Peroxide Catalyst Research Articles

Influence of Hydrogen Peroxide Catalyst Grain Size on Performance and Ageing

Two different diameters of Pt/Al2O3 spherical catalysts (1 mm and 2 mm) for HTP 98% decomposition were tested to compare the catalytic activity and catalyst ageing. Comparable decomposition performance efficiencies were obtained during thruster-like tests in a catalytic decomposition setup, even though the 1-mm showed a better reactivity and temperature rising time, including in cold-start operation. However, a rapid physical degradation accompanied by pressure peaks observed throughout testing of the 1-mm catalyst led to damage of the catalyst and apparition of fines, causing partial clogging of the bed.

Biosynthesis of Fe/Pd Bimetallic Nanoparticles and Used for Removal of Synthetic Oily Wastewater

Eucalyptus plant leaves aqueous extract was used to produce a green bimetallic Fe/Pd nanoparticles (G-Fe/Pd NPs) catalyst for the degradation of synthetic oily effluent. Using Brunauer-Emmett-Teller (BET) analysis, Fourier-transform infrared spectroscopy (FTIR), particle size, and a zeta potential analyzer, the synthesized G Fe/Pd NPs were evaluated. G-Fe/Pd NPs have been found to contain nanoparticles, with a mean size of 182 nm and a surface area of 5.106 m2/g. The resulting nanoparticles were then used as a catalyst for a Fenton-like reaction. The amount of green catalyst G-Fe/Pd NPs (0.125-0.5 g/L), H2O2 concentration (15-37.5 mmol/L), pH (3-7), and temperature (25-45°C) all have a significant impact on the degradation efficiency of synthetic oily wastewater. Batch experiments showed that 88.9% degraded chemical oxygen demand (COD) from synthetic oily wastewater within the optimum conditions of peroxide concentration, catalyst dose, pH, and temperature which were 30.0 mmol/L, 0.375 g/L, 3, and 45℃ respectively along with 60 min contact time. The results of kinetic models showed that oily wastewater removal followed the Behnajady-Modirshahla-Ghanbary (BMG) model. Finally, the thermodynamic study of the reaction was also examined and concluded to endothermic reaction with an enthalpy of 37.39 kJ/mol.

Innovative treatment of industrial effluents through combining ferric iron and attapulgite application

The escalation of industrial activities has escalated the production of pharmaceutical and dyeing effluents, raising significant environmental issues. In this investigation, a hybrid approach of Fenton-like reactions and adsorption was used for deep treatment of these effluents, focusing on effects of variables like hydrogen peroxide concentration, catalyst type, pH, reaction duration, temperature, and adsorbent quantity on treatment effectiveness, and the efficacy of acid-modified attapulgite (AMATP) and ferric iron (Fe(III))-loaded AMATP (Fe(III)-AMATP) was examined. Optimal operational conditions were determined, and the possibility of reusing the catalysts was explored. Employing Fe3O4 as a heterogeneous catalyst and AMATP for adsorption, CODCr was reduced by 78.38–79.14%, total nitrogen by 71.53–77.43%, and phosphorus by 97.74–98.10% in pharmaceutical effluents. Similarly, for dyeing effluents, Fe(III)-AMATP achieved 79.87–80.94% CODCr, 68.59–70.93% total nitrogen, and 79.31–83.33% phosphorus reduction. Regeneration experiments revealed that Fe3O4 maintained 59.48% efficiency over three cycles, and Fe(III)-AMATP maintained 62.47% efficiency over four cycles. This work offers an economical, hybrid approach for effective pharmaceutical and dyeing effluent treatment, with broad application potential.

Selective direct oxidation of 1-butanol into acetal using hydrogen peroxide and Cs5MPW11(H2O)O39 (M=Fe, Co, Cu) catalysts.

