Green Synthesis of ZnO-TiO2 Nano-Photocatalyst Doped with Fe(III) Ions Using Bitter Olive Extract to Treat Textile Wastewater Containing Reactive Dyes

Design and fabrication of nano-composite ceramic membranes for the adsorption of antibiotics from pharmaceutical wastewater

Antibiotic contamination in pharmaceutical wastewater poses environmental and public health risks. This study synthesized a nanocomposite ceramic adsorbent from clay, cow bone powder (hydroxyapatite nanoparticles), and human hair for antibiotic removal. The adsorbent exhibited high mechanical strength (3.6 bar), chemical stability, and a large surface area (171.32 m2 g-1). Characterization (FTIR, XRD, FE-SEM, BET) confirmed successful nanoparticle incorporation. In a vertical fixed-bed column, optimal removal occurred at pH 7, 25 g adsorbent, 25 °C, and 40 min contact time. Adsorption was endothermic, following pseudo-first-order and intraparticle diffusion models. The adsorbent retained >90% efficiency after 142 regeneration cycles, proving its durability and cost-effectiveness.

An online segmented continuous flow analysis system for rapid determining chemical oxygen demand in seawater to assess organic pollution levels

By integrating ultraviolet (UV) photocatalytic oxidation digestion with segmented continuous flow analysis technology, an online measurement method and analysis system for the alkaline chemical oxygen demand (CODMn) in seawater, based on the color-change reaction of potassium permanganate, has been established. This represents the first application of UV photocatalytic oxidation technology in the measurement of CODMn in seawater. The system effectively overcomes the limitations of high-temperature and high-pressure digestion methods employed in traditional CODMn analysis. The detection limit was 0.13 mg/L, the linear range was 0.00 mg/L ~ 4.60 mg/L, with a relative standard deviation of 2.30 % (n = 11), and recovery rates of 95.33 % ~ 109.50 %. Additionally, the system minimized interference from salinity, making it suitable for CODMn determination in seawater. Compared to the national standard method, the maximum average relative error was 0.042, lower than the conventional standard of 0.10, indicating high accuracy. The analysis of seawater samples from the Yangma Island area further confirmed the reliability of the system in practical testing and regional organic pollution assessment. The system demonstrated excellent anti-interference capabilities, rapid detection speed, and ease of operation, providing significant application potential in seawater CODMn measurement.

Versatile laccase-mimicking enzyme for dye decolorization and tetracyclines identification upon a colorimetric array sensor

In this study, the laccase-mimicking enzyme MnO2/Cu-BDC-His was synthesized by a facile procedure, and was applied in tetracycline antibiotics (TCs) identification and dye degradation. The MnO2/Cu-BDC-His nanozymes effectively recognized phenolic hydroxyl groups in TCs and catalyzed the generation of colored oxidation products with different characteristic absorbance peaks at 350 nm, 525 nm and 600 nm. Different TCs mixtures produced different absorbance intensities at the above wavelengths and exhibited cross-color responses. Consequently, a colorimetric array sensor for the simultaneous identification and detection of TCs with wavelength as the sensing element was established. Unlike the traditional "lock-and-key" detection mode, the array sensor enabled simultaneous multi-analyte detection and identification, which achieved the identification and quantification of mixed TCs in the range of 5-200 µM, providing a premise for its application in lake and soil water. Additionally, the MnO2/Cu-BDC-His nanozymes were also applied in colored dyes decolorization. Therefore, MnO2/Cu-BDC-His nanozymes provided a promising application in environmental monitoring.

Efficient photocatalysis activation for reactive red 195 degradation by magnetic MIL-53(Fe)/Fe3O4@TiO2 hybrid nanocomposite

The study investigated the performance of a novel magnetic hybrid MIL-53(Fe)/Fe3O4@TiO2 composite for removing reactive red 195 (RR195) dye from water using UVc light. Various analytical techniques were used to characterize the nanocomposite materials. X-ray diffraction analysis confirmed the presence of MIL-53(Fe) and TiO2 in the composite. FT-IR analysis identified carboxyl and Ti-O-Ti groups in the photocatalyst structure. The study evaluated the effects of pH, dye concentration, photocatalyst dosage, and temperature on RR195 photodegradation. The Langmuir-Hinshelwood kinetic model provided the best fit for the reaction rate. Optimal conditions for an 84 % dye degradation were found at a photocatalyst dose of 15 mg/100 mL, pH 3, dye concentration of 100 mg/L, and 35 °C after 120 minutes of UVc light exposure. Thermodynamic analysis indicated an endothermic reaction with positive values for Δ#H and negative values for Δ#S. The MIL-53(Fe)/Fe3O4@TiO2 composite demonstrated excellent stability and achieved over 90 % dye degradation after five cycles. Overall, the composite shows promise for treating wastewater with dyes.

Photocatalytic degradation of tetracycline using surface defective black TiO2-ZnO heterojunction photocatalyst under visible light

Fabrication of heterojunction and surface defective engineering, through the formation of oxygen vacancies, are among the various photocatalytic enhancement techniques. A combination of these techniques has the prospect of enhancing photocatalytic activities through improved light absorption capabilities and charge separation process of the photocatalysts. In this study, a heterojunction of black titanium oxide-zinc oxide (BTiO2-ZnO) nanocomposite was synthesized using the conventional sol-gel approach, coupled with aluminum foil-assisted NaBH4 reduction. The structure, morphology, surface properties, and optical characteristics of the synthesized material were studied using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), UV-vis absorption spectra, scanning electron microscope (SEM), Energy-dispersive X-ray spectroscopy (EDS), and transmission electron microscope (TEM). The XRD confirmed the successful formation of BTiO2-ZnO heterostructure, while SEM revealed the structural morphology as pseudo-spherical with slight agglomeration. BTiO2-ZnO was found to be more efficient than BTiO2 and BZnO for the removal of tetracycline with degradation efficiencies of 63, 58, and 56 % respectively. The effects of process parameters such as the amount of photocatalyst, pollutant's concentration, and the initial solution pH on photocatalytic degradation study were systematically explored. The results confirm that the formation of the heterostructure from BTiO2 and BZnO could offer a facile route to improving the catalytic degradation of tetracycline. Therefore, this study offers a novel perspective on the design of efficient metal oxide photocatalyst systems that rely on the integration of defect engineering and heterojunction for the removal of organic contaminants.