scholarly journals PRODUCTS OF THE OXIDATION OF THIOSULFATE BY BACTERIA IN MINERAL MEDIA

1935 ◽  
Vol 18 (3) ◽  
pp. 325-349 ◽  
Author(s):  
Robert L. Starkey
Keyword(s):  
Sulfuric Acid ◽  
Sodium Sulfate ◽  
Elemental Sulfur ◽  
Heterotrophic Bacteria ◽  
Sodium Thiosulfate ◽  
Initial Reaction ◽  
Primary Reaction ◽  
Sulfate Sulfur ◽  
Autotrophic Bacteria ◽  
Secondary Chemical

Various cultures (previously described), which oxidize thiosulfate in mineral media have been studied in an attempt to determine the products of oxidation. The transformation of sodium thiosulfate by Cultures B, T, and K yields sodium tetrathionate and sodium hydroxide; secondary chemical reactions result in the accumulation of some tri- and pentathionates, sulfate, and elemental sulfur. As a result of the initial reaction, the pH increases; the secondary reactions cause a drop in pH after this initial rise. The primary reaction yields much less energy than the reactions effected by autotrophic bacteria. No significant amounts of assimilated organic carbon were detected in media supporting representatives of these cultures. It is concluded that they are heterotrophic bacteria. Th. novellus oxidizes sodium thiosulfate to sodium sulfate and sulfuric acid; the pH drops progressively with growth and oxidation. Carbon assimilation typical of autotrophic bacteria was detected; the ratio of sulfate-sulfur formed to carbon assimilated was 56:1. It is calculated that 5.1 per cent of the energy yielded by the oxidation of thiosulfate is accounted for in the organic cell substance synthesized from inorganic materials. This organism is a facultative autotroph. The products of oxidation of sodium thiosulfate by Th. thioparus are sodium sulfate, sulfuric acid, and elemental sulfur; the ratio of sulfate sulfur to elemental sulfur is 3 to 2. The pH decreases during growth and oxidation. The elemental sulfur is produced by the primary reaction and is not a product of secondary chemical changes. The bacterium synthesizes organic compounds from mineral substances during growth. The ratio of thiosulfate-sulfur oxidized to carbon assimilated was 125:1, with 4.7 per cent of the energy of oxidation recovered as organic cell substance. This bacterium is a strict autotroph.

scholarly journals Nitrogen mineralization and microbial activity as influenced by sulfur sources in an alkaline calcareous soil

1970 ◽  
pp. 14-18
Author(s):  
Tufail Shah ◽  
Zahir Shah ◽  
Syed Atizaz Ali Shah ◽  
Nazir Ahmad
Keyword(s):  
Organic Matter ◽  
Sulfuric Acid ◽  
Microbial Activity ◽  
Calcareous Soil ◽  
Bacterial Population ◽  
Elemental Sulfur ◽  
Microbial Population ◽  
Organic Matter Content ◽  
Matter Content ◽  
Fungal Population

A study was performed to check the effects of various sources of sulfur on microbial activity, microbial population, N mineralization and organic matter content in an alkaline calcareous soil by using soil samples collected from Malakandher Farm at 0-20 cm depth, and analyzed for microbial activity, total mineral nitrogen, bacterial and fungal population and organic matter content. The results showed that the rate of CO2 evolution and cumulative CO2 production were higher in soils amended with elemental sulfur followed by sulfuric acid and gypsum treated soils. The microbial activity decreased with incubation period in all treatments, and the microbial population was greatly affected by sulfur sources. Generally, the bacterial population decreased in soils amended with elemental sulfur, but the population was higher in soils amended with gypsum. Bacterial population was suppressed in soils treated with sulfuric acid. However, the fungal population was higher in soils amended with sulfuric acids was less in soil amended with elemental sulfur. The sulfur amendments promoted immobilization of N. The net N immobilized was higher in soil amended with gypsum followed by soils amended with sulfuric acid and elemental sulfur. The percent organic matter was higher in soils amended with gypsum and was decreased compared with that amended with elemental sulfur or sulfuric acid. These results suggested that soil microbiological properties changed with sulfur amendments during laboratory incubation.

