جستجوی مقالات مرتبط با کلیدواژه "uv light" در نشریات گروه "پزشکی"

Increasing use of pesticides along with an inadequate discharging of agricultural effluents has polluted water resources and severely affected the environment. 2,4-dichlorophenoxyacetic acid (2,4-D) is one of the herbicides which is widely used all over the world. The aim of this study was to evaluate the efficiency of an electro-photo catalytic process for the removal of the 2,4-D from aqueous media. In this regard, Zn-doped Ni anode was stabilized on FTO surface by sputtering method.

In the present study, the effects of different variables on the efficiency of the electro-photo catalytic process such as pH (3, 5, 7, 9, and 11), electricity current (1-2 mA/cm2), electrode surface area (16-32 cm2), initial concentration of 2,4-D (10-50 mg/L) and retention time (0-90 min) were investigated in a batch model and on a laboratory scale. Besides, mineralization and kinetics of the process under the optimal conditions were studied. The residual concentration of 2,4-D was measured by HPLC at 283 nm.

The results showed that the highest removal efficiency of 2,4-D was obtained under the following conditions: pH=7, electricity current=2 mA/cm2, electrode surface area=32 cm2, initial concentration=10 mg/L and retention time=90 min. Under the optimal conditions, the maximum removal efficiency (i.e., 100%) and TOC of 79.5% were achieved. In addition, the kinetic studies revealed that the current process followed the first-kinetic-order model.

According to the obtained results, the applied electro-photo catalytic process can be considered as a suitable method for the removal of 2,4-D in aqueous solutions.

Ceftriaxone is an antibiotic which is extensively used to treat a number of various infections. It is mainly accumulated in water and sewage resulting in the environmental and health problems. This study is centered on the evaluation of the efficiency of a photocatalytic process using Fe3O4@SiO2@TiO2 in the removal of ceftriaxone from aqueous solutions.

This research was based on an experimental-practical study.  Fe3O4 @ SiO2 @ TiO2 was initially synthesized via a sol-gel method and characterized by SEM, XRD and EDX analyses. The effects of variables such as pH, catalyst concentration, ceftriaxone concentration, contact time, reusability tests (n=7) and degree of mineralization were separately assessed in a laboratory scale. The concentration of ceftriaxone was measured by HPLC at 240 nm.

Based on the results obtained, the highest process efficiency of 96.7% was obtained under the following optimal conditions: concentration of ceftriaxone 10 mg/L, pH=3, the catalyst dosage of 2 g/L and a time contact of 120 min. At the end of the process, the degree of mineralization was determined to be 83.7%. Additionally, the data regarding the reusability of the nanocatalyst demonstrated that a 5.2% loss in the removal efficiency was observed after 7 times of reuse. Finally, the results revealed that the removal process of ceftriaxone follows the first-order kinetic model.

The results demonstrated that the photocatalytic process using the magnetic nanocatalyst (Fe3O4 @ SiO2 @ TiO2) could be effectively used for the removal of ceftriaxone from aqueous media.

Background and Dyes are one of the major sources of chemicals responsible for environmental pollution. Synthetic dyes degradation in industrial wastewaters has received increasing attention due to their high solubility and stability in water. In the present study, the photocatalytic efficiency of as-synthesized nano- TiO2 supported on the H-form Fe- Fe-ZSM-5 zeolite was investigated for degradation of reactive red 198 dye in water under UV light.
Effects of dye concentration and pH of the water solution were studied in batch techniques to determine the optimum values of operating conditions. The elemental composition of synthesized photocatalyst was determined by EDX (Energy-Dispersive X-ray spectroscopy). The specific surface area and pore volume of Fe-ZSM-5@ TiO2 were determined by BET (Brunauer-Emmett-Teller) technique.
The SEM (scanning electron microscopy) images revealed that nano-TiO2 particles are well distributed on the surface of Fe-ZSM-5 zeolite. The FT-IR analysis (Fourier Transform Infrared Radiation) approved the formation of the Fe-ZSM-5 and anatase phase of TiO2 coating onto the surface of Fe-ZSM-5. From UV-Vis analysis (Ultra violet-visible diffuse reflectance spectroscopy), the band gap energy of synthesized photocatalyst was calculated to be about 2.74 eV. The optimum values of pH and dye concentration for high efficient removal of reactive red 198 dye using as-synthesized Fe-ZSM-5@ TiO2 photocatalyst were found to be 4 and 100 mg/L, respectively. Maximum dye removal of 98% was achieved at optimum condition at UV exposure time of 105 min. The reusability of the photocatalyst was still significant after five times repeated cycles.
The resulting Fe-ZSM-5@ TiO2 is believed to be suitable for potential applications in advanced oxidation processes and could be a good candidate for treatment of industrial real textile dye effluent.

