Ferrous Sulfate Concentration Research Articles

Apoptotic effects of biodentine, calcium-enriched mixture (CEM) cement, ferric sulfate, and mineral trioxide aggregate (MTA) on human mesenchymal stem cells isolated from the human pulp of exfoliated deciduous teeth.

Preservation of primary teeth in children is highly important. Pulpotomy is a commonly performed treatment procedure for primary teeth with extensive caries. Thus, biocompatibility of pulpotomy agents is highly important. Biodentine, calcium enriched mixture (CEM) cement, ferric sulfate, and mineral trioxide aggregate (MTA) Angelus are commonly used for this purpose. Thus, this study aimed to assess the apoptotic effects of Biodentine, CEM cement, ferric sulfate, and MTA on stem cells isolated from the human pulp of exfoliated deciduous teeth. In this in-vitro, experimental study, stem cells isolated from the human pulp of exfoliated deciduous teeth were exposed to three different concentrations of Biodentine, CEM cement, ferric sulfate, and MTA for different time periods. The cytotoxicity of the materials was evaluated by flow cytometry using the annexin propidium iodide (PI) kit. Data were analyzed by ANOVA and Tukey's test at P<0.05 level of significance. All four tested materials induced significantly greater apoptosis compared with the control group. The difference in cell apoptosis caused by the first concentration of ferric sulfate and MTA was not significant at 24 hours. In other comparisons, the cytotoxicity of ferric sulfate was significantly lower than that of other materials. Biodentine showed higher cytotoxicity than MTA at first; but this difference faded over time. The cytotoxicity of CEM cement was comparable to that of MTA. The highest cell viability was noted at 24 hours in presence of the minimum concentration of ferric sulfate. The lowest cell viability was noted at 72 hours in presence of the maximum concentration of CEM cement. In comparison with other materials, ferric sulfate showed minimum cytotoxicity; the cytotoxicity of the three cements was comparable. It appears that the concentration of ferric sulfate and the composition of cements are responsible for different levels of cytotoxicity.

Hybrid Fenton-electrochemical reactor and system as post-treatment of textile wastewater

Textile effluents contain different kinds of chemical additives and mostly are treated by biological processes. However, COD, ammonium, and color cannot be removed completely from wastewater. Decolorization agents are commonly used as a post-treatment method, although high cost and hazardous sludge byproduct are often reported as their main weaknesses. This study proposes a hybrid system of Fenton and electrochemical to replace the costly decolorization agents, as it is low-cost and highly efficient with no sludge production. This system consists of one cylindrical reactor with a working volume of 50 L and 12 pairs of Ti/RuO2 mesh cylinder and graphite carbon rod electrodes. It was also equipped with wastewater tank, pump, power supply, mixer, pH meter, and ammonia meter. The effects of wastewater volume, potential, retention time, pH, mixing speed, ferrous sulphate and salt concentration on COD, ammonium, and color removals were investigated and discussed. This system was able to reduce color, COD, and ammonium significantly in 15 min for 96 %, 64 %, and 77 %, respectively, at 4000 mg/L salt concentration, 30 mg/L ferrous sulphate, pH 4, 90 rpm mixing speed, and 6 V potential. pH was increased to 6.18; 6.73; 7.25 and 7.36 after 15, 30, 45 and 60 min, respectively. A circulatory system was applied to improve pollutants removal efficiency and electrochemical oxidability index as well as to reduce energy consumption. In terms of reactor performance and operating cost, this system is deemed feasible and applicable as a post-treatment method to support anaerobic-aerobic unit of textile WWTP.

Sucrose, NaCl, and citric acid suppress the metallic sensation of FeSO4.

