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The Response Surface Methodology (RSM) was applied as a tool for the optimization of the operational conditions of the photo-degradation of highly concentrated PY12 wastewater, resulting from a textile industry located in the suburbs of Medellin (Colombia). The Box-Behnken experimental Design (BBD) was chosen for the purpose of response optimization. The photo-Fenton process was carried out in a laboratory-scale batch photo-reactor. A multifactorial experimental design was proposed, including the following variables: the initial dyestuff concentration, the H(2)O(2) and the Fe(+2) concentrations, as well as the UV wavelength radiation. The photo-Fenton process performed at the optimized conditions resulted in ca. 100% of dyestuff decolorization, 92% of COD and 82% of TOC degradation. A kinetic study was accomplished, including the identification of some intermediate compounds generated during the oxidation process. The water biodegradability reached a final DBO(5)/DQO = 0.86 value.

Nitroimidazoles are found in pharmaceuticals and personal care products (PPCPs) and, when discharged into the environment, have adverse effects on human health and survival. Advanced oxidation technologies (AOTs) based on persulfate (PS) can rapidly and efficiently degrade organic pollutants via strong oxidizing radicals under activation conditions. This study investigated the degradation of ronidazole (RNZ) by indirect electrolytic generation of PS and its activator, ferrous ion (Fe2+). An electrochemical system was developed, with a high concentration of PS generated at the anode while the activator Fe2+ was produced at the cathode. It showed that ammonium polyphosphate (APP) could effectively promote the electrolysis of PS. A high current efficiency (88%) at the anode could be obtained after 180 min at a high current density (300 mA cm−2). However, Fe2+ was inhibited at the cathode due to material control. The degradation of RNZ in the Fe2+/PS system generated from the electrochemical system was also explored. Increasing PS concentration and Fe2+/PS ratio were beneficial to the RNZ degradation. In homogeneous reactions, the degradation efficiency of RNZ could be improved by decreasing the Fe2+ addition rate through a peristaltic pump. Five intermediates were also detected and the degradation pathways were proposed. These findings provide a new method and mechanism for rapid and efficient degradation of RNZ. © 2019

Nitroimidazoles are found in pharmaceuticals and personal care products (PPCPs) and, when discharged into the environment, have adverse effects on human health and survival. Advanced oxidation technologies (AOTs) based on persulfate (PS) can rapidly and efficiently degrade organic pollutants via strong oxidizing radicals under activation conditions. This study investigated the degradation of ronidazole (RNZ) by indirect electrolytic generation of PS and its activator, ferrous ion (Fe2+). An electrochemical system was developed, with a high concentration of PS generated at the anode while the activator Fe2+ was produced at the cathode. It showed that ammonium polyphosphate (APP) could effectively promote the electrolysis of PS. A high current efficiency (88%) at the anode could be obtained after 180 min at a high current density (300 mA cm−2). However, Fe2+ was inhibited at the cathode due to material control. The degradation of RNZ in the Fe2+/PS system generated from the electrochemical system was also explored. Increasing PS concentration and Fe2+/PS ratio were beneficial to the RNZ degradation. In homogeneous reactions, the degradation efficiency of RNZ could be improved by decreasing the Fe2+ addition rate through a peristaltic pump. Five intermediates were also detected and the degradation pathways were proposed. These findings provide a new method and mechanism for rapid and efficient degradation of RNZ. © 2019

A process of ferrous ion oxidation by sodium nitrite in sulfate uranium in situ leaching solutions was investigated. Kinetic, spectrophotometric, and heat effect studies have been made in order to investigate the chemistry of the oxidation process. As a result the method of ferrous ion oxidation in uranium in situ leaching solution was developed that makes possible to decrease sodium nitrite consumption by 20-30 times comparing with traditional oxidation technique. It was founded also that process of ferrous ion oxidation can be conducted with partial sodium nitrite recirculation. © 2012 Akadémiai Kiadó.

