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Yurum A.,Sabanci University | Kocabas-Atakli Z.T.,Sabanci University | Sezen M.,Sabanci University | Semiat R.,Grand Water Research Institute | Yurum Y.,Sabanci University
Chemical Engineering Journal | Year: 2014

Iron oxide nanoparticles were deposited on activated carbon (AC) with the microwave hydrothermal (MH) treatment technique. The effect of heating duration and AC's oxidation on structural properties were studied. X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), focused ion beam (FIB) microscopy, Brunauer, Emmett and Teller (BET), and porous texture analyses were utilized to characterize iron oxide/AC system. XRD characterization revealed dependence of crystal structure to heating duration. BET and porous texture analyses showed some pore filling in AC, but pore volume increase in iron oxide particles. With the MH technique, porous iron oxide was obtained with a high loading value of 20.27% in just 9. min. Additionally, As(V) adsorption capacity of synthesized materials was studied. As(V) adsorption onto iron oxide deposited supports obeyed Langmuir and pseudo-second order models. Batch adsorption experiments revealed a high efficiency of As(V) removal with the MH synthesized materials. Maximum adsorption capacity was 27.78. mg/g, and for a loading of 0.75. g/L, 99.90% uptake was reached within just 5. min due to the porous nature of iron oxide. Moreover, more than 99.00% of uptake was obtained within the pH range of 6-8. The results suggest that MH synthesized iron oxide particles are promising materials for water treatment. © 2014 Elsevier B.V. Source

Gavrieli B.,Israel Defense Forces | Potasman I.,Infectious Diseases Unit | Armon R.H.,Technion - Israel Institute of Technology | Armon R.H.,Grand Water Research Institute
Journal of Water and Health | Year: 2010

Israel Defense Forces (IDF) guidelines for drinking water require the use of water only from sources that have been inspected and authorized by a medical expert. This study aimed to compare canteen water quality of two military units (infantry and armoured corps), to search for sources of possible microbial contamination and to look for any impact on gastrointestinal symptoms. Statistical analysis revealed that canteens of armoured corp soldiers were significantly more contaminated compared to those of infantry soldiers. Outdoor taps and water in trailers were found to harbour significantly higher numbers of microbial indicators compared to showers/lavatory sources; however, the numbers were much lower compared to canteens. Canteen water retention for more than one day revealed significantly increased numbers of examined microbial parameters, possibly due to secondary contamination or regrowth. Gastrointestinal symptoms were not significantly different between the two units despite the significant canteen water quality difference. An odds ratio evaluation was conducted on 45 exposure-illness combinations based on gastrointestinal symptoms, exposure and soldiers affiliation. Out of these 45 combinations only 14 resulted in odds ratio > 1, where 3 had high values (7.44, 7.46 and 11.2) suggesting a possible connection between diarrhoea and/or vomiting versus coliphages and faecal coliforms. © IWA Publishing 2010. Source

Shemer H.,Grand Water Research Institute | Semiat R.,Grand Water Research Institute
Desalination | Year: 2011

The effect of halogen based disinfectants including monochloramines (NH2Cl), free chlorine (HOCl/OCl-), and free oxidants (mixture of HOCl/OCl- and HOBr/OBr) on polyamide membrane was studied in synthetic Ocean seawater. Formation and stability of these oxidants were also examined. Permeability and salt rejection of flat sheet polyamide RO membranes following exposure to the halogen based oxidants were compared to the baseline performance of unexposed membranes. The ratio between free chlorine and free bromine was found to depend on the ratio between the bromides, naturally found in seawater, and the added chlorine. Bromide enhanced the degradation of monochloramines but did not affect the stability of free chlorine. All the oxidants damaged the polyamide membranes studied while the free oxidants appeared to be the most aggressive. © 2010 Elsevier B.V. Source

Zelmanov G.,Grand Water Research Institute | Semiat R.,Grand Water Research Institute
Separation and Purification Technology | Year: 2013

This study relates to an adsorption method process for treating a fluid containing undesired selenium contaminants (Se4+ and Se6+) in order to clean the fluid of the contaminant and develop a process for recovering the adsorbent material. The approach for this purification process was made using iron (Fe3+) oxide/hydroxide nanoparticles sol (NanoFe) as an adsorbent. The technique provides an efficient and cost-effective method for selenium removal from water. A strong effect was shown of iron (Fe 3+) oxide/hydroxide nanoparticles-based concentration and pH level of polluted water on removal efficiency. The exceptional adsorption properties of synthesized NanoFe adsorbent are demonstrated. This technique achieved residual selenium concentration less than 0.01 ppm, which is acceptable by water quality regulations and at least 95-98% regeneration efficiency of the selenium with the proposed adsorbent. The selenium adsorption capacity on the iron(3) oxide particles at an equilibrium concentration of 0.01 ppm as Se in the solution is about one order of magnitude higher than these values reported in the literature. This technique enables the recovery of the adsorbent by producing concentrated selenium solution that may be treated further to obtain selenium-containing crystals while recovering the cleaning solution. © 2012 Published by Elsevier B.V. All rights reserved. Source

Zach-Maor A.,Grand Water Research Institute | Semiat R.,Grand Water Research Institute | Shemer H.,Grand Water Research Institute
Journal of Colloid and Interface Science | Year: 2011

A homogeneous layer of nano-sized magnetite particles (<4nm) was synthesized by impregnation of modified granular activated carbon (GAC) with ferric chloride, for effective removal of phosphate. A proposed mechanism for the modification and formation of magnetite onto the GAC is specified. BET results showed a significant increase in the surface area of the matrix following iron loading, implying that a porous nanomagnetite layer was formed. Batch adsorption experiments revealed high efficiency of phosphate removal, by the newly developed adsorbent, attaining maximum adsorption capacity of 435mg PO4/g Fe (corresponding to 1.1mol PO4/mol Fe3O4). It was concluded that initially phosphate was adsorbed by the active sites on the magnetite surface, and then it diffused into the interior pores of the nanomagnetite layer. It was demonstrated that the latter is the rate-determining step for the process. Innovative correlation of the diffusion mechanism with the unique adsorption properties of the synthesized adsorbent is presented. © 2011 Elsevier Inc. Source

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