Metallic sensation is often described as unpleasant and can reduce acceptance of foods and beverages and compliance with medication. Masking and suppressing aversive sensations can help to improve acceptance of these products, with many successful strategies identified for bitterness. However, there are few studies investigating effective strategies for suppressing metallic sensation. This study aims to assess the effectiveness of mixture suppression to reduce the metallic sensation elicited from ferrous sulfate and examine whether individual differences in metallic sensation are associated with the effectiveness of suppression strategies. To achieve this, participants (n = 121) reported the intensity of suprathreshold concentrations of ferrous sulfate alone and in binary mixtures with three tastants, specifically, sucrose, citric acid, and sodium chloride. The results revealed that metallic sensation ratings were significantly lower for every binary mixture tested compared to ferrous sulfate presented in isolation. For 0.3mM ferrous sulfate, sucrose was identified to be the most effective compound in suppressing metallic sensation, followed by citric acid and sodium chloride. For the 1.0mM ferrous sulfate solutions, all tastants were equally effective at suppressing metallic sensation. In addition, there is a significant interaction between the perceived metallic intensity and the effectiveness of each strategy. These findings suggest that sucrose, citric acid, and sodium chloride have the potential to be effective in suppressing metallic sensation.

Electrocoagulation Coupled Fenton Process for Treating Refinery Wastewater Using a Cylindrical Design of Ti and Al Electrodes

Due to the serious wizards that industrial waste causes to humans, animals, and plants, besides the fact that wastewater from refineries contains many harmful compounds and that this type of industry is prevalent in most countries, the issue of protecting the environment from industrial waste is importance at the recent time. The organic contaminants elimination from the wastewater connected with the Iraqi refinery at Qayyarah served as our case study. The chemical oxygen demand (COD) was the organic contaminants measure. A titanium electrode (cathode) and an aluminum electrode (anode) were combined with the electrocoagulation and Photo-Fenton-processes. Using a Mini Tab program, the Taguchi method Utilizing statistical techniques, successfully obtained the outcomes and final values. The most effective removal of COD was 90.148. With a standard deviation of 2.651, the best conditions for this experiment were as follows: The time required to achieve this removal efficiency was 50 minutes, 8 pH, 400 mg/L of hydrogen peroxide, 20 mg/L of ferrous sulfate, and a current density of 15 mA cm-2. Through ANOVA analysis of this process, it was found that the current density (C.D.) significantly influenced the removal efficiency, affecting it by 47.79%, followed by the electrolytic solution effect by 18.31%, and the hydrogen peroxide and ferrous sulfate concentrations effect by 12.55% and 2.36%, respectively. Also, a mathematical equation was found to describe the studied case. The reaction kinetics were also investigated, and the reaction rate constant (cm/s) was determined at ideal conditions, with km = 6.60546 x 10-5.

Kinetic isotope effect study of N-6 methyladenosine chemical demethylation in bicarbonate-activated peroxide system.

N-6 methyladenosine is the most abundant nucleic acid modification in eukaryotes and plays a crucial role in gene regulation. The AlkB family of alpha-ketoglutarate-dependent dioxygenases is responsible for nucleic acid demethylation. Recent studies have discovered that a chemical demethylation system using hydrogen peroxide and ammonium bicarbonate can effectively demethylate nucleic acids. The addition of ferrous ammonium sulfate boosts the oxidation rate by forming a Fenton reagent with hydrogen peroxide. However, the specific mechanism and key steps of this process remain unclear. In this study, we investigate the influence of ferrous ammonium sulfate concentration on the kinetic isotope effect (KIE) of the chemical demethylation system using LC-MS. As the concentration of ferrous ions increases, the observed KIE decreases from 1.377 ± 0.020 to 1.120 ± 0.016, indicating a combination of the primary isotope effect and inverse α-secondary isotope effect with the ion pairing effect. We propose that the initial hydrogen extraction is the rate-limiting step and observe a tight transition state structure in the formation of the hm6A process through the analysis of KIE trends. The concentration-dependent KIE provides a novel perspective on the mechanism of chemical demethylation and offers a chemical model for enzyme-catalyzed demethylation.