The oxidation of Fe 2+ in uranium leaching solutions with gaseous mixture of SO 2 and air has been studied. The variables studied include H 2SO 4 concentration, temperature, SO 2 concentration and time. The oxidation rate was founded to increase greatly with an increase in the solution temperature. The almost total oxidation of Fe 2+ is readily achieved at 95 °C. By appropriately adjusting the temperature of solution and SO 2/O 2 in the gas, oxidation of ferrous ion and generation of sulphuric acid can be carried out. It was founded that solutions produced by such oxidation processing are very suitable for the uranium ore leaching. © 2012 Akadémiai Kiadó, Budapest, Hungary.

[EN] A new selective chromo-fluorogenic probe for Fe 3+, Cr 3+ and Al 3+ is reported. Detection limits are in the ¿M range and the fluorogenic sensing ability could be observed by the naked eye when illuminated with UV-light. No response is observed with divalent cations. © 2012 The Royal Society of Chemistry.

[EN] A new selective chromo-fluorogenic probe for Fe 3+, Cr 3+ and Al 3+ is reported. Detection limits are in the ¿M range and the fluorogenic sensing ability could be observed by the naked eye when illuminated with UV-light. No response is observed with divalent cations. © 2012 The Royal Society of Chemistry.

La producción de etanol por fermentación es influenciada por la presencia de iones metálicos como hierro y zinc dado que son cofactores de la enzima alcohol deshidrogenasa. El estudio de este efecto permitiría identificar el comportamiento de los microorganismos fermentadores en sustratos industriales que contienen altas concentraciones de este tipo de iones. Este trabajo evaluó la producción de biomasa, los azúcares residuales y la producción de etanol por fermentación de tres cepas de S. cerevisiae, CBS8066, recombinantes GG570-CIBI y GG570-CIBII, bajo el efecto de la adición de hierro a 0, 50 y 150 M, y zinc a 0 y 50 M. Las cepas presentaron inhibición en la producción de biomasa y etanol bajo efecto de iones de hierro y zinc, siendo dicha inhibición mayor al estar en presencia de zinc o alta concentración de hierro. GG570-CIBI mostró disminución en producción de biomasa de 4 g/L y una caída en producción de etanol de 40% en el tratamiento 150 M hierro-50 M zinc (con respecto al tratamiento basal). GG570-CIBII fue la menos afectada con inhibición en la producción de etanol inferior a 11% a las 20 h de fermentación. Adicionalmente, presentó la mayor producción de etanol cuando hubo adición de 150 M Fe con o sin adición de zinc, siendo dicha producción entre un 9 y 14% superior a la de las cepas CBS8066 y GG570-CIBI respectivamente, bajo las mismas condiciones. Posteriormente, GG570-CIBII será evaluada en sustratos industriales debido a su menor inhibición en la producción de etanol, permitiendo así obtener mejores rendimientos. Palabras clave: gen pdc, gen adhII, Zymomonas mobilis, ión ferroso, ión zinc. ABSTRACT: The ethanol production by fermentation is influenced by the presence of metallic ions like iron and zinc because these are alcohol dehydrogenase enzyme cofactors. The study of this effect would allow for identifying the behavior of microorganisms in industrial substrates that contain high concentrations of this kind of ions. This work evaluated biom

The flooded packed-bed bioreactor plays a major role in the field of applications of ferrous ion bio-oxidation. The pH is an important variable in the control of this type of reactor, upon which the functionality of biofilm depends. In the present work, five continuous flooded packed-bed reactors have been inoculated with mixed cultures (Acidithiobacillus ferrooxidans and Leptospirillum ferooxidans) and fed with 9 k medium in the pH range 0.82 to 1.90. It has been experimentally tested that the operation of these reactors is stable at the maximum productivity levels when the pH varies within the interval 1.00 to 2.30 inside the reactor. It has been observed that the negative effect on the productivity when the upper pH limit is exceeded is reversible. No such reversibility occurs when the pH goes below the lower limit. The results of our experiments indicate that the limitations in operational pH are linked to the chemistry of precipitation ferric compounds and not to biological phenomena.

