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Background and purpose: Removal of lead as a toxic metal from contaminated water resources is necessary due to the dangerous effect of lead. One of the most effective methods of removal is the adsorption process. The aim of this study was adsorption and magnetic separation of lead from synthetic wastewater using iron oxide nanoparticles and carbon (ION/C) composite Material and Methods: In this study nanoparticles of iron oxide (ION) were used as a source of iron for magnetic separation of powder activated carbon from solution samples. The physical and surface properties of the adsorbent were studied along with influencing factors (pH, contact time, adsorbent dosage, initial lead concentration, and temperature) on the adsorption process. Kinetic equations and equilibrium isotherms studies were also conducted. Results: The size of ION and specific surface area of ION/C were found to be 30-80 nm and 671.2 m2/g, respectively. We observed that the adsorption process reached equilibrium at 60 min and pH=6and adsorption efficiency increased by increasing the amount of adsorbent and temperature. Maximum adsorption capacity based on Langmuir isotherms was obtained 67.1mg/g at 50 °C. Conclusion: According to this study it is believed that magnetized active carbon by keeping its physical and surface properties could be a suitable method to solve some related problems including separation and filtration.

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Background and purpose: In MRI the concentration of contrast agent is indirectly measured from signal intensity (SI). It is important to find the maximum linear relationship between SI and concentration of the iron oxide nanoparticles for perfusion measurement. The aim of this study was to investigate the effect of inversion time on SI and the maximum linear relationship between SI and concentration of the polyethylene glycol (PEG) coated iron oxide nanoparticles at different inversion times (TIs) using inversion recovery pulse sequence in T1-weighted MR images. Materials and methods: A phantom was designed to hold the vials with different concentrations of the PEG coated iron oxide nanoparticles in MRI coil. MR imaging was performed using inversion recovery Turbo-FLASH sequence with different TIs. The maximum SI and the maximum linear relationship between SI and concentration of the nanoparticles were measured at different TIs. Results: The maximum SI and the maximum linear relationship between SI and nanoparticles’ concentration were dependent on TI. The maximum SI at different TIs was seen at the highest concentration (500µmolFe/L). The maximum SI which led to a linear relationship with the nanoparticles concentration (R2=0.99) was obtained up to 105.49 and 243.64µmolFe/L for TIs of 400 and 240ms, respectively. Conclusion: TI has an effect on strength of SI in MRI. Increasing the TI values leads to a decrease in concentration of the PEG coated iron oxide nanoparticles that gives the maximum linear SI.

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Background and purpose: Contamination of drinking water with fluoride due to natural and human activities is a serious problem that threatens human health. Long-term and excessive consumption of water containing fluoride could lead to endocrine glands diseases and Alzheimer's disease. Adsorption process is an effective and popular method for removal of fluoride, so the purpose of this research was magnetizing multiwall carbon nanotubes with nano iron oxide and using it as an adsorbent for fluoride removal from aqueous solution. Materials and methods: Co-precipitation method used for synthesized magnetic nano composite and its characteristics were investigated by SEM, TEM, XRD and VSM techniques. The effect of independent variables such as contact time, pH, temperature, adsorbent dose and initial concentration on fluoride removal was analyzed by response surface methodology (box-Behnken design method) and ANOVA. Results: The optimum condition was obtained at pH= 3, 2g/L sorbent dosage in 2h contact time and 45oC temperature. Isotherms and kinetics results showed that the Langmuir model and pseudo-second order were correlated by data with R2>0.98 and R2>0.941, respectively. Thermodynamic values revealed that fluoride adsorption process was endothermic and spontaneous. Conclusion: In this study synthesized adsorbent was found efficient in fluoride removal (98.5% adsorption in optimal condition) and due to magnetic ability it can be easily separated from the samples by an external magnet. Therefore, it can be applied in removal of fluoride from drinking water.