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Aerobic Prokaryotes
Published in Volodymyr Ivanov, Environmental Microbiology for Engineers, 2020
Neutrophilic iron- and manganese-oxidizers are usually microaerophilic. The main point for the neutrophilic oxidation of iron is that Fe(II) is not stable under aerobic conditions and neutral pH and must be immediately oxidized by oxygen. However, atoms of Fe(II), surrounded by chelated organic acids, are protected from chemical oxidation by oxygen. Therefore, the functions of neutrophilic microaerophilic “iron-oxidizers” are to produce H2O2 and to chemically degrade the organic “envelope” of Fe2+ atoms by H2O2. Precipitation of iron hydroxide by these bacteria can clog pipelines and wells. They are used in environmental engineering for the removal of iron and manganese from drinking water treated in slow sand filters. Another important application is the removal of ammonia from wastewater by co-precipitation with fine particles of positively charged iron hydroxide produced by neutrophilic “iron- oxidizers.”
Fish mucus stabilized iron oxide nanoparticles: fabrication, DNA damage and bactericidal activity
Published in Inorganic and Nano-Metal Chemistry, 2021
G. Chinnadurai, R. Subramanian, P. Selvi
Synthesis of fish mucus stabilized iron oxide nanoparticles was carried out according to the literature.[39] Different volumes of mucus were used to prepare iron oxide using 0.1 N ferric chloride solution. For the synthesis, 1, 2, and 3 mL of mucus was added to ferric chloride solution and stirred at 75 °C followed by the addition of 1 N sodium hydroxide solution. Formation of iron hydroxide was confirmed by the appearance of reddish brown color of the reaction mixture. The precipitate was centrifuged and thoroughly washed with distilled water. The samples synthesized using 1, 2, and 3 mL of mucus was named as Fe1, Fe2 and Fe3. A blank sample (Fe0) was prepared without mucus for comparative study.
Analytical and ecotoxicological studies on degradation of fluoxetine and fluvoxamine by potassium ferrate
Published in Environmental Technology, 2019
Przemysław Drzewicz, Agata Drobniewska, Katarzyna Sikorska, Grzegorz Nałęcz-Jawecki
The ferrate can be successfully applied for removal of FLX and FLU from natural water. Both for FLX and FLU, treatment with 50 mg/L FeO42− reduced toxicity of investigated solutions by 50%. Therefore, a small amount of ferrate may be used for removal of toxicity caused by the antidepressant, whose average concentration in municipal effluents is at μg/L (three orders of magnitude lower than concentration of investigated solution of the pharmaceuticals). Because of good coagulation properties, iron hydroxide formation is an advantage of the process. Iron hydroxide may be used for removal of metals and other organic compounds as well as suspended solid particles (minerals, humic acids) [31,32]. It may be assumed that ferrate oxidation process is very fast for most of the compounds [24]. The main disadvantage is high cost of ferrate and its stability both in solid form and in the solution. It may cause some problem in application in water and wastewater treatment. However, ferrate(VI) can be encapsulated in water-soluble and biodegradable material in order to protect against decomposition caused by moisture. Ferrate can be also adsorbed on a sorbent and in this form, applied in water and wastewater treatment process. However, the most promising technology is in situ electrochemical generation of ferrate(VI) from sacrificing anode containing iron [33,34]. Preliminary, pilot-scale studies shown that the estimated specific energy consumption is 0.2 kWh/g ferrate produced [35]. Hence, based on obtained results of FLU and FLX removal and toxicity reduction, it may be assumed that treatment of wastewater contaminated with these pharmaceuticals by ferrate oxidation is a viable option. However, efficiency of ferrate(VI) formation depends on current density, anode material, space between the electrodes and pH of electrolyte. Changing of the reactor design may improve efficiency of ferrate(VI) production by electrochemical process [34]. Therefore, improving of ferrate(VI) production in electrochemical process and its injection into wastewater stream is a subject of ongoing studies conducting by many researchers [33,34].