A low-cost and efficient methodology was used to test the performance of a biofilter removing gaseous hydrogen sulfide generated in the headworks and a primary clarifier of a local Wastewater Treatment Plant. The contaminated gas stream is distributed upward through 1,718 m3 of filter material. With a flow rate varying between 3,503.0 m3/h and 4,587.3 m3/h and hydrogen sulfide inlet concentrations between 0.8 and 146 ppm, hydrogen sulfide was efficiently eliminated by the wood bark biofilter. The removal efficiencies ranged from 97.5% to 99.9%. The mean water content of the filter material was determined to be 67.1%. The excess water existing in the unit and long residence times may have provided the appropriate conditions for a high hydrogen sulfide removal.

Το υδρόθειο (H2S) είναι ένα άχρωμο, εύφλεκτο αέριο με τη χαρακτηριστική οσμή του κλούβιου αυγού. Τα τελευταία χρόνια έχει αναγνωριστεί ο ρόλος του ως ένα σηματοδοτικό μόριο για το καρδιαγγειακό και το νευρικό σύστημα και είναι το τρίτο μέλος της οικογένειας των αέριων διαβιβαστών. Παράγεται ενδογενώς μέσω του μεταβολισμού της L-κυστεΐνης από δυο ένζυμα: τη β-συνθετάση της κυσταθειονίνης (CBS) και τη γ-λυάση της κυσταθειονίνης (CSE). Ένας τρίτος τρόπος σύνθεσης του H2S από L-κυστεΐνη που ανακαλύφθηκε πρόσφατα είναι μέσω της συνδυασμένης δράσης της σουλφοτρανσφεράσης του 3-μερκαπτοπυροσταφυλικού και της αμινοτρανσφεράσης της κυστεΐνης (3MST/CAT). Στην παρούσα εργασία μελετήσαμε την εκλεκτικότητα των διαθέσιμων φαρμακολογικών αναστολέων της σύνθεσης του H2S που επιδρούν στα ένζυμα παραγωγής του, CBS και CSE. Για την υλοποίηση της μελέτης έγινε η έκφραση των ενζύμων CSE και CBS ως χιμαιρικές πρωτεΐνες με GST σε βακτήρια E.coli και ακολούθησε η απομόνωση αυτών με χρωματογραφία συγγένειας με τη χρήση στηλών που έχουν ακινητοποιημένη σε σεφαρόζη τη γλουταθειόνη. Έπειτα ελέγχθηκε η δραστικότητα των ανασυνδυασμένων ενζύμων με την μέθοδο του μπλε του μεθυλενίου και στη συνέχεια εξετάσθηκαν οι αναστολείς έναντι και των δυο ενζύμων CSE και CBS. Τα αποτελέσματα μας επιβεβαιώνουν την εκλεκτικότητα της προπαργυλογλυκίνης (PAG) και της β-κυανοαλανίνης (BCA) για το CSE. Από τη μελέτη μας βρέθηκε ότι η β-κυανοαλανίνη (BCA) είναι ισχυρότερος αναστολέας του CSE από την προπαργυλογλυκίνη (PAG) με IC50 14μΜ και 750μΜ, αντίστοιχα. Το αμινο-οξικό οξύ (ΑΟΑΑ) βρέθηκε ότι είναι πιο ισχυρός αναστολέας για το CSE (IC50 1,1μΜ) παρά για το CBS (IC50 8,5μΜ), παρόλο που θεωρητικά είναι εκλεκτικός αναστολέας του CBS. Μάλιστα είναι ισχυρότερος των PAG και BCA, για το CSE. Η τριφθοροαλανίνη και η υδροξυλαμίνη ανέστειλαν και τα δυο ένζυμα, με την τριφθοροαλανίνη να είναι πιο ισχυρός αναστολέας του CBS, ενώ η υδροξυλαμίνη του CSE. Στην παρούσα εργασία εξετάστηκαν επίσης κάποιες νέες ουσίες ως πιθανοί αναστολείς του CSE, οι οποίες δε φαίνεται να είχαν την ικανότητα να προκαλέσουν σημαντική αναστολή του ενζύμου αυτού. Συμπερασματικά, παρόλο που οι αναστολείς PAG και BCA εμφανίζουν εκλεκτικότητα ως προς το CSE έναντι του CBS, δεν υπάρχει, προς το παρόν, κανένας εκλεκτικός αναστολέας για το CBS. / Hydrogen sulphide (H2S) is a colorless, flammable gas with the characteristic smell of rotten eggs. H2S is now recognized as an important signalling molecule in the cardiovascular and nervous systems and is the third member of the gasotransmitter family. H2S is synthesized via two pyridoxal-5′-phosphate-dependent enzymes responsible for the metabolism of L-cysteine: cystathionine beta synthase (CBS) and cystathionine gamma lyase (CSE), as well as by a recently identified third pathway that catalyzes the production of H2S from L-cysteine via the combined action of 3-mercaptopyruvate sulphurtransferase and cysteine aminotransferase (3MST/CAT). In the present study we examined the selectivity of commonly used pharmacological inhibitors of H2S biosynthesis towards CSE and CBS. To address this question human CSE or CBS enzymes were expressed and purified from E. coli as fusion proteins with Glutathione-S-Transferase (GST). After purification the activity of the recombinant enzymes was tested using the methylene blue method. We found that β-cyanoalanine (BCA) was a more potent CSE inhibitor than propargylglycine (PAG) (IC50 14μΜ and 750μΜ, respectively), and that aminooxyacetic acid (AOAA) was even more potent than BCA and PAG towards CSE (IC50 1.1μΜ), although it is claimed to be a CBS-selective inhibitor; AOAA inhibited CBS with an IC50 8.5μΜ. Trifluoroalanine and hydroxylamine inhibited both enzymes with the former being a more potent inhibitor of CBS, while the later of CSE. We also examined some new synthesized substances as CSE inhibitors. In conclusion, although PAG and BCA exhibit selectivity in inhibiting CSE vs CBS, no selective CBS inhibitor is currently available.

