Magnetically Responsive Janus Nanoparticles with Catalytic Properties for the Treatment of Methyl Orange Wastewater

The heterogeneous beta-supported transition metal catalysts were prepared by incipient wetness impregnation. The catalytic oxidation degradation of methyl orange was carried over the heterogeneous catalyst in the peroxide catalytic oxidation process. The pure beta materials showed quick adsorption equilibrium characterization, and the adsorption ratio was only 30%. Compared with the adsorption of the pure beta carrier, the Cu/beta and Fe/beta catalyst could effectively degrade methyl orange with high catalytic activity and easy catalyst separation from the solution using hydrogen peroxide as oxide. The methyl orange removal efficiency could reach 99% in the optimum experimental conditions. The optimal mental content for Cu, Ag, Mn, Fe and Co was 5%, 8%, 0.3%, 1% and 0.3%, respectively.

In the last few years, metal nanoparticles (NPs) have become one of the major components in the field of nanotechnology. NPs with fascinating and tunable properties (size and shape) have provided solutions for many problems including water pollution which has now become alarming in the current era. Herein, natural polymer-supported AgSr bimetallic NPs have been synthesized. For this purpose, sodium alginate (Na-Alg) was used as a stabilizer along with sodium borohydride (NaBH4) as a reducing agent. The synthesized Na-Alg-supported AgSr NPs were characterized employing UV–Vis, FTIR, SEM, and XRD techniques. The spectrophotometric analysis confirmed the formation and SEM and XRD confirmed the size of NPs up to 24.18 and 12.95 nm, respectively. These NPs were tested for catalytic degradation potential against malachite green (MG) and methyl orange (MO) dyes in the aqueous medium. The catalytic activity of NPs was evaluated in terms of kinetics and percent removal of the dyes. The results revealed that the MO dye was degraded in 21 min with a removal efficiency of 86.45% and MG dye in 24 min with 91.74%. Catalytic degradation of MO and MG dyes was also monitored in the absence of AgSr NPs which showed no catalytic degradation of dyes even after half an hour. The study has confirmed that biopolymer-supported NPs can be synthesized with suitable morphology for catalytic applications and these NPs can be further used for the removal of dyes from aqueous medium.

This work focuses on the microwave enhanced catalytic degradation of methyl orange (MO) in aqueous solution over CuO/CeO2 catalyst in the absence and presence of H2O2. The prepared CuO/CeO2 catalysts were characterized with X-ray diffraction, Brunnauer-Emmett-Teller analysis, temperature-programmed reduction, and temperature-programmed desorption techniques to elucidate the effect of calcination temperature on its properties and catalytic performance. The results show that calcination temperature exerts remarkable influence on the catalytic performance of CuO/CeO2, with that calcined at 300 °C displaying the highest MO degradation ability. On the basis of Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, and X-ray photoelectron spectroscopy measurement results, the mechanism of MO degradation under microwave irradiation in the presence of both CuO/CeO2 and H2O2 was suggested. A synergistic rather than additive effect of catalyst, microwave irradiation, and H2O2 contributes to the high degradation activity toward MO.

Herein, a series of ZnO-doped lignin-based carbons (LC/ZnO) were successfully prepared from different types of lignin and used for methyl orange (MO) photocatalytic degradation. The apparent morphology, internal structure, and photoelectric properties of prepared LC/ZnO composites and their effects on subsequent MO photocatalytic degradation were investigated by various characterization techniques. The results showed that the LC/ZnO composites that were prepared in this work mainly consisted of highly dispersed ZnO nanoparticles and lignin-based carbon nano-sheets, which were beneficial for subsequent photogenerated electrons and holes formation, dispersion, and migration. The MO could be significantly degraded with various ZnO-doped lignin-based carbons, especially over the LCSL/ZnO, and the maximum degradation rate was 96.9% within 30 min under the simulated 300w sunlight exposure. The experiments of free radical elimination showed that the photocatalytic degradation of MO over LC/ZnO were a result of the co-action of multiple free radicals, and h+ might play the predominant roles in MO degradation. In addition, the pH of the solution had little effect on MO degradation, and the MO could be effectively degraded even in an alkaline solution of pH = 12.0. The cycling experiments showed that the prepared LC/ZnO had a good stability for MO photodegradation, especially for LCSL/ZnO, even after 5 times recycling, and the degradation rate of MO only dropped from 97.0% to 93.0%. The research not only provided a fundamental theory for the efficient photocatalytic degradation of MO by LC/ZnO composites, but also offered a new insight into lignin valorization.

