Metal Oxide Loading Research Articles

Atomic Level Understanding of the Structural Stability and Catalytic Activity of Nanoporous Gold/Titania Cluster Inverse Catalysts at Ambient and High Temperatures.

Nanoporous gold (NPG) exhibits exceptional catalytic performance at low temperatures, but its activity declines at elevated temperatures due to structural coarsening. Loading metal oxide nanoparticles onto NPG can enhance its catalytic activity at high temperatures. In this work, we used NPG-supported titania nanoparticles as a model system (denoted as Ti2O4/NPG) to study their catalytic activity at ambient and high temperatures with CO oxidation as a probe reaction by density functional theory (DFT) calculation and ab initio molecular dynamics (AIMD) simulations. The possible factors that may affect the CO oxidation reaction pathways and energy profiles on the Ti2O4/NPG, such as oxygen vacancies; silver impurities; Mars-van Krevelen (MvK), Eley-Rideal (ER), or trimolecular Eley-Rideal (TER) mechanisms; and catalytic active sites, were comprehensively investigated. The results showed that reaction energy barriers on Ti2O4/NPG were not significantly decreased compared to the pristine NPG, indicating that their catalytic activities at ambient temperature were comparable. At the evaluated temperature (400 °C), the Ti2O4/NPG exhibited superior thermal stability and maintained its active sites, while the NPG reduced active sites due to surface coarsening. The strong oxide-metal interaction (SOMI) effect between the NPG and Ti2O4 nanoparticles is found to be a main factor for the high structural stability and catalytic activity at high temperatures.

Encapsulation of cobalt molybdate on modified hierarchical porous TS-1 zeolite catalyst for efficient oxidative desulfurization of fuel

Morphological modulation of heterogeneous catalysts has been shown to be a useful strategy for adjusting the concentration or intrinsic activity of active sites and their catalytic activity in catalysis. Herein, a hierarchical porous TS-1-supported cobalt molybdate catalyst (CoMoO4/TS-1-DR) was obtained through a facile dissolution-regrowth strategy. In an oxidative desulfurization reaction using O2 as the oxidant, the as-prepared catalyst demonstrated exceptional performance compared to the supported catalyst prepared via the impregnation method due to the bimodal pore architecture presented. Moreover, in situ CoMoO4 synthesis lowers active site leaching, thus showing better reaction stability. After 7 recycles, the removal rate of DBT still remained at 88.8%. This work offers a generic in situ encapsulation strategy for designing hierarchical porous zeolite catalysts and the synthesis of loaded metal oxides.

The Conundrum of "Pair Sites" in Langmuir-Hinshelwood Reaction Kinetics in Heterogeneous Catalysis.

Understanding reaction kinetics is crucial for designing and applying heterogeneous catalytic processes in chemical and energy conversion. Here, we revisit the Langmuir-Hinshelwood (L-H) kinetic model for bimolecular surface reactions, originally formulated for metal catalysts, assuming immobile adsorbates on neighboring pair sites, with the rate varying linearly with the density of surface sites (sites per unit area); r ∝ [*]o 1. Supported metal oxide catalysts, however, offer systematic control over [*]o through variation of the active two-dimensional metal oxide loading in the submonolayer region. Various reactions catalyzed by supported metal oxides are analyzed, such as supported VO x catalysts, including methanol oxidation, oxidative dehydrogenation of propane and ethane, SO2 oxidation to SO3, propene oxidation to acrolein, n-butane oxidation to maleic anhydride, and selective catalytic reduction of nitric oxide with ammonia. The analysis reveals diverse dependencies of reaction rate on [*]o for these surface reactions, with r ∝ [*]o n , where n equals 1 for reactions with a unimolecular rate-determining step and 2 for those with a bimolecular rate-limiting step or exchange of more than 2 electrons. We propose refraining from a priori assumptions about the nature and density of surface sites or adsorbate behavior, advocating instead for data-driven elucidation of kinetics based on the density of surface sites, adsorbate coverage, etc. Additionally, recent studies on catalytic surface mechanisms have shed light on nonadjacent catalytic sites catalyzing surface reactions in contrast to the traditional requirement of adjacent/pair sites. These findings underscore the need for a more nuanced approach in modeling heterogeneous catalysis, especially supported metal oxide catalysts, encouraging reliance on experimental data over idealized assumptions that are often difficult to justify.

