Sulfur Oxidation Rate Research Articles

IMPACT OF ELEMENTAL SULFUR FERTILIZATION ON AGRICULTURAL SOILS. II. EFFECTS ON SULFUR-OXIDIZING POPULATIONS AND OXIDATION RATES

Effects of elemental sulfur fertilization on sulfur-oxidizing populations, rhodanese activity, total sulfur content and sulfur oxidation rates in the 0- to 15-cm zone of two Grey Luvisolic soils were assessed. Heterotrophic sulfur oxidizers were the most abundant sulfur oxidizers detected in both soils. Elemental sulfur fertilization caused an increase in populations of autotrophic thiosulfate-oxidizing micro-organisms, and a threefold increase in rhodanese and sulfur-oxidizing activity in a Waitville soil. In contrast, sulfur fertilization did not stimulate autotrophic thiosulfate oxidizers in a Loon River soil and the greatest increase in rhodanese and sulfur oxidation rates was only 31%. The response to sulfur application was biphasic however, and subsequent additions of sulfur fertilizer resulted in a decline in oxidation rates. Total sulfur content of sulfur-treated soils indicated that most of the sulfur applied was still present in the sampled zone. These results imply that prediction of sulfate release and fertilizer efficiency will be difficult to assess. Key words: Sulfur (elemental), S-oxidation, oxidation rates, rhodanese, sulfur-oxidizing micro-organisms

Preservation of Thiobacillus ferrooxidans and Thiobacillus thiooxidans with activity check.

Cultures of Thiobacillus ferrooxidans and Thiobacillus thiooxidans, used in biohydrometallurgical processes of economic importance, are very difficult to preserve by conventional methods. Hence, to preserve the cultures with their activity intact, various techniques were tried, after determining their respective activity in terms of Iron Oxidation Rate (IOR) and Sulfur Oxidation Rate (SOR). Among the methods tested, along with the recommended method of serial transfer in a liquid medium, were methods such as lyophilization, storage in a liquid nitrogen and mixing with sterile, inert carriers like lignite or chalcopyrite ores. After a period check-up at 4 months and 8 months storage, it was found that out of these methods, mixing with sterile ore followed by storage at 8 degrees C, kept both types of activities intact. The temperature of storage was observed to have a definite effect on activity, in that when the preserved cultures were stored at 8 degrees C, the activity was retained, whereas at 28-30 degrees C (RT) storage, the activity of all the cultures preserved by various techniques, dropped significantly.

Discontinuities in the rate of sulfur dioxide oxidation on vanadium catalysts

Through experimental measurements of the intrinsic kinetics of sulfur dioxide (SO 2) oxidation on two types of vanadium catalysts and from studies of their thermal and electrical behaviors and the distribution of active components, the reaction rate of SO 2 oxidation has been shown to be discontinuous due to a phase transformation of the active components of the catalysts. Accordingly, there appear to be two different temperature ranges in which the reaction takes place: the lower temperature range (LTR) and the higher temperature range (HTR). This phenomenon can be further explained with the idea that the self-poisoning of the catalyst is characterized by a reversible temporality, which comes into effect only at the LTR.

Reduced Sulfur in Ashes and Slags from the Gasification of Coals: Availability for Chemical and Microbial Oxidation

This study was initiated to determine if reduced sulfur contained in coal gasifier ash and slag was available for microbial and chemical oxidation because eventual large-quantity landfill disposal of these solid wastes is expected. Continuous application of distilled water to a column containing a high-sulfur-content (4% [wt/wt]) gasifier slag yielded leachates with high sulfate levels (1,300 mg of sulfate liter) and low pH values (4.2). At the end of the experiment, a three-tube most-probable-number analysis indicated that the waste contained 1.3 x 10 thiosulfate-oxidizing bacteria per g. Slag samples obtained aseptically from the column produced sulfate under both abiotic and biotic conditions when incubated in a mineral nutrient solution. Both microbial and chemical sulfate syntheses were greatly stimulated by the addition of thiosulfate to the slag-mineral nutrient solution. These results led to a test of microbial versus chemical sulfur oxidation in ashes and slags from five gasification processes. Sulfate production was measured in sterile (autoclaved) and nonsterile suspensions of the solid wastes in a mineral nutrient solution. These ashes and slags varied in sulfur content from 0.3 to 4.0% (wt/wt). Four of these wastes demonstrated both chemical (2.0 to 27 mug of sulfate g day) and microbial (3.1 to 114 mug of sulfate g day) sulfur oxidation. Obvious relationships between sulfur oxidation rate and either sulfur content or particle size distribution of the wastes were not immediately evident. We conclude that the sulfur contained in all but one waste is available for oxidation to sulfuric acid and that microorganisms play a partial role in this process.

Measurements of the oxidation rate of sulfur (IV) by ozone in aqueous solution and their relevance to SO 2 conversion in nonurban tropospheric clouds

An experimental survey of the rate of oxidation of sulfur (IV) by ozone in aqueous solution at 25 C in the pH range 3.1 to 6.2 has been conducted using stopped-flow spectrophotometry. The rates obtained are faster than those reported by Penkett et al. ( Atmospheric Environment (1979) 13, 123–137), but are in good agreement with an extension of the rates reported by Erickson et al. ( Atmospheric Environment (1977) 11, 813–817). Comparison of the present data with reported rates of oxidation of sulfur (IV) by H 2O 2 in aqueous solution at typical pH levels encountered in non-urban tropospheric cloud water, and at representative concentrations of O 3 and H 2O 2, indicates the potential importance of O 3 as a contributor to the oxidative conversion of SO 2 to sulfate in clouds. However, several orders of magnitude extrapolation in O 3 concentration are required in applying the present results to the environment, and verification by an experimental technique employing more representative O 3 concentrations is desirable.

