جستجوی مقالات مرتبط با کلیدواژه "advanced oxidation processes" در نشریات گروه "پزشکی"

Leachate, containing challenging-to-degrade organic substances and persistent toxins, poses significant environmental concerns. Advanced oxidation processes (AOPs) have emerged as a promising solution for effective leachate treatment. This research provides a comprehensive review of the impact of various AOPs in leachate treatment.

This systematic review was conducted, encompassing commonly used AOPs such as ozone, peroxone, O3/catalyst, Fenton, photo-Fenton, UV/TiO2, photolytic persulfate, O3/UV, and O3/H2O2/ UV. Extensive searches were performed using reputable databases, including EBSCO, PubMed, Web of Science, and Google Scholar. Specific keywords and inclusion/exclusion criteria were applied. Data regarding leachate treatment parameters were meticulously summarized and analyzed using descriptive statistical methods.

The efficiency of AOPs in removing leachate organic matter varied, with chemical oxygen demand (COD) removal ranging from 41% to 83% in treatment systems. The order of effectiveness was found to be: O3/UV/H2O2 > photo-Fenton > UV/TiO2 > Fenton > persulfate (PS) > O3/UV > O3/H2O2 > O3/catalyst > ozonation (O3). The highest COD removal efficiency of 83.75% was achieved using the O3/UV/H2O2 AOP approach. The removal efficiency of color also varied, ranging from 32% to 100%, depending on the leachate’s characteristics, concentration, and specific treatment process utilized.

AOPs, particularly the hybrid approach using O3/UV/H2O2, significantly enhance waste leachate treatment by effectively degrading persistent organic compounds through the generation of hydroxyl radicals. Further research is required to optimize AOPs and improve their efficiency in waste leachate treatment.

According to the results obtained thus far, ozone/magnetic copper ferrite nanoparticles (CuFe2O4 MNPs)/potassium hydrogen monopersulfate (KMPS) is capable of totally degrading 20 mg/L diazinon (DZN) with 6 mg/L ozone, 0.6 g/L KMPS, and 0.1 g/L MNPs at pH = 7 in 20 min. The experiments showed that the concentrations of KMPS and MNPs were more effective than ozone on the system efficiency. Moreover, high concentrations of KMPS and MNPs were not very effective in DZN degradation. Furthermore, the degradation efficiencies of diazinon at pHs 3, 4, 5, 6, 7, 8, 9, and 10 were 94%, 95.35%, 97.45%, 98.15%, 99.2%, 99.3%, 99.3%, and 100%, respectively. The pH of the solution was effective on the system so that in the range of 7 - 10, the system had high efficiency. Even within the range of 3 - 6, the pH had not been so plummeted, resulting in a high percentage of DZN degradation. Besides, MNPs could be utilized in the system for up to five cycles without any loss of catalytic activity. The degradation efficiency of diazinon was 99.2% in the first use and 92.1% in the fifth use. Also, the process efficiency was assessed in four real environments showing that agricultural drainage and urban wastewater with the degradation percentages of 79.1% and 77.3%, respectively, were better treated than the urban and river water with the percentages of 93% and 88.4%, respectively. With the determination of active agents in the reaction using the scavenging agents, it was recognized that sulfate radicals, hydroxyl radicals, superoxide, and singlet oxygen contributed to DZN degradation. By the way, ozone was advantageous to both singlet oxygen and superoxide in the degradation of diazinon.

Dye industries and textile are among the most water-consuming industries, which severely disturb the aquatic life. Therefore, the aim of this study was to determine the feasibility of Fenton process in removing Direct Red 81 dye from aqueous solutions and the optimal conditions for maximum removal. This research was conducted in a laboratory-scale using a one-litre photochemical reactor. The effect of the influential parameters, including pH (3–9), Fe (II) concentration (10–150mg/L), H2O2 concentration (20–150mg/L), initial dye concentration (25–150mg/L), and reaction time (15–120min) on the dye removal was investigated and the optimal conditions were determined according to maximum dye removal efficiency The results showed that the dye removal rate increased as the pH and Fe(II) concentration decreased and as the initial dye concentration and time increased. The optimal condition was at pH=3, Fe (II)=10mg/L, H2O2=50mg/L, initial dye concentration=100mg/L, and reaction time= 45 minutes. Although the maximum removal efficiency (98.29%) was obtained at the reaction time of 120 minutes, 45 min was the appropriate reaction time considering the costeffectiveness. Our results suggest that the Fenton process is a reliable and efficient method with more than 95% efficiency for decolourization of DR-81 dye and many industrial wastewaters.

 In this study, the decolorization of methylene blue (MB) by the electro-Fenton process using stainless steel (SS) mesh electrodes was examined. 

 The effects of initial dye concentration, pH, and ratio of Fe: H2O2, current density, and type of electrode were studied. The kinetics of the reactions was also studied. 

