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Ethylene dichloride is one of the most important chlorinated hydrocarbons in the petrochemical industry, which is mainly used to produce vinyl chloride monomer, the main precurser of PVC production. Iran is one of the largest PVC producers in the world. During the production of 1000 kg of ethylene dichloride, about 0.4 m3 wastewater is produced containing 50-200 mg / L of ethylene dichloride. In this study, heterogeneous photocatalysis was used for degradation of this chlorinated hydrocarbon. PAni-TiO2 nanocomposite was immobilized on glass beads by a modified dip coating and heat attachment method. The morphology characteristics were confirmed by scanning electron microscope, energy dispersive X-ray spectroscopy and ultraviolet–visible spectroscopy. A pilot scale packed bed recirculating batch photocatalytic reactor was used for conducting photocatalytic experiments. response surface methodology based on central composite design was used to evaluate and optimize the effect of ethylene dichloride concentration, residence time, pH and coating mass as independent variables on the photocatalytic degradation of ethylene dichloride as the response function. Based on the results, actual and RSM predicted results were well fitted with R2 of 0.9870, adjusted R2 of 0.9718 and predicted R2 of 0.9422. Optimum conditions were the ethylene dichloride concentration of 250 mg/L, reaction time of 240 min, pH of 5 and immobilized mass of 0.5 mg/cm2, which resulted in 88.84% photocatalytic degradation. Kinetic of the photocatalytic degradation at optimal condition followed the Langmuir-Hinshelwood first order reaction with k=0.0095 min-1 with R2=0.9455. Complete photocatalytic degradation of ethylene dichloride was achieved after 360 min. Based on the results, it may be argued that the designed and constructed photocatalytic reactor has the potential for industrialization.

Background and purpose: Phenol is an aromatic hydrocarbon and one of the banzan derivatives which have a higher dissolution rate in water and common methods cannot completely remove it. The main objective of this research was to study removal of phenol using UV/ZnO. Materials and Methods: This study was conducted in a batch system. the experiments was conducted in a reactor with a capacity of 1 liter using zinc oxide nanoparticles that fixed on glass with the thermal fixing method and UVc radiation were used. The effects of initial concentration of phenol, solution pH, and contact time on the photocatalytic removal of phenol were studied. [MP2D1] Results: The results showed that the best conditions for the removal of phenol were achieved at pH 3, 5 mg/L initial phenol concentration, 3950 μw/cm2 radiation intensity and 120 min contact time (100% removal efficiency). The pH, initial phenol concentration, and contact time have an effect on phenol removal efficiency; the phenol removal efficiency increases with the decrease of initial phenol concentration and pH. Conclusion: Results of the present study showed that the photocatalytic degradation process (UV/ZnO) is an effective method in removal of phenol from aqueous solutions.

Background and Objective: Natural organic matters (NOM) are known as precursors to disinfection byproducts. As conventional treatment processes cannot get disinfection by-product standards, novel methods have been increasingly applied for the removal of disinfection by-products precursors. The UV/ZnO process is one of the advanced oxidation processes using photocatalytic technology. The present study aims to investigate the effect of UV/ZnO photocatalytic technology on the NOM removal from aqueous solution. Materials and methods: This study was conducted in a lab-scale batch photocatalytic reactor. The volume of reactor was 1liter and covered with UV lamps. Peristaltic pump was used for complete mixing. Humic acid is a key component of natural organic matter and it was used in this study. Each of the samples taken from the UV/ZnO process and other processes were analyzed for their UV absorbance at 254 nm by spectrophotometric. Initial concentration of Humic acid, contact time, pH, and UV irradiation were investigated. Results: The highest efficiency of the UV/ZnO photocatalytic process for removal of Humic acid from aqueous solution was achieved at initial concentration = 2 mg/L, contact time = 120 min, UV irradiation = 3950 μw/cm2, and pH=3. In this process, the removal efficiency for 2 mg/L humic acid was 100 % at 2h retention time. Conclusion: The research showed that performance of system was increased by increasing contact time and UV irradiation and was decreased by increasing HA initial concentration and pH and UV radiation with ZnO agent could not remove NOM lonely. Photocatalytic system using zinc oxide immobilized on glass have high performance to remove humic acid from aqueous solution. The UV/ZnO process was efficient and environmental friendly for natural organic matter removal.

