---

Background and purpose: Dyes and cyanide are the most important sources of environmental pollution, found in industrial wastewater, which are harmful for human health and environment. The purpose of this research was to investigate the Kinetic and efficiency of titanium dioxide photacatalytic process in removal of Reactive Black 5 (RB5) dye and cyanide from aquatic solution in a batch system.
Materials and methods: This research was an applied-fundamental study. Â reactor was designed and optimum dosage of TiÔ2 was determined, 1g/L keeping other parameters constant. The effect of pH, contact time and initial Reactive Black 5 )RB5) dye and cyanide concentration was studied at a constant concentration of TiÔ2 (1 g/L).
Results: The result showed that removal efficiency of Reactive Black 5 )RB5) dye and cyanide decreased with increasing pH and initial Reactive Black 5 )RB5) dye and cyanide concentration. There was also an increase in specific removal efficiency by increasing the contact time and the TiÔ2 dosage. Ïn addition, kinetic parameters were obtained by application of Langmuir and Hinshelwood equation.
Çonclusion: The results showed that removal of Reactive Black 5 )RB5) dye and cyanide can be efficiently performed by ÜV/TiÔ2

---

Background and purpose: One of the biggest environmental problems of pulp and paper industries is discharge of colored wastewater containing lignin to environment. The aim of this study was to evaluate the TiO2 photocatalytic process Dap with iron in the presence of UV for lignin degradation. Materials and methods: This cross-sectional study was conducted at laboratory scale (in vitro) in a 2-liter reactor. The synthesis of nano was made by sol-gel method. Lignin absorption was done using UV/Vis spectrophotometry at 280 nm. The samples were estimated based on factorial method (72 samples). The SPSS software version 16.0 and Excel 2007 and regression test were used for statistical analysis. Results: The highest removal rate in the presence of UV was 95.4%, and in the presence of sunlight was 87.4%. The removal rate of lignin increased when the concentration increased from 0.15 to 0.3 g/l. In all of the pH, the removal rate increased with increasing in retention time from 15 to 120 minutes and remains slightly constant after 60 minutes. The optimum pH was obtained 7. The reaction rate increased when the concentration of nano increase and the pH decreased. Conclusion: Based on the findings, the removal rate was considerably above in visible light and in the presence of sunlight, which represented the Dap role of nanoparticle therefore, due to the low consumption, low power consumption and high efficiency, Doped nano can be used as an alternative for the removal of lignin from the pulp and paper industries.

---

Background and purpose: Nickel is one of the heavy metals that originates from various industries such as plating and dyeing and leads to many environmental problems, thus, it is important to remove it. The aim of this study was to assess the photocatalytic process by silica and zirconia nanoparticles in nickel removal. Materials and methods: In this applied-fundamental study after construcring photoreactor, the performance of silica and zirconia nanoparticles in the removal of nickel were studied by changing variables such as the amount of nanoparticles (0.5-2.5 g/L), pH (3,7,11), nickel concentration and exposure time of UV (15-75 min). After assessing the synthetic wastewater (n=50) real wastewater (n=10) samples were evaluated according to the resultant optimum conditions. Nickel adsorption isotherm was determined. SPSS was used to analyze the data. Results: Nickel was removed completely under optimum condittions (pH= 11), 1g/L zirconia, 0.5g/L silica with exposure time of 30min and 5mg/L synthetic nickel. Removal efficiency of nickel in concentrations of 5, 10, 15, 20 and 25 mg/L at pH= 11 and 1g/L zirconia nanoparticles was 100, 91, 88, 87.5 and 84%, respectively and with 0.5g/L dose of silica nanoparticles was 100, 100, 90.90 and 87%, respectively. According to the coefficient of determination (R2), Freundlich isotherm for zirconia nanoparticle (R2= 0.883) and the Langmuir model for silica (R2= 0.949) were found to be more relevant. Conclusion: Increase in the amount of nanoparticles, UV exposure and pH increased the efficacy of photocatalytic process in nickel removal through production of hydroxyl radicals. Nickel concentration reduced the process efficiency due to inhibition of the reaction of holes (h+) and hydroxyl radicals. Efficiency of photocatalytic process in removal of nickel from a real wastewater due to the presence of other substances (cyanide and zinc) was far less compared to the synthetic solutions. According to nickel removal efficiency from real wastewater (49.6% and 56% by zirconia nanoparticles and silica, respectively) photocatalytic processes was able to remove about 50% nickel from actual wastewater.

