جستجوی مقالات مرتبط با کلیدواژه « photocatalytic » در نشریات گروه « پزشکی »

Emerging pollutants such as antibiotics are resistant to biodegradation. The aim of this study was to compare the effect of photocatalytic and Ozonation photolysis on decomposition of Sulfonamide antibiotics (Sulfacetamide, Sulfathiazole, Sulfamethoxazole, and Sulfadiazine) in aquatic environments.

In this study, experiments were conducted discontinuously. The effect of some parameters, including pH, initial antibiotic concentration, ozone concentration, contact time, and concentration of TiO2 on degradation of Sulfonamide antibiotic was investigated. Characteristics of this catalyst were analyzed using FTIR, XRD, SEM, and EDX techniques. The concentrations of antibiotics were measured by an HPLC analyzer equipped with a UV detector at a wavelength of 270 nm.

The highest percentage of sulfonamide removal under optimal conditions (pH 5, initial concentration of antibiotics= 10 mg/l, ozone concentration= 0.22 g/h, and catalyst concentration= 1 g/l) were obtained by photocatalytic and photolysis processes (92.1% and 100%, respectively). Intermediate products produced under these conditions included acetic acid, butyric acid, and low molecular weight products. TOC removal efficiencies of sulfonamides by photocatalytic and ozonation photolys were 80% and 79.6%, respectively.

The study showed that the rate of ozonation photolysis reaction in the removal of sulfonamides was 2.6 times faster than the photocatalytic process.

The organic dyes are environmental pollutants that pour into water sources by industrial wastewater. It is necessary to develop effective methods for removing pollutants. The aim of this study was to evaluate photocatalytic efficiency of bare ZnO nanoparticles doped with Mg and La (1 to 6% by weight) and Mg 5% -La 5% / ZnO and Mg6%-La4% / ZnO nanoparticles in the removal of Rhodamine B from water solution by UVC irradiation.

In this study, nanoparticles were synthesized by the sol-gel method. Their photocatalytic activity was investigated by UVC irradiation to remove Rhodamine B in batch photoreactor. The concentration of Rhodamine B in aqueous solutions was measured by the determination of its absorption at the maximum wavelength of 554 nm with a visible-ultraviolet spectrophotometer. The removal amount in the presence of nanoparticles in 21 min of UVC irradiation was analyzed. In addition, a suitable kinetic model for the photocatalytic activity was investigated.

After 21 min UVC irradiation, the percentage of Rhodamine B removal from 11.5% (absence of nanoparticles) to 72.84% (presence of ZnO), 94.36% (presence of Mg 5% / ZnO), 88.54% (presence of La4% / ZnO) and 96.23% (presence of Mg5%-La5% / ZnO). The kinetic constants of active nanoparticles were also calculated.

The results of the study show that ZnO nanoparticles are effective as a photocatalyst for the removal of Rhodamine B from aqueous solutions under UVC irradiation, by doped and co-doped ZnO with Mg2+ and La3+ ions enhance the efficiency of nanoparticles in the removal of Rhodamine B. Also, results indicated that the kinetic model followed from the pseudo-first order.

Today, environmental pollution is a major problem for human life. Dye is one of the most important environment pollutants that is found in the industrial wastewater, especially in the textile industry wastewater. Therefore, the aim of this study was to evaluate the photocatalytic effect of green iron nanoparticles as catalyst for Reactive red 198 dye degradation in photocatalytic process.

This study was performed laboratory using a batch reactor under UV A irradiation. In this study, the effect of different variables including pH (3-11), dye concentration (10-100 mg / l), catalyst dosage (0.25-3 g/l) and contact time (2-60 min) were investigated. The characterization of prepared nanoparticles were studied using different techniques such as TEM, FESEM and FTIR analysis. The obtained data were analyzed by Excel software.

Also, the photocatalytic tests showed high performance of NPs for dye degradation as catalyst in photocatalytic process. The highest removal efficiency achieved 96.2% at pH 3, catalyst dosage 1.5 g / L, contact time 15 min, and for dye concentration 25 mg / L.

Additionally the results show that the photocatalytic process using green iron nanoparticles can be used with a suitable function to removal of reactive red 198 from aqueous solutions.

Chlorophenols are one of the toxic compounds in the industries that are resistant to biodegradation and they last a long time in environment. Therefore, it is necessary to eliminate them and prevent pollution of the receiving waters. The aim of this study was evaluation of ZnO nano-particles for removal of 2,4,6-trichlorophenol from aqueous solution based on the response surface methodology (RSM) model.

