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Eleni A Deliyanni - One of the best experts on this subject based on the ideXlab platform.
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inorganic nanoadsorbent Akaganeite in wastewater treatment
2019Co-Authors: Eleni A Deliyanni, George Z Kyzas, K A MatisAbstract:Abstract The potential of nanoadsorbents and their many advances was discussed in this review paper in detail—nanomaterials are known to possess a series of unique physical and chemical properties. Emphasis was given in the present, among other, to iron oxyhydroxides. The synthesis method (in the laboratory) led to the production of a material—that is, Akaganeite—consisting of nanocrystals with high surface area and defined pore size distribution. Certainly, adsorption is one of the promising separation techniques applied for the decontamination of wastewaters, and activated carbon constitutes a typical adsorbent material, often modified (mentioning grapheme oxide, too). Applications presented here were mainly to heavy metals, oxyanions, and cations, removal and also dyes, which were coming from our experience, but taking into account meanwhile the current literature.
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nanocrystalline Akaganeite as adsorbent for surfactant removal from aqueous solutions
Materials, 2013Co-Authors: George Z Kyzas, Efrosyni N Peleka, Eleni A DeliyanniAbstract:The present study presents the effective use of nanocrystalline Akaganeite for the adsorption of an anionic (SDS), a cationic (CTAB), and a nonionic (tween80) surfactant from wastewater. Equilibrium experiments, as well as thermodynamic analysis, were performed. The maximum SDS adsorption occurs at the lowest pH value (5), the opposite is observed for CTAB (pH = 11), while for tween80, the change of pH value did not affect the adsorption. The equilibrium data could be described by Freundlich and Langmuir isotherms. The maximum adsorption capacity at 25 °C (pH = 8) was 823.96 mg/g for SDS, 1007.93 mg/g for CTAB, and 699.03 mg/g for tween80. The thermodynamic parameters revealed the exothermic and spontaneity nature of the process. Also, FTIR measurements established that surfactants are adsorbed on the surface of Akaganeite, replacing adsorbed water.
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Arsenates Sorption by Nanocrystalline Hybrid Surfactant-Akaganéite
Separation Science and Technology, 2012Co-Authors: Eleni A Deliyanni, Nick K. Lazaridis, Kostas A. MatisAbstract:The scope of this study was to evaluate an innovative adsorbent, nanocrystalline hybrid surfactant-Akaganeite (denoted as Akh), for arsenate ions removal from dilute solution. Akh was synthesized in the laboratory using FeCl3 as the precursor and a cationic surfactant, hexadecyl-trimethylammonium bromide, as modifier. Akh presented a significantly higher arsenate adsorption capacity (about 180 mg As(V)/g) than the pure nanocrystalline Akaganeite (denoted as Ak, about 120 mg As(V)/g). The kinetics of adsorption obeyed a pseudo-second-order rate equation. Higher ionic strength results in higher arsenate adsorption. The new adsorbent was investigated with X-ray powder diffraction, N2 adsorption-desorption (BET), Fourier transform infrared spectra, and X-ray photoelectron spectroscopy methods for better understanding the effects of surface properties on arsenate adsorption.
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removal of arsenites onto Akaganeite type adsorbents
International Journal of Environment and Waste Management, 2008Co-Authors: Eleni A Deliyanni, Efrosyni N Peleka, K A MatisAbstract:In this study, arsenites removal from aqueous solutions was investigated using synthetic prepared nanocrystalline Akaganeite. The effects of various parameters, such as the solution pH, the ionic strength, the contact time of sorbent material with the treated solution, and the pollutant initial concentration have been investigated during this study. Typical adsorption isotherms were determined, which were found to sufficiently fit the typical Langmuir equation. The mechanism of sorption was examined by Fourier transmission infrared and X-ray photoelectron spectroscopy measurements.