Direct catalytic oxidation of alcohols to acetals in one step process is very attractive, because the two steps process leads firstly to aldehydes, which are unstable species serving as reactive intermediates to generate several by-products reducing process efficiency and selectivity. In this work, a new selective catalytic acetalization of 1-butanol into 1-1-dibutoxybutane acetal using H2O2 in one step process is investigated using Keggin-type polyoxometalates catalysts. The materials developed consisted of new lacunary phophotungstate salts Cs5MPW11(H2O)O39 (M=Fe, Co and Cu) which were prepared by inorganic solution condensation method and characterized using XRD, IR, SEM and EDX analysis to verify their structure, surface morphology and chemical composition. Cs5CuPW11(H2O)O39 catalyst allowed the highest performance for the oxidation of 1-butanol at 60 °C using H2O2 excess with a yield approaching 92 % and a turnover number of 784. Such activity is related to a bifunctional behavior of the catalyst as superacid and redox operating system and the synergistic effect created between the [PW11O39]7- Keggin framework, Cs+ and Cu2+.

Iron-bearing mining reject as an alternative and effective catalyst for photo-Fenton oxidation of phenol in water.

In this work, iron-bearing mining reject was employed as an alternative and potential low-cost catalyst to degrade phenol in water by photo-Fenton strategy. Various techniques, including SEM-EDS, BET, FTIR, and XRD, were applied to evaluate the material's properties. Process parameters such as hydrogen peroxide concentration, catalyst dosage, and pH were studied to determine the optimum reaction conditions ([catalyst] = 0.75g L-1, [H2O2] = 7.5mM, and pH = 3). Phenol degradation and mineralization efficiencies at 180 and 300min were 96.5 and 78%, respectively. These satisfactory results can be associated with the iron amount present in the waste sample. Furthermore, the material showed high catalytic activity and negligible iron leaching even after the fourth reuse cycle. The degradation behavior of phenol in water was well represented by a kinetic model based on the Fermi function. The iron-bearing mining reject can be considered a potential photo-Fenton catalyst for phenol degradation in wastewater.

SERS-electrochemical dual-mode detection of microRNA on same interface assisted by exonuclease III signal transformation

Dual-mode sensing has attracted more attentions which provide more accurate and reliable approach of cancer-related biomarkers. Herein, we developed a novel SERS/electrochemical dual-mode biosensor for miRNA 21 detection based on Exo III-assisted signal transformation. Firstly, the Au NPs were deposited on electrode as SERS substrate and Mn3O4/S4(DNA signal strand) was modified on Au NPs/S5 by the DNA strands S5-S4 pairing principle as hydrogen peroxide catalyst, leading to an obviously high DPV electrical signal without Raman signal. Subsequently, the presence of miRNA 21 will activate the Mn3O4/S4 to be decomposed under exonuclease III-assisted process, then the S3′ chains modified with Raman molecular Cy3(Cy3-S3′) is continuously connected to the Au NPs/S5 by DNA stands S5-S3′ pairing principle, leading to the Raman signal response and DPV signal reduction. The biosensor shows good linear calibration curves of both SERS and electrochemical sensing modes with the detection limit of 3.98 × 10−3 nM and 6.89 × 10−5 nM, respectively. This work finds an ingenious mode for dual detection of microRNA on a same interface, which opens a new strategy for SERS and electrochemical analysis.

Synthesis and characterisation of microcapsules for self-healing dental resin composites

