[en] An investigation was conducted to assess the ability of three species of brown-rot fungi to decolorize and transform methyl orange dye. Methyl orange was decolorized in a potato dextrose agar medium by Fomitopsis pinicola, Gloeophyllum trabeum, and Daedalea dickinsii at different concentrations of 50, 75, and 100 mg L⁻¹. Based on the values of the decolorization index, the highest methyl orange decolorization was found approximately 91% by F. pinicola, followed by D. dickinsii and G. trabeum of 82% and 76%, respectively, at a concentration of 50 mg L⁻¹. F. pinicola had the highest methyl orange transformation with percent decolorization values of approximately 97%, followed by D. dickinsii and G. trabeum of 93% and 67%, respectively, after a 14-day incubation period in potato dextrose broth. F. pinicola transformed methyl orange into six metabolic products: compounds 3, 6, 7, 8, 9, and 10, while G. trabeum transformed methyl orange into five metabolic products: compounds 1, 2, 3, 4, and 5. Among brown-rot fungi, D. dickinsii had more metabolic products, with compounds 3, 4, 6, 11, 12, 13, 14, 15, 16, 17, and 18. Based on the identification of metabolic products, novel bio-transformation was proposed that brown-rot fungi initially transformed methyl orange via three pathways: (1) demethylation, (2) desulfonylation, and (3) hydroxylation. This study indicated that brown-rot fungi can be used to decolorize and transform methyl orange dye as well as proposed novel bio-transformation of methyl orange by brown-rot fungi.

[en] ZnO/Nickel (ZnO/Ni) heterostructures have been studied extensively as potential hybrid materials for photocatalysis applications due to their unique properties and potential applications. The photocatalytic efficiency of ZnO alone is compromised by its wide bandgap energy and high exciton binding energy. To enhance the effectiveness and photostability of ZnO nanoparticles, they can be doped with other elements such as transition metals, non-metals, and noble metals. Herein, we report a facile ultrasonic-assisted chemical mixing technique to prepare ZnO/Ni composite photocatalyst at various weight percentage (10 – 50%). Photocatalytic ability of as synthesized samples was examined for the degradation of methyl orange dye. The ZnO/Ni composite has been characterized by X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM) and Energy-dispersive X-ray (EDX) spectroscopy. It is found that the 10 wt.% ZnO/Ni composite produce the highest photocatalytic efficiency with percentage degradation of 89.17% and photodegradation rate constant of 0.0285 min^-1 compared to other samples. These results suggest that the introduction of Ni acts as an electron sink, promoting charge separation in ZnO results in efficient light absorption and enhanced the photocatalytic activity The enhanced photocatalytic ability of ZnO/Ni composite make it a potential candidate for removal of organic pollutants from wastewater. (author)

[en] Highlights: • Z-scheme Bi₂WO₆/ZnIn₂S₄ composites show enhanced photocatalytic activity. • Zero-order kinetics and pseudo-first-order kinetics are observed at different stages of MO degradation. • Photocatalyst shows high degradation efficiency towards a different class of contaminants. As a potential candidate photocatalyst, high carrier recombination rate of ZnIn₂S₄ limits its application, and it is necessary to improve its performance by constructing suitable structure. In this study, Bi₂WO₆/ZnIn₂S₄ composites with Z-scheme structure were successfully prepared, and they show enhanced photocatalytic performance. The BWO/ZIS-2 shows the highest photocatalytic efficiency of 97.5% within 60 min for degrading methyl orange (MO), and maintain an efficiency of more than 90% after five reuses. Moreover, BWO/ZIS-2 can degrade various organic pollutants without selectivity. Rapid transfer of carriers inhibits the recombination of e⁻ and h⁺, which is responsible for high photocatalytic activity of Bi₂WO₆/ZnIn₂S₄.

[en] In this paper, we report degradation of methyl orange, an azo dye through silver nanoparticles, with the help of UV-Visible spectroscopy. These silver nanoparticles have been found to act as a potential catalyst for the degradation of methyl orange in the presence of sodium borohydride. Rate constants for the catalyzed and uncatalyzed reaction have been determined. The catalyzed reaction spectrum shows a sudden fall in absorbance value confirming catalytic effect of Ag nanoparticles. No significant change in absorbance in case of uncatalyzed reaction is observed, indicating very slow reduction rate of methyl orange. (author)

