Concentrations Of Sulfur Compounds Research Articles

Past and future trends in concentrations of sulphur and nitrogen compounds in the Arctic

Recent trends in nitrogen and sulphur compounds in air and precipitation from a range of Arctic monitoring stations are presented, with seasonal data from the late 70s to 2004 or 2005. Earlier findings of declining sulphur concentrations are confirmed for most stations, while the pattern is less clear for reduced and oxidized nitrogen. In fact there are positive trends for nitrogen compounds in air at several stations. Acidity is generally reduced at many stations while the precipitation amount is either increasing or stable. Variability of sulphate concentrations in air for the period 1991–2000 is reasonably well reproduced at most stations using an Eulerian, hemispherical model. Results for nitrogen compounds are weaker. Scenario studies show that even if large sulphur emission reductions take place in important source regions in South-East Asia in the coming decades, only small changes in Arctic deposition can be expected. This is because South-East Asian emissions have small influence north of the Arctic circle.

Identification and Characterization of Sulfur-Oxidizing Bacteria in an Artificial Wetland That Treats Wastewater From a Tannery

Wastewater from tanneries contains high concentrations of organic matter, chromium, nitrogen, and sulfur compounds. In this study, an artificial wetland is is used as the tertiary treatment in a tannery in León Gto., México. It consists of three subplots with an area of about 450 m2. Two subplots were planted with Typha sp. and the third with Scirpus americanus. Geochemical analyses along the flowpath of the wetland show that contaminants were effectively attenuated. The most probable number technique was used to determine rhizospheric microbial populations involved in the sulfur cycle and suggested that there were 104–106 cells g−1 sediment of sulfate-reducing bacteria and 102–105 of sulfur-oxidizing bacteria (SOB). Representatives of SOB were isolated on media containing thiosulfate. Phylogenetic analysis of 16S rRNA of SOB isolates shows that they belong to the genera Acinetobacter, Alcaligenes, Ochrobactrum, and Pseudomonas. Most of the isolates are organotrophic and can oxidize reduced sulfur compounds such as elemental sulfur or thiosulfate, accumulating thiosulfate, or tetrathionate during growth. All isolates can use reduced-sulfur compounds as their sole sulfur source and some can use nitrate as an electron acceptor to grow anaerobically. Our results illustrate the relevance of SOB in the functioning of the wetland constructed for tannery wastewater remediation.

Interaction between Insulating Paper and Transformer Oil: Bacterial Content and Transport of Sulfur and Nitrogen Compounds [Feature Article

There were variations between different insulating papers, but all contained significant amounts of sulfur. The sulfur showed little migration and it is therefore less likely that transformer paper will contribute, in a significant degree, to the amount of sulfur found in transformer oil in service. Thermally upgraded qualities of transformer paper are treated with different nitrogen-containing compounds. Therefore, the clear increase of nitrogen content in oil exposed to thermally upgraded paper suggests that migration from transformer paper can contribute considerably to the amount of nitrogen-containing substances found in transformer oil in service.

Technologies for production of components of modern automotive gasolines

A manufacturing complex for producing the components of contemporary automotive gasolines based on catalytic hydrocarbon fractions and using existing equipment was developed and is characterized by a low content of sulfur compounds, olefins, and high antiknock value.

Catalysts on the basis of anion-modified metal oxides for production of ecologically pure components of motor fuels

Experimental evidence on the production, structure, and physiochemical properties of aluminum, zirconium, and titanium oxides modified with halides, sulfates, and boron and tungsten oxides. Information on the application of anion-modified metal oxides as catalysts in the production of ecologically pure components of motor fuels, with decreased contents of aromatic hydrocarbons and sulfur compounds. Therewith, along with traditional hydrocarbon oligomerization, isomerization, alkylation reactions, actual arene hydroisomerization processes and production of diesel fuels from vegetable materials are considered.