Introduction: Emission of volatile organic compounds through industrial processes to the environment has been received more attentions currently. Photocatalytic oxidation process as a new emerging technique in air purification can be substituted for conventional techniques such as activated carbon adsorption. In photocatalytic oxidation process, pollutant molecules decompose to water and carbon dioxide molecules. The objective of present study was the examination of influencing parameters such as concentration, relative humidity, and superficial gas velocity on photocatalytic oxidation of Methyl Ethyl Ketone (MEK) in a fluidized bed reactor. . Material and Method: In this study photocatalytic oxidation of MEK was examined in a fluidized bed reactor. Gamma alumina coated titanium dioxide particles under ultraviolet light were used as photocatalyst. The efficiency of photocatalytic oxidation process was determined using measurement of MEK concentrations at the inlet and outlet of the fluidized bed reactor. . Result: The study of MEKphotocatalytic oxidation was carried out in the concentration range of 100 to 800 PPM with 25% and 45% relative humidity. Photocatalytic degradation of MEK at the relative 45 % humidity was slightly lower than 25 %. Increasing MEK concentration from 200 to 800 PPM was led to decrease in degradation efficiency. At concentrations of 100 and 200 PPM MEK, increasing superficial gas velocity did not change the degradation efficiency, whereas, at concentrations of 200 to 800 PPM, increasing superficial gas velocity resulted in decrease in MEK degradation. . Conclusion: In photocatalytic oxidation of MEK, there is a competitive adsorption between water and MEK and at higher relative humidity degradation of MEK decreases. In the fluidized bed reactor increasing superficial gas velocity causes decrement in MEK photocatalytic degradation.Increasinginitial concentration of pollutant results in decreasing ofphotocatalytic efficiency due to the limited number of active sites on the catalyst surface.

Background and Objective: Natural organic matters (NOM) are known as precursors to disinfection byproducts. As conventional treatment processes cannot get disinfection by-product standards, novel methods have been increasingly applied for the removal of disinfection by-products precursors. The UV/ZnO process is one of the advanced oxidation processes using photocatalytic technology. The present study aims to investigate the effect of UV/ZnO photocatalytic technology on the NOM removal from aqueous solution. Materials and methods: This study was conducted in a lab-scale batch photocatalytic reactor. The volume of reactor was 1liter and covered with UV lamps. Peristaltic pump was used for complete mixing. Humic acid is a key component of natural organic matter and it was used in this study. Each of the samples taken from the UV/ZnO process and other processes were analyzed for their UV absorbance at 254 nm by spectrophotometric. Initial concentration of Humic acid, contact time, pH, and UV irradiation were investigated. Results: The highest efficiency of the UV/ZnO photocatalytic process for removal of Humic acid from aqueous solution was achieved at initial concentration = 2 mg/L, contact time = 120 min, UV irradiation = 3950 &muw/cm2, and pH=3. In this process, the removal efficiency for 2 mg/L humic acid was 100 % at 2h retention time. Conclusion: The research showed that performance of system was increased by increasing contact time and UV irradiation and was decreased by increasing HA initial concentration and pH and UV radiation with ZnO agent could not remove NOM lonely. Photocatalytic system using zinc oxide immobilized on glass have high performance to remove humic acid from aqueous solution. The UV/ZnO process was efficient and environmental friendly for natural organic matter removal. [ABSTRACT FROM AUTHOR]

Background and aims: Humic acid (HA) is released from degradation of plant and animal components. Humic substances contribute to chlorination as precursors of disinfection by-products. This study was conducted to investigate the effect of cations Ca2+ and Mg2+ on the removal efficiency of humic acid by the titanium dioxide nanoparticle (UV/TiO2). Methods: In this quasi-experimental study, the effect of different variables such as pH, contact time, various concentrations of TiO2, Ca2+, and Mg2+ on the removal efficiency of humic acid by the UV/TiO2 on synthetic water and raw water of Zayandehroud in Isfahan was studied. The results obtained were analyzed using Pearson correlation coefficient test and SPSS software. Results: Optimal concentration of the TiO2 catalyst for removal of HA was 1g/L. The removal efficiency was the highest in acidic conditions (pH=3) within 60 minutes of contact time. The removal efficiency of HA by the UV/TiO2 decreased with increase of contact time. The presence of Ca2+ and Mg2+ ions increased the rate of HA removal by the UV/TiO2. Conclusion: TiO2 photocatalytic process results in a significant reduction in humic materials in water. If water or wastewater contains a high amount of resistant compounds and hardness, these compounds can be broken by a preliminary photocatalytic catharsis and transform to degradable by-products. [ABSTRACT FROM AUTHOR]

Background and aims: Humic acid (HA) is released from degradation of plant and animal components. Humic substances contribute to chlorination as precursors of disinfection by-products. This study was conducted to investigate the effect of cations Ca2+ and Mg2+ on the removal efficiency of humic acid by the titanium dioxide nanoparticle (UV/TiO2). Methods: In this quasi-experimental study, the effect of different variables such as pH, contact time, various concentrations of TiO2, Ca2+, and Mg2+ on the removal efficiency of humic acid by the UV/TiO2 on synthetic water and raw water of Zayandehroud in Isfahan was studied. The results obtained were analyzed using Pearson correlation coefficient test and SPSS software. Results: Optimal concentration of the TiO2 catalyst for removal of HA was 1g/L. The removal efficiency was the highest in acidic conditions (pH=3) within 60 minutes of contact time. The removal efficiency of HA by the UV/TiO2 decreased with increase of contact time. The presence of Ca2+ and Mg2+ ions increased the rate of HA removal by the UV/TiO2. Conclusion: TiO2 photocatalytic process results in a significant reduction in humic materials in water. If water or wastewater contains a high amount of resistant compounds and hardness, these compounds can be broken by a preliminary photocatalytic catharsis and transform to degradable by-products. [ABSTRACT FROM AUTHOR]

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 FROM AUTHOR]