Synergy between Fe-Co oxide catalysts supported over HZSM-5 for direct conversion of methane to methanol

The direct conversion of methane to methanol over iron and cobalt oxide based composite catalysts supported over HZSM-5 was carried out in a fixed-bed micro reactor under changing process parameters and catalyst compositions. The prepared catalysts were well characterized by various techniques including N2 adsorption desorption, X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), pyridine FTIR, X-ray photoelectron spectroscopy (XPS), UV–vis spectroscopy and temperature programmed reduction (H2-TPR). The characterization results revealed the presence of various reducible iron and cobalt oxide species depending on the Fe/Co molar ratio and total metal oxide loading. Moreover, the XPS and UV–vis spectroscopic results also confirmed the variation of Fe2+/Fe3+ and Co2+/Co3+ species depending on the Fe-Co molar ratio which had strong influence on the performance of the composite catalysts. It was found that the cobalt species favours the formaldehyde formation whereas the iron species promotes the formic acid formation in their respective pure supported oxide catalysts. However, the synergistic effect of iron and cobalt oxide in equimolar ratio in composite catalysts appeared as effective for achieving highest yield of methanol. The methanol selectivity was also influenced by the alteration of various studied process parameters. The higher reaction temperature favoured the overoxidation of methanol to CO2 whereas the methanol selectivity increased with increasing the methane to oxygen ratio. The lattice to adsorbed oxygen ratio also had strong influence on the activity of composite catalysts and methanol selectivity. The highest methanol yield of 1.87% was achieved at the methane conversion of 42.81 % with the 20Fe1Co1Z catalyst at 873 K reaction temperature with CH4/O2 ratio of 2:1 and WHSV of 1030 ml hr−1 gcat−1.

Advanced treatment of landfill leachate by catalytic ozonation with MnCeOx/γ-Al2O3 catalyst

Ozonation combined with an efficient and stable catalyst has been demonstrated to be a feasible solution in for removing refractory contaminants from landfill leachate. In this study, MnCeOx/γ-Al2O3 catalyst fabricated with impregnation method was adopted as ozone catalyst for advanced treatment of landfill leachate biochemical effluent (LLBE). The optimized Mn80Ce20Ox/γ-Al2O3 catalyst was fabricated with Mn/Ce molar ratio of 4:1, a metal oxide loading amount of 3.1 wt%, and calcination temperature of 500 °C. By treating LLBE, the removal of chemical oxygen demand (COD) and UV254 in 120 min reached 82.4 % and 96.3 %, respectively, with ozone dose of 15.3 mg L−1, catalyst dosage of 250 g L−1, and the initial pH of 5. The Mn80Ce20Ox/γ-Al2O3 catalyzed ozonation process conformed to pseudo-first-order kinetics with degradation rate constants of 0.0171 min−1 and 0.0313 min−1 for COD and UV254, respectively, which were 3.4 and 2.8 times higher than those of ozonation alone. The MnCeOx/γ-Al2O3 also showed satisfactory catalytic activity and stability based on eight times catalytic ozonation treatments on LLBE.

Advanced Oxidation Processes for the oxyfunctionalisation of 1,2-dichlorobenzene: a review

Catalytic oxidation is an oxidation process that converts volatile organics and water carbon in the presence of the catalyst. A catalyst is a substance that is used to accelerate the rate of reaction at a given temperature without itself being consumed during the reaction and it can be used repeatedly. This review presents catalytic oxidation of ortho-dichlorobenzene over V2O5 loaded metal oxides (TiO2, SiO2 and Al2O3), supported transition metal oxides, ABO3- type perovskites and Ca-doped FeOx hollow microspheres. The review reveals different reaction conditions in which different catalysts were used during the degradation of 1,2-dichlorobenzene. The catalytic activity performance is reviewed and compared for all the catalysts used during the degradation of 1,2-dichlorobenzene. In our previous study, catalytic oxidation of orthodichlorobenzene in the presence of ozone and the catalyst at ambient reaction conditions was studied.