---

Background and purpose: Cyanide (CN-) is of dangerous pollutants in the environment from industries such as electroplating, mining and paint entering into environment. The present study aimed to review the efficiency of cyanide removal by zirconia photocatalytic process with and without hydrogen peroxide (H2O2). Materials and methods: This was an applied-fundamental study and was conducted in Environmental Health Research Center. After constructing photoreactor, by changing variables nanoparticle dosage (0.25-4 g/l), pH (4-11), H2O2 amount (0.1-1 ml), cyanide concentration (2.5-75 mg/l) and exposure time (5-90 min), efficiency of the photocatalytic processes was studied with zirconia ZrO2 and H2O2 in the cyanide removal. Experiments were followed on real wastewater samples. 200 synthetic samples and 20 real samples were tested. Results: The maximum cyanide removal (2.5 mg/l) was about 96% by UV/ZrO2/H2O2 process under optimal conditions (0.75 g/L nanoparticles, 0.5ml H2O2 and pH = 8). Removal of cyanide (20 mg/l) by the UV/ZrO2/H2O2 was, 35, 38.75, 55, 56, 59, 61.25, 65, 71.5, 81 and 88.5%, respectively in 5-90 minutes. The efficiency of cyanide removal with UV/ZrO2/H2O2 process decreased from 95.6% to 50.4% in 2.5 to 75 mg/l of cyanide. The maximum cyanide removal (2.5 mg/l) was approximately 85.6% by UV/ZrO2 process under the optimal conditions (0.75 g/l nanoparticles and pH = 4). UV/ZrO2 process efficiency in the cyanide removal decreased from 85.6% to 36.4% in 2.5-75 mg/L of cyanide. The maximum cyanide removal from real wastewater was 54.08% and 72.8% with UV/ZrO2 and UV/ZrO2/H2O2 processes, respectively. Conclusion: Increasing nanoparticle, exposure time and reducing pH increased UV/ZrO2 process efficiency. Increasing cyanide concentration decreased efficiency of the both processes. Increasing H2O2 to optimum dosage (0.5 ml/100 ml CN) increased UV/ZrO2/H2O2 process efficiency, but higher levels of H2O2 decreased the process efficiency.

---

Abstract Background and purpose: Bisphenol A is a harmful organic compound which is either used or produced in various industries. This compound is resistant to biodegradation. The aim of this study was to determine the photocatalytic degradation of Bisphenol A from aqueous solutions by ZnO nanoparticles. Material and methods: In this experimental study the morphology of nanoparticles was characterized using scanning electron microscope. The volume of sample was determined by Rotatable inscribed Central Composite design (CCD) method. The samples were separately placed under UV radiation in defined amount of nanoparticles and initial concentration of bisphenol A at different operating conditions. The concentrations of bisphenol A were analyzed by UV Spectrophotometer. Data was then analyzed in Minitab V.16. Results: The degradation efficiency of bisphenol A increased when the pH, contact time and loading nanoparticles increased and the concentration of bisphenol decreased. Efficiency of ZnO was found to be better at alkaline pH than acidic conditions. UV/ZnO process was capable of removing bisphenol A to 97%. Conclusion: This study showed that photocatalytic degradation by ZnO nanoparticles in presence of UV is an effective method for removal of bisphenol A.

---

Background and Objectives: 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. Material and Methods: 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. Results: 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. Conclusion: This study suggests the use of UV/ZnO process as a suitable method in removing humic acid from aqueous solutions.

---

Background and purpose: Among the numerous chemicals utilized in agriculture, 2,4-Dichlorophenoxyacetic acid (2,4-D) is widely used to control weeds. This herbicide is considered as a carcinogen and high toxic pollutant which is very difficult to remove due to its biological and chemical stability. This study aimed at photocatalytic degradation of 2,4-D using indium oxide nanoparticles in the presence of ultraviolet light.

Materials and methods: This study was carried out in bench scale and batch system. The effect of operating parameters such as pH (2-11), contact time (5-240 min), catalyst dose (0.1-2 g/l) and initial concentration of herbicide (5-40 m/l) on the efficiency of the process were studied. The experimental data were fitted to a pseudo-first-order kinetic model.

Results: Increasing the pH and initial concentration of herbicide led to reduced efficiency while increasing the contact time and catalyst dose increased the efficiency. The best result (70% efficiency) was achieved at pH 3, 1 g/l catalyst dose, 120 min contact time, and 5 mg/l initial concentration. The process data well followed the pseudo-first-order kinetic model (R² = 0.915).

Conclusion: The results demonstrated that the photocatalytic process using indium oxide nanoparticles in the presence of ultraviolet light have a relatively good efficiency in removing 2,4-D.

---

Background and purpose: Aniline is widely used as raw material in many chemical industries. The aim of this study was to survey the photocatalytic degradation of aniline using magnesium oxide nanoparticles from aqueous solutions.