Green synthesis of nano silver from euphorbia geniculata leaf extract: Investigations on catalytic degradation of methyl orange dye and optical sensing of Hg2+

Enhanced photo-Fenton degradation performance over multi-metal co-supported SAPO-18 zeolites by promoted active species yield

The efficiency of two catalysts (TiO 2 and TiO 2 supported on zeolite) for the photocatalytic degradation of methyl orange dye and wastewaters from Ethiopian textile industry was evaluated by chemometric methods from UV/Vis data of the reaction mixtures at different times. Multivariate curve resolution statistical analysis combined with an alternating least squares algorithm (MCR-ALS) proved to be an efficient method to resolve the different intermediates present during the photocatalytic degradation of the pollutants and to provide information about their evolution with time. Methyl orange photodegradation at pH = 3 showed different intermediate and concentration profiles than at pH = 6. The evolution of intermediates from textile wastewater photodegradation could also be resolved by this method. From the concentration profile or the reactants, a kinetic study was done. Results revealed that all the photodegradation reactions followed a first order kinetics. When TiO 2 supported in Zeolite is used, reactions are in general slower, probably due to a mechanism of adsorption/desorption. KEY WORDS : Chemometrics, Dye photodegradation, Wastewater, MCR-ALS, Methyl Orange Bull. Chem. Soc. Ethiop. 2017 , 31(2), 223-232. DOI: http://dx.doi.org/10.4314/bcse.v31i2.4

An innovative laboratory scale unit was used to carry out UV photoinduced catalytic degradation of methyl orange. For this purpose, the experimental system was made of a bottom and an upper reservoir (∼120 L each) which were connected by an inclined channel through which water was recirculated. TiO2 (Anatase) was deposited (∼10–2 mg/cm2) at the bottom of the connecting channel while the Methyl Orange solution was exposed to the UVB radiation (λ ≈ 300 nm) during its recirculation through the connecting channel.The unit was first characterized from both the hydrodynamic and the hydraulic points of view. Photodegradation kinetics were followed by UV–vis absorption measurements of the residual methyl orange solution concentration along time, and the synergic effect of the catalyst and the intensity of the UV radiation in promoting degradation of the substrate was demonstrated. The abatement efficiency of the UV/TiO2 system toward methyl orange was evaluated in the concentration range 0.3–8.5 mg/L. Kinetic patterns were described by first (or pseudofirst) order theoretical models up to the concentration of 0.7 mg/L, whereas at higher concentrations kinetic trends were better described by zero-order models independently from the substrate concentration in the liquid-phase. The proposed solution, after an upscale field investigation, may represent a valuable alternative to the methods conventionally used for the abatement of textile dyes from wastewater, that is, water clarification, reverse osmosis, activated carbon sorption, and biosorption.

Although classical homogeneous Fenton reaction systems (FeII + H2O2) are widely used for organic pollutant degradation, this technology has important shortcomings such as waste generation and difficult Fe2+ recycling. These shortcomings originate secondary pollution issues and make it difficult to control the reactions. Polyoxometalates (POMs) are characterized by bearing large electron‐donating conjugate systems able to stabilize Fe2+. To explore a new kind of heterogeneous Fenton reagent, we prepared a new‐type of stable heterogeneous Fenton reagent, (H3O)3.5(H3DETA)3.5{FeII[H4MoV6O15(PO4)4]2} (DETA = diethylenetriamine) (1) by inserting FeII into the POMs. The sandwich‐type 1 was excited by ultraviolet (UV) light, showed high efficiency as a solid‐phase Fenton catalyst, and can be potentially recycled to control the reactions. The coordinating reaction mechanisms for the catalytic degradation of methyl orange (MO) over the 1 + H2O2 reaction system was studied, including photocatalysis and Fenton oxidation effects. As a contrast, another new phosphomolybdate, (H3DETA)4{ZnII[H5MoV6O15(PO4)4]2}·7.5H2O (2), which has the same sandwich‐type polyanion but ZnII acting as the sandwich‐atom, has also been synthesized, characterized. The comparative study of photocatalytically degrading MO has also been carried out. In addition, by studying the thermal decomposition behavior of 1, we revealed, for the first time, the presence of Mo4P3 as a decomposition residue of 1.