Effect of independent variables including pH, catalyst dose, contact time and the initial concentration of 2,4,6-trichlorophenol on response variable (removal of 2,4,6-trichlorophenolfrom) were evaluated based on the response surface methodology (box-behnken method). In this study, all experiments were carried out in a batch reactor containing ZnO nano-particles under 15 Watt UV lamp

The results showed that the best conditions for the removal of 2,4,6-trichlorophenolwere achieved at pH= 3,nano-particle concentration 0.4g/l, reaction time and74.72 min and initial concentration of 2,4,6-trichlorophenol50 mg/l contact time (95.85% removal efficiency).

The results showed that the best conditions for removal of 2,4,6-trichlorophenol were achieved at pH=3, nano-particle concentration 0.4g/l, reaction time 74.72 min, initial concentration of 2,4,6-trichlorophenol 50 mg/l (95.85% removal efficiency).

The results showed that photocatalytic process was accelerated in the presence of ZnO nano-particle and enhanced removal of 2,4,6-trichlorophenol.

Endocrine Disrupting Chemicals (EDCs), and potential EDCs are mostly man-made, found in various materials such as pesticides, metals, additives or contaminants in food, and personal care products. Phthalates are a group of these compounds that are carcinogenic to animals and can cause fetal death and congenital anomalies. The aim of this study was to investigate the photocatalytic process using GO/ZnO nanocomposites under LED irradiation for removal of Endocrine Disrupting Chemicals (EDCs) from aqueous solutions.

In this study, GO/ZnO nanorods were characterized by, Field emission scanning electron microscopy, transmission electron microscope, and Brunauer–Emmett–Teller surface area analysis. A Central Composite Design was used to optimize the reaction parameters for the removal of DEP by GO/ZnO. The four main reaction parameters optimized in this study were the following: the LED radiation time, pH, and the initial concentration of phthalates and the concentration of ZnO and graphene-oxide. The interaction between the four parameters was studied and modeled using the Design Expert 10 software. Phthalate detected by HPLC apparatus equipped with a UV detector at 225 nm wavelength with methanol (90%) and Acetonitrile (10%) phases.

The results of FE-SEM and TEM showed that the ZnO is composed of a bar and separate face. Based on the peak obtained, the diameter and length of the nanorods are 20-60 and 200 nm respectively. A maximum reduction of 90% of DEP was achieved at pH 5 and 120 minutes. The results represent the prediction of a model fitted from the Quadratic model (p-value<00001).

The interaction of variables showed that the maximum effect was belonged to the pH and the time in the process reactions. Also, the results showed that the GO/ZnO low power LED irradiation can be used as an effective method for the removal of EDCs from environmental.

Indoor air environments contain a wide variety of microorganisms such as bacteria, fungi, and viruses in which some of them can affect the human health. Filtration is considered as one of the most common methods to remove microorganisms in these environments. The purpose of current study was to investigation the neat and photocatalytic HEPA filters performance at different face velocities and various intensity of UVC light source on the reduction of airborne microorganisms. Material and Method: After installation of the neat and photocatalytic HEPA filters in a closed–loop chamber, suspension of Staphylococcus epidermidis and Bacillus subtilis bacteria with a concentration of 107 CFU / ml were sprayed into the closed–loop chamber by nebulizer. Sampling of penetrated microorganisms from filters were performed using the NIOSH 0800 method under ambient temperature 22±3oC, relative humidity 35±5%, and different air velocity (0.1 m/s and 0.3 m/s) and UVC different radiation intensity (1 mW/cm2, 1.8 mW/cm2 and no radiation (dark)) at 30 minutes time period. penetrated microorganisms density from filters was determined in term of CFU/m3. There were no significant differences in the penetration rates of microorganisms at the dark mode between the two neat and photocatalytic HEPA filters (p>0.05). The penetration rate of bacteria was significantly decreased in the neat and photocatalytic HEPA filters at UVC radiation mode with various intensities than dark mode (p<0.05). In addition, comparison of the filters in the illuminance modes of 1 mW/cm2 and 1.8 mW/cm2 were statistically significant (P <0.05). Also, UVC radiation with the 1.8mW/cm2 illuminance compared to the 1 mW/cm2 illuminance resulted in a greater reduction in the bacterial penetration from both types of filters, which is statistically significant(p<0.05). The bacteria penetration rate dramatically increased by increasing the face velocity from 0.1 m/s to 0.3 m/s under UVC radiation at an illuminance of 1mW/cm2, 1.8mW/cm2 and as well as in no radiation mode in both types of HEPA filters (P <0.05). Photocatalytic HEPA filters and increasing UVC illuminance, especially at lower surface velocities, have a significant positive effect on reducing airborne microorganisms and increasing the efficiency of HEPA filters