Materials and methods: An experimental study was carried out in a 2 L volume batch reactor. Various parameters such as pH (3-11), dose of nanoparticles (0.1-1), contact time (15-120 min), initial aniline concentration (5-250 mg/L) and irradiation source power (8, 15 and 30 W) were investigated. The concentration of residual aniline was measured by UV spectrophotometer at λ_max of 198 nm.

Results: The results showed that photocatalytic process of nMgO+UV could effectively remove aniline from effluent. The optimal solution pH and dose of nanoparticles for 8 W, 15 W and 30 W UVA lamp were 7.0 and 0.6 g/L, 7 and 0.4 g/L, and 7 and 0.4 g/L, respectively. In 30 min optimum contact time the photocatalytic degradation efficiency decreased when the concentration of aniline was increased. In optimum conditions (5 mg/L of aniline and 30 min reaction time) the aniline removal efficiency was 90.63 % and COD removal was 87.02%.

Conclusion: The photocatalytic process of nMgO+UV can be used as a suitable technique for aniline removal from aqueous solutions.

---

Background and purpose: Phenol is amongst the dangerous environmental pollutants with wide applications in today’s life and industry. Nanoparticles have recently received attention for decomposition of these organic compounds. The aim of this study was to evaluate the efficiency of silver doped titanium dioxide stabilized on concrete bed via photocatalytic process Ag-TiO₂/UV in removal of phenol from synthetic wastewater.
Materials and methods: In this experimental-applied study, the volume of sample was 1000 ml. Initial concentrations were 10, 20, 50, and 100 mg/l and the samples were separately investigated under the effect of UV radiation and Ag-TiO₂. The experiment was then performed under both conditions simultaneously. The variables included pH, initial phenol concentration, storage time, and photocatalyst loading. Phenol analysis was carried out by direct light metering with 4-aminoantipyrine reagent at 500 nm wavelength spectrophotometer according to standard method D5530. We studied the pH in three ranges (5, 7, and 10) and photocatalyst in three regions (20, 60, and 80 g/m²).
Results: Based on the results, the highest levels of phenol decomposition were achieved by initial concentrations of 10 and 20 mg/l in optimal pH (3) at 40 and 80 minutes (100%), and initial concentrations of 50 and 100 mg at 180 and 200 minutes retention time in optimal pH (65% and 50%, respectively). The optimal photocatalyst loading rate was 80 g/m².
Conclusion: This study showed that the Ag-TiO₂ nanophotocatalyst stabilized on a concrete bed, is efficient in phenol decomposition in presence of UV light.
 

---

Background and purpose: 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.
Materials and methods: 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.
Results: 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.
Conclusion: The study showed that the rate of ozonation photolysis reaction in the removal of sulfonamides was 2.6 times faster than the photocatalytic process.

---

 Background and purpose: Malachite green is one of the most widely used dyes in various industries, aquaculture, and fungicides. The residues have adverse effects on environmental and human health and should be removed from the effluent before discharging to the environment. The purpose of this study was to investigate the efficiency of photocatalytic process using halloysite-titanium dioxide nanocomposite in the removal of malachite green from aqueous solutions and the effect of various parameters on the process efficiency.
Materials and methods: This experimental study was performed on a laboratory scale in a discontinuous system. In this process, a 15 W (UV-C) lamp of 26 mm diameter and length of 45 cm and a nanocomposite (halloysite-titanium dioxide) were used. The influence of contact time, nanocomposite dose, dye concentration, and pH of the reaction on the removal efficiency was investigated. The properties of the synthesized nanocomposite were determined by sol-gel method using XRD and SEM techniques. The concentration of malachite green was measured using a UV-VIS spectrophotometer at 619 nm.
Results: The best photocatalytic dye removal efficiency (91.29%) was seen at 3 mg/l dye concentration, pH= 10, contact time= 90 min, and nanocomposite dose= 0.1 g/l.
Conclusion: This study showed that photocatalytic process using nanocomposite (halloysite-titanium dioxide) is efficient in decomposing and removing malachite green.
 

