Presence Of Nitrogen Compounds Research Articles

Roles of Nanostructured Bimetallic Supported on Alumina-Zeolite (AZ) in Light Cycle Oil (LCO) Upgrading

Light cycle oil (LCO) is one of the major products in Fluid catalytic cracking (FCC) processes, and has drawbacks such as high aromatics, sulfur, and nitrogen contents, and low cetane number (CN). Hydro-upgrading is one of the most typical processes for LCO upgrading, and alumina-zeolite (AZ) is an effective hydrotreating catalyst support. This paper examined the effects of different bimetallic catalysts (CoMo/AZ, NiMo/AZ, and NiW/AZ) supported by AZ on hydro-upgrading of both model compounds and real LCO. CoMo/AZ preferred the direct desulfurization (DDS) route while the NiMo/AZ and NiW/AZ catalysts favored the desulfurization route through hydrogenation (HYD). The presence of nitrogen compounds in the feed introduced a competitive adsorption mechanism and reduced the number of available acid sites. Aromatics were partially hydrogenated into methyltetralines at first, and then further hydrogenated, cracked, and isomerized into methyldecalins, monocyclic, and methyltetralines isomers. CoMo/AZ is the best hydrodesulfurization (HDS) catalyst for the model compounds at low H2 pressure (550 psi) and for LCO at lower temperature (573 K), while NiMo/AZ performs the best for LCO at higher temperature (648 K). NiMo/AZ is the best hydrodenitrogenation (HDN) catalyst for LCO. The hydrodearomatization (HDA) performances of NiMo/AZ and NiW/AZ improved significantly and overwhelmingly higher than that of the CoMo/AZ when the H2 pressure was increased to 1100 psi.

Adverse effects of nitrogenous compounds on nitrogen-fixing cyanobacterium Anabaena solitaria Klebahn

The nitrogen-fixing heterocystous cyanobacterium Anabaena solitaria was tested for its response to different concentrations of nitrogen sources, namely nitrate and ammonia. To compare both the effect of concentration and type of nitrogen source, gradual concentrations were prepared for both ammonia and nitrate. The results showed concentration was significantly important on the frequency of heterocyst formation where highest nitrogen compounds concentrations were inhibitory for heterocyst formation. On the other hand, the effect of the type of nitrogenous compounds tested was insignificant which only proves that they are equally usable by cyanobacteria which will use them instead of transforming one of its cells to heterocyst thus not performing nitrogen fixation. Results also revealed the massive growth of heterotrophic bacteria in presence of nitrogenous compounds. This indicates that the presence of nitrogenous compounds in fields in which nitrogen-fixing cyanobacteria are to be used as biofertilizers can be inhibitory for nitrogen fixation and stimulatory for heterotrophic bacterial growth which could be pathogenic and harmful to plants. The use of more nitrogen-fixing cyanobacteria with the minimum amount of nitrogenous compounds is recommended.

NITRATE CONTENT OF DRINKING WATER AND THEIR EFFECTS ON POPULATION HEALTH

The problems of drinking water quality have been considered in some settlements of the Turkivskiy district of Lviv region, in particular concerning the content of Nitrogen compounds. 20 sources of decentralized water supply were investigated. It was found that the main hydrochemical indicators of water samples mainly met the requirements for the degree of contamination of hygienic classification of water bodies. At the same time, analyzing the samples for the presence of nitrogen compounds, it was found that in the tested samples: the content of nitrate ions fluctuated within 0,02 - 016 mg/dm3 (average annual values did not exceed the permissible value); the content of ammonium ions is in the range of 0.5-2.8 mg/dm3, which did not significantly exceed the maximum permissible value. At the time, analysis for NO3- showed an excess of acceptable values in almost all samples by 1.3 у 4.2 times. It was found that the amount of nitrates decreased with the transition from the alluvial aquifers to the indigenous ones, where the average content was 108.9 mg/dm3 and 86.8 mg/dm3, respectively. This is probably due to better protection of the bedrock from surface contamination, greater capacity of the corresponding aquifers and their deeper occurrence. According to the average value of the water pollution index for the nitrate group, the studied objects of decentralized water supply belong to the second class ‒ moderately contaminated. The correlation between the water pollution index by nitrate group and the population morbidity is calculated to be direct and sufficiently high (0.73). The most associated indicators of water quality are diseases of the circulatory system, blood and hematopoietic organs, digestive organs, endocrine and urogenital systems.

