Preparation of re-usable photocatalytic filter for degradation of Malachite Green dye under UV and vis-irradiation

Micron sized anionic poly (methacrylic acid) microgel particles for the adsorptive elimination of cationic water pollutants

In this article, we reported the micron sized particles of poly (methacrylic acid) (p [MAA]) microgel and explored their applications as anionic adsorbents. The micron sized particles of poly (methacrylic acid) microgel were prepared by a simple inverse suspension polymerization method. The adsorptive elimination of adsorbates of cationic nature including malachite green (MG) and methylene blue (MB) from the aqueous medium was studied systematically. The adsorption tests were carried out using various initial concentrations of dyes and with different amounts of adsorbents. The adsorption equilibrium was established in 60 min. The adsorption capacity of the p (MAA) microgel was found as high as 351 mg/g for MG and 65 mg/g for MB. The maximum removal percentage for MG and MB was recorded as 88 and 68%, respectively. The adsorption data was computed with adsorption isotherm models including Langmuir, Freundlich, and Temkin. The Langmuir model was observed to be more applicable for the adsorption of MG while the adsorption of MB was best matched with Temkin model. The adsorption data was also treated with pseudo first order and pseudo second order kinetic models along with intraparticle diffusion and Elovich models. The pseudo second order kinetic model was most suitable with adsorption of both the MG and MB.

GC/MS screening of buckthorn phytochemicals and their use to synthesize ZnO nanoparticles for photocatalytic degradation of malachite green dye in water

Zinc oxide nanoparticles (ZnO NPs) were biosynthesized. According to gas chromatography/mass spectrometry analysis, chalcone, the main phytochemical, is probably complexed with Zn ions that are then oxidized to ZnO NPs by atmospheric O₂ during heating. The ZnO NPs were characterized by thermogravimetric analysis, Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and Brunauer-Emmett-Teller surface area analysis. Sphere-like ZnO NPs were formed with 11 nm mean crystallite size, 5.2 m² g^-1 surface area, and 0.02 cm³ g^-1 total pore volume. The synthesized ZnO showed excellent photocatalytic degradation (96.5±0.24% in 1 hour at 25 °C) of malachite green (MG) in aqueous solutions under ultraviolet light at optimum conditions; pH 10, MG initial concentration of 20 mg L^-1, and ZnO dose of 1.5 g L^-1. Also, ZnO showed very good reusability (92.9± 0.2% after five runs). The experimental data obeyed pseudo-first-order kinetics (R² = 0.92). The photocatalysis process was dependent on the following species in the order: OH^. > electron/positive hole pairs > O₂^.-. Moreover, photodegradation efficiency decreased in the presence of CO₃^2-, HCO₃^-, and Cl^-, but increased in the presence of NO₃^- and SO₄^2- ions. Thus, the green synthesized ZnO NPs can be applied as an efficient photocatalyst for the removal of MG from aqueous media.

Pathway and kinetics of malachite green biodegradation by Pseudomonas veronii

Malachite green is a common environmental pollutant that poses a great threat to non-target organisms, including humans. This study reports the characterization of a bacterial strain, Pseudomonas veronii JW3-6, which was isolated from a malachite green enrichment culture. This strain degraded malachite green efficiently in a wide range of temperature and pH levels. Under optimal degradation conditions (32.4 °C, pH 7.1, and inoculum amount of 2.5 × 10⁷ cfu/mL), P. veronii JW3-6 could degrade 93.5% of 50 mg/L malachite green within seven days. Five intermediate products from the degradation of malachite green were identified: leucomalachite green, 4-(dimethylamino) benzophenone, 4-dimethylaminophenol, benzaldehyde, and hydroquinone. We propose a possible degradation pathway based on these findings. The present study is the first to report the degradation of malachite green by P. veronii and the identification of hydroquinone as a metabolite in the degradation pathway.

