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

The presence of antibiotics in wastes and drinking water has led to serious environmental and health concerns, further necessitating the development of an advanced sustainable strategy to eliminate antibiotics from aquatic media. In this context, the present research reports the successful fabrication of a spinning disc photoreactor (SDPR) supported ZnO/Ag/WO3 S-scheme visible-light-driven thin-film photocatalyst to study the degradation of cephalexin (CPX) as a target pollutant under blue light irradiation. The optical, electrochemical and physicochemical characterization of the as-prepared thin-film samples were carried out by XRD, top-view FE-SEM, EDS-mapping, UV-Vis-DRS, contact angle, EIS, transient photocurrent, mott Schottky and AFM techniques. The rod shape morphology of the samples with moderate surface roughness, desirable hydrophobicity, low bandgap and remarkable band structure alignment confirmed the applicability of as-prepared thin-film with an average photon flux of 1.94 × 10-4-8.61 × 10-5 E's m-2 s-1. The use of a rotating catalytic disc impressively declined the photon propagation distance, decremented the probability of light absorption by the solution, and intensified the mass transfer rate. The maximum throughputs of 98.8% efficiencies for CPX degradation were achieved at a rotational speed of 180 rpm, the solution flow rate of 1.0 L min-1, the light intensity of 11 mW cm-2, and initial CPX concentration of 40 mg L-1, illumination time of 80 min, and pH of 6. Damkohler number (Da) value was found to be 1.23 × 10-2 at the optimum conditions, indicating the negligibility of the external mass transfer resistance in the SDPR. The photocatalytic mechanism was elucidated for finding the most operative radical species, suggesting the crucial role of ·O2- in photodegradation of CPX and a drastic improvement of the charge separation by S-scheme heterostructure and facilitation by Ag mediator. Findings indicated that the developed reusable and robust SDPR benefited from an s-scheme photocatalyst can be a promising technology for degradation of the organic compounds.

Spinning disc photoreactor based visible-light-driven Ag/Ag2O/TiO2 heterojunction photocatalyst film toward the degradation of amoxicillin.

The presence of antibiotics in waste and drinking water is causing increasing concern around the world, thereby an advanced sustainable technology needs to be developed to eliminate the antibiotics from water resources. Hence, an efficient spinning disc photoreactor (SDPR) equipped with visible light-activated Ag/Ag2O/TiO2 heterostructure thin film photocatalyst was assessed for the degradation of amoxicillin (AMX) as a typical antibiotic. The surface morphology, optoelectronic and structural features of Ag/Ag2O/TiO2 heterojunction were characterized by TEM, BET, mott Schottky, FESEM, EDS, AFM, XRD, UV-Vis-DRS, and contact angle measurements. Results confirm that Ag and Ag2O have a significant effect on the photocharge carrier separation and transfer of the as-developed photocatalyst system. The operative variables including illumination time, rotational speed, solution flow rate, aeration rate, pH, and initial AMX concentration were optimized by CCD. The results displayed the maximum AMX photodegradation (97.91%) could be achieved at optimal conditions involving illumination time of 80 min, a rotational speed of 225 rpm, the solution flow rate of 0.6 L/min, aeration rate of 20 L/min, pH = 6, and initial AMX concentration of 20 mg/L. Interestingly, more than 79% COD and 64% TOC were removed under optimum conditions during 80 min illumination time, respectively. Active species tests confirmed the dominant role of ·OH and ·O2- in AMX degradation. finally, the XRD pattern confirmed that the reusability assessments of the heterojunction film could successfully retain its stability for six consecutive photocatalytic degradation runs. This work demonstrates the feasibility of utilizing visible-light-driven thin-film photocatalysts in spinning disc photoreactors in treating the tenacious antibiotic pollutants.

Monitoring udder health status using somatic cell counts in Holstein dairy herds located in north-east of Iran and effectiveness of 10-point mastitis control program.

BACKGROUND: The somatic cell count (SCC) of individual cow samples is a useful proxy for monitoring udder health status. AIMS: The present study aimed to provide updated information about udder health in Iranian Holstein dairy cattle, and to quantify the effectiveness of the mastitis control program. METHODS: A total of 17,990 monthly test-day records from 1,663 Holstein dairy cattle in 10 "regular" herds and 2,389 test-day records from 386 Holstein dairy cattle in 2 herds that were assigned to the 10-point mastitis control program ("controlled" herds) were included. Each test-day record comprised the date of recording, daily milk production (kg), fat and protein (%), days in milk, parity, and SCC. RESULTS: Median (Q1-Q3) SCC × 103 for "regular" and "controlled" herds were 136 (52-391) and 64 (24-204) cells/ml, respectively. Also, the percentage of records containing SCC >200,000 cells/ml (elevated SCC) for these groups were 40.3% and 25.5%, respectively. Mixed effects logistic analysis revealed that milk records from cows in the first lactation, early lactation, and with >40 kg daily milk yield had lower odds of elevated SCC. The odds of elevated SCC were lower in summer and autumn than in winter. CONCLUSION: Host and environmental characteristics influence SCC. This should be considered for the interpretation of SCC results. Mastitis control programs can support dairy producers to reach a standard level of udder health.

Sonophotocatalytic degradation of trypan blue and vesuvine dyes in the presence of blue light active photocatalyst of Ag3PO4/Bi2S3-HKUST-1-MOF: Central composite optimization and synergistic effect study.

An efficient simultaneous sonophotocatalytic degradation of trypan blue (TB) and vesuvine (VS) using Ag3PO4/Bi2S3-HKUST-1-MOF as a novel visible light active photocatalyst was carried out successfully in a continuous flow-loop reactor equipped to blue LED light. Ag3PO4/Bi2S3-HKUST-1-MOF with activation ability under blue light illumination was synthesized and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), photoluminescence (PL) and diffuse reflectance spectra (DRS). The effect of operational parameters such as the initial TB and VS concentration (5-45mg/L), flow rate (30-110mL/min), irradiation and sonication time (10-30min), pH (3-11) and photocatalyst dosage (0.15-0.35g/L) has been investigated and optimized using central composite design (CCD) combined with desirability function (DF). Maximum sonophotodegradation percentage (98.44% and 99.36% for TB and VS, respectively) was found at optimum condition set as: 25mg/L of each dye, 70mL/min of solution flow rate, 25min of irradiation and sonication time, pH 6 and 0.25g/L of photocatalyst dosage. At optimum conditions, synergistic index value was obtained 2.53 that indicated the hybrid systems including ultrasound irradiation and photocatalysis have higher efficiency compared with sum of the individual processes.