AimThe purpose of this study was to i) synthesise TEGDMA-DHEPT microcapsules in a laboratory setting; ii) characterise the resultant microcapsules for quality measures.Materials & methodsMicrocapsules were prepared by in situ polymerization of PUF shells. Microcapsules characterisation include size analysis, optical and SEM microscopy to measure the diameter and analyse the morphology of PUF microcapsules. FT-IR spectrometer evaluated microcapsules and benzyl peroxide catalyst polymerization independently.ResultAverage diameter of TEGDMA-DHEPT microcapsules was 120 ± 45 μm (n: 100). SEM imaging of the capsular shell revealed a smooth outer surface with deposits of PUF nanoparticles that facilitate resin matrix retention to the microcapsules upon composite fracture. FT-IR spectra showed that microcapsules crushed with BPO catalyst had degree of conversion reached to 60.3%.ConclusionTEGDMA-DHEPT microcapsules were synthesised according to the selected parameters. The synthesised microcapsules have a self-healing potential when embedded into dental resin composite as will be demonstrated in our future work.Graphical Graphical abstract showing the microcapsule components. The shell contains poly(urea-formaldehyde), and the core consists of TEGDMA-DHEPT healing agents.

Tuning Porosity of the Catalyst for Hydrogen Peroxide Based Thrusters

Tuning Porosity of the Catalyst for Hydrogen Peroxide Based Thrusters

Investigation of Eichhornia crassipes as a natural fibre in PMC for noise controller

This paper investigated the Eichhornia crassipes as fibers in polymer matrix composite (PMC) for sound absorption. The polyester resin R-108 was mixed with the fibers with the variation percentage. The fibers were varied with three different variations: 20%, 25%, and 30%. The Methyl Ethyl Ketone Peroxide catalyst was added to accelerate the solidification. The sound absorption experiment used a simple insulated box with a sound level meter. After the experiment, the noise absorption coefficient (NAC) result was calculated and analyzed. The maximum noise absorption was obtained at 25% of fibers, indicated by the NAC value of 0.384. In addition, the tensile strength was also obtained for the supplementary data for this study.

Optimizing porosity of the catalyst for hydrogen peroxide based thrusters

The texture of the catalyst support is a crucial factor for H2O2 decomposition due to the expansion of H2O2 in monopropellant thrusters, which can lead to overpressure and catalyst breakage. Therefore, alumina supports with 5 wt%, 10 wt%, and 15 wt% microcrystalline cellulose templates were studied to create macropores. MIP and SEM analysis showed that microcrystalline cellulose template increases the macropore fraction. Low-concentration H2O2 decomposition experiments revealed that over 10 wt% microcrystalline cellulose prevented catalyst breakage. Additionally, the thermal durability of the catalyst was studied at different calcination temperatures. Alumina with 15 wt% microcrystalline cellulose and a 900 °C calcination temperature exhibited the highest fracture strength and suitable reaction kinetics. The catalysts were tested in high-concentration H2O2 monopropellant thruster. The results demonstrated enhancement in catalyst size retention, pressure stability, and pressure drop. Introducing macropores through microcrystalline cellulose addition overcomes unstable thruster performance and it extends catalyst lifespan in H2O2 monopropellant thrusters’ applications.

Mechanisms and Opportunities for Rational In Silico Design of Enzymes to Degrade Per- and Polyfluoroalkyl Substances (PFAS).

Per and polyfluoroalkyl substances (PFAS) present a unique challenge to remediation techniques because their strong carbon-fluorine bonds make them difficult to degrade. This review explores the use of in silico enzymatic design as a potential PFAS degradation technique. The scope of the enzymes included is based on currently known PFAS degradation techniques, including chemical redox systems that have been studied for perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) defluorination, such as those that incorporate hydrated electrons, sulfate, peroxide, and metal catalysts. Bioremediation techniques are also discussed, namely the laccase and horseradish peroxidase systems. The redox potential of known reactants and enzymatic radicals/metal-complexes are then considered and compared to potential enzymes for degrading PFAS. The molecular structure and reaction cycle of prospective enzymes are explored. Current knowledge and techniques of enzyme design, particularly radical-generating enzymes, and application are also discussed. Finally, potential routes for bioengineering enzymes to enable or enhance PFAS remediation are considered as well as the future outlook for computational exploration of enzymatic in situ bioremediation routes for these highly persistent and globally distributed contaminants.