scholarly journals Studies on Epoxidation of Tung oil with Hydrogen Peroxide Catalyzed by Sulfuric Acid

2020 ◽  
Vol 15 (3) ◽  
pp. 674-686
Author(s):  
Eni Budiyati ◽  
Rochmadi Rochmadi ◽  
Arief Budiman ◽  
Budhijanto Budhijanto
Keyword(s):  
Hydrogen Peroxide ◽  
Sulfuric Acid ◽  
Unsaturated Fatty Acids ◽  
Catalyst Concentration ◽  
Reaction Rates ◽  
Catalytic Reactions ◽  
Side Reactions ◽  
Initial Reaction ◽  
Tung Oil ◽  
Epoxidation Reaction

Tung oil with an iodine value (IV) of 99.63 g I2/100 g was epoxidized in-situ with glacial acetic acid and hydrogen peroxide (H2O2), in the presence sulfuric acid as catalyst. The objective of this research was to evaluate the effect of mole ratio of H2O2 to unsaturated fatty acids (UFA), reaction time and catalyst concentration in Tung oil epoxidation. The reaction kinetics were also studied. Epoxidation was carried out for 4 h. The reaction rates and side reactions were evaluated based on the IV and the conversion of the epoxidized Tung oil to oxirane. Catalytic reactions resulted in higher reaction rate than did non-catalytic reactions. Increasing the catalyst concentration resulted in a large decrease in the IV and an increase in the conversion to oxirane at the initial reaction stage. However, higher catalyst concentration in the epoxidation reaction caused to a decrease in reaction selectivity. The mole ratio of H2O2 to UFA had an influence identical to the catalyst concentration. The recommended optimum mole ratio and catalyst concentration in this study were 1.6 and 1.5%, respectively. The highest conversion was 48.94% for a mole ratio of 1.6. The proposed kinetic model provided good results and was suitable for all variations in reaction temperature. The activation energy (Ea) values were around 5.7663 to 76.2442 kcal/mol. Copyright © 2020 BCREC Group. All rights reserved 

scholarly journals Corrosion in CO2 Systems with Impurities Creating Strong Acids

CORROSION ◽  
10.5006/3110 ◽  
2019 ◽  
Vol 75 (11) ◽  
pp. 1307-1314
Author(s):  
Bjørn H. Morland ◽  
Morten Tjelta ◽  
Arne Dugstad ◽  
Gaute Svenningsen
Keyword(s):  
Sulfuric Acid ◽  
Carbon Steel ◽  
Stainless Steels ◽  
Elemental Sulfur ◽  
Experimental Studies ◽  
Visual Observation ◽  
Low Concentrations ◽  
Strong Acids ◽  
Safety And Environment

There are several proposed specifications for CO2 transport regarding how much impurities that can be allowed in the CO2 stream. Many of these specifications are based on health, safety, and environment (HSE) considerations in case of accidental spill, and only limited focus has been on the pipeline integrity. Previous work has demonstrated that many of the impurities that are expected to be present in CO2 captured from flue gasses may react and form corrosive species. The present paper studied impurity reactions and corrosion under simulated transport conditions (25°C and 10 MPa of CO2). An experiment was performed in a transparent autoclave which allowed for in situ visual observation. Chemical reactions between the impurities were observed even at very low concentrations (<100 ppmv). These reactions contributed to the production of nitric and sulfuric acid together with formation of elemental sulfur. Corrosion was observed on coupons of carbon steel, but not on stainless steels. The corrosion rate of carbon steel was low, but the amount of acids and solids (corrosion products) produced cannot be accepted from a pipeline integrity perspective. Further experimental studies are needed to determine specific limits for impurity concentrations in captured CO2 for transport.

