Sayede Samane Taheri Otaghsara; Mohammad Ali Zazouli; Mohammad Ali Ebrahimzade; Shahram Eslami; Yahya Esfandiari
Abstract
Background and purpose: High concentration of nitrate in drinking water can be detrimental to health. It can be reduced to nitrite in children Stomach and lead the methemoglobinemia. Therefore, the removal of nitrate from polluted water is necessary. The purpose of this study is to determine the effectiveness ...
Read More
Background and purpose: High concentration of nitrate in drinking water can be detrimental to health. It can be reduced to nitrite in children Stomach and lead the methemoglobinemia. Therefore, the removal of nitrate from polluted water is necessary. The purpose of this study is to determine the effectiveness of walnut shell adsorbent in removing nitrates from aqueous solutions. Materials and methods: This experimental study was conducted in a batch laboratory scale. The walnut shell were collected and burned in the furnace at 700 סC in 1 hours and sieved in 20 -100 mesh. The optimum values of pH, contact time, adsorbent dosage and and the different concentrations of nitrate were experimented in lab scale conditions were determined. The nitrate concentration was measured in wavelength of 220 and 275 nm by spectrophotometer. Also pHpzc of absorbent have been evaluated. Results: The results showed that optimum pH was 9 so that by increasing and decreasing optimum pH, removal efficiency increase and decrease. The removal efficiency Increased until 120 minutes, but after 120 minutes the percentage of removal was reduced Increasing of adsorbent dosage and the different concentrations of nitrate cause the increase and decrease of adsorbtion respectively. At optimal conditions, nitrate removal efficiency was 78% Conclusion: The result of the present study shows that walnut shell can be used as an effective and cheap adsorbent for nitrate removal and the process is more efficient at Alkaline pH .
Maryam Hemmati; Arezoo Ghaemi; Haman Tavakkoli
Abstract
Introduction: Environmental problems caused by arrival of antibiotics in water resources due to toxicity and lasting effects are a serious threat. This study has been aimed to evaluate the efficiency of granular activated carbon as adsorbent for the removal of Cephalexin from aqueous solutions. Materials ...
Read More
Introduction: Environmental problems caused by arrival of antibiotics in water resources due to toxicity and lasting effects are a serious threat. This study has been aimed to evaluate the efficiency of granular activated carbon as adsorbent for the removal of Cephalexin from aqueous solutions. Materials and Methods: This study was performed at laboratory scale and batch system. The influence of process variables such as pH of solution, adsorbent dosage, initial Cephalexin concentration and contact time were Investigated. Equilibrium study data were modeled using Langmuir, Freundlich and Temkin, moreover, kinetic studies were done by models of pseudo first order and pseudo second order. Findings: This research found that the Cephalexin adsorption efficiency decreased by increasing pH from 2 to 14, so that after 3 hours, the adsorption efficiency at the 20 mg.L-1 initial Cephalexin concentration and 0.2 g adsorbent, obtained 92.812%, 90.525% and 41.394% at pH 2, 3.5 and 14, respectively. The adsorption of Cephalexin was compatible with Langmuir isotherm and pseudo second order kinetic. Discussion and Conclusions: The present study showed that the granular activated carbon has high potential for adsorption and separation of Cephalexin and such pollutants from aqueous solutions, in addition to features like simple and rapid separation.
Abolfazl Rahmani Sani; Ahmad Hosseini Bandehgharaei; Mahsa Naeemi; Ameneh Navidzadeh; Elham Agheli
Abstract
Background and aim:Antibiotics are a category of organic pollutants that can cause serious environmental problems through their disposal and uncontrolled release to the environment. The purpose of this study was to investigate the removal of sulfadimethoxine from aqueous solutions using carbon ...
Read More
Background and aim:Antibiotics are a category of organic pollutants that can cause serious environmental problems through their disposal and uncontrolled release to the environment. The purpose of this study was to investigate the removal of sulfadimethoxine from aqueous solutions using carbon nanotubes.
Materials and Methods:The present work was an experimental study in which the effects of different parameters, such as PH, contact time, doses of carbon nanotubes, and different concentrations of sulfadimethoxine, on the removal of antibiotic from solutions were examined. All experiments were carried out in a 100-mL reactor at laboratory temperature (24 ± 2 ° C) using a magnetic stirrer at 350 rpm.
Results:The results showed that the maximum removal efficiency (94.5%) was occurred at pH = 6, adsorbent dosage 0.04 g, contact time of 30 min, and initial concentration of 20 mg/L. The findings on the effect of pH showed that the adsorption capacity increases with increasing pH, and at pH = 6, it reaches its maximum and then decreases again. The extent of removal was increased by increasing the dose of carbon nanotubes and the optimum amount for initial concentration of 100 mg/L (50 mL) was 0.04 g. The amount of absorption increased with increasing contact time and the maximum absorption occurred when the contact time was 30 min. The sulfadimethoxine antibiotic isotherm followed the Langmuir isotherm model (R2 = 0.9800) and the pseudo-second-order kinetic model (R2 = 0.9937).
Conclusion: The results showed that carbon nanotubes have a high potential for removal of sulfadimethoxine from aqueous solutions, due to its properties like its high surface area.
hossein kamani; ayat hossein panahi; Somayeh Talebi; mohamad havangi
Abstract
Background and Objectives: Phenol is one of most common organic pollutants in aqueous environments. Phenol presence in the environment can make some health problems such as carcinogenesis, abnormality of heartbeat, etc for humans and poisonous problems for other organisms. Therefore, this pollutant must ...