Synthesis of panos extract mediated ZnO nano-flowers as photocatalyst for industrial dye degradation by UV illumination

Green synthesis of zinc oxide has gained extensive attention as a reliable, sustainable, and eco-friendly protocol to reduce the destructive effects associated with the traditional synthesis methods commonly utilized in laboratory and industry. Here for the first time, we have synthesized quaker ladies flower type ZnO (ZnO/QNF) from panos extract (extract from four panax plants such as Panax ginseng, Acanthopanax senticosus, Kalopanax septemlobus and Dendropanax morbifera). The synthesized ZnO materials was characterized using powder X-ray diffraction, Fourier infrared spectroscopy, X-ray photoelectron spectroscopy and Transmission electron microscope. The newly synthesized ZnO/QNF was applied for the removal of industrial dyes such as methylene blue (MB), Eosin Y (EY) and Malachite green (MG) under UV illumination. The photocatalyst degraded the 15 mg L^-1 MB, EY and MG to >99% within 80, 90 and 110 min of contact time, respectively. In addition, the ZnO/QNF photocatalyst removed the low concentrated 5 mg L^-1 of MB, EY, and MG within 30, 35 and 40 min of contact time, respectively. The pedal structure provided all the active sites available for the easy interaction with dye molecule under UV, and that enabled fast kinetics of dye degradation than the many other benchmark materials reported previously. The ZnO photocatalyst could be reused minimum of five cycles without any significant loss in degradation efficiency.

Synthesis of samarium-doped zinc oxide nanoparticles with improved photocatalytic performance and recyclability under visible light irradiation

Samarium-doped ZnO nanoparticles (1%, 3%, and 5%) were synthesized by a gel-combustion route and their application as an efficient photocatalyst for the degradation of Malachite green (MG) dye is demonstrated.

Fabrication of a reusable magnetic multi-walled carbon nanotube–TiO2 nanocomposite by electrostatic adsorption: enhanced photodegradation of malachite green

A simple, quick and efficient method for the fabrication of a magnetic multi-walled carbon nanotube–TiO₂ (MMWCNT–TiO₂) nanocomposite through electrostatic attraction was proposed as a novel method.

Spectroscopic studies on the oxidative decomposition of malachite green using ozone

Spectroscopic studies on the oxidative decomposition of Malachite Green (MG) using ozone were investigated. Parameters such as color removal, initial dye concentration, COD reduction, reaction temperature and pH were studied to determine optimum conditions for complete MG decomposition. Complete removal of MG color was achieved within 10 min of reaction with ozone. The ozone oxidation reaction time increased as concentration of MG increases, inferring, there would be increase in MG removal as concentration decreases. COD reduction was observed as reaction time increases and the rate of reaction monotonically increased as temperature increases. From the spectroscopic analysis of the intermediates and the by-products of MG reaction with ozone, a tentative mechanistic approach of MG decomposition was postulated. It was also observed that after five minutes of ozone oxidation, color removal rate in the wastewater containing Malachite Green obtained from a small scale local dyeing industry reached almost 90%.

Photocatalytic antibacterial performance of Sn(4+)-doped TiO(2) thin films on glass substrate

Pure anatase, nanosized and Sn(4+) ion doped titanium dioxide (TiO(2)) particulates (TiO(2)-Sn(4+)) were synthesized by hydrothermal process. TiO(2)-Sn(4+) was used to coat glass surfaces to investigate the photocatalytic antibacterial effect of Sn(4+) doping to TiO(2) against gram negative Escherichia coli (E. coli) and gram positive Staphylococcus aureus (S. aureus). Relationship between solid ratio of TiO(2)-Sn(4+) in coatings and antibacterial activity was reported. The particulates and the films were characterized using particle size analyzer, zeta potential analyzer, Brunauer-Emmett-Teller (BET), X-ray diffractometer (XRD), SEM, AAS and UV/VIS/NIR techniques. The results showed that TiO(2)-Sn(4+) is fully anatase crystalline form and easily dispersed in water. Increasing the solid ratio of TiO(2)-Sn(4+) from 10 to 50% in the coating solution increased antibacterial effect.