scholarly journals Effect of Surface Modification with Different Acids on the Functional Groups of AF 5 Catalyst and Its Catalytic Effect on the Atmospheric Leaching of Enargite

2019 ◽  
Vol 3 (2) ◽  
pp. 45 ◽  
Author(s):  
Jahromi ◽  
Ghahreman
Keyword(s):  
Sulfuric Acid ◽  
Nitric Acid ◽  
Hydrochloric Acid ◽  
Functional Groups ◽  
Photoelectron Spectroscopy ◽  
Elemental Sulfur ◽  
Catalytic Properties ◽  
Copper Recovery ◽  
Pre Treatment ◽  
Sulfur Adsorption

Carbon-based catalysts can assist the oxidative leaching of sulfide minerals. Recently, we presented that AF 5 Lewatit® is among the catalysts with superior enargite oxidation capacity and capability to collect elemental sulfur on its surface. Herein, the effect of acid pre-treatment of the AF 5 catalyst was studied on the AF 5 surface, to further enhance the catalytic properties of AF 5. The AF 5 catalyst was pretreated by hydrochloric acid, nitric acid and sulfuric acid. The results showed that the acid treatment drastically changes the surface properties of AF 5. For instance, the concentration of quinone-like functional groups, which are ascribed to the catalytic properties of AF 5, is 45.4% in the sulfuric acid pre-treatment AF 5 and only 29.8% in the hydrochloric acid-treated AF 5. Based on the C 1s X-ray photoelectron spectroscopy (XPS) results the oxygenated carbon is 30.6% in the sulfuric acid-treated AF 5, 29.2% in the nitric acid-treated AF 5 and 28.3% in the hydrochloric acid-treated AF 5. The nitric acid pre-treated AF 5 resulted in the highest copper recovery during the oxidative enargite leaching process, recovering 98.8% of the copper. The sulfuric acid-treated AF 5 recovered 97.1% of the enargite copper into the leach solution. Among different leaching media and pre-treatment the lowest copper recovery was achieved with the HCl pre-treated AF 5 which was 88.6%. The pre-treatment of AF 5 with acids also had modified its elemental sulfur adsorption capacity, where the sulfur adsorption on AF 5 was increased from 30.9% for the HCl treated AF 5 to 51.1% for the sulfuric acid-treated AF 5.

scholarly journals Copper metallurgy at the crossroads

2007 ◽  
Vol 43 (1) ◽  
pp. 1-19 ◽  
Author(s):  
F. Habashi
Keyword(s):  
Sulfuric Acid ◽  
Elemental Sulfur ◽  
Copper Production ◽  
Pressure Leaching ◽  
Copper Industry ◽  
Hydrothermal Conditions ◽  
The Past ◽  
Copper Metallurgy ◽  
Horizontal Furnace ◽  
Sulfide Concentrates

Copper technology changed from the vertical to the horizontal furnace and from the roast reaction to converting towards the end of the last century. However, the horizontal furnace proved to be an inefficient and polluting reactor. As a result many attempts were made to replace it. In the past 50 years new successful melting processes were introduced on an industrial scale that were more energy efficient and less polluting. In addition, smelting and converting were conducted in a single reactor in which the concentrate was fed and the raw copper was produced. The standing problem in many countries, however, is marketing 3 tonnes of sulfuric acid per tonne of copper produced as well as emitting large amounts of excess SO2 in the atmosphere. Pressure hydrometallurgy offers the possibility of liberating the copper industry from SO2 problem. Heap leaching technology has become a gigantic operation. Combined with solvent extraction and electrowinning it contributes today to about 20% of copper production and is expected to grow. Pressure leaching offers the possibility of liberating the copper industry from SO2 problem. The technology is over hundred years old. It is applied for leaching a variety of ores and concentrates. Hydrothermal oxidation of sulfide concentrates has the enormous advantage of producing elemental sulfur, hence solving the SO2 and sulfuric acid problems found in smelters. Precipitation of metals such as nickel and cobalt under hydrothermal conditions has been used for over 50 years. It has the advantage of a compact plant but the disadvantage of producing ammonium sulfate as a co-product. In case of copper, however, precipitation takes place without the need of neutralizing the acid, which is a great advantage and could be an excellent substitute for electrowinning which is energy intensive and occupies extensive space. Recent advances in the engineering aspects of pressure equipment design open the door widely for increased application. .

