The promising performance of manganese gluconate as a liquid redox sulfur recovery agent against oxidative degradation (original) (raw)
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Heliyon
Iron chelate liquid redox sulfur recovery (LRSR) has been one of the most frequently recommended technologies for the oxidation of H 2 S in natural gas into elemental sulfur, particularly when the acid gas has a high CO 2 /H 2 S molar ratio. The process is however known to suffer from extensive oxidative ligand degradation that results in high operational costs. Moreover, poor biodegradability or toxicity of the existing ligand has become a concern. In this research, we demonstrated that gluconate, a naturally greener ligand, when coupled with manganese as the metal, has considerable potential to be a better redox agent. Manganese gluconate solution was more resistant against ligand degradation compared with iron NTA. As required, aerated solution was capable of converting dissolved NaHS into elemental sulfur. At sufficiently high pH, manganese gluconate solutions were stable enough from precipitation of manganese hydroxide, carbonate, or sulfides. An equilibrium calculation has been developed to understand the precipitation behavior.
Dependence of Sulfadiazine Oxidative Degradation on Physicochemical Properties of Manganese Dioxides
Industrial & Engineering Chemistry Research, 2009
Manganese dioxides as active oxidants are the common minerals in environment, and different types of manganese dioxides may exhibit varied oxidative activity. In this study, eight manganese dioxides were used to conduct sulfadiazine (SD) oxidative degradation. SD can be oxidatively degraded and even mineralized by these manganese dioxides, and the toxicity of the SD sample can also be reduced significantly. The experiments in this study demonstrated that the kinetic reaction rate constant k values of SD degradation strongly depended on the physicochemical properties of different manganese dioxides, including average oxidation state (AOS), reductive potential (Eh), pH at the point of zero charge (pH PZC ), and apparent activation energy (E a ). The k values were positively correlated with the AOS and Eh, while negatively correlated with pH PZC and E a . The values of these physicochemical properties can be used to quantitatively estimate the oxidative activity of a manganese dioxide to some extent for better understanding of the degradation of organic pollutants with manganese dioxides.
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Journal of the Brazilian Chemical Society, 2015
Photo-Fenton degradation of pollutants involves the reaction of Fe II salts with hydrogen peroxide under ultraviolet A irradiation, which significantly enhances the process. The reaction with Fe III salts is slower and therefore less studied. In this work, we compared the efficiencies of Fe III and Fe II salts in the photo-Fenton degradation of malachite green (MG), a known carcinogen. We optimized the concentration of reagents and the pH to achieve the highest MG degradation with the lowest amounts of reagents. Complete MG degradation was achieved under 2 h for the Fe III system and 1 h for Fe II , reaching a high degree of mineralization, even in the presence of chloride and sulfate anions. The results show that although slower, the reaction with Fe III salts allows significant photodegradation of MG under mild reaction conditions.
Hydrometallurgy, 2006
The oxidation of glucose during the reductive leaching of pure MnO 2 and manganese ore in sulphuric acid at 90°C MnO 2 was investigated. The aim was to identify the derivatives and the chemical pathway of glucose oxidation. Organic derivatives were monitored by HPLC using an Aminex HPX-78H column and UV detection. Chromatographic patterns of leaching solutions showed that major compound formed was formic acid. Minor quantities of glycolic, glyceric and traces of gluconic acids were identified. Results suggest that during the leaching reaction, the carbon chain of glucose is shortened by detachment of one carbon atom as formic acid.
The Effect of Process Conditions on Sulfuric Acid Leaching of Manganese Sludge
Manganese sludge, an industrial waste in the ferroalloy industry, contains various components and holds significant importance for sustainable development through its valorization. This study focuses on characterizing a manganese sludge and investigating its behavior during sulfuric acid leaching. The influence of process conditions, including temperature, acid concentration, liquid to solid ratio, and leaching duration, was examined. The results revealed that Mn, Zn, and K are the main leachable components, and their leaching rates increase with increasing temperature, liquid to solid ratio, and time. However, acid concentration requires optimization. High leaching rates of 90% for Mn, 90% for Zn, and 100% for K were achieved. Moreover, it was found that Pb in the sludge is converted to sulfate during the leaching which yields a sulfate concentrate rich in PbSO4. The leaching process for Mn and Zn species appears to follow a second or -third order reaction, and the calculation of r...
