Thermodynamic Analysis of the Reactions of Iron Oxides: Dissolution in Oxalic Acid

Panias, Dimitrios; Taxiarchou, Maria; Douni, I.; Paspaliaris, Ioannis; Kontopoulos, A.

doi:10.1179/cmq.1996.35.4.363

Cited by 49 publications

(25 citation statements)

References 11 publications

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“…The model predicts that the iron concentration from the dissolution of hematite is governed by three iron-oxalate complexes, [Fe(C 2 (Lee (1995), Panias (1996), and Christodoulou (2001)), however, the accepted form of the mono-oxalate species thought to be involved is [Fe(HC 2 O 4 )] 2+ . This difference in the model would affect the predicted pH and therefore the predicted solubility of the iron.…”

Section: Model Predictions Compared To Experimental Datamentioning

confidence: 99%

“…2-1 reveals the importance of providing sufficient protons to promote dissolution and oxalate complex formation. The monobioxalate iron dication complex ion, FeHC 2 O 4 2+ , is believed to be the primary species present in Fe(III)-oxalate solutions at low pH, as indicated by Lee (1995), Panias (1996), andChristodoulou (2001). Two molar equivalents of additional protons (excluding H + from oxalic acid) are needed for every oxalic acid molecule and every iron atom to promote the preferred complex formation and iron dissolution.…”

Section: Background and Introductionmentioning

confidence: 97%

“…Since magnetite (Fe 3 O 4 ) can be formally viewed as a mixture of hematite (Fe 2 O 3 ) and wustite (FeO), the above discussion likely applies to the dissolution of this phase as well. At low pH values the dissolution of Fe(II) in oxalic acid is believed to result in the formation of uncomplexed Fe 2+ ion in solution, which does not consume oxalate ion, but does consume H + (Panias, 1996).…”

Section: Background and Introductionmentioning

confidence: 99%

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Alternative and Enhanced Chemical Cleaning: Basic Studies Results Fy2010

King¹,

Hay²

2011

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Section: Model Predictions Compared To Experimental Datamentioning

confidence: 99%

Section: Background and Introductionmentioning

confidence: 97%

Section: Background and Introductionmentioning

confidence: 99%

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Alternative and Enhanced Chemical Cleaning: Basic Studies Results Fy2010

King¹,

Hay²

2011

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“…The following oxalate and iron-oxalate equilibrium reactions were introduced in MINEQL+, with dissociation constants (Panias et al, 1996) corrected using the Davies equation for the approximate ionic strength of the corresponding matrix:…”

Section: Photo-fenton Step Performancementioning

confidence: 99%

Solar photocatalytic oxidation of recalcitrant natural metabolic by-products of amoxicillin biodegradation

et al. 2014

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The contamination of the aquatic environment by non-metabolized and metabolized antibiotic residues has brought the necessity of alternative treatment steps to current water decontamination technologies. This work assessed the feasibility of using a multistage treatment system for amoxicillin (AMX) spiked solutions combining: i) a biological treatment process using an enriched culture to metabolize AMX, with ii) a solar photocatalytic system to achieve the removal of the metabolized transformation products (TPs) identified via LC-MS, recalcitrant to further biological degradation. Firstly, a mixed culture (MC) was obtained through the enrichment of an activated sludge sample collected in an urban wastewater treatment plant (WWTP). Secondly, different aqueous matrices spiked with AMX were treated with the MC and the metabolic transformation products were identified. Thirdly, the efficiency of two solar assisted photocatalytic processes (TiO2/UV or Fe 3+ /Oxalate/H2O2/UV-Vis) was assessed in the degradation of the obtained TPs using a lab-scale prototype photoreactor equipped with a compound parabolic collector (CPC). Highest AMX specific biodegradation rates were obtained in buffer and urban wastewater (WW) media (0.10 ± 0.01 and 0.13 ± 0.07 gAMX gbiomass -1 h -1 , respectively). The resulting TPs, which no longer presented antibacterial activity, were identified as amoxicilloic acid (m/ z = 384). The performance of the Fe /Oxalate/H2O2/UV-Vis system in the 2 removal of the TPs from WW medium was superior to the TiO2/UV process (TPs no longer detected after 40 min (QUV = 2.6 kJ L -1 ), against incomplete TPs removal after 240 min (QUV = 14.9 kJ L -1 ), respectively).

