Anthraquinones as mediators for the indirect cathodic reduction of dispersed organic dyestuffs

Bechtold, Thomas; Burtscher, Eduard; Turcanu, Aurora

doi:10.1016/s0022-0728(99)00057-1

Cited by 49 publications

(43 citation statements)

References 19 publications

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“…Quinones have been reported to act as redox mediators for azo reduction (Bechtold et al, 1999;Keck et al, 1997;Kudlich et al, 1997;Weber, 1996) as well as for other nonspeci®c reductive transformations, including reductive dehalogenation of organohalogens and reduction of nitroaromatics . The mechanism of redox mediation by quinones comprises two reactions: the oxidation of the hydroquinone by a terminal electron acceptor (e.g., RR2), and the reduction of the quinone by an electron donor.…”

Section: Application Of a Redox Mediatormentioning

confidence: 99%

“…As evidenced by the nonspeci®city of anaerobic azo dye reduction processes, the hydroquinone will generally be oxidized by the azo dye in a direct chemical reaction. Likewise, quinone reduction has usually been reported as a direct chemical reaction with reduced compounds such as sul®de or ferrous iron (Bechtold et al, 1999;Butler and Hayes, 1998;Curtis and Reinhard, 1994;Perlinger et al, 1996Perlinger et al, , 1998Perlinger et al, , 2000. However, biological quinone reduction by speci®c bacteria that couple the oxidation of organic substrates to enzymatic quinone reduction has also been reported, not only for situations in which a quinone acts as a terminal electron acceptor (Bradley et al, 1998;Coates et al, 1998;Lovley et al, 1996) but also for quinone-mediated azo reduction (Keck et al, 1997; Kudlich et al, 1997) and humic acid-mediated dechlorination (Collins and Picardal, 1999).…”

Section: Application Of a Redox Mediatormentioning

confidence: 99%

“…Enzyme cofactors like FAD are known as eective redox mediators for azo dye reduction (Fujita and Peisach, 1982;Gingell and Walker, 1971;Russ et al, 2000) and, in addition, arti®cial quinones can act as redox mediators: In abiotic systems, quinones have been shown to accelerate chemical azo dye reduction by sul®de as well as electrochemical azo dye reduction (Bechtold et al, 1999) and, in biological systems, they were shown to accelerate azo dye reduction by anaerobically incubated aerobic biomass Kudlich et al, 1997) as well as azo dye reduction by anaerobic granular sludge (van der Zee et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

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Application of redox mediators to accelerate the transformation of reactive azo dyes in anaerobic bioreactors

Zee

Bouwman

Strik

et al. 2001

Biotech & Bioengineering

177

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Azo dyes are nonspecifically reduced under anaerobic conditions but the slow rates at which reactive azo dyes are converted presents a serious problem for the application of anaerobic technology as a first stage in the complete biodegradation of these compounds. As quinones have been found to catalyze reductive transfers by acting as redox mediators, the application of anthraquinone-2,6-disulfonic acid (AQDS) during continuous anaerobic treatment of the reactive azo dye, Reactive Red 2 (RR2), was evaluated. A mixture of volatile fatty acids was used as the electron-donating primary substrate. Batch experiments demonstrated that AQDS could increase the first-order rate constant of RR2 reductive cleavage by one order of magnitude. In the continuous experiment, treatment of RR2 containing synthetic wastewater in a lab-scale upflow anaerobic sludge blanket (UASB) reactor yielded low dye removal efficiencies (<30%). Consequently, severe toxicity problems occurred, eventually resulting in almost complete inhibition of the methanogenic activity. Addition of catalytic concentrations of AQDS (19 microM) to the reactor influent caused an immediate increase in the dye removal efficiency and recovery of biological activity. Ultimately, RR2 removal efficiency stabilized at 88%, and higher AQDS loads resulted in higher RR2 removal efficiencies (up to 98% at 155 microM AQDS). Examination of the RR2 decolorizing properties of dye-adapted reactor sludge and of nonadapted reactor seed sludge revealed that RR2 decolorization was principally a biologically driven transfer of reducing equivalents from endogenous and added substrates to the dye. Hydrogen, added in bulk, was clearly the preferred electron donor. Bacteria that couple dye decolorization to hydrogen oxidation were naturally present in seed sludge. However, enrichment was required for the utilization of electrons from volatile fatty acids for dye reduction. The stimulatory effect of AQDS on RR2 decolorization by AQDS-unadapted sludge was mainly due to assisting the electron transfer from endogenous substrates in the sludge to the dye. The stimulatory effect of AQDS on RR2 decolorization by sludge from the AQDS-exposed reactor was, in addition, strongly associated with the transfer of electrons from hydrogen and acetate to the dye, probably due to enrichment of specialized AQDS-reducing bacteria.

