oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Removal of Pharmaceutical Residues by Ferrate(VI)  [PDF]
JiaQian Jiang, Zhengwei Zhou
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0055729
Abstract: Background Pharmaceuticals and their metabolites are inevitably emitted into the waters. The adverse environmental and human health effects of pharmaceutical residues in water could take place under a very low concentration range; from several μg/L to ng/L. These are challenges to the global water industries as there is no unit process specifically designed to remove these pollutants. An efficient technology is thus sought to treat these pollutants in water and waste water. Methodology/Major Results A novel chemical, ferrate, was assessed using a standard jar test procedure for the removal of pharmaceuticals. The analytical protocols of pharmaceuticals were standard solid phase extraction together with various instrumentation methods including LC-MS, HPLC-UV and UV/Vis spectroscopy. Ferrate can remove more than 80% of ciprofloxacin (CIP) at ferrate dose of 1 mg Fe/L and 30% of ibuprofen (IBU) at ferrate dose of 2 mg Fe/L. Removal of pharmaceuticals by ferrate was pH dependant and this was in coordinate to the chemical/physical properties of pharmaceuticals. Ferrate has shown higher capability in the degradation of CIP than IBU; this is because CIP has electron-rich organic moieties (EOM) which can be readily degraded by ferrate oxidation and IBU has electron-withdrawing groups which has slow reaction rate with ferrate. Promising performance of ferrate in the treatment of real waste water effluent at both pH 6 and 8 and dose range of 1–5 mg Fe/L was observed. Removal efficiency of ciprofloxacin was the highest among the target compounds (63%), followed by naproxen (43%). On the other hand, n-acetyl sulphamethoxazole was the hardest to be removed by ferrate (8% only). Conclusions Ferrate is a promising chemical to be used to treat pharmaceuticals in waste water. Adjusting operating conditions in terms of the properties of target pharmaceuticals can maximise the pharmaceutical removal efficiency.
Process for the Synthesis of Ferrate (VI) Alkali Metal Dry  [PDF]
Abdellatif El Maghraoui, Abdelaziz Zerouale, Mustapha Ijjaali
Advances in Materials Physics and Chemistry (AMPC) , 2015, DOI: 10.4236/ampc.2015.51002
Abstract: The iron compounds in the oxidation state (VI) have the specific advantage of being powerful oxidants and bactericides. This feature explains their particular interest in the treatment of water. The aim of this work is to prepare Na2FeO4 stable at ambient in order to optimize the key parameters influencing the performance of the oxidation of iron (II) to iron (VI), as well as to monitor its degradation over time. The synthesis of this phase has been carried out by using the dry reaction Na2O2 with Fe2O3 with a temperature of 700°C for a reaction time of 13 hours with a Na/Fe ratio of 4 to make it possible to simplify the synthesis procedure, to minimize the cost and enhance the production of iron (VI) to meet the growing demand of ferrate (VI) for its interest in water treatment. The obtained phase was characterized by UV spectrophotometer by measuring the optical density at a wavelength of 507 nm.
Ferrate(VI) synthesis at boron-doped diamond anode  [PDF]
?ekerevac Milan,Nikoli?-Bujanovi? Ljiljana,Joki? Anja,Simi?i? Milo?
Journal of the Serbian Chemical Society , 2013, DOI: 10.2298/jsc120309108c
Abstract: The oxidation of iron compounds from alkaline 10 M KOH electrolytes on a boron doped diamond electrode is examined by cyclic voltammetry between the potentials of hydrogen evolution reaction and oxygen evolution reaction, due to ferrate(VI) electrochemical synthesis. It is shown that the anodic current peak that appears in iron free electrolyte at a less positive potential than the potential of oxygen evolution probably coincides with oxidation of hydrogen in >CH2 groups and C-sp2 graphite impurities with formation of >C=O groups at C-sp3 diamond structure. Addition of Fe(III) compounds to the electrolyte provoke formation of the anodic wave on cyclic voltammograms in the potential region which correlates with generation of ferrate(VI). It is concluded that the direct electrochemical synthesis of Fe(VI) at the boron doped diamond anode is possible because of the less positive potential of ferrate(VI)FeO2-4 formation in respect to the potential of oxygen evolution reaction. Presence of ferrate(VI) in electrolyte, formed after anodic polarization of boron electrode in 10 M KOH electrolyte saturated with Fe(III) at + 0.9 V against Hg|HgO electrode, has been proven by UV-VIS spectrometry.