Read More
Background and Objectives: Phenol is one of most common organic pollutants in aqueous environments. Phenol presence in the environment can make some health problems such as carcinogenesis, abnormality of heartbeat, etc for humans and poisonous problems for other organisms. Therefore, this pollutant must be removed from polluted effluents to prevent water pollution. Using nanoparticles in adsorption processes is considered as an effective method for contaminants removal. The aim of this study was to investigate the efficiency of magnesium oxide nanoparticles in phenol removal from aqueous solutions. Materials and Methods:In this research, nanoparticles of magnesium oxide were used with size of 43 nm. After the preparation of phenol stock solution, effects of pH،(3- 5- 7- 9- 11)، contact time(10,30, 60, 90, and 120 min)، MgO dosage(20, 40, 60, 80 and 100 mg/L) and initial concentration of phenol (25, 50, 75 and 100 mg/l) Were investigated. Results: Results indicated that the removal efficiency increased with increasing pH, contact time, MgO dosage to a certain range and decreasing initial concentration. Such that the maximum efficiency was equal to 81% in the pH of about 11, initial concentration of 50 mg/L, MgO dosage of 80 mg/l and contact time of 60 min. It was found that adsorption kinetics and equilibrium data follow a pseudo-second-order kinetics model and a Langmuir isotherm model respectively. Conclusion: This study showed that the magnesium oxide nanoparticles have the ability to remove the phenol and can be used effectively in removing phenol from aqueous solution
Majid Kermani; Roshanak rezaei; hossein Salehi; sevda fallah jokandan
Abstract
Background: One of the most important environmental pollutants is color Compounds that are generally used in the textile, paper, cosmetics, food and leather industries, and their discharge into wastewater has harmful effects on the environment. The aim of this study is determination of efficiency of ...
Read More
Background: One of the most important environmental pollutants is color Compounds that are generally used in the textile, paper, cosmetics, food and leather industries, and their discharge into wastewater has harmful effects on the environment. The aim of this study is determination of efficiency of ash and powder Rosa Damascena Wastes in removal of Reactive Blue from aqueous solutions. Methods:In this experimental study, after the preparing of powder and ash Rosa Damascena Wastes absorbent, the effect of various parameters of operation such as pH (3-10), the initial concentration of dye (25, 50, 100 and 300 mg/L), contact time (5-180 minutes) and absorbent dose (0.5- 6 g/L) were studied. Finally the results were analyzed by kinetics and isotherm modeling. Results: In this study, equilibrium time of powder and ash Rosa Damascena Wastes Obtained 60 and 45 minutes respectively. The Maximum efficiency of absorbent powder and ash was obtained 74 and 91 percent, respectively, at pH 3, contact time of equilibrium and absorbent dosage 4 g/L. isotherm studies matched with Freundlich isotherm models for both absorbents. Kinetic equations followed the pseudo-second of the model better. Conclusion: The results showed that Powder and ash of Rosa Damascena Wastes can be used as an effective, available and affordable absorbent for removal of color pollutants from aqueous solutions.
Davoud Balarak; Edris Bazrafshan; Yousef Mahdavi
Abstract
Background & objective: Chromium, found in many industrial effluents, is one of most important heavy metal with health and environmental risks. Therefore, the aim of this study is to survey the effect of Cr (VI) removal by using Cyperus rotundus Weed biomass. Material & methods: This empirical ...
Read More
Background & objective: Chromium, found in many industrial effluents, is one of most important heavy metal with health and environmental risks. Therefore, the aim of this study is to survey the effect of Cr (VI) removal by using Cyperus rotundus Weed biomass. Material & methods: This empirical study was done in lab scale. The variation of pH, dose of adsorbent, contact time, and concentration of chromium were investigated. The adsorption data was explained by adsorption isotherms and kenitics.The residual concentration was analyzed by spectrophotometer in maximum wavelength of 540 nm. Results: It was determined that the pH value of 3, contact time of 60 min, adsorbent dosage of 4 g/L and Cr (VI) concentration of 10 mg/L were the optimum conditions for adsorbents. The most Cr (VI) removal efficiency of 99% was obtained for Cystoseira indica biomass in optimum conditions. The equilibrium data is best fitted on Langmuir isotherm and the adsorption kinetic model follows pseudo-second model. The maximum capacity of adsorption was 10.12 mg/g. conclusion: The results revealed that by using Bio-absorption the removal of Cr+6 can be done quickly and effectively.
Ali Naghizadeh
Abstract
Background an Objectives: Natural organic matters because of production of disinfection by products such as trihalomethanes, which are often carcinogenic disinfection, are of particular importance. Carbon nanotubes due to large surface area, and many other applications, are effective adsorbents for the ...
Read More
Background an Objectives: Natural organic matters because of production of disinfection by products such as trihalomethanes, which are often carcinogenic disinfection, are of particular importance. Carbon nanotubes due to large surface area, and many other applications, are effective adsorbents for the removal of natural organic matter. The present study aimed to investigate the removal of natural organic compounds from aqueous solution by single-walled carbon nanotubes and kinetics and equilibrium adsorption process. Methods: in present study, single wall carbon nanotubes used for removal of natural organic matters from aqueous solution. Different variables such as pH of zero point of charge, pH and different concentration of natural organic matters were investigated. Results: pH survey show that with decreasing pH adsorption capacity increased also pH of zero charge was 6.7. Adsorption capacity of single wall carbon nanotubes for initial concentration of natural organic matters of 10, 5 and 3 mg/L were 66.24, 40.63 and 29.77, respectively. Conclusion: Single-walled carbon nanotubes due to features such as high surface area have great potential for the removal of natural organic matter from aqueous solution