Molten salt-assisted anti-defect engineering to tailor ordered, highly crystalline g-C3N4 nanorods for efficient photocatalytic H2O2 production

Graphite carbon nitride (g-C3N4) is widely recognized as one of the most popular catalysts for photocatalytic hydrogen peroxide (H2O2) production. However, it is often overlooked that general g-C3N4 materials contain numerous dangling bonds and defects, which serve as recombination centers for photogenerated carriers and significantly hinder their catalytic activity. Herein, we present a novel approach to address this issue by rationally tailoring well-ordered g-C3N4 nanorods (CNR) through molten salt-assisted anti-defect engineering. The resulting highly crystalline CNR demonstrates high efficiency in the artificial photosynthesis of H2O2. Experimental results indicate that enhancing the crystallinity of g-C3N4 while reducing the defect concentration effectively promotes charge separation and transport. As a result, it exhibits a remarkable H2O2 generation rate of 1.58 mmol g-1h−1 using air as the oxygen source, accompanied by an apparent quantum yield of 18.00 % (λ = 400 nm). The excellent photocatalytic performance of CNR surpasses that of all previously reported pristine g-C3N4 materials. This work sheds light on the effectiveness of molten salt-assisted anti-defect engineering in improving catalyst activity, with potential applications in solar cells, sensor devices and other catalytic systems.

Production of SBS Reinforced Polyester Composite: Characterization of Physical and Chemical Properties

In this study, dissolved styrene butadiene styrene (SBS) copolymer is homogeneously reinforced into orthophthalic unsaturated polyester (UP) resin. Polyester composite production is carried out with the help of methyl ethyl ketone peroxide (MEKP) and cobalt octoate (Co Oc) catalysts. The density, Shore D hardness, thermal conductivity coefficient, thermal stability, morphological surface structure, and chemical bond structure of the obtained composite have been examined. According to the results, SBS reinforcement decreases the density of the composite and increases the thermal conductivity coefficient. The addition of SBS at different weight ratios (1%, 3%, 5%, 7%, and 10% w/w) reduces both the hardness and thermal stability of the polyester composite. According to the test and analysis results, 5 wt.% SBS reinforced polyester composite production is determined as the optimum ratio. 7 wt.% and above SBS reinforcement negatively affect the physical and chemical properties of the obtained composite. For example, when 10 wt.% SBS reinforced composite is examined by scanning electron microscope (SEM), and irregular pores are observed in the surface morphology. Also, it is understood by Fourier transform infrared spectroscopy (FTIR) that there is a physical interaction between SBS and polyester and that no chemical bond is formed. The thermal decomposition behavior of the composite has been determined according to the decrease in the activation energy. As SBS ratio increases, it is understood that the thermal stability of the product obtained with the decrease in the activation energy of the polyester composite weakens.

Selective Depolymerization of Lignin Towards Isolated Phenolic Acids Under Mild Conditions.

The selective transformation of lignin to value-added biochemicals (e. g., phenolic acids) in high yields is incredibly challenging due to its structural complexity and many possible reaction pathways. Phenolic acids (PA) are key building blocks for various aromatic polymers, but the isolation of PAs from lignin is below 5 wt.% and requires harsh reaction conditions. Herein, we demonstrate an effective route to selectively convert lignin extracted from sweet sorghum and poplar into isolated PA in a high yield (up to 20 wt.% of lignin) using a low-cost graphene oxide-urea hydrogen peroxide (GO-UHP) catalyst under mild conditions (<120 °C). The lignin conversion yield is up to 95 %, and the remaining low molecular weight organic oils are ready for aviation fuel production to complete lignin utilization. Mechanistic studies demonstrate that pre-acetylation allows the selective depolymerization of lignin to aromatic aldehydes with a decent yield by GO through the Cα activation of β-O-4 cleavage. A urea-hydrogen peroxide (UHP) oxidative process is followed to transform aldehydes in the depolymerized product to PAs by avoiding the undesired Dakin side reaction due to the electron-withdrawing effect of the acetyl group. This study opens a new way to selectively cleave lignin side chains to isolated biochemicals under mild conditions.