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effect of cationic surfactant on the adsorption of arsenites onto Akaganeite nanocrystals
Separation Science and Technology, 2007Co-Authors: Eleni A Deliyanni, Efrosyni N Peleka, K A MatisAbstract:Abstract The current research focuses on removal of arsenite ions from aqueous solutions by a new adsorbent, surfactant modified Akaganeite (Akm), prepared after the adsorption of the cationic surfactant, hexadecyl trimethyl ammonium bromide (N‐Cetyl‐N,N,N‐Trimethylammonium Bromide) onto Akaganeite. The new adsorbent was investigated with Fourier transform infrared spectra and X‐ray photoelectron spectroscopy methods for a better understanding of the effects of surface properties on arsenite adsorption. Surfactant modified Akaganeite was found to be an effective adsorbent for the removal of arsenite ions from aqueous systems. It presented a significantly higher arsenite adsorption capacity than the pure nanocrystalline Akaganeite. Kinetics of adsorption obeys a second‐order rate equation. The maximum adsorption capacity was found to 328.3 mg g−1 over a wide pH range significantly higher than those of other adsorbents reported.
Haigang Xiao - One of the best experts on this subject based on the ideXlab platform.
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Formation process of Akaganeite in the simulated wet-dry cycles atmospheric environment
Journal of Materials Science & Technology, 2018Co-Authors: Haigang Xiao, Xiaoping SongAbstract:Abstract In order to clarify the formation mechanism and conditions for Akaganeite in long-term exposure, the influence of the former corrosion results on Akaganeite formation was investigated by simulated experiments in laboratory. The combination of XRD, FTIR, SEM and EPMA enabled the identification of the rust layer formed on the surface. Accordingly, the nature of the rust layer and the amount of the corrosive species in the rust layer varied with the extension of the exposure. Among them, comparing with the corrosion condition in initial stage, the structure of rust layer after repeated wet-dry cycles was disadvantage for Akaganeite formation. Element Cl aggregated at the interface between rust and substrate in the thick part can participate in the formation of Akaganeite after the rust layer covered removed. The accumulation effect of salt deposited contributed to Akaganeite formation under the condition that salt deposition rate was relatively low.
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evolution of Akaganeite in rust layers formed on steel submitted to wet dry cyclic tests
Materials, 2017Co-Authors: Haigang Xiao, Xiaoping Song, Y JAbstract:The evolution of Akaganeite in rust layers strongly impacts the atmospheric corrosion behavior of steel during long-term exposure; however, the factors affecting the evolution of Akaganeite and its mechanism of formation are vague. In this work, wet-dry cyclic corrosion tests were conducted to simulate long-term exposure. Quantitative X-ray diffraction analysis was employed to analyze variations in the relative amounts of Akaganeite; scanning electron microscopy and electron probe microanalysis were used to study the migration of relevant elements in the rust layer, which could help elucidate the mechanism of Akaganeite evolution. The results indicate that the fraction of Akaganeite tends to decrease as the corrosion process proceeded, which is a result of the decrease in the amount of soluble chloride available and the ability of the thick rust layer to block the migration of relevant ions. This work also explores the location of Akaganeite formation within the rust layer.
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determination of the key parameters involved in the formation process of Akaganeite in a laboratory simulated wet dry cyclic process
Corrosion Science, 2017Co-Authors: Haigang Xiao, Xiaoping Song, Yanmin WangAbstract:Abstract To determine the key parameters of Akaganeite formation during a wet-dry cyclic process, cyclic immersion tests and simulated experiments were employed under laboratory conditions. The constituents of rust were characterized using XRD and FTIR. According to the results, green rust (Fe II 4 Fe III 2 Cl 2−x (OH) 12+x ) was a crucial intermediate product during the formation of Akaganeite. The evaporation rate of the electrolyte and the amount of Cl − per area played a key role in the formation of the green rust. Additionally, the required amounts of salt for Akaganeite formation were determined from simulation experiments in different relative humidity environments.
Xiaoping Song - One of the best experts on this subject based on the ideXlab platform.