Investigation of electrochemical synthesis of ferrate - Part II: Optimization of the process parameters of ferrate(VI) electrochemical synthesis
?ekerevac Milan I.,Nikoli?-Bujanovi? Ljiljana N.,Joki? Anja B.,Simi?i? Milo? V.
Hemijska Industrija , 2010, DOI: 10.2298/hemind100114006c
Abstract: In part I [1] of the investigation the behavior of iron and selected low carbon steels in concentrated (10M - 15 M) water solution of NaOH and KOH in wide range of electrode potentials, between hydrogen evolution reaction and oxygen evolution reaction, is investigated and discussed. On the base of experimental data obtained by LSV and galvanostatic pulse methods, it is concluded [1] that efficient synthesis of ferrate (VI) can be expected in the region of anodic potentials between + 0,55 V and + 0,75 V against Hg|HgO reference electrode. In this paper optimization of electrolysis parameters of the electrochemical synthesis of ferrate(VI) is elaborated. The most important parameters chosen for optimization process were: anode material, alkaline electrolyte concentration, regime of electrical potential control, current density and electrolyte temperature. The best current efficiency and yield of ferrate(VI) synthesis of the explored anode materials (electrical steel, low carbon cold rolled steel plate, and structural steel) is obtained when electrical steel with 3 wt% of silicon is applied. The worst current efficiency is obtained with anodes made of structural steel with higher concentration of manganese, chromium and nickel. The influence of alloying elements on the process of electrochemical synthesis of ferrate(VI) is discussed in terms of their influence on formation and stability of anodic passive layer and oxygen evolution reaction. The increase of electrolyte concentration from 10M to 15M NaOH and KOH provided the increase of current efficiency with maximum obtained for 14M NaOH. The yield of ferrate(VI) synthesis increases with temperature raise, having maximal value at about +50°C, and after that, at higher temperatures, instability of ferrate(VI) increases and the yield of synthesis lessens. Considering the influence of electrical regime control it is concluded that the biggest yield of ferrate(VI) can be expected with constant anodic potential of about +0,65 V against Hg|HgO reference electrode and with pulsating potential with ratio Emax : Emin = +0,8 V : +0,5 V against Hg|HgO electrode and pulse duration of tmax : tmin = 2s : 1s, figure 1. Circulation of electrolyte has shown relatively small, but positive, effect on the synthesis efficiency, particularly in cases when potassium hydroxide is present in the electrolyte.
Effect of Degree of ClO‾ Hypochlorite on the Wet Synthesis of Ferrate (VI)  [PDF]
Abdellatif El Maghraoui, Abdelaziz Zerouale, Mustapha Ijjaali
Advances in Materials Physics and Chemistry (AMPC) , 2015, DOI: 10.4236/ampc.2015.54014
Abstract: This work is a result of previously done studies on the synthesis of A2FeVIO4 wet ferrate (VI) formula, using chlorine as an oxidant. The major problem of these ferrates is related to their stability over time. This brings us to identify and optimize the critical parameters influencing the preparation of the Na2FeO4 at room stable phase with acceptable performance. The use of water bleach (hypochlorite ClO‾) at a chlorometric degree of 50°F in the synthesis of the Na2FeO4 ambient stable phase promotes the oxidation of iron (II) iron to (VI) in a concentrated NaOH alkaline medium. The synthesis reaction is in the presence of FeSO4 7H2O hydrated iron sulfate at a temperature of about 55°C in order to simplify the synthesis process, to enhance the production of the Fe (VI) and to meet the growing demand of ferrates (VI) for their interest in the treatment of water. Monitoring the degradation of synthesized Na2FeO4 shows its stability up to 12 months, which facilitates storage and transportation. The phases obtained were characterized by IR spectroscopy, and RX by UV spectrophotometer, measuring the optical density at 507 nm.
