WO3/Ag/ZnO S-scheme heterostructure thin film spinning disc photoreactor for intensified photodegradation of cephalexin antibiotic

Novel nanostructure approach for antibiotic decomposition in a spinning disc photocatalytic reactor

Conventional wastewater treatment processes are often unable to remove antibiotics with resistant compounds and low biological degradation. The need for advanced and sustainable technologies to remove antibiotics from water sources seems essential. In this regard, the effectiveness of a spinning disc photocatalytic reactor (SDPR) equipped with a visible light-activated Fe3O4@SiO2-NH2@CuO/ZnO core-shell (FSNCZ CS) thin film photocatalyst was investigated for the decomposition of amoxicillin (AMX), a representative antibiotic. Various characterization techniques, such as TEM, FESEM, EDX, AFM, XRD, and UV-Vis-DRS, were employed to study the surface morphology, optoelectronic properties, and nanostructure of the FSNCZ CS. Key operating parameters such as irradiation time, pH, initial AMX concentration, rotational speed, and solution flow rate were fine-tuned for optimization. The results indicated that the highest AMX decomposition (98.7%) was attained under optimal conditions of 60 min of irradiation time, a rotational speed of 350 rpm, a solution flow rate of 0.9 L/min, pH of 5, and an initial AMX concentration of 20 mg/L. Moreover, during the 60 min irradiation time, more than 69.95% of chemical oxygen demand and 61.2% of total organic carbon were removed. After the photocatalytic decomposition of AMX, there is a substantial increase in the average oxidation state and carbon oxidation state in SDPR from 1.33 to 1.94 and 3.2, respectively. Active species tests confirmed that ·OH and ·O2- played a dominant role in AMX decomposition. The developed SDPR, which incorporates a reusable and robust FSNCZ CS photocatalyst, demonstrates promising potential for the decomposition of organic compounds.

Enhanced photocatalytic degradation of amoxicillin using a spinning disc photocatalytic reactor (SDPR) with a novel Fe3O4@void@CuO/ZnO yolk-shell thin film nanostructure

Antibiotics are resistant compounds with low biological degradation that generally cannot be removed by conventional wastewater treatment processes. The use of yolk-shell nanostructures in spinning disc photocatalytic reactor (SDPR) enhances the removal efficiency due to their high surface-to-volume ratio and increased interaction between catalyst particles and reactants. The purpose of this study is to investigate the SDPR equipped to Fe3O4@void@CuO/ZnO yolk-shell thin film nanostructure (FCZ YS) in the presence of visible light illumination in the photocatalytic degradation of amoxicillin (AMX) from aqueous solutions. Stober, co-precipitation, and self-transformation methods were used for the synthesis of FCZ YS thin film nanostructure and the physical and chemical characteristics of the catalyst were analyzed by XRD, VSM,, EDX, FESEM, TEM, AFM, BET, contact angle (CA), and DRS. Then, the effect of different parameters including pH (3-11), initial concentration of AMX (10-50 mg/L), flow rate (10-25 mL/s) and rotational speed (100-400 rpm) at different times in the photocatalytic degradation of AMX were studied. The obtained results indicated that the highest degradation efficiency of 97.6% and constant reaction rate of AMX were obtained under LED visible light illumination and optimal conditions of pH = 5, initial AMX concentration of 30 mg/L, solution flow rate of 15 mL/s, rotational speed of 300 rpm and illumination time of 80 min. The durability and reusability of the nanostructure were tested, that after 5 runs had a suitable degradation rate. Considering the appropriate efficiency of amoxicillin degradation by FCZ YS nanostructure, the use of Fe3O4@void@CuO/ZnO thin film in SDPR is suggested in water and wastewater treatment processes.