Inducible Antibacterial Activity in the Bacillales by Triphenyl Tetrazolium Chloride

The world is in the midst of an antimicrobial resistance crisis, driving a need to discover novel antibiotic substances. Using chemical cues as inducers to unveil a microorganism’s full metabolic potential is considered a successful strategy. To this end, we investigated an inducible antagonistic behavior in multiple isolates of the order Bacillales, where large inhibition zones were produced against Ralstonia solanacearum only when grown in the presence of the indicator triphenyl tetrazolium chloride (TTC). This bioactivity was produced in a TTC-dose dependent manner. Escherichia coli and Staphylococcus sp. isolates were also inhibited by Bacillus sp. strains in TTC presence, to a lesser extent. Knockout mutants and transcriptomic analysis of B. subtilis NCIB 3610 cells revealed that genes from the L-histidine biosynthetic pathway, the purine, pyrimidine de novo synthesis and salvage and interconversion routes, were significantly upregulated. Chemical space studied through metabolomic analysis, showed increased presence of nitrogenous compounds in extracts from induced bacteria. The metabolites orotic acid and L-phenylalaninamide were tested against R. solanacearum, E. coli, Staphylococcus sp. and B. subtilis, and exhibited activity against pathogens only in the presence of TTC, suggesting a biotransformation of nitrogenous compounds in Bacillus sp. cells as the plausible cause of the inducible antagonistic behavior.

Effects of urea and lipid removal from Carcharhinus leucas and Galeocerdo cuvier white muscle on carbon and nitrogen stable isotope ratios

The analysis of stable isotope ratios of carbon and nitrogen is a tool commonly used in trophic ecology. However, the presence of nitrogen compounds and lipids in tissues of studied organisms can bias the ratio measurements. Treatments to eliminate problematic compounds have been highlighted in the literature. In this study the effect of two different treatments and their combination on the δ 15 N and δ 13 C ratio values of Carcharhinus leucas and Galeocerdo cuvier white muscle samples were tested. All sharks were caught along the west coast of Reunion Island (western Indian Ocean), within the framework of a shark-control programme. Deionized water rinsing proved to be the most effective treatment for nitrogen compound removal and lipid extraction, using a 2:1 chloroform-methanol solution, the most effective for lipid removal. The combination of both treatments was as effective as deionized water rinsing for nitrogen compound removal but produced an unexpected decrease of δ 13 C ratio values. Deionized water rinsing caused a similar decrease on some δ 13 C values in the bull shark. Some differences on the effects of the different treatments appeared when considering the sexes separately. Analytical normalization equations for the different treatments on the two stable isotope ratios are provided.

Adsorptive Selectivity and Mechanism of Three Different Adsorbents for Nitrogenous Compounds Removal from Microalgae Bio-Oil

Microalgae bio-oil is of interest as a potential alternative to traditional fossil-fuel-based transportation fuels. However, the presence of nitrogenous compounds in the bio-oil can lead to the rel...

Modelo conceitual da degradação de poliacrilamidas (PAM) em compostos nitrogenados

Esse estudo teve como objetivo avaliar os impactos gerados por polímero Poliacrilamida (PAM), encontrados em resíduos de estação de tratamento de água. A degradação do PAM pode estar associada à presença de compostos nitrogenados na água, como amônio, nitratos e nitritos, sendo essencial a avaliação da degradação deste polímero. A metodologia envolveu a elaboração de um Modelo Conceitual para a disposição de lodo de ETA em aterros tecnogênicos, com enfoque em poliacrilamidas e sua degradação em compostos nitrogenados. O modelo foi validado a partir de dados observados em um estudo de caso desenvolvido em Taiaçupeba, Suzano, SP. Observou-se que no processo de nitrificação, por via aeróbia, o íon amônio é oxidado a nitritos e posteriormente a nitratos; e por via anaeróbia, uma reação anamox, em que amônio é oxidado e nitrito reduzido, liberando gás nitrogênio em ambiente redutor. Adicionalmente, foram observados íon amônio, óxido de manganês e hidróxido de ferro (abundantes no solo in situ e também no lodo) sendo oxidados a nitrogênio gasoso e consumindo íons H+ no meio. A variação do nível de água do aquífero freático pode influenciar as concentrações observadas em razão do incremento da espessura da zona saturada, possibilitando o contato com camadas superficiais de PAM.

