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Background and purpose: Phthalate esters (PEs) are a large family of industrial chemicals widely used as plasticizers. Phthalates can cause endocrine disruption and cancers. Nowadays, phthalate esters are commonly used in cosmetics, adhesives and toy industries and simply get into the surface water and groundwater. The aim of this study was to evaluate the performance of UV / Na₂S₂O₈ / Fe²⁺ in DEP removal from aqueous solution.

Materials and methods: In this study the effect of pH, concentration of persulfate, Fe²⁺ concentration and contact time on removal of diethyl phthalate were studied in laboratory scale using a cylindrical-shaped reactor containing a UV-C lamp (16 watts) by batch method. The residual concentrations of Diethyl phthalate )DEP( were determined by HPL. The effects of independent parameters on DEP removal were evaluated by Multi simplex and the response surface method (box Behnken method).

Results: In this study the optimum condition was obtained at pH = 11, persulfate concentration of 0.4 Mmol/L, 0.07 Mmol/L Fe²⁺ and 90 minutes contact time. The results showed that the DEP removal by UV / Na₂S₂O₈ / Fe²⁺ process followed a first-order reaction kinetic.

Conclusion: The results indicated high efficiency of UV / Na₂S₂O₈ / Fe²⁺ process (95% removal under optimal condition) in removal of DEP from aqueous solutions. This efficiency demonstrates that this method is acceptable in DEP removal on industrial scale.

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Background and purpose: Trihalomethanes and haloacetic acids are formed through chlorination of waters containing natural organic matters and pose potential health problems. So, it is necessary to remove humic acid as the most significant natural organic matter in water. The aim of this study was to evaluate the efficiency of catalytic ozonation in removal of humic acid in presence of local green and red montmorillonite.

Materials and methods: Green and red soils were collected from Sarcham area in Ardabil, Iran and used as catalysts after cleaning up. The variables in this study included initial pH of the solution, catalyst dosage, reaction time, and initial concentration of the pollutant.

Results: The efficiency of catalytic ozonation process increased by increase in contact time, pH, and doses of catalysts and also by decrease in initial concentration of humic acid. In COP process, 100% removal of humic acid (10mg/l) was achieved at natural pH in 15 and 20 min in presence of green and red soils, respectively. Compared with conventional ozonation, presence of radical scavengers such as nitrate, chloride, sulphate and carbonate at high concentrations were found to have minor effects on reducing the efficiency of catalytic ozonation process.

Conclusion: Based on this study, green and red soils highly increase the efficiency of catalytic ozonation process. Due to the low cost and availability of these soils, they can be used as catalysts to remove humic acid in catalytic ozonation process or other similar processes.

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Background and purpose: Due to the poor performance of industrial dye settings about 50% of the washing dye liquor is discharged into the environment. Inappropriate discharge of dye-containing effluents is undesirable because of their color, resistance to biological treatment systems, toxic, and their carcinogenic or mutagenic nature to life forms. In the present study we investigated the photocatalytic degradation of reactive yellow 147 using magnetic Fe₃O₄@SiO₂@TiO₂.

Materials and methods: A central composite design (CCD) under response surface methodology (RSM) was employed to study the interaction between some parameters, including photocatalyst dose, solution pH, and temperature in order to optimize the removal condition of Reactive Yellow 147 via photocatalytic process. Therefore, 20 tests were designed in Design Expert Software (version 7.0.0). All of these Factors were classified in 5 levels +α, +1, 0, -1, -α.

Results: There was an increase in removal efficiency with increase in the photocatalyst dosage of Fe₃O₄@SiO₂@TiO₂ and with decrease in the temperature. Under acidic conditions, the photocatalytic process was more efficient than that under alkaline conditions. The results also indicated that the application of RSM method not only helped to find the optimum levels of experimental parameters, but also proved that the role of initial pH of the solution and temperature were much more dominant than that of photocatalyst dosage in the photodegradation Reactive Yellow 147 under UV light exposure.

Conclusion: Current study showed that photocatalytic process with optimization of effective
operational factors, is highly efficient in removal of Reactive Yellow 147. The regenerated as-synthesized photocatalyst shows high stability and high efficiency in the degradation of Reactive Yellow 147 even after ten times of successive reuse without a significant drop in removal efficiency which makes this process economical.

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Background and purpose: Industries are one of the main sources of producing wastewater accounting for 20% of water pollution. Treatment of dye wastewaters is one of the major challenges in textile industry. The aim of this study was to investigate the performance of advanced oxidation processes, Fenton-Peracetic acid and Photo-Fenton-Peracetic acid for removal of methylene blue (MB) dye from aqueous solutions.
Materials and methods: We conducted an experimental study in which the effects of operating parameters such as pH (3-9), contact time (2-30 min), Peracetic acid concentration (5-50 mg/L), ferric chloride concentration (5-200 mg/L), and methylene blue concentration (5-100 mg/L) were investigated on the removal efficiency of MB dye in the presence and absence of ultraviolet radiation. The experiment was conducted in a batch reactor and the efficiency of method to remove color was measured using a spectrophotometer.
Results: In current study the highest removal efficiency (99%) was attained by Fenton-Peracetic acid process under the optimized conditions as follows: pH 3, Peracetic acid concentration 30 mg/L, ferric chloride concentration 60 mg/L, methylene blue concentration 10 mg/L, and contact time of 30 min, but, the same amount of color was removed in shorter time (20 min) by Photo-Fenton-Peracetic acid process.
Conclusion: High removal efficiency of the Photo-Fenton-Peracetic acid process in a relatively short time, which is because of hydroxyl radical production, show that this process can effectively be applied to remove MB dye and can be considered as a suitable alternative to conventional systems for treatment of wastewaters containing similar organic matters.
 

