Refining of crude sulfate turpentine obtained from a kraft pulp mill: A pilot scale treatment

Crude sulfate turpentine (CST), a by-product of the kraft process, has commercial value that depends on the removal of sulfur compounds. The current study investigates desulfurization of CST using basic process steps for a paper mill at a pilot scale treatment. In another aspect, the sulfurous compounds in CST were removed by passing to the aqueous phase with terpin hydrate production, followed by α-terpineol conversion with citric acid catalysis. The goal was to design an environmentally friendly, low-cost, zero waste process and thereby refine the CST or byproducts to a quality that can produce chemical raw materials. Refining processes included hypochlorite oxidation, air oxidation, washing with water, and distillation. The sulfur content was decreased to 170, 106, and 29 ppm from respectively by 1260 ppm initial sulphur content of CST. The chlorine amount, due to treatment with hypochlorite oxidation, did not decrease with refining processes, even in distilled fraction. By obtaining α-terpineol from terpin hydrate, the sulfur compounds were completely removed. According to the GS-MS analysis results, distilled sulfate turpentine (DST) as the final product of the refining process of the CST sample increased the ratio with pinenes. On the other hand, with two reaction steps by obtaining terpin hydrate from CST and then α-terpineol, pinenes were converted to α-terpineol.

Periodontitis, Halitosis and Oral-Health-Related Quality of Life—A Cross-Sectional Study

We aimed to explore the association between volatile sulfurous compounds (VSCs) and periodontal epithelial surface area (PESA) and periodontal inflamed surface area (PISA) on a cohort of periodontitis patients. Consecutive patients were assessed for periodontitis and halitosis. A full-mouth periodontal status assessment tested probing depth (PD), clinical attachment loss (CAL), gingival recession (REC), bleeding on probing (BoP), PISA and PESA. A halitosis assessment was made using a VSC detector device. Periodontal measures were regressed across VSC values using adjusted multivariate linear analysis. From a total of seventy-two patients (37 females/35 males), the PESA of posterior-lower regions was found to be significantly higher in halitosis cases than their non-halitosis counterparts (p = 0.031). Considering all patients, the PESA of the posterior-lower region (B = 1.3, 95% CI: 0.2–2.3, p = 0.026) and age (B = −1.6, 95% CI:−3.1–0.2, p = 0.026) showed significant association with VSCs. In halitosis patients, the PESA of the posterior-lower region (B = 0.1, 95% CI: 0.0–0.1, p = 0.001), PISA Total (B = −0.1, 95% CI:−0.1–0.0, p = 0.008) and the OHIP-14 domain of physical disability (B = −2.1, 95% CI:−4.1–0.1, p = 0.040) were the most significant variables in this model. The PESA from the posterior-lower region may be associated with VSCs when other causes of extra-oral halitosis are excluded. Further intervention studies are needed to confirm this association.

A Graphical Explanation of Climate Change

Volcanic eruptions with an intensity of VEI4, or higher, affect Earth’s climate by injecting sulfurous compounds into the stratosphere, where they are quickly converted to the SO2 aerosol, H2SO4. These aerosols circulate around the globe, temporarily cooling the climate, with the maximum cooling generally occurring a year or more after the date of the eruption. These aerosols eventually settle out of the atmosphere, after about 18-30 months, and temperatures recover to pre-eruption levels, or a bit higher, as the descending aerosol droplets coalesce with others in the troposphere, causing some temporary cleansing of the atmosphere. Warming due to the less polluted air usually results in the formation of a volcanic-induced El Nino, if there have been no other eruptions in the interim. Global “Clean Air” activities since the late 1970’s focused strongly upon the reduction in industrial (anthropogenic) SO2 aerosol emissions, primarily because of acid-rain and health concerns. As a result, a plot of average anomalous global temperatures will reflect the increases and decreases caused by the changing amounts of SO2 in the atmosphere, from both “Clean Air” reductions in industrial emissions and volcanic eruptions. In examining such a plot, increases in average anomalous global temperatures were occasionally observed which appeared to be unrelated to either volcanic eruptions or to “Clean Air” activities. One such increase was noted for the year 1958, when the author graduated from college, and jobs were difficult to find because of the ongoing business recession (1957 Aug-1958 Sept.). It thus seemed possible that other recessions might also be responsible for the unexpected temperature increases, since industrial SO2 aerosol pollution of the atmosphere decreases during such times.