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Formation process of Akaganeite in the simulated wet-dry cycles atmospheric environment
Journal of Materials Science & Technology, 2018Co-Authors: Haigang Xiao, Xiaoping SongAbstract:Abstract In order to clarify the formation mechanism and conditions for Akaganeite in long-term exposure, the influence of the former corrosion results on Akaganeite formation was investigated by simulated experiments in laboratory. The combination of XRD, FTIR, SEM and EPMA enabled the identification of the rust layer formed on the surface. Accordingly, the nature of the rust layer and the amount of the corrosive species in the rust layer varied with the extension of the exposure. Among them, comparing with the corrosion condition in initial stage, the structure of rust layer after repeated wet-dry cycles was disadvantage for Akaganeite formation. Element Cl aggregated at the interface between rust and substrate in the thick part can participate in the formation of Akaganeite after the rust layer covered removed. The accumulation effect of salt deposited contributed to Akaganeite formation under the condition that salt deposition rate was relatively low.
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evolution of Akaganeite in rust layers formed on steel submitted to wet dry cyclic tests
Materials, 2017Co-Authors: Haigang Xiao, Xiaoping Song, Y JAbstract:The evolution of Akaganeite in rust layers strongly impacts the atmospheric corrosion behavior of steel during long-term exposure; however, the factors affecting the evolution of Akaganeite and its mechanism of formation are vague. In this work, wet-dry cyclic corrosion tests were conducted to simulate long-term exposure. Quantitative X-ray diffraction analysis was employed to analyze variations in the relative amounts of Akaganeite; scanning electron microscopy and electron probe microanalysis were used to study the migration of relevant elements in the rust layer, which could help elucidate the mechanism of Akaganeite evolution. The results indicate that the fraction of Akaganeite tends to decrease as the corrosion process proceeded, which is a result of the decrease in the amount of soluble chloride available and the ability of the thick rust layer to block the migration of relevant ions. This work also explores the location of Akaganeite formation within the rust layer.
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determination of the key parameters involved in the formation process of Akaganeite in a laboratory simulated wet dry cyclic process
Corrosion Science, 2017Co-Authors: Haigang Xiao, Xiaoping Song, Yanmin WangAbstract:Abstract To determine the key parameters of Akaganeite formation during a wet-dry cyclic process, cyclic immersion tests and simulated experiments were employed under laboratory conditions. The constituents of rust were characterized using XRD and FTIR. According to the results, green rust (Fe II 4 Fe III 2 Cl 2−x (OH) 12+x ) was a crucial intermediate product during the formation of Akaganeite. The evaporation rate of the electrolyte and the amount of Cl − per area played a key role in the formation of the green rust. Additionally, the required amounts of salt for Akaganeite formation were determined from simulation experiments in different relative humidity environments.
D W Ming - One of the best experts on this subject based on the ideXlab platform.
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synthesis of Akaganeite in the presence of sulfate implications for Akaganeite formation in yellowknife bay gale crater mars
Geochimica et Cosmochimica Acta, 2016Co-Authors: T S Peretyazhko, A Fox, Brad Sutter, Paul B Niles, M Adams, R V Morris, D W MingAbstract:Abstract Akaganeite, a Cl-bearing Fe(III) (hydr)oxide, has been recently discovered in Yellowknife Bay in Gale crater on Mars by the Mars Science Laboratory (MSL) Curiosity Rover. Akaganeite was associated with sulfate and sulfide minerals at Yellowknife Bay indicating that sulfate ions could be present in solution during Akaganeite formation. The mechanism and conditions of Akaganeite formation in the Yellowknife Bay mudstone are unknown. We investigated formation of Akaganeite through hydrolysis of ferric chloride solution in the presence of 0, 0.01, 0.05, 0.1 and 0.2 M sulfate and at initial pH of 1.5, 2 and 4 at 90 °C. Mineralogy of the precipitated Fe(III) phases was characterized by X-ray diffraction and infrared spectroscopy. The precipitates were also acid digested to determine total sulfate and chloride contents. Akaganeite and natrojarosite formed at initial solution pH of 1.5; Akaganeite, goethite and natrojarosite precipitated in initial pH 2 solutions and goethite, hematite and 2-line ferrihydrite precipitated at initial solution pH of 4. Sulfate addition did not inhibit Akaganeite formation. Increasing initial solution sulfate concentrations resulted in increasing sulfate to chloride ratio in the precipitated Akaganeite. Infrared spectroscopy revealed Akaganeite bands at ∼2 μm (H 2 O combination band) and at ∼2.46 μm (OH combination band). The H 2 O combination band position linearly correlated with total chloride content in Akaganeite. Overall, laboratory studies demonstrated formation of Akaganeite at initial sulfate concentration ⩽0.2 M (sulfate to chloride molar ratio ⩽0.3) and pH ⩽ 2, implying that those conditions might prevail (perhaps as micro-environments) during Akaganeite formation in Yellowknife Bay mudstone. The occurrence of Fe(II) sulfides (pyrite and pyrrhotite) in Yellowknife Bay mudstone is a potential acidity source. Dissolution of sulfide minerals might occur under localized oxidizing water-limiting Cl-rich conditions creating favorable environments for Akaganeite formation.