---

Background and purpose: Paraquat (PQ) is the third most widely used herbicide in the world. This herbicide has the potential to damage cell membranes by lipid peroxidation and free radical attack. In this study, ZnO /rGO (ZG) heterogeneous photocatalyst was used for oxidation of PQ herbicide in aqueous solution under ultraviolet light irradiation.
Materials and methods: In this experimental study, EDS, FE-SEM, BET, XRD, and FTIR analyzes were performed to determine the characteristics of synthesized catalyst. Effect of operating parameters, including solution pH, catalyst concentration, rGO percentage loading, PQ concentration, and UV-light intensity on degradation of PQ was studied in batch mode. Residual concentration of PQ and type and toxicity of intermediate compounds were measured by HPLC and GC-MS, respectively and toxicity test was done by Daphnia Magna. Studies on reusability of catalysts, effect of radical scavengers, and inorganic anions were also performed.
Results: Under optimum conditions (pH=7, catalyst loading=10%, catalyst concentration=0.5 g/l, PQ concentration= 10mg/l, and UV-light intensity=220 mw/cm²), degradation and mineralization rate were 91.61% and 51% in 120 minutes, respectively. Radical scavenger experiments showed electron as the most effective factor in PQ oxidation process in ZG/UV system. In samples of agricultural run-off, degradation efficiency was 58.27%. Biotoxicity test also showed that toxic unit in pesticide-containing samples was 61.72 in raw samples that decreased to 12.19 in treated samples after 96 hours.
Conclusion: ZG/UV process has high efficiency and excellent catalytic activity, so, it the can be successfully used to degrade organic pollutants, especially pesticides, in wastewater.

---

Background and purpose: Textile industries produce huge amounts of colored wastewater. Synthetic dyes cause serious problems to human health and aquatic organisms due to their toxic and carcinogenic properties. In this study, Acid Blue 113 (AB113), which is stable and persistent against conventional treatment methods was selected as the target contaminant.
Materials and methods: The synthesis of the ZnO-Kaolin nanocomposite was performed by simple co-precipitation approach. The crystalline structure, functional groups, morphology, and elemental composition of the prepared samples were characterized using XRD, FT-IR, SEM and EDX analyses, respectively. Next, the photocatalytic response was evaluated via degradation of AB113 dye under visible irradiation. Also, the influences of operating parameters, including pH, catalyst value, initial AB113 concentration, various gases, organic compound types, and catalyst recycling on the photocatalytic performance were studied in a batch reactor.
Results: The SEM analysis confirmed the ZnO-Kaolin spherical structure. Presence of organic compounds in the aqueous medium decreased AB113 removal efficiency. The highest removal efficiency (84.33%) was obtained at catalyst loading=0.4 g.L^-1, initial dye concentration=20 mg.L^-1, and pH=7. Compared with ZnO and Kaolin nanoparticles, the resulting catalyst (ZnO-Kaolin) exhibited significantly improved photocatalytic activity in AB113 degradation. The degradation of AB113 was found to follow the first order kinetic (K_obs: 0.122 min^-1 and R²: 0.9516) and the Langmuir-Hinshelwood model (K_C: 0.278 mg.L^-1.min^-1 and K_AB113: 0.128 L.mg^-1).
Conclusion: The proficient performance of the LED/ZnO-Kaolin system illustrated that it can be used for practical applications in water treatment.

---

Background and purpose: Due to the increasing importance of protecting human health and preserving the environment, drug resistance and water pollution have drawn significant attention. Nanoparticles have emerged as one of the most promising solutions, with cobalt nanoparticles being particularly interesting due to their unique properties. This study focuses on the green synthesis of cobalt nanoparticles using Mentha pulegium and investigates their potential antimicrobial and photocatalytic activities.
Materials and methods: n this experimenal study, cobalt nanoparticles were synthesized through green methods using M. pulegium aqueous extract. The synthesized nanoparticles were characterized using various analytical techniques, including UV-visible spectroscopy, SEM, EDX, FTIR, and XRD. Furthermore, the antibacterial effects of these nanoparticles were investigated against ATCC strains and ciprofloxacin-resistant strains. Their photocatalytic activity was evaluated for the degradation of methylene blue (MB) in the presence of NaBH4.
Results: XRD analysis revealed that the synthesized nanoparticles were amorphous, while SEM images showed irregularly shaped particles with an average diameter of 53.91 nm. The cobalt nanoparticles demonstrated excellent antibacterial activity. The maximum antibacterial effects were observed against ATCC strains, specifically K. pneumoniae (MIC and MBC values of 0.859 and 13.75 μg/mL, respectively) and S. aureus (MIC and MBC values of 1.72 and 27.5 μg/mL, respectively). For ciprofloxacin-resistant strains, the maximum effects were observed against E. coli (MIC and MBC values of 0.859 and 6.87 μg/mL, respectively) and P. mirabilis (MIC and MBC values of 0.859 and 1.72 μg/mL, respectively). These nanoparticles efficiently degraded methylene blue in the presence of NaBH4 within 30 minutes, following first-order kinetics with a rate constant of 0.0567 min^-¹.
Conclusion: The results showed that M. pulegium effectively contributed to the formation of nanoparticles, acting as a reducing, stabilizing, and capping agent. In this study, the synthesized cobalt nanoparticles exhibited significant antibacterial activity and effective dye degradation properties. These findings suggest the potential application of cobalt nanoparticles in various biological fields.