 The highest removal rate 99%was obtained at pH 3 within 20 min. Kinetics experiment studies showed that removal of dye was faster at lower initial dye concentrations. The results revealed that color removal was highest at a Fe2+:H2O2 ratio of 1:4. An increase in current density resulted in an increase in oxidation rate and faster removal of color. The results demonstrated that increasing the size of the mesh pores led to an increase in the percentage of dye removal. The highest removal percentage (94.5%) was observed in 25 min with a mesh 2 electrode. The constant rate of dye removal on steel mesh 2 was 6.6 times higher than a steel plate. Energy consumed in this state was = 1.6 kWh/m3, compared to 2.6 kWh/m3 under other conditions. 

 Using SS mesh electrodes was very effective in color removal for MB under optimal conditions. The present study showed that increasing the steel mesh size improved the conditions for color removal and reduced the energy consumption. Therefore, it is suggested that steel mesh be used as an electrode for electrochemical processes.

 This study was conducted to compare the effectiveness of conventional technologies, UV irradiation and ozonation process, and UV/O3 as advanced oxidation processes to remove phthalate from aqueous solutions. 

 The initial concentration of di-2-ethylhexyl phthalate (DEHP) was 5 mg/L. The photolysis, ozonation, and UV/O3 processes were conducted separately at different contact times (5-30 min). Then, the DEHP residuals in the solutions were analyzed by gas chromatography mass spectrometry. The effect of ozone dosage was also evaluated in the range of 50-400 mg/h on DEHP degradation. Kinetic and the rate constants were determined. 

 The results indicated that using UV and ozonation alone, the maximum DEHP removal efficiency were 43% and 50%, respectively. The UV/O3 process considerably improved the degradation of DEHP up to 80%. The synergistic effect observed in the combined processes mainly due to the effects of UV in enhancing the ozone decomposition, led to higher degradation for 30 min treatment. A kinetic study showed the degradation in UV/O3 followed the first-order model. In addition, the maximum DEHP removal rate was 74% with 200 mg/h ozone dosage by ozonation alone process, but it was 93% at same condition by UV/O3 process. 

 It could be found that the UV/O3 process is a method for DEHP degradation in aqueous solution and may be recommended as a supplement with other processes for treatment of solutions containing low DEHP concentrations.

 In this work, degradation of 4-chlorophenol (4-CP) was investigated in aqueous solutions using several oxidation systems involving ultraviolet/(UV)/H 2 O 2 , microwave (MW)/H 2 O 2 , and ultrasonic (US)/Fenton systems. 

 Three pilot plant reactors consist of a photolytic reactor, a modified domestic MW, and an US bath reactor of 22 kHz frequency were constructed and separately used in batch mode. The effects of several operation parameters such as pH of the solution ranging 3-10, H 2 O 2 initial concentration ranging from 0.005 to 0.2 mol/l, and reaction time were examined. Concentration changes of 4-CP were determined using a spectrophotometer at an absorption wavelength of 500 nm. 

 The results show that the oxidation rate was influenced by many factors, such as the pH value, reaction times, and the amount of H 2 O 2 concentration. The optimum conditions obtained for the best degradation rate were pH = 7, H 2 O 2 concentration of about 0.05 mol/l and pH = 10, H 2 O 2 concentration of about 0.1 mol/l for UV/H 2 O 2 and MW/H 2 O 2 system, respectively. For US/Fenton system, the highest 4-CP degradation was achieved in pH = 3, H 2 O 2 concentration of about 0.05 mol/l in the percent of 0.025 mmol Fe/l. The highest 4-CP removal rate in optimum conditions of pH and concentration of H 2 O 2 , in UV/H 2 O 2 , MW/H 2 O 2 , and US/Fenton systems was >99% over the retention time of 40 min, 85% after 180 min, and >99% after 40 min, respectively. 

 Based on the results of this study, the UV/H 2 O 2 and US/H 2 O 2 are successfully applicable for degradation of 4-CP in aqueous solution. Also, the kinetic study represented that the US/H 2 O 2 is capable of removing 4-CP slightly rather than UV/H 2 O 2 process.

 This study was conducted for degradation of 4-chlorophenol by microwave (MW) radiations alone and in combination with hydrogen peroxide from aqueous solution. 

 A modified domestic microwave oven was used alone and in combination with hydrogen peroxide for removing 4-chlorophenol. Furthermore, the influences of pH value, irradiation time, the power of MW radiations, and the initial concentration of 4-chlorophenol were studied. 

 It was shown that 4-chlorophenol removal efficiency extremely depend on the concentration of hydrogen peroxide, pH value, MW irradiation power and initial 4-chlorophenol concentration. The optimum conditions obtained for the best degradation rate were pH = 10.5, H 2 O 2 concentration of about 0.1 mol/l, and MW irradiation power of about 600 W. Other result shows that the best degradation rate of 4-chlorophenol was obtained when initial 4-chlorophenol concentration was 50 mg/l. Also the amount of the specific energy consumption in this method was 17460 kwh/kg of the removed organic compound. 

 This result shows that MW irradiation in the presence of hydrogen peroxide can greatly enhance the degradation of 4-chlorophenol. However, the high consumption of energy for this method must be taken into consideration.