Mild and economy homogeneous UV-LED/persulfate process for degradation of fluoxetine model drug

A homogeneous persulfate (PS) activation under low energy consumption ultraviolet light-emitting diodes (UV-LEDs) was established in order to degrade the resistive fluoxetine-hydrochloride drug in aqueous media. For this aim, a falling film photo-reactor, equipped with four arrays of six UV-LEDs (395 nm, 1 W each), was utilized. Trace concentrations of ferrous sulfate and heating the media could significantly improve the degradation efficiency. Under the established optimal conditions of 100 mg/L of persulfate, 1 mg/L of ferrous sulfate, natural pH of 6.4 and temperature of 40 °C, a 71.1% degradation efficiency was achieved for 40 mg/L fluoxetine initial concentration after 50 min. The kinetic study revealed a pseudo-first order overall degradation rate. Based on scavenger quenching results, it was revealed that the hydroxyl radical and sulfate anion radical had, respectively, 52.3 and 31.4% contribution in degradation. To extend results to real conditions, the influence of inorganic cations/anions and also humic acid was investigated. From LC-MS analysis results, the transformation products were identified and three degradation pathways were proposed. Interestingly, a cost evaluation indicated electrical energy consumption of 16.7 kWh/m3 and operating cost of only $1.71 per each cubic meter. Consistently, the profound UV-LED/PS/Fe2+/heat process exhibited desired capabilities in scenarios for treating resistive drug wastewaters.

Processing and Characterization of Nano Silica and Iron Oxide Coated Silica Composites Extracted from Rice Hulls

This study examined the effects of adding iron to rice hulls samples (RHs) on the thermal degradation to prepare nano silica and iron oxide-silica mixtures. Iron is precipitated in different amounts within the RH fibers (as hydroxide) by dipping them in a solution of different concentrations of acidic ferrous sulfate and then immersing it in a dilute ammonia solution. The dry RHs were fired at temperatures between 400 °C and 700 °C in a static or limited air atmosphere. Both weight loss and residual weight are determined to follow its thermal degradation. The products of the RH degradation of silica or iron oxide-silica mixtures were characterized by X-ray diffraction and Fourier transform infrared spectroscopy. The surface area, average particle size, and pore diameter of both products were determined. The chemical treatment of RHs before firing accelerates their thermal degradation and leads to obtaining firing products of high purity. Firing RHs in a limited air atmosphere increases thermal degradation and, at the same time, accelerates the catalyst effect of iron on its degradation. Under these conditions, silica and iron oxide bonded silica with an average particle size of 1.31 and 0.07 μm were obtained by firing treated RHs at 600 °C and 500 °C, respectively. Firing in a limited air atmosphere encourages CO2 to react with burned C to form CO, and iron as an accelerator for this reaction completes its degradation. In contrast, iron oxide remained in the ferrous state. Therefore, the bonding between iron and silica was complete.

Oxidative degradation of electroplating wastewater by an electro-Fenton process using GO/TiO&lt;sub&gt;2&lt;/sub&gt;NTs electrode

Electro-Fenton (E-Fenton) is a versatile treatment method; however, it has not yet been used for the treatment of electroplating wastewater using graphene oxide (GO) coated TiO&lt;sub&gt;2&lt;/sub&gt; nanotubes (GO/TiO&lt;sub&gt;2&lt;/sub&gt;NTs) electrode. A simple anodization technique has been adopted to synthesize GO/TiO&lt;sub&gt;2&lt;/sub&gt;NTs electrode. The present work aimed to study an E-Fenton treatment to investigate the effect of different parameters on % COD removal and energy consumption using GO/TiO&lt;sub&gt;2&lt;/sub&gt;NTs electrode. The performance of the treatment process was examined in terms of % COD removal and energy consumed at three process parameters: current, time, and ferrous sulfate concentration. The optimum operating conditions were determined using multiple responses optimization based on Box-Behnken design (BBD). At optimum operational parameters, the results revealed that the % COD removal and energy consumed were 96.27% and 15.35 kWh/m&lt;sup&gt;3&lt;/sup&gt;, respectively. The pseudo-first-order reaction kinetics was fitted to the experimental data at optimum conditions. Possible intermediates were identified based on the GC-MS analysis, and a corresponding tentative degradation pathway has been proposed. Furthermore, a recyclability and stability study of the synthesized electrode has also been performed. Moreover, total organic carbon (TOC) study revealed that E-Fenton has the potential to detoxify electroplating effluents. Hence, GO/TiO&lt;sub&gt;2&lt;/sub&gt;NTs electrodes can be highly efficient in degrading hazardous pollutants.