Chemistry and Biochemistry of Sulfur Natural Compounds: Key Intermediates of Metabolism and Redox Biology

Sulfur contributes significantly to nature chemical diversity and thanks to its particular features allows fundamental biological reactions that no other element allows. Sulfur natural compounds are utilized by all living beings and depending on the function are distributed in the different kingdoms. It is no coincidence that marine organisms are one of the most important sources of sulfur natural products since most of the inorganic sulfur is metabolized in ocean environments where this element is abundant. Terrestrial organisms such as plants and microorganisms are also able to incorporate sulfur in organic molecules to produce primary metabolites (e.g., methionine, cysteine) and more complex unique chemical structures with diverse biological roles. Animals are not able to fix inorganic sulfur into biomolecules and are completely dependent on preformed organic sulfurous compounds to satisfy their sulfur needs. However, some higher species such as humans are able to build new sulfur-containing chemical entities starting especially from plants’ organosulfur precursors. Sulfur metabolism in humans is very complicated and plays a central role in redox biochemistry. The chemical properties, the large number of oxidation states, and the versatile reactivity of the oxygen family chalcogens make sulfur ideal for redox biological reactions and electron transfer processes. This review will explore sulfur metabolism related to redox biochemistry and will describe the various classes of sulfur-containing compounds spread all over the natural kingdoms. We will describe the chemistry and the biochemistry of well-known metabolites and also of the unknown and poorly studied sulfur natural products which are still in search for a biological role.

Recent Developments on the Origin and Nature of Reductive Sulfurous Off-Odours in Wine

Reductive sulfurous off-odors are still one of the main reasons for rejecting wines by consumers. In 2008 at the International Wine Challenge in London, approximately 6% of the more than 10,000 wines presented were described as faulty. Twenty-eight percent were described as faulty because they presented “reduced characters” similar to those presented by “cork taint” and in nearly the same portion. Reductive off-odors are caused by low volatile sulfurous compounds. Their origin may be traced back to the metabolism of the microorganisms (yeasts and lactic acid bacteria) involved in the fermentation steps during wine making, often followed by chemical conversions. The main source of volatile sulfur compounds (VSCs) are precursors from the sulfate assimilation pathway (SAP, sometimes named as the “sulfate reduction pathway” SRP), used by yeast to assimilate sulfur from the environment and incorporate it into the essential sulfur-containing amino acids methionine and cysteine. Reductive off-odors became of increasing interest within the last few years, and the method to remove them by treatment with copper (II) salts (sulfate or citrate) is more and more questioned: The effectiveness is doubted, and after prolonged bottle storage, they reappear quite often. Numerous reports within the last few years and an ongoing flood of publications dealing with this matter reflect the importance of this problem. In a recent detailed review, almost all relevant aspects were discussed on a scientific data basis, and a “decision tree” was formulated to support winemakers handling this problem. Since we are dealing with a very complicated matter with a multitude of black spots still remaining, these advices can only be realized using specific equipment and special chemicals, not necessarily found in small wineries. The main problem in dealing with sulfurous compounds arises from the high variability of their reactivities. Sulfur is a metalloid with a large valence span across eight electron transformations from S (−II) up to S (+VI). This allows it to participate in an array of oxidation, reduction and disproportionation reactions, both abiotic and linked to microbial metabolism. In addition, sulfur is the element with the most allotropes and a high tendency to form chains and rings, with different stabilities of defined species and a high interconvertibility among each other. We suppose, there is simply a lack of knowledge of what is transferred during filling into bottles after fermentation and fining procedures. The treatment with copper (II) salts to remove sulfurous off-odors before filling rather increases instead of solving the problem. This paper picks up the abundant knowledge from recent literature and tries to add some aspects and observations, based on the assumption that the formation of polythionates, hitherto not taken into consideration, may explain some of the mystery of the re-appearance of reductive off-odors.

A comparison of removal performance of volatile organic and sulfurous compounds between odour abatement systems

Three types of odour abatement systems in sewer networks in Australia were studied for 18 months to determine the removals of different compounds. Six volatile sulfurous compounds and seven volatile organic compounds (VOCs) were further investigated. All types of odour abatement systems exhibited good removal of hydrogen sulfide with the biotrickling filters (BTFs) showing the highest consistent removal. Biofilters outperformed BTFs and activated carbon (AC) filters in the removal of dimethyl mono-, di- and tri-sulfide species at the low inlet concentrations typically found. AC filters exhibited little VOC removal with no compound consistently identified as having a removal greater than 0%. Biofilters outperformed BTFs in VOC removal, yet both had high removal variability.

Sulfurous Gases As Biological Messengers and Toxins: Comparative Genetics of Their Metabolism in Model Organisms

Gasotransmitters are biologically produced gaseous signalling molecules. As gases with potent biological activities, they are toxic as air pollutants, and the sulfurous compounds are used as fumigants. Most investigations focus on medical aspects of gasotransmitter biology rather than toxicity toward invertebrate pests of agriculture. In fact, the pathways for the metabolism of sulfur containing gases in lower organisms have not yet been described. To address this deficit, we use protein sequences fromHomo sapiensto query Genbank for homologous proteins inCaenorhabditis elegans,Drosophila melanogaster, andSaccharomyces cerevisiae. InC. elegans, we find genes for all mammalian pathways for synthesis and catabolism of the three sulfur containing gasotransmitters, H2S, SO2and COS. The genes for H2S synthesis have actually increased in number inC. elegans. Interestingly,D. melanogasterand Arthropoda in general, lack a gene for 3-mercaptopyruvate sulfurtransferase, an enzym for H2S synthesis under reducing conditions.