The catalytic ozonation of diazinon using nano-MgO@CNT@Gr as a new heterogenous catalyst: The optimization of effective factors by response surface methodology

In this research, the degradation of the insecticide diazinon was studied using a new hybrid catalyst consisting of magnesium oxide nanoparticles (nano-MgO), carbon nanotubes (CNTs), and graphite (Gr), nano-MgO@CNT@Gr, under various experimental conditions. This study shows the optimization of the nano-MgO@CNT@Gr/O3 process for diazinon degradation in aqueous solutions. Box-Behnken experimental design (BBD) and response surface methodology (RSM) were used to assess and optimize the solo effects and interactions of four variables, pH, catalyst loading, reaction time, and initial diazinon concentration, during the nano-MgO@CNT@Gr/O3 process. Analysis of regression revealed an adequate fit of the experimental results with a quadratic model, with R2 > 0.91. Following the collection of analysis of variance (ANOVA) results, pH, catalyst loading, and reaction time were seen to have significant positive effects, whereas the concentration of diazinon had a considerable negative impact on diazinon removal via catalytic ozonation. The four variables for maximum diazinon removal were found to be optimum (82.43) at the following levels: reaction time, 15 min; pH, 10; catalyst dosage, 1.5 g L-1; and diazinon concentration, 10 mg L-1. The degradation of diazinon gave six kinds of by-products. The mechanism of diazinon decomposition was considered on the basis of the identified by-products. According to these results, the nano-MgO@CNT@Gr/O3 process could be an applicable technique for the treatment of diazinon-containing wastewater. © 2020 The Royal Society of Chemistry

Optimization of synthesis a new composite of nano-MgO, CNT and Graphite as a catalyst in heterogeneous catalytic ozonation for the treatment of pesticide-laden wastewater

The production of an efficient, reusable, stable and easily separable catalyst in the ozonation process through a reliable procedure is one of the essential requirements of the catalytic ozonation process (COP). In this study, the nano-MgO/CNT/Graphite composite was synthesized to use as a new catalyst in the COP. Synthesis of the nano-MgO/CNT/Graphite was carried out based on the extreme vertices mixture design (EVMD) using three components; MgO nanoparticles, carbon nanotubes (CNTs) and Graphite. Based on EVMD, 9 compositions were produced. For assessing the catalytic activity of synthesized compositions, pesticide manufacturing plant wastewater (PMPW) (initial COD=617 mg/L and TOC = 121) was treated in COP with new synthesized catalytic. The highest COD and TOC removal and destruction efficiencies were attained with composition C-9. The surface area of the optimum nano-MgO/CNT/Graphite was calculated to be had 221.631 m2 g�1 and a high density of basic surface functional groups. Kinetics of PMPW oxidation indicated that the rate of COD and TOC removal efficiencies in the optimum nano-MgO/CNT/Graphite/O3 process were 12.73 (13.24/1.04 mg COD/L.min) and 7.11 (1.44/0.2 mg TOC/L.min) times as high as those in the single ozonation (SOP), respectively. Clearly, the optimum nano-MgO/CNT/Graphite showed a significant ability in catalysis of the ozonation process of organic materials by means of increasing O3 decomposition and radOH production. The synthesized optimum nano-MgO/CNT/Graphite was reusable because of the stability and durability of the catalytic activities. © 2019 Elsevier Lt

Investigation of Apple Scum and Its Modification with Magnesium Chloride and Hydrogen Peroxide for Removal of Toxic Hexavalent Chromium from Aqueous Solution