Catalytic upgrading of biomass pyrolysis vapors for selective production of phenolic monomers over metal oxide modified alumina catalysts

This study investigates the catalytic vapor phase upgrading of sawdust to produce improved biocrude enriched in phenolic monomers. Various mixed metal oxide catalysts (MgO, CuO, Bi2O3, NiO, ZnO supported on Al2O3) were screened to determine the product composition. Further, the effect of different process parameters such as temperature (350 – 600 °C), metal oxide loadings (0 – 20 wt%), catalyst to biomass ratios (1:1–1:6), sweeping gas flow rates (0 – 15 LPH) were studied in terms of biocrude composition. Under non-catalytic conditions, maximum biocrude yields (∼39%) were obtained at an optimum temperature of 550 °C. The biocrude composition varied significantly with the type of metal oxide in which MgO and CuO produced higher amounts of phenolics (∼58%). Increasing MgO loading (5–20 wt%) and higher catalyst to biomass ratios (1:1) resulted in enhanced hydrocarbon yields to ∼15%. Premixing of biomass and catalyst in a fixed bed arrangement resulted in enhanced hydrocarbons/aromatics with simultaneous reduction in the phenolic content.

Mn-NSC co-doped modified biochar/permonosulfate system for degradation of ciprofloxacin in wastewater

Mn-Nitrogen-sulfur co-doped modified biochar (Mn-NSCX) is prepared by high-temperature pyrolysis and hydrothermal method, and its properties are analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). A metal-non-technical co-doping system was constructed and first used for PMS activation towards ciprofloxacin degradation. The results show that doping of Mn, N and S significantly improve the catalytic performance of activated PMS to degrade CIP, among which Mn-NSC2 exhibit the best catalytic performance, when the dosage of MN-NSC2 is 0.4 g·L−1, the concentration of PMS is 0.4 mmol·L−1, and the concentration of CIP is 20 mg·L−1. After 60 min, more than 99% of CIP can be removed, among which the CIP removal rate of BC/PMS is 43.6%, and the CIP removal rate of NSC5/PMS is 50.3%. The removal effect of CIP is greatly improved after the incorporation of manganese, attributing to the oxidation reaction between the PMS and manganese dioxide. The results of electron paramagnetic resonance (EPR) indicate that both free radicals (·SO4-,·OH) and non-free radicals (1O2) play important roles in the degradation of CIP, and 1O2 plays a foremost role in the degradation of CIP. Doping of Mn, N and S accelerate the electron transfer rate and improve the catalytic activity of the material. In this paper, the loading of metal oxides can increase the corresponding catalytic sites and promote electron transfer, thus promoting the ability of activated PMS to degrade organic pollutants. The metal modification not only improves the oxygen-containing groups of the material, but also promotes the activation of persulfate by metal oxidation on the surface of the material. A novel design and preparation strategy for catalyst is proposed to simultaneously achieve stable Mn-Nitrogen-sulfur co-doped modified biochar and improve the catalytic performance of biochar by adding Mn, S, and N.

Enhancing arsenic adsorptions by optimizing Fe-loaded biochar and preliminary application in paddy soil under different water management strategies.