Conventional wastewater treatment plants are not able to remove effective drugs, such as antibiotics, so eliminating remaining antibiotics from the environment is important. The purpose of this study was to evaluate the efficacy of UV / ZnO photocatalytic process in removing antibiotic cephalexin from aqueous solutions.
This is an experimental-applied study that was performed on a batch scale in a laboratory scale. The variables studied in this study included the initial pH of the solution (11, 9, 7, 5, 3), the dose of nanoparticles (1, 75/0, 0.5, 0.25, 0.1, 0.05 grams per liter), Reaction time (60-50-40-30-20-15-55 minutes) and initial concentration of pollutant (100, 50, 25, 10 mg / l) were investigated. Measurement of cephalexin in samples was performed using HPLC apparatus.
The results showed that by decreasing pH and reducing the initial concentration of cephalexin and increasing contact time, process efficiency increased. But with increasing nanoparticle dosages up to 0.1 grams per liter, the process efficiency increases and more than this amount is reduced.
The results of this study showed that the use of UV / ZnO photocatalytic process in removing humic acid from aqueous solutions can be used as an effective method for cephalexin from aqueous solutions.

Textile industries, due to a high volume of wastewater and harmful environmental factors such as a variety of dyes, are significant industries in industrial wastewaters treatment. So, the aim of this study was to examine the efficiency of dye removal from the textile industry wastewater using the titanium dioxide photocatalytic process under UV-LED light irradiation (UV-LED/TiO2) in the treatment of the Nakh Rang factory wastewater in Hamadan City, Iran.
In this experimental study, in every experiment, 100 mL sample was placed inside the LED reactor to expose to the UV light and TiO2. The effects of some parameters such as contact time, pH and dosage of TiO2 were examined, and decomposition kinetics and the synergistic effects were also determined for each process.
The results of the experiments showed that the UV-LED/TiO2 process can remove the dye from textile wastewater with the efficiency of 80.23% and can also remove the chemical oxygen demand (COD) with the efficiency of 64.75% under the optimum conditions and during 120 minutes. Also, the reaction of dye decomposition in this wastewater was a first-order kinetic function.
The results of this study show that the UV-LED/TiO2 can be used effectively to remove the dye and reduce the COD of the textile industry wastewater under optimal operating conditions.

Acetaminophen is one of widely used analgesics/antipyretics worldwide for human and animals. Electro-photocatalytic removal of acetaminophen from drinking water using zinc oxide nanoparticles immobilized on zinc electrode was investigated in this study.
This study is an applied-experimental study. The contaminated water in a batch electrochemical reactor (with zinc-copper electrodes), ultra violet-electrochemical reactor (with zinc-copper electrodes), electro-photocatalytic reactor (with zinc oxide nanoparticles immobilized on zinc-copper electrodes) is prepared by adding 50, 100, 200 mg/L acetaminophen to drinking water. The studied variables are pH (4-8), the concentration of acetaminophen in suspensions (50, 100, 200 mg/L), the UV-A lamps (120-360 mW/cm2), radiation times (30, 60, 90 min), layering of ZnO nanoparticles (1, 2, 3), and current electrical densities (3, 6, 9 mA/cm2). Ethical considerations in this study were adhered based on the Helsinki guidelines.
The findings shows that the time required for the removal of the 100% acetaminophen concentration (200 mg/L) is about This result suggests that this electro-photocatalytic system is a suitable method for removal of acetaminophen.

Humic substances belong to a group of micro molecular of organic substance with different molecular weight produced by reaction of biological and geochemical process. They are known as one of the main prefabrications of disinfection byproducts. This study aimed at investigating the efficacy of (ZnO) nanoparticle under UV/ZnO radiation in removing humic acid. This study was conducted under laboratory condition. An interval reactor was used to eliminate humic acid by (ZnO) nanoparticle and UV lamp (125 W Philips HPLN). The humic acid was considered in 2, 5, 7 and 10 mg/lit concentrations. To measure the residue of humic acid after radiation of photo Photocatalytic, Spectrophotometer model (UV/VIS Lambda 25 Perkin Elmer, Shelton) was used. The results showed a decrease in efficiency rate when humic acid concentration and pH increased. By increasing the time of photocatalytic activity the removal effect increased. Also, we observed that single-step process and two-step process with higher removal efficiency at Zno concentration of 0.2 mg/l and 0.5 mg/l, respectively. The two-step process was found more capable of removing humic acid with 98.95% efficiency at the concentration of 0.5 mg/l ZnO, detention time of 30min, and at pH 4. This study suggests the use of UV/ZnO process as a suitable method in removing humic acid from aqueous solutions.