Acidophilic Microorganisms from Geothermal Copahue Volcano System. Assessment of Biotechnological Applications

2009 ◽  
Vol 71-73 ◽  
pp. 87-91 ◽  
Author(s):  
P. Chiacchiarini ◽  
L. Lavalle ◽  
Alejandra Giaveno ◽  
Edgardo R. Donati
Keyword(s):  
Hot Springs ◽  
Heterotrophic Bacteria ◽  
Extreme Environment ◽  
Acidithiobacillus Thiooxidans ◽  
Biotechnological Applications ◽  
Acidophilic Microorganisms ◽  
Autotrophic Bacteria ◽  
Physiological Properties ◽  
Biological Studies ◽  
System Assessment

This work presents an overview of the physicochemical and biological studies carried out along Rio Agrio and in different hot springs belonging to the geothermal Copahue volcano system, in Neuquén Argentina. This is an extreme environment characterized by wide ranges of temperature, pH (<1 to 8) and heavy metals concentration. In these extreme conditions chemolitho-autotrophic bacteria, archaea, heterotrophic bacteria, yeasts and filamentous fungi were detected. Members of Leptospirillum ferrooxidans, Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans and Acidianus spp., among others, were successfully cultivated and physiological properties of different isolates were determined. Additionally, bioleaching and biooxidation of regional ores were carried out using mixed native cultures.

scholarly journals The Novel Strategy for Increasing the Efficiency and Yield of the Bipolar Membrane Electrodialysis by the Double Conjugate Salts Stress

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 343 ◽  
Author(s):  
Dong Wang ◽  
Wenqiao Meng ◽  
Yunna Lei ◽  
Chunxu Li ◽  
Jiaji Cheng ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Cation Exchange ◽  
Ammonium Sulfate ◽  
Sodium Sulfate ◽  
Sulfate Solution ◽  
Anion Exchange Membrane ◽  
Ammonium Sulfate Solution ◽  
Bipolar Membrane ◽  
Bipolar Membrane Electrodialysis ◽  
Exchange Membrane

To improve sulfuric acid recovery from sodium sulfate wastewater, a lab-scale bipolar membrane electrodialysis (BMED) process was used for the treatment of simulated sodium sulfate wastewater. In order to increase the concentration of sulfuric acid (H2SO4) generated during the process, a certain concentration of ammonium sulfate solution was added into the feed compartment. To study the influencing factors of sulfuric acid yield, we prepared different concentrations of ammonium sulfate solution, different feed solution volumes, and different membrane configurations in this experiment. As it can be seen from the results, when adding 8% (NH4)2SO4 into 15% Na2SO4 under the experimental conditions where the current density was 50 mA/cm2, the concentration of H2SO4 increased from 0.89 to 1.215 mol/L, and the current efficiency and energy consumption could be up to 60.12% and 2.59 kWh/kg, respectively. Furthermore, with the increase of the volume of the feed compartment, the concentration of H2SO4 also increased. At the same time, the configuration also affects the final concentration of the sulfuric acid; in the BP-A-C-BP (“BP” means bipolar membrane, “A” means anion exchange membrane, and “C” means cation exchange membrane; “BP-A-C-BP” means that two bipolar membranes, an anion exchange membrane, and a cation exchange membrane are alternately arranged to form a repeating unit of the membrane stack) configuration, a higher H2SO4 concentration was generated and less energy was consumed. The results show that the addition of the double conjugate salt is an effective method to increase the concentration of acid produced in the BMED process.

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