Arsenic (As) is widely distributed in nature and is a highly toxic element impacting human health through drinking water and rice. In this study, an optimized approach was attempted to improve As adsorption capabilities by combining pre- and post-pyrolysis modification of Fe(oxy)hydroxides to rice husk biochar (FRB), of which the method is rarely addressed in previous studies. Maghemite and goethite were successfully loaded onto biochar, characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoemission spectroscopy (XPS) analyzer. The FRB had maximum As(III) and As(V) adsorption capabilities of 7908 and 11,268mg/kg, respectively, which was significantly higher than that of Fe-modified biochar in the pre-pyrolysis and/or post-pyrolysis process. Adsorption mechanisms for As explored by Fourier-transform infrared spectroscopy (FTIR), XPS analysis mainly included electronic attraction and ligand exchange with hydroxyl groups on the FRB. It was noteworthy that more than half of the As(II) species loaded on FRB were converted into less toxic As(V) species, which could be mediated by the redox-active groups on the biochar. The preliminary application of FRB in soil indicated that it has an effective remediation potential for As-contaminated soil under flooded conditions, while promoted As release under dry conditions. Finding of this study highlighted that the loading of metal oxides onto biochar by combining pre- and post-pyrolysis modification could potentially increase As adsorption capabilities and further help in strategic water management.

Degradation of Sodium Acetate by Catalytic Ozonation Coupled with a Mn-Functionalized Fly Ash: Reaction Parameters and Mechanism.

Supported ozone catalysts usually take alumina, activated carbon, mesoporous molecular sieve, graphene, etc. as the carrier for loading metal oxide via the impregnation method, sol-gel method and precipitation method. In this work, a Mn-modified fly ash catalyst was synthesized to reduce the consumption and high unit price of traditional catalyst carriers like alumina. As a solid waste discharged from coal-fired power plants fueled by coal, fly ash also has porous spherical fine particles with constant surface area and activity, abd is expected to be applied as the main component in the synthesis of ozone catalyst. After the pretreatment process and modification with MnOx, the obtained Mn-modified fly ash exhibited stronger specific surface area and porosity combined with considerable ozone catalytic performance. We used sodium acetate as the contaminant probe, which is difficult to directly decompose with ozone as the end product of ozone oxidation, to evaluate the performance of this Mn-modified fly. It was found that ozone molecules can be transformed to generate ·OH, ·O2- and 1O2 for the further oxidation of sodium acetate. The oxygen vacancy produced via Mn modification plays a crucial role in the adsorption and excitation of ozone. This work demonstrates that fly ash, as an industrial waste, can be synthesized as a potential industrial catalyst with stable physical and chemical properties, a simple preparation method and low costs.

Analysis of Dielectric Parameters of Fe2O3-Doped Polyvinylidene Fluoride/Poly(methyl methacrylate) Blend Composites.

In this paper, we report the effect of metal oxide (Fe2O3) loading in different weight ratios (0.5%, 1%, 2%, and 4%) on the structural and electrical parameters, viz., the complex dielectric constant, electric modulus spectra, and the AC conductivity, of polymeric composites of PVDF/PMMA (30/70 weight ratio) blend. The structural and geometric measurements have been analyzed with the help of peak location, peak intensity, and peak shape obtained from XRD as well as from FTIR spectra. The electrical properties have been investigated using an impedance analyzer in the frequency range 100 Hz to 1 MHz. The real parts of the complex permittivity and the dielectric loss tangent of these materials are found to be frequency independent in the range from 20 KHz to 1 MHz, but they increase with the increase in the concentration of nano-Fe2O3. The conductivity also increases with an increased loading of Fe2O3 in PVDF/PMMA polymer blends. The electric modulus spectra were used to analyze the relaxation processes associated with the Maxwell-Wagner-Sillars mechanism and chain segmental motion in the polymer mix.

Impact of Variable Metal Oxide Loadings on Photocatalytic and Antibacterial Behaviour of CNT-NiO Nanocomposites

Impact of Variable Metal Oxide Loadings on Photocatalytic and Antibacterial Behaviour of CNT-NiO Nanocomposites

Controllable reduction of NiCoO2@NiCo core–shell nanospheres on CNTs for high-performance electrochemical energy storage