Biomass derived reduced-graphene-oxide supported α-Fe2O3/ZnO S-scheme heterostructure: Robust photocatalytic wastewater remediation

The emergence of new diseases and the unplanned industrialization of cities have led to new diseases and the subsequent use of antibiotics. Hence the remediation of wastewater containing antibiotics and their severe pollution has raised serious concerns in recent years. Herein coral-shaped α-Fe₂O₃/ZnO/reduced graphene oxide (r-GO)-like carbon heterojunction in-situ were prepared from basil seed as a sustainable biomass resource and applied for the photodegradation of the oxytetracycline (OTC) as a typical antibiotic in a helical plug flow photoreactor (HPFPR) via persulfate activation under visible light irradiation. Spectroscopy and electrochemical results confirmed the tunable band structure and quick light absorption, superior charge separation and transfer, satisfactory charge carrier lifetime, and long-term stability for the prepared photocatalyst. The 98% degradation efficiency was achieved for OTC within 90 min fitted by a first-order kinetic model with the rate constant of 0.1248 min^-1. The finding proves that HPFPR exhibited a higher degradation rate of OTC by 2.3 times compared to the batch reactor. The 3D computational fluid dynamics (CFD) model confirmed the outstanding performance of the HPFPR. Scavenging experiments integrated with mott Schottky and DRS results revealed that rGO intensifies the S-scheme charge carrier transfer and built-in electric field and reduces the recombination. Finally, this work has substantial potential for the in-situ synthesis of environmental-friendly and large-scale metal oxide heterojunctions in natural carbon supports as well as scale-up and gives novel insights from molecular and engineering points of view into the wastewater remediation processes and clean water production.

Experimental analysis of a slant perforated mesh-plate photoreactor for water detoxification

A novel slant perforated mesh-plate photoreactor (SPPR) was designed and fabricated. The central assembly of SPPR was an array of slant perforated mesh-plate coated with TiO₂ (P25). The performance of SPPR in water detoxification was evaluated with regard to the degradation of phenol as the target pollutant. The effects of slant plate tilt angle (α) and perforated plate opening aperture diameter on SPPR performance were investigated and analyzed. The photocatalytic performance of SPPR increased with decreasing α. The SPPR with an α of 15° and a pore size of 1 mm showed the best performance with 9.17 h required to reach 80% of phenol degradation (4-L, initial concentration: 15 mg/L). The mass transfer was introduced into the kinetic reaction model, and mass transfer coefficients were calculated for SPPRs with different structures. Flow rate and initial pollutant concentration were investigated for their effects on degradation efficiency. In addition, the activity of SPPR under natural sunlight has also been tested to explore its potential to be applied in practice.

Strategic insight into enhanced photocatalytic remediation of pharmaceutical contaminants using spherical CdO nanoparticles in visible light region

The sustainable control of pharmaceutical micropollutants in water and wastewater environments is a great challenge in the 21st century. To address these issues, unique CdO nanoparticles (NPs) were synthesized using a facile hydrothermal approach and investigated for photocatalytic control of the antibiotic tetracycline, multidrug-resistant bacteria (MDRB), and total coliform in the wastewater effluent. The NPs were characterized using a range of techniques and it exhibited a spherical-like crystal structure with a mean size of 40 nm. The vibrational stretching mode of 1419 cm^-1 confirmed the formation of Cd-O (M - O). The synthesis protocol formed smoother surfaces and 1.88 eV band gap energy of CdO NPs, inducing excellent photocatalytic activity under visible LED light (blue and white) irradiation. The optimal catalyst dose and pH were 100 mg/L and 8-9, respectively. Blue light proved more effective than white light, resulting in 28% higher efficiency (93 ± 0.47%) in tetracycline degradation than white light under an identical intensity (20 mW/cm²). White light required a four-fold higher light intensity (80 mW/cm²) than blue light to induce comparable photocatalytic MDRB inactivation. Bacterial cell lysis by the photocatalytic treatment was confirmed by transmission electron microscopy (TEM). The used catalyst was easily recovered by 5 min of centrifugation and re-used without any noticeable change in the photocatalytic decomposition. The trapping experiment revealed that the CdO-based NPs contributed primarily to the generation of •O₂^- and •OH radicals (Type I), but the •O₂^- radicals were the dominant reactive oxygen species (ROS) in the photocatalytic process.