Application of electrochemically synthesized ferrate(VI) in the purification of wastewater from coal separation plant
?ekerevac Milan I.,Nikoli?-Bujanovi? Ljiljana N.,Mirkovi? Marko B.,Popovi? Negica H.
Hemijska Industrija , 2010, DOI: 10.2298/hemind100325047c
Abstract: The oxidative and coagulation efficiency of Na2FeO4 solution, electrochemically generated by trans-passive anodic oxidation of electrical steel in 10M NaOH solution, is confirmed in the process of purification of heavily contaminated wastewater from coal separation plant. The decontamination efficiency is evaluated comparing the values of selected contamination parameters obtained by chemical and biochemical analysis of plant effluent water and water obtained after decontamination with ferrate(VI) solution in relatively simple laboratory procedure. The sample of 450 ml of wastewater is treated in laboratory conditions with 100cm3 solution of 1 mg dm-3 Na2FeO4 in 10M NaOH. The chemical analysis of effluent water after treatment have shown almost 3 times lower permanganate index, about 3 times lower iron content, 1.45 times lower As3+ content, 7.35 times lower ammonia content. Turbidity and chemical oxygen demand (COD) is reduced for more than 5.77and 13.4 times, respectively. The suspended and colloid matter is eliminated from effluent water after treatment with ferrate(VI) solution. Also, biochemical exploration has confirmed high efficiency of ferrate(VI) in organics and microbial elimination showing 7.1 times lower 5-days bio-chemical oxygen demand (BOD5), and total elimination of aerobic and anaerobic bacteria from effluent water. According to standards on quality of industrial wastewater effluents, it may be concluded that ferrate(VI) treatment of wastewater almost completely eliminates excess of dangerous chemicals and pathogen bacteria, with the exemption of arsenic. Thus, ferrate(VI) shows capable performance in treatment of coal separation plant wastewater.
Synthesis and Characterization of Ferrate(VI) Alkali Metal by Electrochemical Method  [PDF]
Abdellatif El Maghraoui, Abdeleaziz Zerouale, Mustapha Ijjaali, Mohamed Sajieddine
Advances in Materials Physics and Chemistry (AMPC) , 2013, DOI: 10.4236/ampc.2013.31013
Abstract: This works aims at preparing at room stable Na2FeO4 and tracking its degradation over time. The synthetic, during this step, was carried out by electrochemical method. The latter was given maximum focus because of its simplicity and the high degree of purity of the resulting product with respect to wet and dry method. This paper reviews the development of the electrochemical method applied to the synthesis of stable at room Na2FeO4, optimizing the parameters impacting the performance of the oxidation of iron(II) in to iron(VI) in alkaline NaOH, saturated at a temperature of 61°C and a current density of 1.4 A/dm2, in order to simplify the synthesis process, to minimize the cost and to improve the production of iron(VI) to meet the growing demand of ferrate(VI) useful for water treatment. The supervision of the degradation of synthesized Na2FeO4 shows its stability over a period of 10 months, which makes storage and transport easier.