Introduction: Chromium is one of the heavy metals present in effluents produced from industrial activities and exists in the trivalent and hexavalent state. It is mentioned that hexavalent chromium has is more hazardous due to its carcinogenic properties. Due to its hazard, Cr(VI) must be removed from wastewaters prior discharge into the environment. For this reason, the present aimed for removal of hexavalent chromium by Apple Scum and its modification with magnesium chloride and hydrogen peroxide. Material and Methods: Apple Scum was obtained from Galin Plan as waste materials. The Apple Scum was modified with 2M MgCl2 and 30% H2O2. Several experimental parameters such as solution pH (1-9), contact time (1-100 min), solution temperature (20-60oC), adsorbent dosage (2-10 g/L) and initial chromium concentration (10-100 mg/L) was investigated. All experiments were done in batch system. Results: The results of present work reveals that chromium removal efficiency was increased with increase in adsorbent dosage, contact time and initial chromium concentration, while decreased for increase in solution pH and temperature. Higher removal efficiency was observed at pH 1, 100 min contact time, 100 mg/L chromium concentration and 20oC temperature. At this optimal condition up to 90% of chromium was removed. In addition, the modification of Apple Scum leads to increase in chromium removal efficiency up to 98% for MgCl2 modified adsorbent and up to 95% forH2O2 modified one. Conclusion: The results of present work well demonstrate the waste Apple Scum for removal of hexavalent chromium and its sorption capacity will be improved in the case of modification with H2O2 and MgCl2

Evaluation of the Hospital Wastewater Activated Sludge Extended Aeration System in the Removal of Estrogenic Compounds (Case Study: Khuzestan Hospitals)

Background and Objective: Estrogen is a steroid hormone that is in the water and cause risks for aquatic organisms, especially fish is. Estrogenic hormones naturally (caused by endocrine) or artificial (due to hormonal contraceptives such as birth control pills) to sewage and hospital to find. This study aimed to determine the amount of estrogen in the sewage and Golestan and Abuzar hospital in Ahvaz were studied. Material and Methods: Sampling was done by tracking estrogen in the aquatic environment. 56 samples 4 months in different parts of the Golestan and Abuzar hospital wastewater treatment plant in Ahvaz were taken. Sample a little electro luminescence (ECL) were analyzed by laboratory Iranian city of Ahvaz. In this study, different forms of estrogen (estrone, 17-beta-estradiol, estriol, 17-alpha-ethinyl estradiol) has been studied as estrogen. Results: Mean hormone found in raw wastewater to the Golestan hospital wastewater treatment plant effluent from the treatment plant hormone 69.08 ng/l and 7.28 ng/l mean. Mean testosterone in Ahvaz Abuzar hospital treatment input 70.61 ng/l and 18.94 ng/l is refinery output. According to the results of high impact biological treatment is the removal of estrogenic compounds. Conclusion: Secondary treatment of sewage is effective in reducing hormones that can do this at this stage of the biological treatment effect

Nitrate Measurment in Water Source of Karaj City and Zonning it Geographic Information Systems (GIS)

Background & Objectives: Nitrate is one of drinking water pollutant which is introduced to water body from municipal wastewater. Information on nitrate concentration and its distribution in water resource is necessary in safe drinking water supply. For that reason, the present work was done for investigation of nitrate in Karaj water supply resource and its zonning with Geographic Information Systems (GIS). Materials and Methods: In this work, the nitrate concentration in 200 wells of Karaj water supply system was determined with DR5000 spectrophotometet. After that, the measured nitrate concentration was modeled by Geographic Information Systems. Results: The results show in many area of Karaj, nitrate concentration was below the available standard (45 mg/L). Modeling of nitrate concentration shows the nitrate concentration was lower in North and West North west parts of Karaj City and higher concentration was observed in Sothern eastern. However, in that area, nitrate concentration was also below available standard. Conclusion: The overall results from present work well demonstrate that drinking water source of Karaj was safe based on nitrate concentration and no health risk threat consumer health body

Adsorption of Acid Red 18 by Activated Carbon Prepared from Cedar Tree: Kinetic and Equilibrium Study