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synthesis of Akaganeite in the presence of sulfate implications for Akaganeite formation in yellowknife bay gale crater mars
Lunar and Planetary Science Conference, 2016Co-Authors: T S Peretyazhko, A Fox, Brad Sutter, Paul B Niles, M Adams, R V Morris, D W MingAbstract:Akaganeite (beta-FeOOH) is an Fe(III) (hydr)oxide with a tunnel structure usually occupied by chloride. Akaganeite has been recently discovered in a mudstone on the surface of Mars by the Chemistry and Mineralogy (CheMin) and Sample Analysis at Mars (SAM) instruments onboard the Mars Science Laboratory (MSL) Curiosity Rover in Gale crater [1, 2]. Akaganeite was detected together with sulfate minerals [anhydrite (CaSO4) and basanite (2CaSO4·2H2O)] in the drilled Cumberland and John Clein mudstone samples at Yellowknife Bay [2]. Discovery of Akaganeite and sulfates in the same samples suggests that sulfate ions could be present in aqueous solution during Akaganeite formation. However, mechanism and aqueous environmental conditions of Akaganeite formation (e.g., pH and range of sulfate concentration) in Yellowknife Bay remain unknown. The objective of our work was to perform synthesis of Akaganeite without or with sulfate addition at variable pHs in order to constrain formation conditions of Akaganeite in Yellowknife Bay, Gale crater on Mars.
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effect of sulfur concentration and ph conditions on Akaganeite formation understanding Akaganeite formation conditions in yellowknife bay gale crater mars
Lunar and Planetary Science Conference, 2015Co-Authors: A Fox, T S Peretyazhko, Brad Sutter, D W Ming, P Niles, R V MorrisAbstract:The Chemistry and Mineralogy Instrument (CHEMIN) on board the Mars Science Laboratory (MSL) Curiosity Rover identified minor amounts of Akaganeite (beta-FeOOH) at Yellowknife Bay, Mars. There is also evidence for Akaganeite at other localities on Mars from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM). Akaganeite is an iron(III) hydroxide with a hollandite- like structure and Cl in its tunnels. Terrestrial Akaganeite usually forms in Cl-rich environments under acidic, oxidizing conditions. Previous studies of Akaganeite have revealed that Akaganeite formation is affected by the presence of sulfate (hereafter denoted as S. The prediction of circumneutral pH coupled with the detection of S at Yellowknife Bay dictate that work is needed to determine how S and pH together affect Akaganeite formation. The goal of this work is to study how changes in both S concentration and pH influence Akaganeite precipitation. Akaganeite formation was investigated at S/Cl molar ratios of 0, 0.017, 0.083, 0.17 and 0.33 at pH 1.5, 2, and 4. Results are anticipated to provide combined S concentration and pH constraints on Akaganeite formation in Yellowknife Bay and elsewhere on Mars. Knowledge of solution pH and S concentrations can be utilized in understanding microbial habitability potential on the Martian surface.
T S Peretyazhko - One of the best experts on this subject based on the ideXlab platform.