In order to improve the catalytic degradation property of α-FeOOH, α-FeOOH was doped with sodium silicate. The α-FeOOH doped with silicon was used as catalyst to catalyze the degradation of methyl orange. The XRD spectra showed that the crystalline phase of α-FeOOH doped with silicon was same as that of α-FeOOH; The catalytic degradation property of α-FeOOH doped with silicon was 21.7% higher than that of α-FeOOH; The results showed that catalytic degradation of methyl orange was almost degraded thoroughly at the conditions that the concentration of α-FeOOH doped with silicon in the solution was 0.73 g/L, the concentration of H2O2 was 0.231 mmol/L. The pH value was between 2 and 3, and the degradation reaction was carried out at 60 oC for at least 20 min.

Metal oxides as dual-functional adsorbents/catalysts for Cu2+/Cr(VI) adsorption and methyl orange oxidation catalysis

Microwave-assisted catalytic degradation of methyl orange in aqueous solution by ferrihydrite/maghemite nanoparticles

Enhanced degradation of an azo dye by catalytic ozonation over Ni-containing layered double hydroxide nanocatalyst

The degradation of organic dyes poses a significant challenge in achieving sustainable environmental solutions, given their extensive usage across various industries. Iron oxide (Fe2O3) nanoparticles are studied as a reliable technique for remediating dye degradation. The objective of this research is to improve methods of nanomaterial-based environmental remediation. The solvothermal technique is used to synthesize carbon-modified Fe2O3 nanoparticles that exhibit the capability to modify their size morphology and increase reactivity, and stability for MO photodegradation. Their inherent qualities render them highly advantageous for biomedical applications, energy storage, environmental remediation, and catalysis. The mean crystallite size of the modified Fe2O3 nanoparticles is approximately 20 nm. These photocatalysts are tested for their ability to degrade methyl orange (MO) under Visible light radiation and in presence of hydrogen peroxide reagent. The optimal degradation efficiency (97%) is achieved with Fe2O3@C in the presence of H2O2 by meticulously controlling the pH, irradiation time, and photocatalyst dosage. The enhanced photocatalytic activity of the Fe2O3@C nanoparticles, compared to pure Fe2O3, is attributed to the conductive carbon layer, which significantly reduces electron-hole recombination rates. To summarize, Fe2O3@C nanoparticles not only offer a promising technique for the degradation of MO dye pollutants but also have an advantage for environmental remediation due to their increased stability and reactivity.

An ultrasound-assisted advanced oxidation process (AOP) has been demonstrated for sonocatalytic degradation of methyl orange (MO) with Fe3O4/polyaniline (Fe3O4/PANI) microspheres in near neutral solution (pH ∼6). The Fe3O4/PANI microspheres were characterized with XRD, SEM, TEM, FT-IR, XPS, and ζ-potential measurements, and were further tested in the role of adsorption and sonocatalytic decolorization of MO in solution. The isotherms and kinetics of MO adsorption with Fe3O4/PANI follow the Langmuir model and the pseudo-second-order model, respectively. The kinetics of sonocatalytic decolorization of MO with Fe3O4/PANI conforms to a combinational model involving the pseudo-second-order adsorption model and the pseudo-first-order degradation model, since Fe3O4/PANI has a high capacity to adsorb MO in solution. The percentage of room-temperature sonocatalytic degradation of MO with Fe3O4/PANI is about 4.8, 8.8, and 5.7 times that with Fe3O4, dedoped Fe3O4/PANI, and ultrasonication alone, respectively. The ec...