Concentration Test for Ferrous Sulfate (FeSO4) and Thiamin in Murashige and Skoog Medium on The Orchid Sub-Culture Dendrobium SP By In-Vitro

The Dendrobium orchid is one type with special features and many variations. This study aims to determine the administration of various concentrations of ferrous sulfate (FeSO4) and Thiamin to Dendrobium sp orchid explants on Murashige And Skoog media. The design used in this study was a Factorial Completely Randomized Design (CRD) consisting of 2 treatment levels (F = FeSO4 and T = Thiamin) with three replications. Namely: F0 (Without FeSO4), F1 (FeSO4 26.8 mg/l ), F2 (FeSO4 27.8 mg/l), F3 (FeSO4 28.8 mg/l), and T0 (Without Thiamin), T1 (Thiamin 0.1 mg/l), T2 (Thiamin 0.2 mg/l) l), T3 (Thiamin 0.3 mg/l). Based on the study results, by giving various concentrations of ferrous sulfate (FeSO4) had a single effect on the shoots quantity parameters with the best treatment found in treatment with an average shoots quantity (.03 ea), F3 for shoot height parameters (1.37 cm), for the total leaves (6.14), for the roots quantity (5.17), and root length were found in treatment with an average of 1.29 cm on the Dendrobium sp. Orchid explants. For the treatment of various concentrations of Thiamin, the single effect on the number of shoots with the best treatment was found at an average (3.44 ea), for the shoot height parameter (0.98 cm), and for the leaves quantity (6.14 ea), for the root length parameter (1.28 cm). The interaction significantly affected the observed parameters, namely the number of shoots with treatment (giving FeSO4 28.8 mg/l and Thiamin 0.3 mg/l) with an average shoot quantity of 1.71 (ea).

Application of Machine Learning in a Mineral Leaching Process-Taking Pyrolusite Leaching as an Example.

In this study, several machine learning models were used to analyze the process variables of electric-field-enhanced pyrolusite leaching and predict the leaching rate of manganese, and the applicability of those models in the leaching process of hydrometallurgy was compared. It showed that there was no correlation between the six leaching conditions; in addition to the leaching time, the concentrations of sulfuric acid and ferrous sulfate had great influences on the leaching of pyrolusite. The results of the prediction models showed that the support vector regression model has the best prediction performance, with regression index (R 2) = 0.92 and mean square error = 25.04, followed by the gradient boosting regression model (R 2 > 0.85). In this research, machine learning models were applied to the optimization of the manganese leaching process, and the research process and methods were also applicable to other hydrometallurgical processes for majorization and result prediction.

Precipitation of Ferrous Oxalate from Ferrous Ammonium Sulfate in Oxalic Acid Solution

A kinetic study was conducted experimentally for the precipitation of ferrous oxalate. The ferrous oxalate, in the form of dihydrate (FeC2O4·2H2O), was produced by the acidic dissolution of ferrous ammonium sulfate (Fe(NH4)2(SO4)2) in an aqueous solution of oxalic acid, and then precipitated by nucleation and particle growth from supersaturated solution. The effect of the concentration of ferrous ammonium sulfate and oxalic acid as raw materials was investigated on the kinetics of the ferrous oxalate precipitation. Temperature was kept constant at 25 °C. The surface morphology, atomic compositions, and crystal phase were characterized for the ferrous oxalate precipitate collected. As the initial concentration of ferrous ammonium sulfate increased, the initial precipitation of ferrous oxalate occurred faster. The concentration of oxalic acid did not significantly affect the rate of precipitation of ferrous oxalate. The experimental behavior of ferrous oxalate precipitation was modeled with first-order models of reaction kinetics.