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“…Íon trioxalatoferrato (III) [Fe 3+ (C 2 O 4 ) 2 ] -6,31x10 -17 Íon dioxalatoferrato (III) [Fe 3+ C 2 O 4 ] + 3,98x10 -10 Íon oxalatoferro (III) [ -10 Íon bioxalatoferro (III) Fonte: PANIAS et al, (1996).…”

Section: Aplicação Do Processo De Coagulação Em Chorume Brutomentioning

confidence: 99%

Avaliação isolada e integrada dos processos de coagulaçãofloculação- decantação e foto-Fenton para o tratamento de chorume

Silva¹

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Landfill leachate contains a variety of contaminating substances organic and inorganic, dissolved and at suspension, such as humic and fulvic acids, xenobiotics, metals (Hg 2+ , Pb 2+ , Cd 2+ , Cu 2+ , Zn 2+ , Cr 3+ /Cr 6+) and ammoniacal nitrogen, which give it characteristics of low biodegradability, high organic load and toxicity. In the face of concern about the damages that this composition may cause to the environment and to animal and plant, the use and combination of new treatment technologies has a high research interest. In the first part of this work, interfering factors in the removal of dissolved organic carbon (DOC) of leachate by the photo-Fenton process, the coupling of treatments were evaluated. Firstly, the isolated application of the photo-Fenton process was employed, evaluating the influence of the concentration of Fe 2+ (25, 50, 100 and 200 mg L-1) on DOC removal efficiency, obtaining better results in the presence of 100 mg L-1 of Fe 2+. However, a long treatment time (20 h) and high consumption of hydrogen peroxide was required. Then, the influence of two coagulant ions (Al 3+ and Fe 3+) was evaluated as well as different dosages in the removal of the apparent color, turbidity and DOC by the coagulation-flocculation process in the leachate matrix at pH 3. It was defined as the best coagulant and dosage, 240 mg L-1 of Fe 3+ , which resulted in 60, 80 and 11%, respectively, of apparent color, turbidity and DOC removals. The influence of the matrix composition (SO 4 2and Clions and presence of color and turbidity) in the photo-Fenton process was also evaluated. For this, the isolated or combined precipitation of the SO 4 2and Clions with Ba 2+ and Ag + , respectively, as well as the application of a coagulation-flocculation pretreatment using Fe 3+ in the leachate were carried out. It was observed that the photo-Fenton process in the absence of inorganic ions resulted in a kinetic 2.4 times better, consuming half of the amount of oxidant when compared to the treatment of the raw leachate, with greater interference of sulfate ions. On the other hand, applying coagulation-flocculation pretreatment using Fe 3+ and in sequence photo-Fenton process, resulted in a similar efficiency in the treatment of raw leachate (70-77% DOC removal), with only 17% of the time and 7% of the consumption of H 2 O 2. In a second step, a protocol was evaluated for the treatment of landfill leachate by the integration of coagulation flocculation, filtration stage for the elimination of suspended material and solar photo-Fenton process at pH close to neutrality. The coagulation-flocculation process was applied at natural pH of the raw leachate (7.9), evaluating different concentrations of the coagulating agents-Fe 3+ or Al 3+ and salts of different anions (Cl-, NO 3 and SO 4 2-). Improved turbidity removal efficiency (66%) was obtained using 4.4 mmol Al 3+ L-1 (119 mg Al 3+ L-1) as nitrate salt. Afterwards, the photo-Fenton process was applied to the supernatant aiming to the degradation of residual DOC, being evaluated...

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Thermodynamic Analysis of the Reactions of Iron Oxides: Dissolution in Oxalic Acid

Cited by 49 publications

References 11 publications

Alternative and Enhanced Chemical Cleaning: Basic Studies Results Fy2010

Alternative and Enhanced Chemical Cleaning: Basic Studies Results Fy2010

Solar photocatalytic oxidation of recalcitrant natural metabolic by-products of amoxicillin biodegradation

Avaliação isolada e integrada dos processos de coagulaçãofloculação- decantação e foto-Fenton para o tratamento de chorume

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