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reaction of Akaganeite with mars relevant anions
ACS Earth and Space Chemistry, 2019Co-Authors: T S Peretyazhko, R V Morris, Michelle J Pan, Douglas W Ming, E B Rampe, David G AgrestiAbstract:Akaganeite is an Fe(III) (hydr)oxide with a tunnel structure typically occupied by chloride. The mineral can undergo anion-exchange reactions in aqueous solution, resulting in incorporation of other anions together with Cl– into the tunnels. Identification of anions present in Akaganeite tunnels may permit characterization of solution compositions in which Akaganeite precipitated and/or existed. Akaganeite has been reported in several locations on Mars, including Yellowknife Bay in Gale crater. However, the nature of the tunnel anions has not been investigated. In order to constrain the nature of the tunnel anions in martian Akaganeite, synthetic Akaganeite (72 mg/g total Cl– content) was reacted with Mars-relevant anions (F–, OH–, and SO42–). Release of Cl– into solution was monitored with ion chromatography. Anion-reacted Akaganeite was characterized with instruments analogous to instruments onboard robotic space crafts including X-ray diffraction (XRD), Mossbauer spectroscopy, thermal and evolved gas a...
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effect of solution ph and chloride concentration on Akaganeite precipitation implications for Akaganeite formation on mars
Goldschmidt 2017, 2017Co-Authors: T S Peretyazhko, R V Morris, E B Rampe, J V Clark, P D Archer, D V MingAbstract:Akaganeite (Beta-FeOOH, chloride-containing Fe(III) (hydr)oxide) has been recently discovered on the surface of Mars by the Mars Science Laboratory Curiosity rover in Yellowknife Bay, Gale Crater, Mars [1] and from orbit by the Mars Reconnaissance Orbiter in Robert Sharp crater and Antoniadi basin [2]. However, the mechanism and aqueous environmental conditions of Akaganeite formation (e.g., pH and chloride concentration) remain unknown. We have investigated formation of Akaganeite through Fe(III) hydrolysis at variable initial pH and chloride concentrations. The formed Fe(III) precipitates were characterized by instruments similar to instruments on Mars robotic spacecraft. Syntheses were performed through hydrolysis of Fe(III) perchlorate with addition of Na cloride (Fe/Cl ratio between 0.5 and 5) and at initial pH of 1.5, 2, 4, 6 and 8 at 90degC. X-ray diffraction analysis revealed formation of Akaganeite alone or in mixture with goethite, hematite and ferrihydrite at all initial pHs and Fe/Cl ratio between 0.5 and 2 while Akaganeite precipitated only at pH 1.5 and Fe/Cl greater than2. Chloride content of Akaganeite was affected by initial pH and decreased from 20-60 mg/g at pH 1.5 to less than 0.1 mg/g at pH 8. The synthesized Akaganeite samples were also characterized by Mossbauer and infrared spectroscopy and volatiles were analysed by thermal and evolved gas analysis. The obtained characterization data will be compared to published data from rover and orbital missions [1-3] to determine martian Akaganeite composition, crystallinity and formation conditions.
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synthesis of Akaganeite in the presence of sulfate implications for Akaganeite formation in yellowknife bay gale crater mars
Geochimica et Cosmochimica Acta, 2016Co-Authors: T S Peretyazhko, A Fox, Brad Sutter, Paul B Niles, M Adams, R V Morris, D W MingAbstract:Abstract Akaganeite, a Cl-bearing Fe(III) (hydr)oxide, has been recently discovered in Yellowknife Bay in Gale crater on Mars by the Mars Science Laboratory (MSL) Curiosity Rover. Akaganeite was associated with sulfate and sulfide minerals at Yellowknife Bay indicating that sulfate ions could be present in solution during Akaganeite formation. The mechanism and conditions of Akaganeite formation in the Yellowknife Bay mudstone are unknown. We investigated formation of Akaganeite through hydrolysis of ferric chloride solution in the presence of 0, 0.01, 0.05, 0.1 and 0.2 M sulfate and at initial pH of 1.5, 2 and 4 at 90 °C. Mineralogy of the precipitated Fe(III) phases was characterized by X-ray diffraction and infrared spectroscopy. The precipitates were also acid digested to determine total sulfate and chloride contents. Akaganeite and natrojarosite formed at initial solution pH of 1.5; Akaganeite, goethite and natrojarosite precipitated in initial pH 2 solutions and goethite, hematite and 2-line ferrihydrite precipitated at initial solution pH of 4. Sulfate addition did not inhibit Akaganeite formation. Increasing initial solution sulfate concentrations resulted in increasing sulfate to chloride ratio in the precipitated Akaganeite. Infrared spectroscopy revealed Akaganeite bands at ∼2 μm (H 2 O combination band) and at ∼2.46 μm (OH combination band). The H 2 O combination band position linearly correlated with total chloride content in Akaganeite. Overall, laboratory studies demonstrated formation of Akaganeite at initial sulfate concentration ⩽0.2 M (sulfate to chloride molar ratio ⩽0.3) and pH ⩽ 2, implying that those conditions might prevail (perhaps as micro-environments) during Akaganeite formation in Yellowknife Bay mudstone. The occurrence of Fe(II) sulfides (pyrite and pyrrhotite) in Yellowknife Bay mudstone is a potential acidity source. Dissolution of sulfide minerals might occur under localized oxidizing water-limiting Cl-rich conditions creating favorable environments for Akaganeite formation.
