting solids have been tested for their potential as organic pollutants removal under Fenton-like conditions in heterogeneous catalytic wet peroxide oxidation of phenol and clarithromycin lactobionate. Our results indicate that the three aforementioned parameters show a strong interplay towards the abatement of pollutants in liquid phase. Thus, samples with high crystallinity show an improved performance in the oxidation of organic contaminants over amorphous samples in which the Fe speciation is very well controlled.

Intensification of catalytic wet peroxide oxidation with microwave radiation: Activity and stability of carbon materials

Several commercial carbon materials have been tested as catalysts in the Microwave-assisted Catalytic Wet Peroxide Oxidation process (MW-CWPO). Two graphites (G-F and G-S), two activated carbons (AC-M and AC-C), two carbon blacks (CB-V and CB-A) and silicon carbide (SiC) were selected due to their MW-absorbing properties. Phenol (100 mg L−1) was used as target pollutant, operating in batch at pH0 3, 120 °C, 500 mg L−1 catalyst load and the theoretical stoichiometric amount of H2O2 (500 mg L−1). All carbon materials showed to be active in terms of H2O2 decomposition and phenol oxidation. Nonetheless, G-S and AC-M stood out as the most active materials in terms of TOC removal, with values of 94 and 93% TOC elimination, respectively. On the other hand, both carbon blacks and G-F yielded a significantly lower TOC degradation. Surface chemistry seems to rule the activity of graphites, in particular the pH slurry (4.5 for G-S and 8.4 for G-F). The most active catalysts, G-S and AC-M were used in 5 consecutive cycles in order to study their stability. While G-S remained active, AC-M.

Low-cost iron-doped catalyst for phenol degradation by heterogeneous Fenton

The aim of this work was to study the feasibility of textile sludge as a precursor to prepare catalysts for catalytic wet peroxide oxidation (CWPO) by chemical and thermal treatments. Textile sludge was characterized by physical-chemical and metal composition analyses. The chemical activation was evaluated using iron sulfate and the thermal treatment was carried out at 720 °C in a vacuum pyrolysis reactor. Two catalysts with iron contents of 1.5% and 5.6% were selected. Process parameters influence on CWPO of phenol were evaluated and a maximum removal of phenol and TOC was observed at pH 3 and 60 °C, using 3 g L−1 of the catalyst containing 5.6% of iron and 11.8 mmol L−1 of H2O2. Metal analysis indicated that the textile sludge is suitable to be employed as both iron catalyst and adsorbent. The catalysts characterization indicated a reasonable surface area with a well-developed microporosity and the presence of Hematite structures in the carbonaceous matrix. The degradation process achieved 98.2% of phenol conversion, 68.2% of mineralization and 2.11 mg L−1 of iron leaching in 150 min of reaction. The catalyst presented activity for up to 5 cycles of use, but with loss of efficiency.

Kinetics of Catalytic Wet Peroxide Oxidation of Phenolics in Olive Oil Mill Wastewaters over Copper Catalysts

During olive oil extraction, large amounts of phenolics are generated in the corresponding wastewaters (up to 10 g dm–3). This makes olive oil mill wastewater toxic and conventional biological treatment challenging. The catalytic wet peroxide oxidation process can reduce toxicity without significant energy consumption. Hydrogen peroxide oxidation of phenolics present in industrial wastewaters was studied in this work over copper catalysts focusing on understanding the impact of mass transfer and establishing the reaction kinetics. A range of physicochemical methods were used for catalyst characterization. The optimal reaction conditions were identified as 353 K and atmospheric pressure, giving complete conversion of total phenols and over 50% conversion of total organic carbon content. Influence of mass transfer on the observed reaction rate and kinetics was investigated, and parameters of the advanced kinetic model and activation energies for hydrogen peroxide decomposition and polyphenol oxidation were estimated.