The flooded packed-bed bioreactor plays a major role in the field of applications of ferrous ion bio-oxidation. The pH is an important variable in the control of this type of reactor, upon which the functionality of biofilm depends. In the present work, five continuous flooded packed-bed reactors have been inoculated with mixed cultures (Acidithiobacillus ferrooxidans and Leptospirillum ferooxidans) and fed with 9 k medium in the pH range 0.82 to 1.90. It has been experimentally tested that the operation of these reactors is stable at the maximum productivity levels when the pH varies within the interval 1.00 to 2.30 inside the reactor. It has been observed that the negative effect on the productivity when the upper pH limit is exceeded is reversible. No such reversibility occurs when the pH goes below the lower limit. The results of our experiments indicate that the limitations in operational pH are linked to the chemistry of precipitation ferric compounds and not to biological phenomena.

The importance of NIR spectroscopy has been successfully demonstrated in the present study of smithsonite minerals. The fundamental observations in the NIR spectra, in addition to the anions of OH- and CO32- are Fe and Cu in terms of cation content. These ions exhibit broad absorption bands ranging from 13000 to 7000cm-1 (0.77 to 1.43 µm). One broad diagnostic absorption feature centred at 9000 cm-1 (1.11 µm) is the result of ferrous ion spin allowed transition, (5T2g ® 5Eg). The splitting of this band (>1200 cm-1) is a common feature in all the spectra of the studied samples. The light green coloured sample from Namibia show two Cu(II) bands in NIR at 8050 and 10310 cm-1 (1.24 and 0.97 µm) are assigned to 2B1g ® 2A1g and 2B1g ® 2B2g transitions. The effects of structural cations substitution (Ca2+, Fe2+, Cu2+, Cd2+ and Zn2+) on band shifts in the electronic spectra1 region of 11000-7500 cm-1 (0.91-1.33 µm) and vibrational modes of OH- and CO32- anions in 7300 to 4000 cm-1 (1.37-2.50 µm) region were used to distinguish between the smithsonites.

The interaction of ferrocene- 1, 1' -dithiol (FDT) with two parallel Ag(111) surfaces has been theoretically studied at density-functional level. The effect of surface defects on the energetic and electronic structure was investigated. The electronic transport properties are studied with the nonequilibrium Green's function approach. The adsorption geometry has a strong effect on the electronic levels and conductivity. The presence of point defects strongly enhances the molecule-surface interaction but has a surprisingly small effect on the density of states near the Fermi energy. The FDT-surface bond is particularly strong near terraces or steps and leads to significant shifts of the molecular orbitals relative to the gas phase. For all considered defect types except the single adatom the electronic conductivity through the FDT molecule is decreased compared to adsorption on perfect surfaces. © 2008 American Institute of Physics.

It has been postulated that the oceans on early Earth had a salinity of 1.5 to 2 times the modern value and a pH between 4 and 10. Moreover, the presence of the banded iron formations shows that Fe(+2) was present in significant concentrations in the primitive oceans. Assuming the hypotheses above, in this work we explore the effects of Fe(+2) and other ions in the generation of biomolecules in prebiotic simulation experiments using spark discharges and aqueous aerosols. These aerosols have been prepared using different sources of Fe(+2), such as FeS, FeCl(2) and FeCO(3), and other salts (alkaline and alkaline earth chlorides and sodium bicarbonate at pH = 5.8). In all these experiments, we observed the formation of some amino acids, carboxylic acids and heterocycles, involved in biological processes. An interesting consequence of the presence of soluble Fe(+2) was the formation of Prussian Blue, Fe(4)[Fe(CN)(6)](3), which has been suggested as a possible reservoir of HCN in the initial prebiotic conditions on the Earth.