The preparation and desulfurization of nano-size ZnO by a matrix-assisted method for the removal of low concentration of sulfur compounds

Abstract Zinc oxide (ZnO) nano-particles have been synthesized by a matrix-assisted method with various precursors. An activated carbon was used as a matrix and zinc acetate, zinc nitrate, and zinc chloride were selected as precursors. The ZnO nano-particles appeared to be either spherical or elliptical shapes when zinc acetate and zinc nitrate were used as precursors, while those particles became irregular in their shapes when zinc chloride was used as a precursor. The products were characterized by using TGA, XRD, BET, TEM and SEM. A nano-size ZnO was formulated for the effective removal of a very low concentration of sulfur compounds (H 2 S, COS) contained in a gasified fuel gas and their reactivity was also investigated in this study. Zinc acetate was the best precursor for the formulation of the ZnO nano-particles in the experiment. The size of the formulated ZnO nano-particles was in the range of 10–30 nm and its surface area was about 40.7 m 2 /g. From TGA (thermal gravity analysis) test, it was found that its sulfur capacity was about 9.27 g S/100 g-sorbent for H 2 S and 0.56 g S/100 g-sorbent for COS and its initial sulfur absorption rates with H 2 S and COS absorption were about 257.5 mg S/min · 100 g-sorbent and 15.6 mg S/min · 100 g-sorbent, respectively. Their reactivity increased as their sizes became smaller and their surface areas of the sorbents were larger. Most prepared nano-size ZnO showed an excellent performance for the removal of not only H 2 S but also COS.

Long-time risk of groundwater/drinking water pollution with sulphuric compounds beneath burned peatlands in Indonesia

Smoke-haze episodes caused by vegetation and peat fires affect parts of Indonesia every year with significant impacts on human health and climate. The forest fires 1997/1998 were by far the largest in Indonesian history, burning between 5 and 8 million hectares before they were stopped by the monsoon rains in December 1997. Fires sprang up again in 1998 on Kalimantan when monsoon rain paused. Peat forests and peatlands are in particular severely affected. In the 1997/1998 haze event, 2.1-2.5 million hectare of peat swamp forest burnt in Indonesia. The remaining ash contains high concentrations of sulphur and sulphuric compounds which eventually leach into the groundwater, thus polluting groundwater and drinking water. The thicker the peat layer is and the higher the number of fires in the respective area the more sulphuric compounds will leach into the groundwater. Risk areas for the sulphur loads of the ash are identified.

Synthesis of various zinc oxide nanostructures with zinc acetate and activated carbon by a matrix-assisted method

Zinc oxide nanostructure materials were prepared by a matrix-assisted method in this study. In the preparation of zinc oxide nanostructures, a granular type of activated carbon was used as a matrix and zinc oxide precursor was doped on the surface of activated carbon by an impregnation method. Zinc acetate was used as a precursor in the preparation of zinc oxide nanostructures. The amount of the doped zinc over the activated carbon was varied from 5 to 50wt%. It was observed that the morphology of ZnO nanostructure was influenced by the amount of the zinc doped over the activated carbon. Three different morphologies were obtained in this study. Since ZnO nanostructures synthesized by the matrix-assisted method had a small particle size and a large surface area, they were applicable either to catalyst or to the ultra hot gas cleaning for the effective removal of a very low concentration of sulfur compounds contained in a gasified fuel gas.

New compact scrubber for odour removal in wastewater treatment plants

This work presents the performances of a new odour scrubber. The reactor is packed with a new structure which enables co-current operations at high gas velocities. Energy consumption and removal efficiency of sulphur compounds by oxidative alkaline scrubbing were studied. The influence of both superficial gas (U(SG)) and liquid (U(SL)) velocities, ranging from 5.6 to 28 m.s(-1) and 0.016 to 0.055 m.s(-1) respectively, were quantified. Thus, the range of 0.5 to 5 liquid-to-gas mass ratio (L/G) was studied. A comparison has been made with a previous study on static mixers (SM) and with classical random packed towers (PT). It has been shown that superficial liquid and gas velocities have a significant influence on these parameters. Hydrogen sulphide (H2S) abatement reached values up to 99%. As concerns methylmercaptan (CH3SH), the maximal removal efficiency was 87%. As a result, if well scaled-up, our reactor can be a small single stage efficient apparatus for the elimination of low concentrations of sulphur compounds as H2S and CH3SH in high flow rates of polluted gas effluents.