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Background and purpose: In recent years, the presence of antibiotics in aquatic environment has received increasing attention. These compounds remain in the environment, because of incomplete elimination in conventional wastewater treatment processes. Advanced oxidation processes are used to remove many pollutants. The aim of this study was to evaluate the efficiency of sono-fenton degradation in removal of sulfacetamide in presence of zerovalent iron nanoparticles.
Materials and methods: An experimental-laboratory scale study was carried out in which NZVI was synthesized through reducing iron sulfate by sodium borohydride. The effects of some variables such as pH (3-9), NZVI concentration (1-8g/L), H₂O₂ concentration (0.05-2 M) and contact time (5-90 min) were investigated on the process efficiency. Concentration of residual antibiotic was analyzed by HPLC-UV equipped with a C18 column.
Results: The maximum removal efficiency was observed at pH=3, 60 min contact time, 5 g/L NZVI concentration and H₂O₂ concentration of 1 M. In these optimal conditions, the removal efficiency was 91% and COD removal degree was 27%.
Conclusion: The experiments showed that the sonocatalytic process using NZVI nanoparticles along with adding H₂O₂ as an oxidant is an efficient method to remove sulfacetamide and other biological resistant compounds.
 

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Background and purpose: Wastewater olive processing industries have significant amounts of organic compounds resistant to biodegradation which are hazardous if not treated and discharged to the environment. Advanced oxidation processes such as Fenton process have been considered to increase and improve the biological degradability of this type of wastewater. Current study aimed at investigating the efficiency of Fenton process in olive oil mill wastewater treatment.
Materials and methods: A laboratory-scale experimental study was carried out. Wastewater properties of olive oil such as COD, BOD₅, TOC, color, and turbidity were determined, then the efficiency of Fenton process in wastewater treatment was evaluated. The effects of parameters such as ferrous ion, hydrogen peroxide concentration, pH, time, etc. on the performance of the process were determined. Then, the optimal conditions were found for the Fenton process. All examinations were done according to Standard Methods for the examination of Water and Wastewater.
Results: Concentrations of COD and BOD were 67427 and 22400 mg/L, respectively. The highest removal rates in optimum conditions for major pollutants such as COD, BOD, TOC, and color were 81.9%, 60.13%, 57.43%, 44.2%, and 91.7%, respectively obtained at 150 minutes.
Conclusion: Fenton process by producing hydroxyl radicals can highly remove pollutants resulting from olive oil waste and can be applied before biological processes.
 

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Background and purpose: Pesticides are well-known for their carcinogenic, mutagenic, and teratogenic properties, and they exhibit resistance to environmental degradation. Organophosphorus compounds represent one of the largest and most diverse groups of pesticides globally. Diazinon, an organophosphorus pesticide widely used in agriculture, was selected as the target pollutant for the present study.
Materials and methods: The co-precipitation method was employed to synthesize zinc oxide nanocomposites coated on polyethylene terephthalate (PET). Subsequently, the nanoparticle structure was analyzed using XRD, FT-IR, SEM, and EDX analyses. The efficiency of diazinon sonocatalytic removal by zinc oxide nanocomposites coated on PET was investigated, and the impact of various parameters, including pH (3-11), nanocomposite dosage (0.2-2.5 g/L), initial diazinon concentration (5-50 mg/L), contact time (5-60 min), hydrogen peroxide concentration (2-50 mM), different gases (oxygen and nitrogen gas (2 L/min)), organic compounds (folic acid, citric acid, humic acid, EDTA, oxalate acid, phenol), radical scavengers (ammonium oxalate as h⁺ scavenger, benzoquinone as scavenger, tert-butyl alcohol as ^•OH scavengers), various processes (PET, US, PET/US, ZnO, ZnO-PET, ZnO/US, ZnO-PET/US), and recycled experiment, was evaluated. Firstly, the pH optimum was acquired to be 5, with changing pH and constant nanocatalyst dosage and initial diazinon concentration. The effects of different parameters on the removal of diazinon were investigated at the constant value of pH. Diazinon residual concentration was measured by a spectrophotometer (UV/VIS, DR5000) at a wavelength of 295 nm.
Results: FT-IR and XRD analyses confirmed the coating of ZnO nanorods onto PET. Under optimal conditions, initial diazinon concentration of 20 mg/L, pH of 5, and nanocomposite dosage of 2.5 g/L for 60 minutes the sonocatalytic removal efficiency of diazinon reached 99.81%. The removal efficiency decreased from 100 to 40.15% as the diazinon concentration increased from 5 to 100 mg/L. The first-order rate constant (k_obs) decreased from 0.123 to 0.0086 min^-1, while R² decreased from 0.985 to 0.9152, and electrical energy per order (E_Eo) increased from 181.073 to 2589.77 kWh.m^-3 with increasing diazinon concentration. The sonocatalytic removal of diazinon increased with rising H₂O₂ concentration up to 5 mM. However, the addition of organic compounds and nitrogen gas led to a decrease in diazinon removal efficiency. The effectiveness of processes for pesticide removal from drinking water decreased due to anions scavenger activity. Examination of radical scavengers revealed that •OH radicals were the most active in diazinon removal. Notably, proper sonocatalytic activity in diazinon removal was observed even after six successive cycles. Intermediate products identified by GC-MS in the sonocatalytic removal process included diazoxon, IMP, hydroxy-diazinon, and diazinon-methyl-ketone.
Conclusion: The findings suggest that zinc oxide coated on polyethylene terephthalate, as an affordable, practical, and environmentally friendly material, exhibits satisfactory efficiency for the sonocatalytic removal of diazinon from water environments.