http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
von Gunten, Konstantin,Alam, Md. Samrat,Hubmann, Magdalena,Ok, Yong Sik,Konhauser, Kurt O.,Alessi, Daniel S. Elsevier 2017 Bioresource technology Vol.236 No.-
<P><B>Abstract</B></P> <P>A modified Community Bureau of Reference (CBR) sequential extraction method was tested to assess the composition of untreated pyrogenic carbon (biochar) and oil sands petroleum coke. Wood biochar samples were found to contain lower concentrations of metals, but had higher fractions of easily mobilized alkaline earth and transition metals. Sewage sludge biochar was determined to be less recalcitrant and had higher total metal concentrations, with most of the metals found in the more resilient extraction fractions (oxidizable, residual). Petroleum coke was the most stable material, with a similar metal distribution pattern as the sewage sludge biochar. The applied sequential extraction method represents a suitable technique to recover metals from these materials, and is a valuable tool in understanding the metal retaining and leaching capability of various biochar types and carbonaceous petroleum coke samples.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Modified four step sequential extraction method suitable for pyrolyzed materials. </LI> <LI> Untreated biochar may easily release alkaline earth and transition metals. </LI> <LI> Wood biochar releases metals more readily than does sewage sludge biochar. </LI> </UL> </P>
Shin, Jaedon,von Gunten, Urs,Reckhow, David A.,Allard, Sebastien,Lee, Yunho American Chemical Society 2018 Environmental science & technology Vol.52 No.13
<P>Oxidative treatment of iodide-containing waters can form toxic iodinated disinfection byproducts (I-DBPs). To better understand the fate of iodine, kinetics, products, and stoichiometries for the reactions of ferrate(VI) with iodide (I<SUP>-</SUP>) and hypoiodous acid (HOI) were determined. Ferrate(VI) showed considerable reactivities to both I<SUP>-</SUP> and HOI with higher reactivities at lower pH. Interestingly, the reaction of ferrate(VI) with HOI (<I>k</I> = 6.0 × 10<SUP>3</SUP> M<SUP>-1</SUP> s<SUP>-1</SUP> at pH 9) was much faster than with I<SUP>-</SUP> (<I>k</I> = 5.6 × 10<SUP>2</SUP> M<SUP>-1</SUP> s<SUP>-1</SUP> at pH 9). The main reaction pathway during treatment of I<SUP>-</SUP>-containing waters was the oxidation of I<SUP>-</SUP> to HOI and its further oxidation to IO<SUB>3</SUB><SUP>-</SUP> by ferrate(VI). However, for pH > 9, the HOI disproportionation catalyzed by ferrate(VI) became an additional transformation pathway forming I<SUP>-</SUP> and IO<SUB>3</SUB><SUP>-</SUP>. The reduction of HOI by hydrogen peroxide, the latter being produced from ferrate(VI) decomposition, also contributes to the I<SUP>-</SUP> regeneration in the pH range 9-11. A kinetic model was developed that could well simulate the fate of iodine in the ferrate(VI)-I<SUP>-</SUP> system. Overall, due to a rapid oxidation of I<SUP>-</SUP> to IO<SUB>3</SUB><SUP>-</SUP> with short-lifetimes of HOI, ferrate(VI) oxidation appears to be a promising option for I-DBP mitigation during treatment of I<SUP>-</SUP>-containing waters.</P> [FIG OMISSION]</BR>
Reaction of Ferrate(VI) with ABTS and Self-Decay of Ferrate(VI): Kinetics and Mechanisms
Lee, Yunho,Kissner, Reinhard,von Gunten, Urs American Chemical Society 2014 Environmental science & technology Vol.48 No.9
<P>Reactions of ferrate(VI) during water treatment generate perferryl(V) or ferryl(IV) as primary intermediates. To better understand the fate of perferryl(V) or ferryl(IV) during ferrate(VI) oxidation, this study investigates the kinetics, products, and mechanisms for the reaction of ferrate(VI) with 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) and self-decay of ferrate(VI) in phosphate-buffered solutions. The oxidation of ABTS by ferrate(VI) via a one-electron transfer process produces ABTS<SUP>•+</SUP> and perferryl(V) (<I>k</I> = 1.2 × 10<SUP>6</SUP> M<SUP>–1</SUP> s<SUP>–1</SUP> at pH 7). The perferryl(V) mainly self-decays into H<SUB>2</SUB>O<SUB>2</SUB> and Fe(III) in acidic solution while with increasing pH the reaction of perferryl(V) with H<SUB>2</SUB>O<SUB>2</SUB> can compete with the perferryl(V) self-decay and produces Fe(III) and O<SUB>2</SUB> as final products. The ferrate(VI) self-decay generates ferryl(IV) and H<SUB>2</SUB>O<SUB>2</SUB> via a two-electron transfer with the initial step being rate-limiting (<I>k</I> = 26 M<SUP>–1</SUP> s<SUP>–1</SUP> at pH 7). Ferryl(IV) reacts with H<SUB>2</SUB>O<SUB>2</SUB> generating Fe(II) and O<SUB>2</SUB> and Fe(II) is oxidized by ferrate(VI) producing Fe(III) and perferryl(V) (<I>k</I> = ∼10<SUP>7</SUP> M<SUP>–1</SUP> s<SUP>–1</SUP>). Due to these facile transformations of reactive ferrate(VI), perferryl(V), and ferryl(IV) to the much less reactive Fe(III), H<SUB>2</SUB>O<SUB>2</SUB>, or O<SUB>2</SUB>, the observed oxidation capacity of ferrate(VI) is typically much lower than expected from theoretical considerations (i.e., three or four electron equivalents per ferrate(VI)). This should be considered for optimizing water treatment processes using ferrate(VI).