The effect of chicken eggshell (Gallus gallus domesticus) particle size as filler to polyester composite as motorcycle’s exhaust pipe cover material

This research was done to know the effect of chicken eggshell (Gallus gallus domesticus) powder particle size on unsaturated polyester resin mechanical properties. The eggshell was mashed and sifted to get the 50 mesh, 70 mesh, 90 mesh, 110 mesh, 130 mesh, 150 mesh, and 170 mesh particle size by using a ball mill. Then, the eggshell was mixed with an unsaturated polyester resin matrix with the ratio of 70:30 and methyl ethyl ketone peroxide (MEKP) catalyst as much as 1 % of the matrix mass. After that, it was pressed by using compression molding. The composite formed was characterized by Scanning Electron Microscopy Energy Dispersive X-ray (SEM EDX), Fourier Transform Infra-Red (FTIR), and X-Ray Diffraction (XRD). The physical properties of the composite were analyzed and the mechanical properties were tested. The SEM EDX result showed that the eggshell and composite were made up of Ca, C, and O, and the polyester was made up of C, O, and Si. The composite highest tensile strength and impact strength were at 150 mesh particle size of chicken eggshell powder which is 45.153 MPa and 9. 04 J/m2.

Bacteria inactivation using spinel cobalt ferrite catalyst

The E. coli inactivation using hydrogen peroxide (H2O2) and cobalt ferrite granulated catalyst was investigated in a fixed-bed flow reactor. CoFe2O4 catalyst was synthesized by the co-precipitation method, granulated, and annealed at 1150°C. X-ray diffraction analysis was used to identify the crystal structure of the catalyst. CoFe2O4 catalyst demonstrates good catalytic activity for bacteria inactivation in the presence of H2O2. An increase in the hydrogen peroxide concentration increases the inactivation efficiency. The reactor demonstrates the E. coli inactivation of 99.94% at the H2O2 hydrogen peroxide concentration of 15 mM and initial bacterial concentration of 6·103 CFU/L. The water disinfection using a fixed-bed reactor demonstrates the broad prospects for industrial use.

Selective peroxidation of isobutane with molecular oxygen over molybdenum oxide catalyst for direct synthesis of di-tert-butyl peroxide

The direct conversion of isobutane to high value-added chemicals is important for utilization of C4 hydrocarbon resources. This work proposed a novel route of isobutane peroxidation with molecular oxygen for green synthesis of di-tert-butyl peroxide (DTBP), widely used as polymerization initiating/crosslinking agent and diesel additive. For the first time, MoO3 was demonstrated as selective catalyst for isobutane peroxidation to DTBP. The results indicated that, the reactivity depended on the oxygen adsorption capacity of MoO3 catalyst, and the selectivity to DTBP was determined by the amount of surface Mo = O sites. During the reaction, tert-butyl hydroperoxide (TBHP) was generated from isobutane peroxidation as intermediate product, and subsequently converted to DTBP on Mo = O active sites. Under the optimized conditions, a high oxygen conversion (>95%) and stable product selectivities (DTBP ∼ 20 wt%, TBHP ∼ 13 wt%) were obtained during continuous catalyst re-usage runs. This work provides an environmental route for both C4 hydrocarbon utilization and DTBP production.

Ultrahigh Performance H2 O2 Generation by Single-Atom Fe Catalysts with N/O Bidentate Ligand via Oxalic Acid and Oxygen Molecules Activation.