Comparison of various detection limit estimates for volatile sulphur compounds by gas chromatography with pulsed flame photometric detection

This paper addresses the variations that presently exist regarding the definition, determination, and reporting of detection limits for volatile sulphur compounds by gas chromatography with pulsed flame photometric detection (GC-PFPD). Gas standards containing hydrogen sulphide (H 2S), carbonyl sulphide (COS), sulphur dioxide (SO 2), methyl mercaptan (CH 3SH), dimethyl sulphide (DMS), carbon disulphide (CS 2), and dimethyl disulphide (DMDS) in concentrations varying from 0.36 ppb (v/v) up to 1.5 ppm (v/v) in nitrogen were prepared with permeation tubes and introduced in the gas chromatograph using a 0.25-ml gas sampling loop. After measuring the PFPD response versus concentration, the method detection limit (MDL), the Hubaux–Vos detection limit ( x D), the absolute instrument sensitivity (AIS), and the sulphur detectivity ( D s) were determined for each sulphur compound. The results show that the MDL determined by the US Environmental Protection Agency procedure consistently underestimates the minimum concentrations of volatile sulphur compounds that can be practically distinguished from the background noise with the PFPD. The Hubaux–Vos detection limits and the AIS values are several times higher than the MDL, and provide more conservative estimates of the lowest concentrations that can be reliably detected. Sulphur detectivities are well correlated with AIS values but only poorly correlated with MDL values. The AIS is recommended as a reliable and cost-effective measure of detection limit for volatile sulphur compounds by GC-PFPD, since the AIS is easier and faster to determine than the MDL and the Hubaux–Vos detection limit. In addition, this study confirmed that the PFPD response is nearly quadratic with respect to concentration for all volatile sulphur compounds.

A cross‐over study on the effect of various therapeutic approaches to morning breath odour

The aim of this study was to investigate the effect of tongue scraping and inter-dental flossing on morning bad breath in periodontally healthy subjects. A four-step blind, cross-over study was conducted in 19 volunteers, divided into four groups: Group I: tooth brushing; Group II: tooth brushing and inter-dental flossing; Group III: tooth brushing and tongue scraping; and Group IV: tooth brushing, inter-dental flossing and tongue scraping. The volunteers performed these oral hygiene procedures three times a day for 7 days. Seven-day wash-out intervals were observed. Morning mouth breath was assessed organoleptically and by volatile sulphur compound concentrations. The highest mean organoleptic and volatile sulphur compound measurement values were found in the treatment groups in which tongue scraping was not performed and there were statistical differences between the two groups (p < 0.05). In the organoleptic evaluation (p > 0.05), inter-dental flossing did not show any statistical improvement in the effect of tongue hygiene on morning bad breath, but it significantly reduced the concentration of volatile sulphur compounds (p < 0.05). The findings suggest that tongue scraping appears to be the most important hygienic procedure to reduce morning bad breath in periodontally healthy subjects.

(159) Effects of Sulfur Compounds on CO2 Assimilation, Evapotranspiration, and Stomatal Conductance of Apple

Pesticides and alternative fruit thinners are needed for certified organic fruit growers. Transient reductions in photosynthesis (Pn) have proven an effective technique for fruit thinning. Pesticides can be detrimental to plant growth by Pn reduction. A two-part study was developed to measure plant response to foliar applications of sulfur compounds. In study 1, 2% concentrations of various sulfur compounds were observed for potential physiological or pesticidal effects. Foliar treatments were applied to vegetative apple trees grown under controlled environment conditions to study photosynthetic effects. No treatments significantly reduced CO2 assimilation (A) and stomatal conductance (gs). Copper sulfate, ammonium sulfate, and potassium sulfate significantly reduced evapotranspiration (Et) 7 days after treatment. No significance was observed for plant growth. In study 2, a 2% potassium sulfate concentration significantly reduced A 22 days after treatment; however, no differences were observed for Et and gs. Differences in plant growth were not significantly different among treatments.