Degradation of malachite green in aqueous solution by Fenton process
In this study, advanced oxidation process utilizing Fenton's reagent was investigated for degradation of malachite green (MG). The effects of different reaction parameters such as the initial MG concentration, initial pH, the initial hydrogen peroxide concentration, the initial ferrous concentration and the reaction temperature on the oxidative degradation of MG have been investigated. The optimal reacting conditions were experimentally found to be pH 3.40, initial hydrogen peroxide concentration = 0.50 mM and initial ferrous concentration = 0.10 mM for initial MG concentration of 20 mg/L at 30 • C. Under optimal conditions, 99.25% degradation efficiency of dye in aqueous solution was achieved after 60 min of reaction.
The effect of sulfide concentrate mineralogy and texture on Reactive Oxygen Species (ROS) generation
The generation of Reactive Oxygen Species (ROS), H2O2 and OH, has been observed from sulfide mineral containing particles in acidic solutions. The implications of this phenomenon, as a potential microbial stress-causing effect, have been studied previously with respect to thermophilic bioleaching performance in the presence of finely milled pyrite and chalcopyrite concentrates. In this study, the effect of sulfide mineralogy on ROS generation in the absence of microbes under physicochemical conditions typical for the bioleach environment was investigated. The mineralogical and elemental composition of eleven different samples containing sulfide mineral was obtained. These Au, Cu and other base metal-containing sulfide mineral concentrates as well as a milled whole ore of low Cu grade were tested for ROS generation. The whole ore sample and two refractory Au concentrates containing approximately 50% pyrite, generated significantly less ROS compared to the base metal-containing concentrates when compared on a constant surface area loading basis. Sulfide mineral-related variables were correlated with ROS generation. A significant difference was observed between FeS2 and CuFeS2 grades separately, whereas a combined measure of both minerals present in samples showed a consistently strong correlation to ROS generation. The Cu grade, total Cu-containing sulfides and the chalcopyrite content of Cu-containing samples correlated well with ROS generation. However, a common deterministic variable with a strong association to increased ROS generation was not found. A sub-set of samples were subjected to QEMSCAN® for textural analysis. Results suggested that a decrease in sulfide mineral liberation, caused by gangue silicate mineral occlusion to solution, resulted in decreased reactivity as shown in one of the Au-containing samples. Well-liberated chalcopyrite and pyrite phases corresponded to increased reactivity of samples. Pyrite, which was present in all of the reactive samples, was shown to be associated with other sulfide minerals, implicating its importance in galvanic interactions. Micro-analysis of chalcopyrite and pyrite phases from highly reactive samples showed an abundance of particles with extensive cracking and the possible presence of secondary transformation phases (szomolnokite). These results suggest that sulfide mineralogy, liberation and extent of physical processing affect sulfide mineral concentrate reactivity in acidic solutions.► Metal-containing sulfide mineral concentrates generate ROS (H2O2 + OH). ► ROS generation linked to decreased thermophilic bioleaching performance. ► ROS generation consistently correlated to combined Py + Cp content. ► Sulfide liberation and association effects ROS generation under acidic conditions. ► Increased “micro-cracked” particle volume results in increased sample reactivity.
Canadian Journal of Chemical Engineering, 2008
Local pyrolusite ore from Om-Bogma, Sinai, has been treated by sulfuric acid leaching process using either sawdust (C6H10O5)n or lactose (C12H22O11) as reducing agent to produce manganese sulfate. The manganese recoveries were 92.5 and 90.5% at sawdust and lactose respectively.Un minerai de pyrolusite local d'Om-Bogma, au Sinaï, a été traité par un procédé de lessivage à l'acide sulfurique en utilisant de la sciure de bois (C6H10O5)n ou du lactose (C12H22O11) comme agent de réduction pour produire du sulfate de manganèse. Les récupérations de manganèse sont de 92,5% et 90,5% pour la sciure de bois et le lactose, respectivement.
A review of classic Fenton's peroxidation as an advanced oxidation technique
Hydrogen peroxide (H 2 O 2) is a strong oxidant and its application in the treatment of various inorganic and organic pollutants is well established. Still H 2 O 2 alone is not effective for high concentrations of certain refractory contaminants because of low rates of reaction at reasonable H 2 O 2 concentrations. Improvements can be achieved by using transition metal salts (e.g. iron salts) or ozone and UV-light can activate H 2 O 2 to form hydroxyl radicals, which are strong oxidants. Oxidation processes utilising activation of H 2 O 2 by iron salts, classically referred to as Fenton's reagent is known to be very effective in the destruction of many hazardous organic pollutants in water. The first part of our paper presents a literature review of the various Fenton reagent reactions which constitute the overall kinetic scheme with all possible side reactions. It also sum-marises previous publications on the relationships between the dominant parameters (e.g. [H 2 O 2 ], [Fe 2+ ],. . .). The second part of our review discusses the possibility of improving sludge dewater-ability using Fenton's reagent.