Potassium ferrate [Fe(VI)] does not mediate self-sterilization of a surrogate mars soil
Ronald L Crawford, Andrzej Paszczynski, Lisa Allenbach
BMC Microbiology , 2003, DOI: 10.1186/1471-2180-3-4
Abstract: Under ambient conditions (25°C, oxygen and water present) K2FeO4 mixed into sand mineralized some reactive organic molecules to CO2, while less reactive compounds were not degraded. Dried endospores of Bacillus subtilis incubated in a Mars surrogate soil comprised of dry silica sand containing 20% by weight K2FeO4 and under conditions similar to those now on Mars (extreme desiccation, cold, and a CO2-dominated atmosphere) were resistant to killing by the ferrate-enriched sand. Similar results were observed with permanganate. Spores in oxidant-enriched sand exposed to high fluxes of UV light were protected from the sporocidal activity of the radiation below about 5 mm depths.Based on our data and previously published descriptions of ancient but dormant life forms on Earth, we suggest that if entities resembling bacterial endospores were produced at some point by life forms on Mars, they might still be present and viable, given appropriate germination conditions. Endospores delivered to Mars on spacecraft would possibly survive and potentially compromise life detection experiments.The results of life-detection experiments performed almost three decades ago on Mars by the Viking lander have long been subject to controversy [1-3]. Many scientists, though certainly not all [3,4], have concluded that results of Viking biological experiments can be interpreted as an indication of the presence of strong oxidants in the Martian soil [5-7], rather than biological activity. They suggest that these oxidants are capable of oxidizing organic materials causing release of carbon dioxide as seen in the Viking experiments. Since oxygen was also released after humidifying a sample of Martian soil, these proposed oxidants would also oxidize water. The spontaneous reduction of Ferrate(VI) in water forms molecular oxygen and Fe(III) [8]. The rate of this reaction is strongly pH dependent [9]. Other observations by Viking have complicated data interpretation, including the transient absor
Application of ferrate(VI) in the treatment of industrial wastes containing metal-complexed cyanides : A green treatment
Application of ferrate(VI) in the treatment of industrial wastes containing metal-complexed cyanides : A green treatment

SEUNG-MOK Lee,DIWAKAR Tiwari,
SEUNG-MOK Lee
,DIWAKAR Tiwari

环境科学学报(英文版) , 2009,
Abstract: Ferrate(VI) was employed for the oxidation of cyanide (CN) and simultaneous removal of copper or nickel in the mixed/complexed systems of CN-Cu, CN-Ni, or CN-Cu-Ni. The degradation of CN (1.00 mmol/L) and removal of Cu (0.095 mmol/L) were investigated as a function of Fe(VI) doses from 0.3–2.00 mmol/L at pH 10.0. It was found that Fe(VI) could readily oxidize CN and the reduction of Fe(VI) into Fe(III) might serve efficiently for the removal of free copper ions. The increase in Fe(VI) dose apparently favoured the CN oxidation as well as Cu removal. Moreover, the pH dependence study (pH 10.0–13.0) revealed that the oxidation of CN was almost unaffected in the studied pH range (10.0–13.0), however, the maximum removal efficiency of Cu was obtained at pH 13.0. Similarly, treatment was carried out for CN-Ni system having the initial Ni concentration of 0.170 mmol/L and CN concentration of 1.00 mmol with Fe(VI) dose 2.00 mmol at various pH values (10.0–12.0). Results showed a partial oxidation of CN and partial removal of Ni. It can be observed that Fe(VI) can partially degrade the CN-Ni complex in this pH range. Further, Fe(VI) was applied for the treatment of simulated industrial waste/effluent waters treatment containing CN, Cu, and Ni.
Kinetic and Mechanistic Study of the Reduction of Chromium(VI) by Lactic Acid
Jinhuan Shan,Fang Wang,Changying Song,Heye Wang
International Journal of Inorganic Chemistry , 2008, DOI: 10.1155/2008/314045
Abstract: The kinetics and mechanism of the reduction of chromium(VI) by lactic acid (Lac) in aqueous acidic medium was studied with spectrophotometry in a temperature range of 298.15 K~313.15 K. Under the conditions of the pseudo-first order ([Lac]0?[Cr(VI)]0), the observed rate constant (obs) increased with the increase in [Lac] and [H
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.