Preparation of Solid Lipid Nanoparticle-Ferrous Sulfate by Double Emulsion Method Based on Fat Rich in Monolaurin and Stearic Acid.

Ferrous sulfate is one type of iron that is commonly used in iron supplementation and fortification in food products, but it has low stability and an unfavorable flavor, causing its use to be limited. Encapsulation in a solid lipid nanoparticle (SLN) system is one technology that offers stable active compound protection and a good delivery system; however, a solid lipid matrix should be selected which has good health effects, such as glycerol monolaurate or monolaurin. The purpose of this study was to obtain SLN-ferrous sulfate based on stearic acid and fat rich in monolaurin. SLN-Ferrous sulfate was synthesized at various concentrations of monolaurin-rich fat (20%; 30%; 40% w/w lipid) and various concentrations of ferrous sulfate (5%; 10%; 15% w/w lipid). The results showed that the use of monolaurin-rich fat 40% w/w lipid and 15% w/w ferrous sulfate produced the best characteristics with high entrapment efficiency and loading capacity of 0.06%. The Z-average value of SLN was 292.4 nm with a polydispersity index (PI) of 1.03. SLN-ferrous sulfate showed a spherical morphology, where the Fe trapped in the SLN was evenly dispersed in the lipid matrix to form a nanosphere system. Preparation of SLN-ferrous sulfate by double emulsion method based on stearic acid and fat rich in monolaurin effectively encapsulated ferrous sulfate with high entrapment efficiency and good physicochemical properties.

MODIFICATION OF LINDUR STARCH (Bruguiera Gymnorrhiza L.) BY OXIDATION USING SODIUM HYPOCLORITE AND FERRO SULPHATE CATALYST

Lindur fruit (Bruguiera gymnorrhiza L.) is widely available in Indonesia and has a high carbohydrate content, so it has the potential to be developed as a new source of energy and starch. So far, the use of lindur fruit is still limited to substitute rice and snacks. Therefore, it is necessary to make efforts to increase the utilization of lindur fruit by processing it into lindur starch and its derivatives (modified starch). The properties of lindur starch need to be improved in order to have wider uses in the food and non-food industries. The purpose of this study was to modify lindur starch by oxidation using NaOCl with ferrous sulfate as a catalyst. In this study, the effect of sodium hypochlorite concentration (2%, 4%, 6%, and 8%) and ferrous sulfate concentration (0%, 0.1%, 0.2%, and 0.3%) on the physicochemical characteristics of starch was studied. the resulting oxidized leachate and determined the optimal conditions. The results showed that all the variables studied affected the oxidation reaction of lindur starch. Oxidation at 4% NaOCl concentration and 0.2% ferrous sulfate concentration was able to produce the best values for carboxyl content, solubility, and swelling.

Potential and whole-genome sequence-based mechanism of elongated-prismatic magnetite magnetosome formation in Acidithiobacillus ferrooxidans BYM.