The behaviour of two commercial oxygen-scavenging products with respect to migration of active ingredients into foodstuffs was investigated. Migrants were identified, and by using appropriate analytical methods, migration was determined in a variety of liquid, solid or gelled food simulants and foods. Simulants were chosen to cover a range of water activities and viscosities. Foods and the gelled food simulant agar were packed with and without vacuum, and with the oxygen scavenger in various locations relative to the packed food. The main migrants, as identified by X-ray fluorescence spectrometry, infrared spectroscopy and scanning electron microscopy with energy-dispersive spectrometry were Na+ and Cl- in non-acidic aqueous simulants, and Na+, Cl- and Fe2+ in 3% acetic acid. Migration into aqueous simulants exceeded the current European Union limit for total migration from plastic materials (assumed to be currently applicable to these systems) and was probably excessive by any reasonable standard. However, neither oxygen scavenger appeared to release significant quantities of migrants into solid foods when the scavenger was properly located in the package and the packing process does not favour the contents becoming wet by water released from the food.

Aluminum is a recognized neurotoxin in dialysis encephalopathy and may also be implicated in the etiology of neurodegenerative disease, particularly Alzheimer's disease. Alzheimer's disease is suspected to be associated with oxidative stress, possibly due to the pro-oxidant properties of beta-amyloid present in the senile plaques. The underlying mechanism by which this occurs is not well understood although interactions between amyloid and iron have been proposed. The presence of low molecular weight iron compounds can stimulate free radical production in the brain. This study provides a possible explanation whereby both aluminum and beta-amyloid can potentiate free radical formation by stabilizing iron in its more damaging ferrous (Fe2+) form which can promote the Fenton reaction. The velocity, at which Fe2+ is spontaneously oxidized to Fe3+ at 37 degrees C in 20 mM Bis-Tris buffer at pH 5.8, was significantly slowed in the presence of aluminum salts. A parallel effect of prolongation of stability of soluble ferrous ion, was found in the presence of beta-amyloid fragment (25-35). Ascorbic acid, known to potentiate the pro-oxidant properties of iron, was also capable of markedly stabilizing ferrous ions.

Aluminum is a recognized neurotoxin in dialysis encephalopathy and may also be implicated in the etiology of neurodegenerative disease, particularly Alzheimer's disease. Alzheimer's disease is suspected to be associated with oxidative stress, possibly due to the pro-oxidant properties of beta-amyloid present in the senile plaques. The underlying mechanism by which this occurs is not well understood although interactions between amyloid and iron have been proposed. The presence of low molecular weight iron compounds can stimulate free radical production in the brain. This study provides a possible explanation whereby both aluminum and beta-amyloid can potentiate free radical formation by stabilizing iron in its more damaging ferrous (Fe2+) form which can promote the Fenton reaction. The velocity, at which Fe2+ is spontaneously oxidized to Fe3+ at 37 degrees C in 20 mM Bis-Tris buffer at pH 5.8, was significantly slowed in the presence of aluminum salts. A parallel effect of prolongation of stability of soluble ferrous ion, was found in the presence of beta-amyloid fragment (25-35). Ascorbic acid, known to potentiate the pro-oxidant properties of iron, was also capable of markedly stabilizing ferrous ions.

Coordination compounds of 3,3-dimethyl-1-N-phenylimino-1,2,3,4- tetrahydroisoquinoline (L) and 3,3-dimethyl-1-N-(o-tolyl)imino-1,2,3,4- tetrahydroisoquinoline (L1) with a number of transition metal salts, namely, Cr(III), Fe(III), Co(II), Cu(II), and Zn chlorides; Cu(II) bromide; and Co(II) and Cu(II) nitrates, were synthesized. The ligands L and L′ are incorporated in the complexes either in the molecular or in the ionic form. The structure of (HL)2[CoCl4] (I) was determined by X-ray diffraction. Complex I has a cation-anion structure, the proton in the cation being located at the exocyclic nitrogen atom. The anions and cations are combined by an extended system of hydrogen bonds. The structures of the complexes obtained were studied by X-ray diffraction and IR and electronic absorption spectroscopies.