Single-atom catalysts (SACs) for photocatalytic hydrogen peroxide (H2 O2 ) generation are researched but it is still challenging to obtain high H2 O2 yields. Herein, graphite carbon nitride (FeSA /CN) confined single Fe atoms with N/O coordination is prepared, and FeSA /CN shows high H2 O2 production via oxalic acid and O2 activation. Under visible light illumination, the concentration of H2 O2 generated by FeSA /CN can achieve 40.19mM g-1 h-1 , which is 10.44 times higher than that of g-C3 N4 . The enhanced H2 O2 generation can be attributed to the formation of metal-organic complexes and rapid electron transfer. Moreover, the O2 activation of photocatalysts is revealed by 3,3',5,5'-tetramethylbenzidine oxidation. The results display that the O2 activation capacity of FeSA /CN is higher than that of g-C3 N4 , which facilitates the formation of H2 O2 . Finally, density functional theory calculation demonstrates that O2 is chemically adsorbed on Fe atomic sites. The adsorption energy of O2 is enhanced from -0.555 to -1.497eV, and the bond length of OO is extended from 1.235 to 1.292 Å. These results exhibit that the confinement of single Fe atoms can promote O2 adsorption and activation. Finally, the photocatalytic mechanism is elaborated, which provides a deep understanding for SACs-catalyzed H2 O2 generation.

Light-Driven Fuel Cell with a 2D/3D Hierarchical CuS@MnS Z-Scheme Catalyst for H2O2 Generation

A photoelectrocatalytic (PEC) oxygen reduction reaction (ORR) strategy with fuel-efficient and cost-effective catalysts for on-demand hydrogen peroxide (H2O2) production is booming as an attractive alternative to the conventional anthraquinone process. Herein, we constructed a novel two-dimensional (2D)/three-dimensional (3D) hierarchical CuS@MnS p-p Z-scheme catalyst with full spectrum absorption and strong coupling interface by regulating the crystal structure, morphology, and photocharge transfer mechanism, which was used as a photocathode for PEC synthesis of H2O2 with a yield of 1.65 mM within 180 min. Taking advantage of a coupling strategy with Sn3O4/Ni foam, the as-prepared two-compartment cell with water oxidation reaction and ORR exhibited boosted activity and stability for the dual production of H2O2. An energy-saving H2O2 generation system was also constructed with a direct hydrazine/O2 fuel cell, realizing the significant advantage in reducing electricity consumption during the H2O2 synthesis. Moreover, the onsite generation of H2O2 remarkably accelerated the degradation of pollutants via a cascade heterogeneous Fenton reaction with a Fe anode. This work provides a new strategy for designing a multifunctional PEC system for the production of high-value chemicals, energy recovery, and pollutant degradation.

Fe-containing carbon-coated monoliths prepared by CVD in gaseous toluene abatement - parametric analysis of the Fenton process

The degradation of toluene (present in a gas stream) by the heterogeneous Fenton process was evaluated in a bubble column reactor. The process was catalyzed by macrostructured carbon-coated monoliths that were synthesized by chemical vapor deposition (CVD), which allowed carbon growth in honeycomb cordierite monoliths, while the iron (metal phase) was incorporated by adsorption. A detailed parametric study was carried out to evaluate the effect of the main variables and process operating conditions, namely channel density of the monolith, hydrogen peroxide concentration, pH and catalyst load; as process responses, the amount of toluene transferred - η, hydrogen peroxide consumption and dissolved organic carbon (DOC) concentration in the liquid phase were assessed. The maximum ratio between the toluene transferred per catalysts mass - η/W - (6.8 ×10−2 moltoluene gcat−1), with total oxidant consumption and higher intermediate compounds remaining in solution (DOC = 33 mgC dm−3), was reached when the process was performed with a monolith with a channel density of 230 cpsi, initial pH = 3.0, [catalyst] = 0.8 g dm−3, [H2O2] = 20 mmol dm−3. During all experiments, only a small amount of iron was leached from the catalyst to the liquid phase (ca. ≤1.0 wt%), proving its stability for such application; in fact, it was found that homogenous process contribution due to iron leaching towards the overall performance is ca. 10%.