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synthesis of Akaganeite in the presence of sulfate implications for Akaganeite formation in yellowknife bay gale crater mars
Lunar and Planetary Science Conference, 2016Co-Authors: T S Peretyazhko, A Fox, Brad Sutter, Paul B Niles, M Adams, R V Morris, D W MingAbstract:Akaganeite (beta-FeOOH) is an Fe(III) (hydr)oxide with a tunnel structure usually occupied by chloride. Akaganeite has been recently discovered in a mudstone on the surface of Mars by the Chemistry and Mineralogy (CheMin) and Sample Analysis at Mars (SAM) instruments onboard the Mars Science Laboratory (MSL) Curiosity Rover in Gale crater [1, 2]. Akaganeite was detected together with sulfate minerals [anhydrite (CaSO4) and basanite (2CaSO4·2H2O)] in the drilled Cumberland and John Clein mudstone samples at Yellowknife Bay [2]. Discovery of Akaganeite and sulfates in the same samples suggests that sulfate ions could be present in aqueous solution during Akaganeite formation. However, mechanism and aqueous environmental conditions of Akaganeite formation (e.g., pH and range of sulfate concentration) in Yellowknife Bay remain unknown. The objective of our work was to perform synthesis of Akaganeite without or with sulfate addition at variable pHs in order to constrain formation conditions of Akaganeite in Yellowknife Bay, Gale crater on Mars.
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effect of sulfur concentration and ph conditions on Akaganeite formation understanding Akaganeite formation conditions in yellowknife bay gale crater mars
Lunar and Planetary Science Conference, 2015Co-Authors: A Fox, T S Peretyazhko, Brad Sutter, D W Ming, P Niles, R V MorrisAbstract:The Chemistry and Mineralogy Instrument (CHEMIN) on board the Mars Science Laboratory (MSL) Curiosity Rover identified minor amounts of Akaganeite (beta-FeOOH) at Yellowknife Bay, Mars. There is also evidence for Akaganeite at other localities on Mars from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM). Akaganeite is an iron(III) hydroxide with a hollandite- like structure and Cl in its tunnels. Terrestrial Akaganeite usually forms in Cl-rich environments under acidic, oxidizing conditions. Previous studies of Akaganeite have revealed that Akaganeite formation is affected by the presence of sulfate (hereafter denoted as S. The prediction of circumneutral pH coupled with the detection of S at Yellowknife Bay dictate that work is needed to determine how S and pH together affect Akaganeite formation. The goal of this work is to study how changes in both S concentration and pH influence Akaganeite precipitation. Akaganeite formation was investigated at S/Cl molar ratios of 0, 0.017, 0.083, 0.17 and 0.33 at pH 1.5, 2, and 4. Results are anticipated to provide combined S concentration and pH constraints on Akaganeite formation in Yellowknife Bay and elsewhere on Mars. Knowledge of solution pH and S concentrations can be utilized in understanding microbial habitability potential on the Martian surface.