The performances of energy storage devices are strongly dependent on the electrode materials. Owing to the high theoretical capacity, NiCoO2 is a promising transition metal oxide for supercapacitors. Despite many efforts have been devoted, it still lacks of effective methods to overcome its shortcomings such as low conductivity and poor stability, in order to achieve its theoretical capacity. Herein, utilizing the thermal reducibility of trisodium citrate and its hydrolyzate, a series of NiCoO2@NiCo/CNT ternary composites in which NiCoO2@NiCo core–shell nanospheres deposited on CNT surface with adjustable metal contents are synthesized. Benefiting from the enhanced synergistic effect of both metallic core and CNTs, the optimized composite exhibits an extremely high specific capacitance (2660 F g−1 at 1 A g−1, the effective specific capacitance of the loaded metal oxide is 4199 F g−1, close to the theoretical value), an excellent rate performance and stability, when the metal content is about 37%. After depolarized calculation, the energy storage mechanism of the composite is reasonably analyzed. By controlling the contents of hexamethylenetetramine, trisodium citrate and CNTs in the reactant, the roles of them are distinguished. This study reveals an efficient novel strategy for transition metal oxides to maximize the electrochemical performances.

Efficient degradation of 2,3,5-trimethylpyrazine by catalytic ozonation over MnOx supported on biochar derived from waste tea leaves

In this study, a series of biochars derived from waste tea leaves and loaded with MnOx (Mn-nWT) was fabricated for use in heterogeneous catalytic ozonation (HCO). Excellent degradation of 2,3,5-trimethylpyrazine (TMP) was achieved. Characterization data indicated that Lewis acid sites, including multivalent Mn sites, oxygen vacancies and surface hydroxyl groups, were the main active sites responsible for the HCO activity of Mn-nWT. The Mn-nWT catalysts exhibited superior HCO activity compared with bulk biochar and MnOx under various experimental conditions. In particular, 0.05 g L−1 Mn-5WT gave 95.3% degradation of 5 μM TMP in 30 min at pH 7.0. Reactive oxygen species (mainly •OH) generated from catalytic decomposition of ozone by Mn-nWT contributed to the enhanced HCO performance. The second-order degradation rate constants of TMP with O3 and •OH are 2.3 ± 0.13 and (7.3 ± 1.31) × 109 M−1 s−1. The reusability and stability of Mn-5WT was demonstrated by outstanding TMP degradation efficiency (88.8%), negligible metal dissolution and minor differences in physical characterization after four cycles. Additionally, the impacts of water matrices (catalyst dose, ozone dose, pH, temperature, carbonate and natural organic matter) on the Mn-5WT HCO process were investigated thoroughly. This study found that loading of metal oxides onto biochar synergistically promoted the HCO process by enhancing the physical and chemical properties.

Sludge biochar as an electron shuttle between periodate and sulfamethoxazole: The dominant role of ball mill-loaded Mn2O3

In this study, a one-step solvent-free method using the ball milling technique was employed to prepare Mn2O3-loaded sludge biochar (BM-SBC/Mn2O3), and it was applied to the efficient activation of periodate (IO4−) to achieve rapid removal of sulfamethoxazole from the water column. A nearly two-fold improvement in the degradation rate of sulfamethoxazole (pseudo-first-order constants from 0.049 to 0.09 min−1) was achieved with only a small loading of Mn2O3 (the mass ratio of Mn2O3 and SBC was 1:6). The BM-SBC/Mn2O3 possessed excellent IO4− activation ability and achieved 95.3% removal efficiency of sulfamethoxazole within 30 min. The removal efficiency of sulfamethoxazole was maximized at an initial pH of 3 and was almost unaffected by the coexisting inorganic anions and humic acid. Mechanistic studies suggested that free radical (•OH) and non-radical pathways were collectively responsible for the removal of sulfamethoxazole, while the non-radical pathway of electron transfer was predominant. Ball milling loading of Mn2O3 improved the degree of defects in the catalyst and enhanced the electron transfer efficiency. This study advances the fundamental understanding of the underlying mechanisms involved in the process of IO4− activation catalyzed by ball milling loaded metal oxides onto sludge biochar.