A magnetosome-producing bacterium Acidithiobacillus ferrooxidans BYM (At. ferrooxidans BYM) was isolated and magnetically screened. The magnetosome yield from 0.5896 to 13.1291mg/g was achieved under different aeration rates, ferrous sulfate, ammonium sulfate, and gluconic acid concentrations at 30℃. TEM observed 6-9 magnetosomes in size of 20-80nm irregularly dispersed in a cell. STEM-EDXS and HRTEM-FFT implied that the elongated-prismatic magnetite magnetosomes with {110} crystal faces grown along the [111] direction. Whole-genome sequencing and annotation of BYM showed that 3.2Mb chromosome and 47.11kb plasmid coexisted, and 322 genes associated with iron metabolism were discovered. Ten genes shared high similarity with magnetosome genes were predicted, providing sufficient evidence for the magnetosome-producing potential of BYM. Accordingly, we first proposed a hypothetic model of magnetosome formation including vesicle formation, iron uptake and mineralization, and magnetite crystal maturation in At. ferrooxidans. These indicated that At. ferrooxidans BYM would be used as a commercial magnetosome-producing microorganism.

Saturated Dissolved Oxygen Concentration in in situ Fragmentation Bioleaching of Copper Sulfide Ores.

In situ fragmentation bioleaching is a promising way to perform deep mining safely, economically, and in an environmentally friendly manner, where oxygen plays a critical role in microbial growth and mineral dissolution. However, the lack of oxygen limits the implementation of in-situ fragmentation bioleaching. To overcome this limitation, aeration was proposed, with saturated dissolved oxygen concentration as an important indicator. Orthogonal experiments were conducted to measure saturated dissolved oxygen concentration at various temperature, pH, and electrolyte (ferrous sulfate, ferric sulfate, copper sulfate, and sulfuric acid) concentration conditions. Experimental data were analyzed by Python programming language and least squares method to obtain a saturated dissolved oxygen concentration model. Results showed that temperature had the most significant effect on oxygen solubility, which was concluded by comparing the results of surface fitting based on the least squares method. At 30–40°C, the saturated dissolved oxygen concentration decreased faster as metal ions concentration increased. The conjoint effect of the five variables on oxygen solubility showed that pH was linearly negatively related to oxygen solubility. Additionally, a mathematical model was also proposed to predict the saturated dissolved oxygen concentration in in situ fragmentation bioleaching of copper sulfide ores. This work enables bioleaching processes to be modeled and controlled more effectively.

Fundamental Investigation on a Foam-Generating Microorganism and Its Potential for Mobility Reduction in High-Permeability Flow Channels

This study proposed a novel foam EOR technique using Pseudomonas aeruginosa to generate the foam and investigated the potential of the microbial foam EOR to modify the permeability of a high-permeability porous system. We investigated oxygen nanobubble, carbon dioxide nanobubble and ferrous sulfate concentrations to discover the optimal levels for activating the foam generation of the microorganism through cultivation experiments. We also clarified the behavior of the microbial foam generation and the bioproducts that contribute to the foam generation. The potential of the foam to decrease the permeability of high-permeability porous systems was evaluated through flooding experiments using sand pack cores. The foam generation became more active with the increase in the number of nanobubbles, while there was an optimal concentration of ferrous sulfate for foam generation. The foam was identified as being induced by the proteins produced by the microorganism, which can be expected to bring about several advantages over surfactant-induced foam. The foam successfully decreased the permeability of high-permeability sand pack cores to half of their initial levels. These results demonstrate that the microbial foam EOR has the potential to decrease the permeability of high-permeability porous systems and improve the permeability heterogeneity in oil reservoirs.

Influence of Fe+2 on the biomass, pigments, and essential fatty acids of ‏Arthrospira platensis

The effects of different ferrous sulfate (FeSO4) concentrations on the fatty acid profile of the blue-green alga Arthrospira platensis cultured in Zarrouk’s medium to produce biodiesel were studied. Different ferrous sulfate concentrations (0, 0.005, 0.01, 0.05, and 0.1 g/L) and 0.01 g/L were examined on the biochemical composition of the alga and fatty acids profile of A. platensis. Findings revealed that the highest and lowest yields of fatty acid were 0 and 0.1 g/L FeSO4, respectively. It was also noticed an increase of palmitic acid, oleic acid, linoleic acid, γ-linolenic acid, and docosahexaenoic acid when ferrous sulfate was between 0.05 and 0.1 g/L, while these fatty acids decreased at low concentration. Ferrous sulfate at a concentration of 0.1 g/L exhibited an increase and best yields in the following: growth rate and the shortest doubling time, chlorophyll-a, phycocyanin, allophycocyanin, phycobiliproteins, and carotenoids. Thus, increasing the FeSO4 concentration to 0.1 g/L has led to the increase in fatty acid individuals, which in turn, resulted in potential enhancement of the biodiesel production from A. platensis.

