• Journal of Power System Engineering
• /
• v.20 no.1
• /
• pp.42-49
• /
• 2016

This study showed that on-site ferrate(VI) solution was synthesized by wet oxidation method and applied aqueous 2,4-dichlorophenol(DCP) solution to evaluate the degradation efficiency. On-site ferrate(VI) solution was synthesized by putting $FeCl_3{\cdot}6H_2O$ in the strong alkali solution with NaClO and NaOH and applied DCP solution directly. DCP solution was extracted by the liquid-liquid method and analyzed by GC-ECD. The factors such as pH, DCP initial concentration, injected ferrate(VI) dosage, temperature were investigated. The optimum pH and temperature conditions of DCP degradation were obtained in neutral condition and $35^{\circ}C$. And the experimental results showed that DCP removal efficiency also increased with the decrease of DCP initial condition and the injected ferrate(VI) dosage.

• Environmental Engineering Research
• /
• v.10 no.6
• /
• pp.269-282
• /
• 2005

The novel behavior of ferrate(VI) has received an increased attention for its possible applications in various purposes particularly in the treatment of waste/effluent waters. It possess relatively high oxidizing capacity and the reduced ferrate(VI) into Fe(III) again an important and useful precipitant, coagulant, flocculants and likely to be a good adsorbent via the formation of ferric hydroxide for various metal cations. Moreover, the non-toxic effect makes it a 'green chemical' and further enhances its widespread uses in various purposes. Here an attempt has been made to review the applications of ferrate(VI) in the treatment of waste waters and also its possible future applications in the wastewater treatment technology.

• Journal of Korean Society of Water and Wastewater
• /
• v.29 no.6
• /
• pp.685-692
• /
• 2015

The concern over the risk of environmental exposure to brominated phenols has been increased and has led the researchers to focus their attention on the study of bromophenol treatment. In this study, the effects of pH and ferrate(VI) dose on the degradation of 2-bromophenol were investigated. The results indicated that the oxidation of 2-bromophenol by liquid ferrate(VI) was found to be highly sensitive to the pH condition. Furthermore, the highest removal efficiency was observed at the neutral condition with the removal efficiency of 94.2%. In addition, experimental results showed that 2-bromophenol removal efficiency increased with increasing of ferrate dosage. Ferrate(VI) dose of 0.23 mM was sufficient to remove most of the 2-bromophenol with the efficiency of 99.73% and kapp value of $2982M^{-1}s^{-1}$. Seven compounds were identified as the intermediate products by the GC/MS analysis.

• Journal of Korean Society of Environmental Engineers
• /
• v.29 no.12
• /
• pp.1337-1344
• /
• 2007

In this research, we synthesized potassium ferrate(VI) acting as an oxidant, disinfectant, and coagulant, and used it to treat natural organic matter(NOM, HA and FA) in river water. The removal efficiencies obtained by $UV_{254}$ ranged from 20.7 to 73.6% for 10 mg/L HA and from 52.6 to 77.5% for 10 mg/L FA in Nakdong river sample as the ferrate dose varied from 2 to 46 mg/L(as Fe). However, the removal efficiencies by TOC analysis ranged from 0 to 20.3% for HA and from 0 to 26.6% for FA at the same ferrate doses. The removal efficiencies of NOM increased either with decreasing pH or with increasing temperature. The removal efficiency of HA by ferrate was comparable to those by traditional coagulants such as $Al_2(SO_4)_3{\cdot}18H_2O$, $FeSO_4{\cdot}7H_2O$, and FeO(OH). The reaction between ferrate and HA reached a steady state within 60 seconds, showing first-order with respect to the reaction time. The removal efficiencies of HA by traditional coagulants were improved by pretreatment of HA using a small amount of ferrate.

• Environmental Engineering Research
• /
• v.11 no.6
• /
• pp.318-324
• /
• 2006

The higher valence state of iron i.e., Fe(VI) was employed for the oxidation of one of an important toxic ion, cyanide in the aqueous medium. Cyanide was oxidized into cyanate, which is 1,000 times less toxic to cyanide and often accepted for its ultimate disposal. It was to be noted that Fe(VI) is a very powerful oxidizing agent and can oxidize most of the cyanide within few minutes i.e., ca 5 mins of contact. The data was obtained by the UV-Visible measurements for the Fe(VI) decomposition. The UV-Visible data was used to evaluate the overall rate constant for second order redox reaction between ferrate(VI) and cyanide. Also the pseudo first order rate constant was calculated as keeping the cyanide concentration in excess.