This diploma thesis deals with reductive sulphur off-odors in wines and possibilities of their removal. The theoretical part describes substances causing these defects, their threshold values, most common causes of defects and possibility of their prevention or removal. The practical part is focused on the determination of hydrogen sulphide (H2S) in wine with reductive sulphur off-odor and the possibility of reducing its content using particles of gold, silver and copper. A wine with reductive off-odor made of the Zweigeltrebe variety from 2018 was used for the experiment. 10 l micro-samples were created and various doses of silver, gold and copper-based products were applied to the wine. The control samples were left untreated. The UV / VIS HPLC instrumentation was used for determination of the hydrogen sulphide concentration using so far unpublished method for converting H2S to methylene blue with direct injection of the derivatized wine sample. The H2S concentration in the samples varied from 13,1 to 68,7 µg/l. Basic analytical parameters were also measured and compared in this work, but they did not changed significantly with added products doses. The GC-MS method was used to measure the levels of particular volatile compounds. Treated wines were also sensory evaluated. The best sensory properties exhibited wines treated with copper products.

Indiana University Purdue University Indianapolis / H2S is a gaseous mediator that acts as an anti-inflammatory agent contributing to gastrointestinal mucosal defense. It promotes vascular dilation, mucosal repair, and resolution of inflammation following intestinal ischemia and may be exploited as a novel therapeutic agent. It is unclear if H2S works through nitric oxide-dependent pathways in the intestine. We appreciated that H2S was able to improve post-ischemic recovery of mesenteric perfusion, mucosal integrity, and inflammation. The beneficial effects of H2S appear to be mediated through endothelial nitric oxide-dependent pathways.