Relationship of polycyclic aromatic sulfur compounds and gold enrichment in the Kupferschiefer from Poland and Germany

The contents of polycyclic aromatic sulfur compounds (PASCs) in the Kupferschiefer varied from sample to sample. Twenty PASCs were determined in the Kupferschiefer from Poland and Germany. Gold enrichment was only observed in samples with higher PASC contents. At the same time, all the samples with gold enrichment originated from areas close to the redox boundary (the front section ofRote Faule) that was formed by oxidizing brines in contact with the reducing Kupferschiefer. It is proposed that the gold-bearing solutions encountered PASCs in the Kupferschiefer. PASCs could easily displace chloride ions from aurous chloride complexes to form stable gold S-chelates. Subsequent oxidation of these gold organic compounds could destroy the organic components and lead to the formation of metallic gold.

The change of oral volatile sulfur compounds(VSC) concentration after periodontal treatment

The change of oral volatile sulfur compounds(VSC) concentration after periodontal treatment

Identification of trace volatile compounds in freshly distilled Calvados and Cognac: Carbonyl and sulphur compounds

Carbonyl and sulphur compounds were investigated in freshly distilled Calvados and Cognac. Forty-eight aldehydes and ketones were identified in both products using specific extraction, with Girard's T reagent supported on silica-gel. The recovery procedure of these compounds in a high ethanolic medium was optimized. Samples contained a majority of saturated aliphatic aldehydes and ketones. The presence of unsaturated aliphatic aldehydes and ketones, such as alkenals, oct-1-en-3-one, 6-methylhept-5-en-2-one and β -damascenone, was also detected. Numerous terpenoic or norisoprenoic carbonyl compounds were characterized and seem to be specific to Cognac. Twenty-seven sulphur compounds were quantified in the same samples; small amounts of thiols were detected. Concentrations of dimethyl disulphide were from 50–500 μg L −1 of pure alcohol (PA), and a high content of dibutyl sulphide (20–100 μg L −1 of PA) was recorded. Concentrations of ethyl propyl sulphide and diethyl sulphide, which were not significant in Calvados, were above 25 μg L −1 of PA in Cognac. 2- and 3-thiophenecarboxaldehyde were also quantified, and concentrations as high as 1000 μg L −1 in some samples, were the most important in Cognac. The ratio of 3- and 2-thiophenecarboxaldehyde was higher than 10 for Calvados, but was less than 0.5 for Cognac. Although weak concentrations of methional were recorded, this may contribute to the overall aroma of these two spirits due to extremely low detection threshold. The total concentration of sulphur compounds in Cognac samples was five to six times that of Calvados samples.

Comparison of ninhydrin method of detecting amine compounds with other methods of halitosis detection

Halitosis is a result of overactivity of Gram-negative bacteria for which protein amino acids are the major source of energy. Therefore, statistical correlation between concentrations of volatile sulphur compounds (VSCs) and low-molecular-weight amines should be expected. Eighty-four patients suffering from halitosis and 40 healthy volunteers aged 20-62 years (average 39.7) participated in the study. In all subjects low-molecular-weight amines were evaluated by the ninhydrin method. Patients with halitosis were randomized into treatment groups. Zinc tablets, tablets and mouthwash containing chlorhexidine or lyophilized lactic acid-forming bacteria were used. Analysis showed that the level of amines was highest in subjects with halitosis (0.39, s.d. +/- 0.06, P < 0.001) and correlated significantly with results of VSC measurement and organoleptic scores (P < 0.001). Reduction of amine levels after treatment was statistically significant (P < 0.001). Three months following treatment the amine levels began to increase (0.37, s.d. +/- 0.05). The amine levels in healthy controls were lower (0.29, s.d. +/- 0.07) and remained at a stable level. The salivary amine levels significantly correlated with VSC levels and organoleptic scores. Therefore, the ninhydrin method of detecting salivary amines may be an alternative or additional method of diagnosing halitosis. This method may also be used to evaluate treatment efficacy.