• Journal of Korean Society of Environmental Engineers
• /
• v.31 no.6
• /
• pp.454-459
• /
• 2009

In this paper, we have performed an experimental study to simultaneously remove humic acid (RA) and heavy metals (Cu, Mn, and Zn) from the river water using potassium ferrate(VI), a multi-purpose and environment-friendly chemical. In the experiments for treating three 0.1 mM single heavy metals using 0.03${\sim}$0.7 mM (as Fe) ferrate, the removal efficiencies ranged 28${\sim}$99% for Cu, 22${\sim}$73% for Mn, and 18${\sim}$100% for Zn. In addition, humic acid and heavy metals could be very efficiently removed at the same time using 0.03${\sim}$0.7 mM (as Fe) ferrate: for example, 49${\sim}$81% (humic acid), 93${\sim}$100% (Cu), 22${\sim}$86% (Mn), and 20${\sim}$100% (Zn). The removal efficiencies of humic acid and heavy metals in the mixture of humic acid and heavy metals were higher than that in the solution of single humic acid or heavy metal. It can be explained by the fact that, before adding ferrate to the mixed solution, part of solutes were already removed by the complexation between the negatively-charged functional groups of humic acid and heavy metal cations.

• Journal of Korean Society of Environmental Engineers
• /
• v.30 no.7
• /
• pp.729-734
• /
• 2008

The higher valence state of iron i.e., Fe(VI) was employed for the treatment of Cu(II)-EDTA in the aqueous/waste waters. The ferrate(VI) was prepared through wet oxidation of Fe(III) by sodium hypochlorite. The purity of prepared Fe(VI) was above 93%. The stability of Fe(VI) solution decreased as solution pH decreased through self decomposition. The reduction of Fe(VI) was obtained by using the UV-Visible measurements. The dissociation of Cu(II)-EDTA complex through oxidation of EDTA using Fe(VI) and subsequent treatment of organic matter and metal ions by Fe(III) reduced from Fe(VI) in bench-scale of continuous flow reactor were studied. The removal efficiencies of copper were 69% and 79% in pH control basin and reactor, respectively, at 120 minutes as retention time. In addition, Cu(II)-EDTA in the reactor was decomplexated more than 80% after 120 minutes as retention time. From this work, a continuous treatment process for the wastewater containing metal and EDTA by employing Fe(VI) as muluti-functional agent was developed.

• Proceedings of the Korean Ceranic Society Conference
• /
• 2002.10a
• /
• pp.122.1-122
• /
• 2002

• Environmental Engineering Research
• /
• v.13 no.3
• /
• pp.131-135
• /
• 2008

In this study, Fe(VI) was employed as a multi-functional agent to treat the simulated industrial wastewater contaminated with Cu(II)-EDTA through oxidation of EDTA, decomplexation of Cu(II)-EDTA and subsequent removal of free copper through precipitation. The decomplexation of $10^{-4}\;M$ Cu(II)-EDTA species was performed as a function of pH at excess concentration of Fe(VI). It was noted that the acidic conditions favor the decomplexation of Cu(II)-EDTA as the decomplxation was almost 100% up to pH 6.5, while it was only 35% at pH 9.9. The enhanced degradation of Cu(II)-EDTA with decreasing the pH could be explained by the different speciation of Fe(VI). $HFeO_4^-$ and $H_2FeO_4$, which are relatively more reactive than the unprotonated species $FeO_4^{2-}$, are predominant species below neutral pH. It was noted that the decomplexation reaction is extremely fast and within 5 to10 min of contact, 100% of Cu(II)-EDTA was decomplexed at pH 4.0. However, at higher pH (i.e., pH 10.0) the decomplexation process was relatively slow and it was observed that even after 180 min of contact, maximum ca 37% of Cu(II)-EDTA was decomplexed. In order to discuss the kinetics of the decomplexation of Cu(II)-EDTA, the data was slightly fitted better for the second order rate reaction than the first order rate reaction in the excess of Fe(VI) concentration. On the other hand, the removal efficiency of free Cu(II) ions was also obtained at pH 4.0 and 10.0. It was probably removed through adsorption/coagulation with the reduced iron i.e., Fe(III). The removal of total Cu(II) was rapid at pH 4.0 whereas, it was slow at pH 10.0. Although the decomplexation was 100% at lower pH, the removal of free Cu(II) was relatively slow. This result may be explicable due to the reason that at lower pH values the adsorption/coagulation capacity of Fe(III) is greatly retarded. On the other hand, at higher pH values the decomplexation of Cu(II)-EDTA was partial, hence, slower Cu(II) removal was occurred.