</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/esthag/2014/esthag.2014.48.issue-9/es500804g/production/images/medium/es-2014-00804g_0011.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/es500804g'>ACS Electronic Supporting Info</A></P>
Lee, Yunho,Yoon, Jeyong,Gunten, Urs von 한국공업화학회 2005 응용화학 Vol.9 No.1
The kinetics of oxidation of phenolic water contaminants by ferrate (Fe(Ⅵ)) were investigated, especially focusing on phenolic endocrine disrupting chemicals (EDCs), such as, ethinylestradiol (EE2), estradiol (E2), and bisphenol-A (BPA). The second-order rate constants of Fe(Ⅵ) (k_(app)) with selected EDCs and many substituted phenols were determined in the pH range 611. The k_(app) of selected EDCs at pH 7 were above 600 M^(-1) sec^(-1), indicating that these EDCs can be completely transformed during water treatment with Fe (Ⅵ) . From the pH-dependency of kapp, each elementary reaction rate constant, i.e., the reaction of HFeO₄^(-) with neutral phenols (k_(HFeO4-/PhOH)) and the reaction of HFeO₄^(-) with ionized phenols (k_(HFe04-/PhO-)) was calculated. Correlation analysis based on a constants and pK_(a) values of substituted phenols revealed significant quantitative structure-activity relationships for both k_(HFe04-/PhOH) and k_(HFeO4-/PhO-). Experiments performed with lake water and wastewater showed that the rate constants determined in pure water could be applied to predict the oxidation of selected EDCs in real waters. From the comparison of reactivity toward phenolic EDCs, Fe(Ⅵ) was found to be less reactive than ozone and chlorine dioxide, but more reactive than chlorine. Overall, the results indicate that Fe(Ⅵ) is effective to treat waters containing phenolic contaminants.
Lee, Yunho,Imminger, Stefanie,Czekalski, Nadine,von Gunten, Urs,Hammes, Frederik Elsevier 2016 Water research Vol.101 No.-
<P><B>Abstract</B></P> <P>Inactivation kinetics of autochthonous bacteria during ozonation of wastewater effluents were investigated using cultivation-independent flow cytometry (FCM) with total cell count (TCC) and intact cell count (ICC) and intracellular adenosine triphosphate (ATP) analysis. The principles of the methods including ozone inactivation kinetics were demonstrated with laboratory-cultured <I>Escherichia coli</I> spiked into filtered and sterilized wastewater effluent. Both intracellular ATP and ICC decreased with increasing ozone doses, with ICC being the more conservative parameter. The log-inactivation levels (−log(N/N<SUB>0</SUB>) of <I>E. coli</I> reached the method detection limits for FCM (∼3) and ATP (∼1.7) at specific ozone doses of ≥0.5 gO<SUB>3</SUB>/gDOC. During ozonation of four real wastewater effluents, the log-inactivation of autochthonous bacteria with FCM ICC was 0.3–1.0 for 0.25 gO<SUB>3</SUB>/gDOC and increased to 1.1–2.1 for 0.5 gO<SUB>3</SUB>/gDOC, but remained at a similar level of 1.5–2.8 for a further increase of the specific ozone doses to 1.0 and 1.5 gO<SUB>3</SUB>/gDOC. The FCM data also showed that autochthonous bacteria were composed of communities with high and low ozone reactivity. The inactivation levels measured with intracellular ATP were reasonably correlated to ICC (r<SUP>2</SUP> = 0.8). Overall, FCM and ATP measurements were demonstrated to be useful tools to monitor the inactivation of autochthonous bacteria during ozonation of municipal wastewater effluents.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ozone inactivation kinetics of wastewater effluent studied by FCM, ATP and cultivation. </LI> <LI> For <I>E. coli</I>, inactivation was in order of cultivation, ATP, and FCM-ICC. </LI> <LI> FCM and ATP were useful for measuring inactivation of autochthonous wastewater bacteria. </LI> <LI> 0.5 gO<SUB>3</SUB>/gDOC resulted in over 99% decrease of cell viability by FCM and ATP analysis. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>