The aim of this investigation was to synthesize ZnO nanoparticles and compare their photocatalytic activity with its commercial form in terms of photocatalytic oxidation of methylene blue dye in aqueous environment.
In this study, ZnO nanoparticles were prepared using hydrogen peroxide treatment and were immobilized on glass surface using thermal immobilization. The prepared glasses were placed inside the reactor. Finally, the photocatalytic degradation of methylene blue in the reactor was investigated using different parameters.
Findings: The results of the study showed that the photocatalytic process with the synthesized catalyst (96.35%) had higher efficiency compared to the commercial catalyst (82.87%) in terms of degradation of 5 mg/l methylene blue within 120 minutes. Subsequently, using the synthesized catalyst, at distances of 2, 3.5, and 5 cm between the UV lamps and glass plates containing immobilized ZnO nanoparticles, the dye removal rates were 96.35%, 63.34%, and 45.31%, respectively.
According to the findings, it can be concluded that synthesized ZnO nanoparticles can be applied as an efficient catalyst in photocatalytic processes.

Decontamination is a process that infectious organisms are removed by physical and chemical methods. The advantages and disadvantages of each of these values can lead to a clear viewpoint of an appropriate sterilization process. The aim of this study was to investigate the effectiveness of 70% alcohol، Deconex (SOLARSEPT) and H2O2، also the additive effect of supplemental UV light on decontamination of laboratory items. The rates of contaminations of laboratory equipment’s and surface areas were assessed before and after exposure with mentioned chemicals and in the final stage by UV light. Overall the 12 laboratory equipment and the 7 office instrument were evaluated. The UV light was used for 40 min from distance of 2. 5 meter. Then، all points were sampled after decontamination and the microbial plates were incubated for microbial colony counts after 48h. The number of colonies before disinfection stage was 26. 43 colonies per unit (cfu) in administrative and 15. 17 in laboratory equipment. After using UV، H2O2، ethanol and Deconex، the numbers of colonies were reduced to 2. 57، 0. 4، 1. 29 and 0. 71، respectively (p <0. 05). Simultaneous use of H2O2 and Deconex with UV light reduced the numbers of colony to 0. 14 and 0. 17. In the administrative equipment’s، the number of colonies after H2O2، ethanol، deconex and UV light were 0، 1. 67، 1. 25 and 0. 83، respectively. Also، combination of UV with deconex and H2O2 reduced the colony formation to zero. H2O2 was effective on reducing the number of colonies. Due to low toxicity، it is recommended to be used in infertility lab. We must make sure that application of disinfection chemicals will not interfere with the laboratory experiments and limits the threat to health of staff.

To control the spread of pathogens in hospital environments، good hygienic routines are required to disinfect surfaces contaminated with biological materials. Chemicals have traditionally been used to disinfect surfaces during final room disinfection. However، chemical disinfection is both time- and labor-consuming، and it might be harmful for staff and the environment. The search for more environmentally friendly and healthier methods has therefore been under way for many years. UVC light (200-280 nm) has germicidal effect on microorganisms in water، on surface، and in air. However، its lethal dose for various microbes is different. In this study، the dose of UVC lamps (wavelength 254 nm) in hospital operating rooms of Shahid Sadughi Burn Center were measured and its disinfectant strength was compared with a standard chemical disinfectants (Cornex). In this cross-sectional descriptive study at first the UVC irradiance levels were measured after 14 houres light exposure at the outset. The distance between the measurement locations was 50 Cm and the radiometer was put on the 80 Cm height of the floor. In addition the UVC irradiance levels were measured in 15 other sites including surfaces on the table، bed، door handle، inside the rack etc. Microbial samples were obtained from surfaces in isolated units before and after standard hospital environmental cleaning، irradiation with UVC and cornex disinfection. Samples were collected using standard contact plates and were compared together. The results of this study showed that the UVC detected dose was 0-37951 j/m2. Also the results showed that UVC markedly reduced the number of bacteria on surfaces in operating rooms، from a mean of 64. 80 cfu per sample to 41. 67 cfu per sample after UVC disinfection and to 16. 53 cfu per sample after additional cornex disinfection. So the use of UVC and of cornex disinfection alone or in different combinations significantly reduced the amount of surface contamination (P<. 001 for both) According to the results obtained، the detected dose in about half part of the locations was almost 0 j/m2، while in the places near to the lamps the detected dose was higher than the required dose for resistant virus inactivation due to long time exposure. Therefore it is concluded that the number، locations of the UVC lamps، and also the exposure time should be changed according to the standard dose for all parts of the room. On the other hand، UVC is not suitable and efficient disinfectant for the sites that are in shadow. There fore،these places must be disinfected by a combination of UVC and chemical disinfectants.