[en] Highlights: • Multi-walled carbon nanotubes were functionalized with cysteamine groups. • The adsorption of methylene blue and orange dyes was investigated on these surfaces. • The effect of temperature, contact time and initial concentration was considered. • The optimal contact time was found to be about 60 min. • Kinetic of the adsorption process was explored. Multi-walled carbon nanotubes (MWCNTs) were functionalized with cysteamine groups by several percentage of mass as adsorbents, then kinetics adsorption capacity was investigated for methylene blue (MB) and methyl orange (MO) as anionic and cationic dyes adsorbate molecules, respectively. The effect of temperature (from 283 to 303 K), contact time and initial concentration of the MB and MO dyes in a solution (10 to 40 ppm) was considered. The optimal contact time was found to be about 60 min. Some kinetics model such as pseudo-first-order, pseudo-second-order, intra-particle diffusion and the Elovich were tested. The adsorptions of MB dye on the pristine and functionalized MWCNT surfaces were found to be the intra-particle diffusion and the pseudo-second-order kinetic model, respectively and for adsorption of MO dye by the pristine and low functionalized MWCNTs and highly functionalized tubes, found to be the pseudo-second-order and intra-particle diffusion kinetic model, respectively, based on the chi-square statistic (X²) and also high correlation coefficient (R²) values.

[en] Highlights: • ZnO/SnO₂ nanocomposites as photocatalysts were synthesized by co-precipitation. • The ZnO/SnO₂ nanocomposites showed enhanced photocatalytic activities. • The enhanced photo-degradation of MO was corresponded to better charge separation. • Super oxide radicals and photo-generated holes were involved in photo-degradation of MO.

[en] Naturally abundant bentonite clay minerals have high cation exchange capacity (80–120 meq/g), greater surface area, enhanced swelling properties with micro and meso-porosity. However, their hydrophilic surface limits their adsorption ability. In the present study, bentonite clay (BT) was modified with a cationic surfactant by using cation exchange reaction to modify its surface from hydrophilic to hydrophobic; thus making it a better adsorbent for the removal of pollutants from contaminated water. The modified clay was characterized through fourier transform infrared spectroscopy, and thermo gravimetric analysis. It was used as an adsorbent for the removal of methyl orange and deltamethrin from aqueous solutions. The results showed that modified bentonite has strong tendency to remove organic pollutants from water. About 97% removal of methyl orange was observed with surfactant modified bentonite in contrast to only 56% removal with unmodified bentonite. Similarly, modified bentonite removed up to 98% deltamethrin as compared to only 47% removal with unmodified bentonite. Kinetic study of both experiments showed that the absorption process follows a pseudo second order equation. (author)

[en] In this work, we perform the study of zinc oxide hierarchical structures synthesized by the low-temperature hydrothermal method. The paper considers morphological properties of obtained structures. Photocatalytic activity of samples was analysed by methyl orange degradation under UV irradiation. The sufficient decrease in methyl orange has been demonstrated. (paper)

[en] The sorption capacity of carbon-mineral sorbents for Cu(II) ions, methyl orange, and iodine was studied. The optimal carbonization temperature for 100:5, 100:10, and 100:20 mixtures was 600°C, which agreed with experimental IR spectroscopic, elemental analytical, and modern thermal analytical data for carbonized saprope-bentonite-clay mixtures. The carbon-mineral sorbent prepared by carbonization of 100:5 saprope-bentonite-clay mixture showed high maximum adsorption for Cu(II) ions, methyl orange, and iodine. The volumes of meso- and micropores of all studied sorbents were determined using molecular probes. Carbon-mineral sorbents prepared by carbonization of saprope-bentonite-clay mixtures at 600°C in an oxidizing medium were found to be meso-macroporous.The sorption capacity of carbon-mineral sorbents for Cu(II) ions, methyl orange, and iodine was studied. The optimal carbonization temperature for 100:5, 100:10, and 100:20 mixtures was 600°C, which agreed with experimental IR spectroscopic, elemental analytical, and modern thermal analytical data for carbonized sapropel—bentonite-clay mixtures. The carbon-mineral sorbent prepared by carbonization of 100:5 sapropel—bentonite-clay mixture showed high maximum adsorption for Cu(II) ions, methyl orange, and iodine. The volumes of meso- and micropores of all studied sorbents were determined using molecular probes. Carbon-mineral sorbents prepared by carbonization of sapropel—bentonite-clay mixtures at 600°C in an oxidizing medium were found to be meso-macroporous.

[en] Highlights: • Largely enhanced photocatalytic properties in the visible light region. • The shape-controlled Cu₂O crystals are obtained by adjusting the reaction condition. • A plausible growth mechanism of Cu₂O nanostructures was proposed. An interesting evolution to prepare shape-controlled Cu₂O nanocrystals was realized by a convenient one pot synthesis. The Cu₂O nanocrystals with different shapes can be obtained simply by adjusting the composition of reaction system. And, a plausible mechanism was also proposed to explain the nanostructures formation. The surface of Cu₂O spheres with thorn exhibited high photocatalytic activity on the degradation of methyl orange (MO) solution under visible light irradiation. The photodegradation efficiency of MO solution reach up to 99.67% at the first 10 min. It is still as high as 98% even at the end of the fourth cycle.