Harvesting of Chlorella sorokiniana BR001 cultivated in a low-nitrogen medium using different techniques

ABSTRACT: The harvesting process is a current challenge for the commercial production of microalgae because the biomass is diluted in the culture medium. Several methods have been proposed to harvest microalgae cells, but there is not a consensus about the optimum method for such application. Herein, the methods based on sedimentation, flocculation, and centrifugation were evaluated on the recovery of Chlorella sorokiniana BR001 cultivated in a low-nitrogen medium. C. sorokiniana BR001 was cultivated using a low-nitrogen medium to trigger the accumulation of neutral lipids and neutral carbohydrates. The biomass of C. sorokiniana BR001 cultivated in a low-nitrogen medium showed a total lipid content of 1.9 times higher (23.8 ± 4.5%) when compared to the biomass produced in a high-nitrogen medium (12.3 ± 1.2%). In addition, the biomass of the BR001 strain cultivated in a low-nitrogen medium showed a high content of neutral carbohydrates (52.1 ± 1.5%). The natural sedimentation-based process was evaluated using a sedimentation column, and it was concluded that C. sorokiniana BR001 is a non-flocculent strain. Therefore, it was evaluated the effect of different concentrations of ferric sulfate (0.005 to 1 g L-1) or aluminum sulfate (0.025 to 0.83 g L-1) on the flocculation process of C. sorokiniana BR001, but high doses of flocculant agents were required for an efficient harvest of biomass. It was evaluated the centrifugation at low speed (300 to 3,000 g) as well, and it was possible to conclude that this process was the most adequate to harvest the non-flocculent strain C. sorokiniana BR001.

Fuzzy system in a ferrous sulfate pre-treatment of elephant grass

ABSTRACT Renewable energies have been occupying more and more space in energy matrices worldwide, and lignocellulosic biomasses are promising for these energy sources. This study aimed to develop a fuzzy model to optimize the ferrous sulfate concentration and temperature in the pre-treatment of elephant grass. Five concentrations (10, 15, 20, 25 and 30 mM) and three temperatures (25, 40 and 55 ºC) were used as input. The application of the fuzzy model evidenced that the best results for cellulose exposure (53.1 %) were achieved by using a ferrous sulfate concentration between 20 and 22.5 mM and temperature between 39.5 and 42.5 ºC.

Evaluation of ozone as an efficient and sustainable reagent for chalcopyrite leaching: Process optimization and oxidative mechanism

Chalcopyrite is the main copper-bearing mineral and is refractory to oxidative leaching. There are many investigations to optimize copper extraction from this mineral but most of the processes are energy intensive and environmental threatening. Ozone at low concentration is an efficient reagent for high extraction of copper from chalcopyrite, which is also ecofriendly. This paper presents a comprehensive investigation on the process optimization for both copper and iron extraction from chalcopyrite using ozone. The following variables were tested during 48-h leaching periods: temperature, ferric sulfate, ozone and sulfuric acid concentrations, solid/liquid ratio, and leaching time. Ozone leaching recovered 100% of the copper from chalcopyrite at 25 °C without addition of ferric. The overall reaction kinetics followed the shrinking core model by mixed control of diffusion through the product layer and chemical reactions. The proposed leaching mechanism was verified via various characterization techniques. Green chemistry metrics were evaluated, and the optimized process was demonstrated to be environmentally attractive. Ozone leaching appears to have strong potential as a “green” and technically feasible method to leach copper from chalcopyrite.