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Section: Application Of a Redox Mediatormentioning

confidence: 99%

Section: Application Of a Redox Mediatormentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Application of redox mediators to accelerate the transformation of reactive azo dyes in anaerobic bioreactors

Zee

Bouwman

Strik

et al. 2001

Biotech & Bioengineering

177

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“…Regarding the extraordinary complex character of this matter it implies that a lot of long-term, very well coordinated multidisciplinary research activities need to be initiated. Use of electron and redox mediators Compounds like humic acids, activated-carbon, quinones, e.g., anthraquinone disulfonate (AQDS), anthraquinone-2-sulphonate (AQS) catalyze the anaerobic degradation reactions of numerous recalcitrant compounds; they facilitate electron transport in the degradation of, e.g., azo dyes [79][80][81][82][83][84][85][86][87], and reductive de-halogenation [88]. However, as with the issue of 'trace elements' in this particular field, a better understanding is required which will lead to a wider and more optimal application of AnWT.…”

Section: Mixing Conditionsmentioning

confidence: 99%

Challenges of a feasible route towards sustainability in environmental protection

Lettinga

2010

Front. Environ. Sci. Eng. China

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Anaerobic processes for treatment of low and high strength wastewaters and solid wastes constitute the core method in the natural biological mineralization (NBM) treatment concept. When adequately combined with the complementary NBM-systems and modern clean water saving practices in wastewater collection and transport, they represent a feasible route to sustainable environmental protection (EP sus ), in essence even towards a more sustainable society. Despite the development and implementation of modern high rate Anaerobic Wastewater Treatment (AnWT-) systems and complementary innovative NBM-processes, the considerable progress made since the seventies in fundamental insights in microbiology, biochemistry and process technology, still numerous challenging improvements in the NBM-field can be realized. This contribution is mainly based on the insights attained from wide ranging literature evaluations and the results of experimental research conducted by numerous PhD students who participated in our group over the last four decades. An attempt is made here to identify major facets on which an improved insight can, and consequently should, be obtained in order to accomplish more optimal operation and design of various types of Anaerobic Degradation (AnDeg-) processes.

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“…The use of mediators for indirect cathodic dyestuff reduction in textile dyeing operations using vat dyes and indigo dye is a promising technique for substitution of non regenerable reducing chemicals [1][2][3]. A field of particular scientific interest is the use of soluble complexes as mediators for indirect electrochemical reduction of dispersed dyes.…”

Section: Introductionmentioning

confidence: 99%

Fe3+--gluconate and Ca2+-Fe3+--gluconate complexes as mediators for indirect cathodic reduction of vat dyes ? Cyclic voltammetry and batch electrolysis experiments

Bechtold

Turcanu

2004

Journal of Applied Electrochemistry

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The indirect cathodic reduction of dispersed vat dyes CI Vat Yellow 1 and CI Vat Blue 5 was investigated by cyclic voltammetry and with batch electrolysis experiments. 0.01 mol L )1 solutions of the complexes Fe 3+ -Dgluconate and Ca 2+ -Fe 3+ -D-gluconate were studied. The addition of dispersed dyestuff to the mediator solution lead to a catalytic current. While the cathodic peak currents of both complexes is comparable, Fe 3+ -DGL shows higher enhancement factors, which are defined as quotient of catalytic peak current and cathodic peak current of the mediator system ðI p Þ c =ðI p Þ d . In the presence of 0.5 g L )1 of dispersed vat dye enhancement factors of 1.8 were determined at scan rates of 0.005-0.010 V s )1 . Galvanostatic batch reduction experiments with use of a laboratory multi-cathode cell confirmed the favourable properties of the Fe 3+ -DGL in comparison to the binuclear Ca 2+ -Fe 3+ -DGL. With use of the Fe 3+ -DGL mediator complete dyestuff reduction could be achieved. The batch reduction process was followed experimentally by photometry and redox potential measurement in the catholyte.

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Anthraquinones as mediators for the indirect cathodic reduction of dispersed organic dyestuffs

Cited by 49 publications

References 19 publications

Application of redox mediators to accelerate the transformation of reactive azo dyes in anaerobic bioreactors

Application of redox mediators to accelerate the transformation of reactive azo dyes in anaerobic bioreactors

Challenges of a feasible route towards sustainability in environmental protection

Fe3+--gluconate and Ca2+-Fe3+--gluconate complexes as mediators for indirect cathodic reduction of vat dyes ? Cyclic voltammetry and batch electrolysis experiments

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