Metronidazole is well-known antibiotic which, globally, ranks high in popular usage. Therefore, traces of residues of this antibiotic were identified in aquatic bodies. A photosynthetic cyanobacterium, of the microalgae category, S. platensis, has been found to be efficient in the removal of this antibiotic. This study was performed to evaluate the efficiency of S. platensis in the removal of metronidazole from aqueous environments. To set up the optimum conditions for facilitating metronidazole removal, BBD model was employed. The experiment included the following parameters: the initial metronidazole level (10–80 mg/L), pH (4–10), contact time (10–60 min), and biomass dose (0.1–0.5 g/L). From the findings it was evident that S. platensis was able to remove 88.15% of the metronidazole under the following conditions: contact time 38.05 min, metronidazole level 35 mg/L, pH 7.71 and a biomass dose 0.3 g/L. The quadratic model revealed that metronidazole concentration was the chief variable that influenced its removal rate. MNZ removal rate was observed to follow the pseudo-second-order model and the Freundlich model. From the thermodynamic data it appeared that the process of metronidazole biosorption was spontaneous, exothermic and physical. The results of this study revealed that S. platensis could be used as an inexpensive and efficient biosorbent to remove the metronidazole from aqueous solutions.

The present study explores the solar-induced photocatalytic degradation of reactive red (RR) and reactive turquoise (RT) dyes in a single system using TiO₂ immobilized in xanthan gum (TiO₂/XG), synthesized using the sol–gel dip-coating technique for direct precipitation. SEM-EDX, XRD, FTIR, and UV–Vis were used to assess the characteristics of the resulting catalyst. Moreover, the effects of different operating parameters, specifically pH, dye concentration, TiO₂/XG concentration, H₂O₂ concentration, and contact time, were also investigated in a batch photocatalytic reactor. The immobilized TiO₂/XG catalyst showed a slight adsorption degradation efficiency and then improved the RR and RT dye degradation activity (92.5 and 90.8% in 120 min) under solar light with a remarkable Langmuir–Hinshelwood pseudo-first-order degradation rate of 0.0183 and 0.0151 min⁻¹, respectively, under optimum conditions of pH 5, dye concentration of 25 mg/L, TiO₂/XG concentration of 25 mg/L, H₂O₂ concentration of 400 mg/L, and reaction time of 120 min. The improved photocatalytic ability was ascribed to the impact of TiO₂/XG nanoparticles with a high surface area, and lower band gap energy. Solar light energy has significant potential for addressing energy deficit and water pollution concerns.

In the present study, the objective was to probe the capacity of the Fe₂O₃/Bentonite/TiO₂ (Fe₂O₃/B/TiO₂) nanoparticles to act as a catalyst in degrading the reactive red 198 (RR198) dye and textile factory wastewater, utilizing irradiation with visible and UV light. The efficiency of this degradation was studied for a variety of experimental parameters by employing real samples of textile wastewater. After 60 min of reaction time, complete degradation of the target pollutant was visible using the synthesized catalyst, i.e., Fe₂O₃/B/TiO_2, under UV light; the same effect was noted after 90 min under visible light. Further, the ease of separation and quick collection of the synthesized Fe₂O₃/B/TiO₂ can result in keeping the photocatalytic efficiency high, as well as raising the reusability. The photocatalytic processes under UV and visible light were found capable of converting the non-biodegradable textile wastewater into biodegradable one. Besides, with the introduction of Daphnia manga, the toxicity of the effluent was examined. Through photocatalysis, utilizing both techniques, the dye toxicity in the solution was fully neutralized, and the intensity of toxicity of the textile effluent was lowered by around 70%. The conclusion drawn in this study showed that the synthesized catalyst displayed good efficiency in removing organic compounds from the textile effluents by both photocatalytic processes using UV and visible light.

The Journal retracts the article titled “UV and Visible Light Induced Photodegradation of Reactive Red 198 Dye and Textile Factory Wastewater on Fe₂O₃/Bentonite/TiO₂ Nanocomposite”