Introduction: Textile effluents are one of the main environmental pollution sources and contain toxic compounds which threat the environment. For that reason, the activated carbon prepared from Cedar Tree was used for removal of Acid Red 18 as an Azo Dye. Material and Methods: Activated carbon was prepared by chemical activation and was used in batch system for dye removal. Effect of various experimental parameters such as pH (3 to11), initial dye concentration (50, 75 and 100 mg/L), contact time (1 to 120 min) and adsorbent dosage (2 to 10 g/L) were investigated. Equilibrium data was fitted onto Langmuir and Freundlich isotherm model. In addition, pseudo first order and pseudo second order models were used to investigate the kinetic of adsorption process. Results: Results shows that dye removal was increase with increase in adsorbent dosage, contact time and initial dye concentration. In addition, higher removal efficiency was observed in low pH (pH=3). At 120 min contact time, pH=3, 6 g/L adsorbent dosage and 100 mg/L of initial dye concentration, more than 95% of dye was removed. Equilibrium data was best fitted onto Freundlich isotherm model. According to Langmuir constant, maximum sorption capacity was observed to be 51/28 mg/L. in addition pseudo second order model best describe the kinetic of adsorption of Acid Red 18 onto present adsorbent. Conclusion: The results of present work well demonstrate that prepare activated carbon from Pine Tree has higher adsorption capacity toward Acid Red 18 Azo dye and can be used for removal of dyes from textile effluents

Investigation Of Efficiency Of Polyferric Sulfate(PFS) Coagulant Compared To Poly Aluminium Choloride (PAC) in Ahvaz Water Treatment

Background: Coagulation process has a important place in water treatment. Currently, poly aluminum chloride is used in Kian-abad water treatment plant. The purpose of this study is to compare and investigate the efficiency of coagulants of poly ferric sulfate(PFS) against poly aluminum chloride (PAL) in removing turbidity and coliform bacteria in Ahwaz water treatment plant. Methods: This study, was performed in lab scale and using of jartest apparatus in Ahwaz water treatment. Experiments was conducted in 35NTU turbidity in Ahwaz water treatment plant. The studied parameters included concentrations of coagulants, pH, turbidity, total coliform, fecal coliform and heterotrophic bacteria. Results: The most optimal efficiency conditions of poly aluminum chloride were pH=8, rapid mixing of 120rpm and optimal dose of 5ppm which was 93.14% in pH=8 and 93.80% for optimal dose of 5ppm. The most optimal condition for poly ferric sulfate included pH=8, rapid mixing of 120 rpm and optimal dose of 8ppm. In optimal condition of performance for poly aluminum chloride, efficiency of removing total coliform, fecal coliform and heterotrophic bacteria were 90.12, 83.70, 84.08% respectively. In optimal condition of poly ferric sulfate in dose of 8ppm efficiency removing total coliform, fecal coliform, and heterotrophic bacteria were 90.48, 84.83, and 84.69. Conclusion: Finally, there was small difference between both PFS and PAC group about turbidity removal efficiency that was not significant statistically

Removal of Nitrate by Zero Valent Iron in the Presence of H2O2

Background & Aims: Nitrate is the oxidation state of nitrogen compounds, which is founded in water resources that contaminated by municipal, industrial and agricultural waste water. If nitrate leek in to ground water resources, it can cause health problems. Material and Methods: Removal of nitrate from ground water by iron powder in the presence of H2O2 was investigated. Experiments have been done by use of 250 ml of water samples containing 100 mg/L nitrate in various condition. Various parameters such as pH (3, 5, 7, 9), iron dosage (10, 15, 20, 30 g/L), initial H2O2 concentration (5, 10, 15, 20 ml/L) and contact time (10-120 min). Results: Obtained results shows the removal of nitrate was increased by pH reduction, increment of iron mass and contact time. In addition, nitrate reduction was increased by increment of initial H2O2 concentration up to 15 ml/L. High removal was observed at pH=3, iron mass=30 g/L, contact time equal 120 min and H2O2 concentration=15 ml/L. At above condition, upon 98% of nitrate was removed. Conclusion: In summary, this method is simple, low cost and effective for removal of nitrate from ground water and industrial activity