Exploring the Multifunctionality of Mechanochemically Synthesized γ-Alumina with Incorporated Selected Metal Oxide Species

γ-Alumina with incorporated metal oxide species (including Fe, Cu, Zn, Bi, and Ga) was synthesized by liquid-assisted grinding-mechanochemical synthesis, applying boehmite as the alumina precursor and suitable metal salts. Various contents of metal elements (5 wt.%, 10 wt.%, and 20 wt.%) were used to tune the composition of the resulting hybrid materials. The different milling time was tested to find the most suitable procedure that allowed the preparation of porous alumina incorporated with selected metal oxide species. The block copolymer, Pluronic P123, was used as a pore-generating agent. Commercial γ-alumina (SBET = 96 m2·g-1), and the sample fabricated after two hours of initial grinding of boehmite (SBET = 266 m2·g-1), were used as references. Analysis of another sample of γ-alumina prepared within 3 h of one-pot milling revealed a higher surface area (SBET = 320 m2·g-1) that did not increase with a further increase in the milling time. So, three hours of grinding time were set as optimal for this material. The synthesized samples were characterized by low-temperature N2 sorption, TGA/DTG, XRD, TEM, EDX, elemental mapping, and XRF techniques. The higher loading of metal oxide into the alumina structure was confirmed by the higher intensity of the XRF peaks. Samples synthesized with the lowest metal oxide content (5 wt.%) were tested for selective catalytic reduction of NO with NH3 (NH3-SCR). Among all tested samples, besides pristine Al2O3 and alumina incorporated with gallium oxide, the increase in reaction temperature accelerated the NO conversion. The highest NO conversion rate was observed for Fe2O3-incorporated alumina (70%) at 450 °C and CuO-incorporated alumina (71%) at 300 °C. The CO2 capture was also studied for synthesized samples and the sample of alumina with incorporated Bi2O3 (10 wt.%) gave the best result (1.16 mmol·g-1) at 25 °C, while alumina alone could adsorb only 0.85 mmol·g-1 of CO2. Furthermore, the synthesized samples were tested for antimicrobial properties and found to be quite active against Gram-negative bacteria, P. aeruginosa (PA). The measured Minimum Inhibitory Concentration (MIC) values for the alumina samples with incorporated Fe, Cu, and Bi oxide (10 wt.%) were found to be 4 µg·mL-1, while 8 µg·mL-1 was obtained for pure alumina.

Hydrogen Peroxide Production by Inorganic Photocatalysts Consisting of Gold Nanoparticle and Metal Oxide toward Oxygen Cycle Chemistry

Hydrogen peroxide (H2O2) is not only a versatile clean and strong oxidant but also a promising fuel for fuel cells. This Feature Article has shown that gold nanoparticle (NP)-loaded metal oxides (Au/MOs) can be promising photocatalysts for H2O2 production via two electron-oxygen reduction reaction (2e–-ORR). The fundamental parts deal with the general requirements for the H2O2 synthesis, electrocatalytic activity of Au NPs for 2e–-ORR, Fermi level control of the Au NP of Au/MOs in the dark and under light irradiation, and the factors for governing the catalytic activity for H2O2 production. Subsequently, an artificial photosynthesis of H2O2 from water and O2 under visible light irradiation at ambient temperature and pressure is described. Finally, the conclusions are summarized with a direction of the future research on the hot topics.

Insights into the reaction mechanism of toluene oxidation by isotope dynamic experiment and the kinetics over MCeZr/TiO2 (M = Cu, Mn, Ni, Co and Fe) catalysts

Catalytic properties of multiple metals deposited on TiO2 nanoparticles were investigated in the oxidation of toluene. Isovolume impregnation method prepared the catalysts containing Cu, Mn, Ni, Co, and Fe deposited on TiO2, including CeO2 and ZrO2. The effects of loaded metal oxides on the structure and activity of initial catalysts were investigated using various characterization techniques. Toluene's removal efficiency and CO2 selectivity in the catalyst system were classified as follows: CuCeZr/T > MnCeZr/T > NiCeZr/T > CoCeZr/T > FeCeZr/T. Presence of water vapor exhibits an inhibitory effect on the conversion of toluene, which diminishes at higher temperatures. One contribution of this paper is to obtain the oxidation pathway of toluene and the relationship between the activation energy of all-inclusive and elementary reactions based on the variation of infrared spectrum using Freeman-Carroll method. Another contribution is to clarify the share of Langmuir-Hinshelwood and Mars-van Krevelen mechanisms during the oxidation of toluene over CuCeZr/T catalyst by transient response experiments of isotopically labeled oxygen. These findings provide a feasible method for the design and synthesis of transition metal oxide catalysts for industrial applications.

