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Herein, we report the efficient photocatalytic degradation of the diclofenac drug using the Zn1-x-yPrxAlyO photocatalyst [x, y] = (0.00, 0.00), (0.03, 0.01), (0.03,0.03) under UV light irradiation. The analysis of the structure reveals that the Pr3+ and Al3+ cations insertion into the ZnO lattice leads to a decrease in the lattice constant (a and c), Zn–O bond length, strain lattice, and crystallite size. These alterations are linked to the high degree of atomic disorder triggered by the dopants, which produce stress and strain in the ZnO structure. The Raman measurements confirmed the structural phase and showed changes in the position and intensity of the E2High mode, associated with oxygen vibrations and material crystallinity. The presence of the dopants reduces the concentration of VZn and VO++ type defects while increasing the levels of VO, VO+, and Oi defects, as observed from the fitting of the Photoluminescence spectra. Furthermore, it was noted that de Pr3+ and Al3+ cations insertion into ZnO increases the optical band gap, which is associated with the Moss-Burstein effect. The micrograph images show that dopants transform the morphology from quasi-spherical particles to irregular cluster structures. The textural analysis indicated that an increase in the concentration of Al3+ in the ZnO lattice led to a higher surface area, likely enhancing photocatalytic activity. The sample containing 3% Pr3+ and 3% Al3+ showed the highest photocatalytic activity and degraded up to 71.42% of diclofenac. In addition, experiments with scavengers revealed that hydroxyl radicals are the main species involved in the drug's photodegradation mechanism. Finally, the Zn1-x-yPrxAlyO compound is highly recyclable and stable. [ABSTRACT FROM AUTHOR]

Herin, we present a study on the influence of simultaneous La3+ and Cu2+ cations insertion on the structural, optical properties, and methylene blue pollutant degradation of ZnO synthesized by co-precipitation route. Changes in the structural parameters, Zn–O stretching, and vibrational modes shifts were confirmed by X-ray diffraction, Fourier transform infrared spectroscopy, and Raman, respectively. The co-precipitation method resulted in ZnO compounds with non-homogeneous spherical morphology, as monitored by Scanning electron microscopy. It has been verified that the Zn2+ by La3+ and Cu2+ cations replacement in the ZnO crystal structure, modifies the optical band gap and Urbach energy, varies the percentages of defects associated with zinc vacancies (Vzn) and monovacancies (V0) and inhibits the creation of ionized oxygen vacancies (V+0). In addition, the Zn0.96La0.03Cu0.01O and Zn0.94La0.03Cu0.03O compounds presented a high photocatalytic effectiveness, with a degradation rate of 99.3 and 99.5%, respectively. In contrast, undoped ZnO samples synthesized under similar conditions presented a degradation for the MB pollutant of 77.3%. According to the degradation rate, samples containing La3+ and Cu2+ cations exhibit a photocatalytic efficiency of approximately 1.28 times higher than the undoped sample. The species responsible for photocatalytic activity were identified through inhibitor tests, which showed that •OH radicals mainly cause the degradation of MB. According to the results, the contribution of species to photocatalytic activity is ranked in the following order: •OH radicals > holes > electrons. [ABSTRACT FROM AUTHOR]

Water pollution remains a global problem that urges researchers to develop new technologies aimed at environmental restoration. Here, this study aimed at obtaining an activated biochar from pequi almonds for dye removal. Before and after adsorption, the materials underwent characterization using techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Raman spectroscopy, and thermogravimetric analysis (TG). The biochar from the pequi almond was called BA, and the activated biochar from the pequi almond was called ABA. The influence of the pH, contact time, and adsorbate concentration on adsorption was investigated using the dye methylene blue. The morphological assessment revealed higher cracks and pores in the ABA than in the BA. The TG showed that the BA lost approximately 19% more mass than the ABA, indicating that activation occurred. The activation contributed to the decrease in the degree of disorder in the BA because of the increased number of graphitic carbon atoms (ordered) in the ABA, as observed via Raman. The adsorption kinetics followed a pseudo-second-order model, while the adsorption isotherms followed the Langmuir model. The BA adsorption capacity was 500.00 mg g−1, constituting a robust solution for dye removal from aqueous environments. Therefore, this implies the success of the process. [ABSTRACT FROM AUTHOR]

Emerging contaminants and pollution are environmental problems threatening public health. Antibiotic ciprofloxacin and methylene blue dye are pollutants frequently detected in water systems worldwide. Photocatalysis is a process for water treatment. TiO2-based catalysts synthesized with natural gums show improved photocatalytic properties. Here, the sol–gel method synthesized TiO2/Arabic gum for photocatalytic performance. The innovation of this work was synthesized at 400 °C and investigated their photocatalytic proprieties using methylene blue and ciprofloxacin as model pollutants. XRD showed that the photocatalyst was in the anatase phase. The result showed that TiO2 with a band gap of 3.29 eV was achieved at a calcination temperature of 400 °C. Corresponding FTIR results suggest only the existence of functional groups related to TiO2. The SEM and BET method characterization indicated that TiO2/Arabic gum were spherical-shaped nanoparticles arranged in clusters with a mesoporous structure, contributing to photocatalytic performance. In addition, photocatalytic studies showed that the methylene blue dye and ciprofloxacin antibiotic degradation rates reached 99% and 94% under UV light, respectively. The hole (h+) and O H   ⦁ radicals are essential in photodegradation. The synthesized material showed excellent photostability and maintained almost the same degradation percentage in the three consecutive cycles tested on the different pollutants. The TiO2/Arabic gum is an excellent candidate for future use in treating contaminants in aqueous media using photocatalysis. Therefore, TiO2/Arabic gum nanoparticles are a promising material for wastewater treatment. [ABSTRACT FROM AUTHOR]

TiO2/Karaya composite was synthesized by the sol-gel method for the photoinactivation of pathogens. This is the first time that we have reported this composite for an antimicrobial approach. The structure, morphology, and optical properties were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-rays (EDS), Fourier transform infrared spectroscopy (FTIR), and diffuse reflectance, and the surface area was characterized by the BET method. The XRD and EDS results showed that the TiO2/Karaya composite was successfully stabilized by the crystal structure and pore diameter distribution, indicating a composite of mesoporous nature. Furthermore, antibacterial experiments showed that the TiO2/Karaya composite under light was able to photoinactivate bacteria. Therefore, the composite is a promising candidate for inhibiting the growth of bacteria. [ABSTRACT FROM AUTHOR]