Biomass gasification is a promising technology for conversion of various biomass feedstocks to producer gas for subsequent production of fuels and chemicals. A dual fluidised bed (DFB) steam gasifier is used in the present research to produce the producer gas for Fischer-Tropsch (FT) liquid fuel synthesis. However, NH3 and H2S gases in the producer gas remain an issue to be resolved because they are poisonous to the catalysts employed in the FT reactor. To remove NH3 and H2S, two methods were investigated in this research: (1) primary measures which were employed in the DFB steam gasifier including process optimisation and application of bed materials for catalytic NH3 decomposition and H2S adsorption; and (2) secondary measures or downstream cleaning methods after the gasifier. The combination of the primary measures and the secondary measures is an effective way to remove the NH3 and H2S in the producer gas from gasification process. Studies on the primary measures were divided into two parts. In the first part, in situ reduction of NH3 and H2S in biomass producer gas from the DFB steam gasifier was performed. The primary measures consisted of optimisation of operation conditions and application of bed materials. The main operation conditions in the DFB steam gasifier studied were gasification temperature, steam to fuel (S/F) ratio, and mean gas residence time (f). The bed materials tested include silica sand, iron sand (ilmenite), and calcined olivine sand. For the second part of the primary measures, an influence of the lignite to fuel (L/F) ratio on NH3 and H2S concentrations and conversions in co-gasification of blended lignite and wood pellets in the DFB steam gasifier was investigated. Experiments were performed in the DFB steam gasifier at 800C with blended lignite and radiata pine wood with the L/F ratio ranging from 0% to 100%. It was found that all of the studied parameters including gasification temperature, S/F ratio, f, bed material, and L/F ratio significantly influenced the NH3 and H2S concentrations and conversions in the producer gas. For the secondary measures, a novel hot catalytic reactor and adsorber was developed in the present research for the simultaneous removal of NH3 and H2S. In a hot gas reactor operated at 500-800C and under atmospheric pressure, titanomagnetite was tested for NH3 and H2S removal by hot catalytic NH3 decomposition and H2S adsorption reactions. Titanomagnetite was tested with three different gas streams including 2,000 ppmv NH3 in Ar, 2,000 ppmv NH3 and 230 ppmv H2S in Ar, and 2,000 ppmv NH3 and 230 ppmv H2S in simulated biomass producer gas. From the experimental results, it was discovered that ferrite (α-Fe) readily formed by the H2 reduction of titanomagnetite has shown almost complete NH3 decomposition (100%) in Ar gas at 700 and 800C. The presence of H2S in the gas mixture of NH3 and Ar slightly reduced the catalytic activity for NH3 decomposition at 700 and 800C (>96%) and H2S adsorption of more than 98% could be achieved at the same temperature range. However, in the test with simulated biomass producer gas, 60% NH3 decomposition and 9% H2S adsorption were obtained at 800C, whereas 40% NH3 decomposition and 80% H2S adsorption were obtained at 500C. The decrease of NH3 decomposition and H2S adsorption at 800C in simulated biomass producer gas could be due to the high content of H2 (45 vol%) in the feed gas that favours the reverse reactions of NH3 decomposition and H2S adsorption, the increased surface coverage of the active α-Fe phase by adsorbed hydrogen, and the competition of α-Fe for the reverse water-gas shift reaction. Besides, it was discovered that the temperature significantly affected the removal of NH3 and H2S in simulated biomass producer gas and thus it needs to be optimised.