Synergistic role of metal oxide loading cocatalysts on photocatalytic degradation of organic pollutants and inactive bacteria over template-free ZnFe2O4 nanocubes

For wastewater treatment, a highly reliable and ecologically friendly oxidation method is always preferred. This work described the production of a new extremely effective visible light-driven Ag2Ox loaded ZnFe2O4 nanocomposties photocatalyst using a wet impregnation technique. Under visible light irradiation, the produced Ag2Ox loaded ZnFe2O4 nanocomposties were used in the photodegradation of rhodamine B (RhB) and Reactive Red 120 (RR120) dyes. Analysis using X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy revealed that Ag2Ox nanoparticles were well dispersed on the surface of ZnFe2O4 NPs and that the Ag2Ox loaded ZnFe2O4 NPs were created. When compared with bare ZnFe2O4 NPs, Ag2Ox-loaded ZnFe2O4 nanocomposites showed better photocatalytic activity for RhB and RR120 degradation under visible light (>420 nm) illumination. The reaction kinetics and degradation methodology, in addition to the photocatalytic degradation functions of Ag2Ox-loaded ZnFe2O4 nanocomposites, were thoroughly investigated. The 3 wt% Ag2Ox loaded ZnFe2O4 nanocomposites have a 99% removal efficiency for RhB and RR120, which is about 2.4 times greater than the ZnFe2O4 NPs and simple combination of 1 wt% and 2 wt% Ag2Ox loaded ZnFe2O4 nanocomposites. Furthermore, the 3 wt% Ag2Ox loaded ZnFe2O4 nanocomposites demonstrated consistent performance without decreasing activity throughout 3 consecutive cycles, indicating a potential approach for the photo-oxidative destruction of organic pollutants as well as outstanding antibacterial capabilities. According to the findings of the experiments, produced new nanoparticles are an environmentally friendly, cost-efficient option for removing dyes, and they were successful in suppressing the development of Gram-negative and Gram-positive bacteria.

MgFe2O4-loaded N-doped biochar derived from waste cooked rice for efficient low-temperature desulfurization of H2S

To improve their low-temperature desulfurization performance, the activated carbon-based materials have typically been modified by either metal oxide loading or nitrogen doping. However, most of the aforementioned materials are limited to only one of the above modification methods, resulting in relatively poor desulfurization performance. Herein, a novel MgFe2O4-loaded N-doped biochar (MgFe2O4@NBC) was fabricated by one-pot pyrolysis of a nitrogen containing precursor of g-C3N4, cooked rice waste, and metal salts for efficient low-temperature desulfurization of H2S. Different fabrication conditions such as pyrolysis temperature and the nitrogen mixing ratio (i.e., the mass ratio of cooked rice waste to g-C3N4) have been extensively studied. The optimized MgFe2O4@NBC-500–2 sample delivered a superior breakthrough capacity of 1052.83 mg/g in an atmosphere of O2 content of 20% and relative humidity of 80% at 25 °C, and demonstrated high tolerance and stability of desulfurization performance to harsh environmental conditions with 80% relative humidity and no oxygen. The desulfurization mechanism of H2S on the surfaces of the MgFe2O4@NBC composites was attributed to the synergistic effects of reactive adsorption and catalytic oxidation process. The composite also demonstrated excellent reusability, retaining 85% of the initial breakthrough capacity after 5 recycled uses. Therefore, the as-prepared MgFe2O4@NBC composite offers a potentially promising carbon-based desulfurizers for practical applications in the low-temperature desulfurization field.