Clinical assessment of oral malodor intensity expressed as absolute value using an electronic nose

In our previous study, scores determined via a multiple linear regression method (EN-MLR) involving an electronic nose provided objective halitosis-related measurements; however, this model afforded only relative expression exclusively. The objective of this investigation was to assess clinically oral malodor intensity expressed as an absolute value using an electronic nose. Sixty-six subjects were evaluated based on results of an actual organoleptic test (OLT), measurements of volatile sulfur compound (VSC) concentrations, a score representing malodor intensity (EN-MI) as the absolute value and EN-MLR measured with an electronic nose system. Oral health parameters were also examined. The OLT score served as a benchmark. The area under the receiver-operating characteristic (ROC) plots of EN-MI score (0.975) was significantly larger than that of log VSC (0.896) (P = 0.036); however, the area did not differ significantly from that of EN-MLR score (0.932). Percentage of teeth with pocket depth greater than or equal to 4 mm, tongue coating score and plaque control record displayed meaningful association with EN-MI score in multiple logistic regression analyses. Oral malodor intensity expressed as an absolute value employing an electronic nose may be a suitable method for clinical evaluation of oral malodor.

Relationship between the SF‐36 questionnaire and patient's satisfaction following halitosis therapy

To assess the health-related quality of life (HRQOL) of patients complaining of halitosis at their first visit and at a later time when their complaint had diminished following therapy, using a self-administered questionnaire, the Medical Outcome Study Short Form-36 (SF-36). The aim of this study was to examine the relationship between HRQOL of patients before and after self-reported disappearance of their complaint following oral hygiene improvements for halitosis. Seventy patients of our special clinic for halitosis served as subjects. At the first visit, each completed the SF-36 before determination of volatile sulfur compound (VSC) concentration in mouth air. After excluding dropouts, the same measurements were performed for subjects whose self-reported complaint had disappeared following oral hygiene therapy. At the initial visit, SF-36 scale scores for general health, vitality, social functioning, role-emotion, and mental health were significantly lower when compared with the national averages in Japan. For subjects with self-reported disappearance of complaint, only social functioning rose significantly among SF-36 scores at the end of the study. These results suggest that an awareness of improvement in social life could be related to patient's satisfaction with halitosis oral hygiene therapy.

EFFECTS OF ROOM OZONATION ON AIR QUALITY AND PIG PERFORMANCE

Reducing odor emissions from swine farms to avoid complaints about odor nuisance is a major issue. Ozonationhas been used to reduce odor in swine buildings, but little research exists on its benefits. A swine-finishing building wasdivided into two identical rooms and two treatments, ozonation and the control, were applied in a cross-over design. Thetreatments were switched between rooms every three weeks. The overall experimental period was 12 weeks, during whichthere were four trials. Pig growth performance, dust mass and size concentration, odor intensity, total sulfur compounds,hydrogen sulfide concentration, ammonia concentration, and total heterotrophic bacterial counts were measured andanalyzed during the test period. Sulfur-containing compounds detected included dimethyldisulfide, dimethylsulfide(methanethiol), and dimethyltrisulfide. Ozone application to a swine building at the maximum safe concentration of 0.1 ppmdid not have any statistically significant effects on dust mass concentration, odor concentration and emission rate, sulfurcompound concentrations, and bacteria counts. However, it did increase ammonia concentration and decrease pig averagedaily gain. The ozonation effects on hydrogen sulfide concentration could not be evaluated by the gas tube method used duringthis study.

Impact of blanching and packaging atmosphere on the formation of aroma compounds during long-term frozen storage of leek (Allium ampeloprasum Var. Bulga) slices.

The content of aroma compounds and the catalytic activity of lipoxygenase (LOX), alliinase, hydroperoxide lyase (HPL), and alcohol dehydrogenase (ADH) were analyzed in unblanched and blanched 15-mm leek slices packed in atmospheric air (21% O2) or 100% nitrogen (0% O2) three times during 12 months of frozen storage (12 M). The total amount of sulfur compounds and the total amount of aldehydes were greatly influenced by storage time, atmosphere, and blanching [concentration of sulfur compounds in fresh unblanched (UNB) slices = 1.35 mg/L, fresh blanched (B) slices = 1.09 mg/L, UNB 21% O2 12 M = 0.656 mg/L, UNB 0% O2 12 M = 2.11 mg/L, B 21% O2 12 M = 1.14 mg/L, B 0% O2 12 M = 1.59 mg/L]. B 0% O2 was closest to the original ratio between sulfur compounds and aldehydes after 12 months. The activities of HPL and alliinase were totally lost after 12 months, and ADH showed minimal activity, whereas LOX (UNB 0% O2) showed approximately 25% of the original activity. LOX was the most and HPL the least heat labile enzyme investigated.