Novel anode catalysts have been developed for sour natural gas solid oxide fuel cell (SOFC) applications. Sour natural gas comprises light hydrocarbons, and typically also contains H2S. An alternative fuel SOFC that operates directly on sour natural gas would reduce the overall cost of plant construction and operation for fuel cell power generation. The anode for such a fuel cell must have good catalytic and electrocatalytic activity for hydrocarbon conversion, sulfur-tolerance, resistance to coking, and good electronic and ionic conductivity. The catalytic activity and stability of ABO3 (A= La, Ce and/or Sr, B=Cr and one or more of Ti, V, Cr, Fe, Mn, or Co) perovskites as SOFC anode materials depends on both A and B, and are modied by substituents. The materials have been prepared by both solid state and wet-chemical methods. The physical and chemical characteristics of the materials have been fully characterized using electron microscopy, XRD, calorimetry, dilatometry, particle size and area, using XPS and TGA-DSC-MS. Electrochemical performance was determined using potentiodynamic and potentiostatic cell testing, electrochemical impedance analysis, and conductivity measurements. Neither Ce0.9Sr0.1VO3 nor Ce0.9Sr0.1Cr0.5V0.5O3 was an active anode for oxidation of H2 and CH4 fuels. However, active catalysts comprising Ce0.9Sr0.1V(O,S)3 and Ce0.9Sr0.1Cr0.5V0.5(O,S)3 were formed when small concentrations of H2S were present in the fuels. The oxysuldes formed in-situ were very active for conversion of H2S. The maximum performance improved from 50 mW cm2 to 85 mW cm2 in 0.5% H2S/CH4 at 850 oC with partial substitution of V by Cr in Ce0.9Sr0.1V(O,S)3 . Selective conversion of H2S offers potential for sweetening of sour gas without affecting the hydrocarbons. Perovskites La0.75Sr0.25Cr0.5X0.5O3, (henceforth referred to as LSCX, X=Ti, Mn, Fe, Co) are active for conversion of H2, CH4 and 0.5% H2S/CH4. The order of activity in the different fuels depends on the substituent element: CH4, X=Fe>Mn>Ti; H2,X = Fe>Mn>Ti; and 0.5% H2S/CH4, X = Fe>Ti>Mn. The electrocatalytic activity for methane oxidation in a fuel cell correlates with ex-situ temperature programmed catalytic activity. A process is proposed to explain the difference in catalyst order and enhanced activities in H2S/CH4 as fuel compared to CH4 alone. The maximum power density of 250 mW cm2 was attained using a fuel cell with a composite anode, LSCFe-GDC | YSZ(0.3 mm) | Pt, operated at 850 oC (GDC is Ce0.9Gd0.1O3, a good mixed conductor under reducing conditions). / Materials Engineering

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Hydrogen sulfide (H2S) is the newest member of the gasotransmitter family and is becoming well known for its cardioprotective effects in preclinical trials. Many recent studies have shown the benefits of exogenous H2S in the setting of acute myocardial infarction (AMI) and pressure overload-induced heart failure, but current formulations are derived from inorganic salts which have shortcomings in the precision and control of release of H2S. The main objective of this thesis was to determine if the novel, orally active, slow-releasing compound, SG1002, can attenuate the severity of damage and adverse remodeling caused by ischemia/reperfusion injury through an induction of angiogenesis. A traditional sodium salt, Na2S, which has been previously shown to be cardioprotective, was used as a positive control. SG1002 improved overall left ventricular function as measured by increased ejection fraction from echocardiography and decreased QRS interval from electrocardiography compared to untreated animals following MI. SG1002 therapy was also associated with an induction of angiogenesis, which was determined through qRT-PCR, western blot, and histological methods. SG1002 increased VEGF protein levels, which was paralleled with an increase in capillary density in the infarct region. SG1002 also upregulated microRNA-126, which is thought to repress the inhibitor of VEGF, Spred-1. It is possible that this “angiomiR” plays a key role in the angiogenesis-related cardioprotection of H2S. The combination of increased pro-angiogenic factors along with greater vascular density resulting from SG1002 therapy indicates the therapeutic potential for this drug in the prevention and/or treatment of ischemic heart failure.

Hydrogen sulfide (H2S) has been identified to be produced in small quantities in plants and animals. H2S has been shown to have numerous benefits including improving the tolerance of plants to a variety of stressors and improving the harvest yields of plants. Because of the ever-increasing population of the planet, it is necessary to grow more food and increasing the yield of a harvest is essential to do that. GYY-4137, a H2S donor, releases H2S very slowly in water but released it much faster with organic solvents and soil. The long-term growth of plants with GYY-4137 was investigated for 6 weeks with radishes, peas, and lettuce. Dithiophosphosphates were investigated as H2S donors to be used to improve the growth of crops. These donors were studied to determine their degradation rates in water and organic solvents. Rates of H2S release were compared at various concentrations in water and contrasted with the release of H2S from GYY-4137. Dialkyldithiophosphates have not been used in prior work as H2S donors to improve crop yields. Maize was grown for 4 weeks with dibutyldithiophosphate ammonium salt and the plants showed up to 38% increase in weight. These results show that dibutyldithiophosphate releases H2S at a similar rate to that of GYY-4137 and can have a significant benefit to increase the weight of maize.