ESR studies of slow relaxations of the rate of sulfur dioxide oxidation on vanadium catalyst

Slow changes in the rate of the title reaction are shown to be due to pahse transformations of the active component, in particular, the agglomeration or crystallization of vanadyl complexes. The possible mechanism of these phenomena is discussed.

Specific rates of substrate oxidation and product formation in autotrophically growingChromatium vinosum cultures

Kinetics ofChromatium metabolism under autotrophic conditions were studied in batch culture. Description of various over-all metabolic rates in equal dimensions enabled direct comparison of such different processes as electron donor oxidation, storage-polymer synthesis, and growth. In the presence of sulfide, the specific rate of sulfur oxidation is partly depressed. Upon sulfide depletion, the latter rate showed an instantaneous increase of 22%. Simultaneously, glycogen was degraded. These two modifications fully compensate for the absence of sulfide, thus enabling growth to continue withμmax (0.12 h-1). These findings indicate that the potential rate of supply of electrons exceeds the biosynthetic demand for reducing power. The synthesis of glycogen in the presence of sulfide may be regarded overflow metabolism, assuming theμmax is intrinsically limited at 0.12 h-1. An alternative hypothesis is based on the assumption of an ineffective glycogen-synthesis regulation. Conceivably, growth and glycogen synthesis are competing for biosynthetic intermediates, the supply of which is limited by the maximum specific rate of e.g. the Calvin cycle. If so, both growth and glycogen synthesis are performed at submaximal rates. The rate of glycogen synthesis is greatly enhanced by the addition of growth inhibitors, and an increasedμmax value is found in the presence of acetate. These two findings together are consistent with the second hypothesis.

Microbial Activity in Soils Treated with Acephate and Monitor

AbstractA Hanford loamy sand, a Domino silt loam, and an Altamont clay loam were treated separately with three repeated applications (20 ppm) of the organophosphate insecticides, acephate (O,S‐dimethyl acetylphosphoramidothioate) and Monitor (O,S‐dimethyl phosphoramidothioate) over a 50‐day time span. Population levels of actinomycetes, bacteria, and fungi were not substantially affected by the addition of either pesticide. Neither could a marked effect be shown upon ammonification, nitrification, sulfur oxidation, or respiration rates. Replica plating failed to isolate bacteria from soils that were adversely affected by either pesticide. It is concluded that neither acephate nor Monitor had any adverse effect upon soil microorganisms.

Continuous culture of Thiorhodaceae

In sulfide limited continuous culture of a marine isolate of Chromatium vinosum, sulfide was undetectable in steady states below dilution rates of 0.06h-1, that is 1/2 of the maximum specific growth rate. In the same range, sulfur is assumed to attain the role of the growth rate limiting substrate. Furthermore, it could be shown that the rate of sulfur oxidation is a function of the surface area of the sulfur globules rather than of the sulfur concentration. In completely filled chemostats, steady states were obtainable only at dilution rates not exceeding 0.09 h-1. In the presence of a nitrogen flushed gas phase, steady states were obtained at dilution rates approaching the maximum specific growth rate (0.12h-1). This phenomenon is ascribed to the particular sulfide tolerance of our strain of Chromatium vinosum. The saturation constant and the inhibition constant (lowest, respectively highest total sulfide concentration at which the specific growth rate is equal to one-half of the maximum specific growth rate in the absence of inhibition) were 0.007 mM and 0.85 mM, respectively. The ecological significance of the data is discussed.

KINETICS OF SULFUR DIOXIDE OXIDATION OVER ACTIVATED CARBON

The rate of sulfur dioxide oxidation over activated carbon was measured in gaseous stream of sulfur dioxide-oxygen-nitrogen mixtures. It was found that catalyst fouling during the reaction was caused by sulfur trioxide formed on carbon. According to the Langmuir-Hinshelwood model, the over-all rate equation was derived on the basis of the mechanism where the rate-determining step is a surface reaction. The rate data were well correlated with the rate equation.

Availability of Zinc, Copper and Iron in Fusions with Sulfur1

AbstractA study was made of the uptake of zinc, copper, and iron by four successive crops of corn (Zea mays L.) from applications of trace element‐sulfur fusions to Plainfield sand in pots. The various zinc treatments gave increased total yields, but those with copper gave somewhat reduced yields and those of iron had little or no effect. The concentrations of tissue zinc were inversely related to granule size of the ZnO‐S and ZnCO3‐S fusions and were much lower for banding than mixing with the soil. Both the 20 to 40‐ and 40 to 80‐mesh sizes appeared to be quite favorable for prolonged release of zinc. Similar trends were obtained for tissue copper from the application of CuC2O4‐S fusions. The iron released from the FeS‐S fusions appeared to be precipitated too quickly to be satisfactory in supplying the plants with iron. The inclusion of zinc, copper, or iron compounds in the fusions had little or no effect on the rate of sulfur oxidation. Total recovery of applied elemental sulfur by the crops and as soil sulfate varied inversely with granule size and ranged from 5 to 49%. The data obtained so far suggest that fusions of certain trace element compounds with sulfur hold promise as a means of providing prolonged release of Manganese, zinc and copper for plants.