Adsorption of ammonium on clinoptilolite in presence of competing cations: Investigation on groundwater remediation

Abstract Various civilian, agricultural and industrial activities cause the presence of nitrogen compounds in surface and groundwater, where they are further converted into ammonia and its salts. The progressive increase in ammonium concentration in the environment represents a serious concern since it is one of the main causes of eutrophication and its transformation may lead to carcinogens. On the other hand, wastewater has recently been considered as a potential source of nitrogenous nutrients for plants, once adequate recovery processes have been provided. Among the latter, the adsorption processes must be considered reliable and clean due to the mild operating conditions. An experimental study on the removal of ammonium by adsorption on a zeolite cation exchanger (clinoptilolite mineral) was undertaken, considering the water from an Italian groundwater treatment facility with a treatment capability of 150,000 L/h. The activity was focused on the polishing step before surface discharge (from 20 mg/L to 5 mg/L, according to restrictions due to neighboring water bodies of naturalistic relevance). The experimental study was part of a wider activity for the evaluation of the performances of a 1000 L/h cation-exchange pilot plant operated at the same industrial site. Thus, the peculiar features of the reported study are ammonium removal until the level of traces, use of a conditioned zeolite, and co-presence of high concentrations of other dissolved cationic species competing for exchange.

Short time synthesis of titania modified-CMK-3 carbon mesostructure as support for Ir-catalyst applied in catalytic hydrotreating

Abstract Ti-CMK-3 carbon mesoporous was prepared using a novel synthesis method. This new method avoids the hard template synthesis used commonly. The method developed here, allows to reduce time, energy consumptionand cost. Structural and textural characterization of the titanium modified-mesoporous carbonwas performed by N2 adsorption, XRD, UV–vis-DRS, Raman spectroscopy and TEM. The characterization results indicated that the textural and structural properties of the material synthesized by the short time method are comparable with the properties of the material prepared by the hard template method. Ti modified-mesoporous carbon was used as support of the iridium nanoparticles, in order to prepare a catalyst to be tested in model hydrotreating reactions. The catalyst obtained by wet impregnation with iridium acetylacetonate were characterized by ICP-AES, H2 chemisorption, TEM, XPS and FTIR of adsorbed pyridine. The high Ir dispersion and small particle size, along with the moderate Lewis acidity generated by the presence of titanium in the support, were responsible for the good performance and stability of the catalyst in the hydrogenation of tetralin in presence of nitrogen compounds. Main advantage of the present study is the reduction of time and cost in the synthesis of the new material and the applicability for HDT reactions.

Deep extractive desulfurization of oil over 12-molibdophosphoric acid encapsulated in metal-organic frameworks

A desulfurization process for model oil and real oil was investigated based on the chemical oxidation of mixed sulfur containing compounds in the presence of nitrogen compounds (indole and quinoline) using hydrogen peroxide as oxidizing agent and dodecamolibdophosphoric acid (H3PMo12O40) encapsulated in a kind of metal-organic framework (HKUST-1) as PMo@HKUST-1. The effect of isopropanol, ethanol and acetonitrile as extractive solvent and 1-ring (toluene, xylene and mesitylene) and 2-ring (naphthalene) aromatic hydrocarbons in desulfurization of model oil was studied. The desulfurization of sulfur-containing compounds was accelerated in the presence of aro- matic hydrocarbons. In fact, a higher desulfurization efficiency of the heterogeneous catalyst could be achieved with system containing a polar solvent in contact with an aromatic hydrocarbon. Quinoline had no effect on oxidative desulfurization (ODS) reaction, whereas indole had a slightly negative effect. Presence of aromatic compounds had slightly positive effect on ODS reaction.

Hydrotreating activity of bulk NiB alloy in model reaction of hydrodesulfurization 4,6-dimethyldibenzothiophene

For the first time hydrodesulfurization reaction of 4,6-dimethyldibenzothiophene (4,6-DMDBT) was performed on bulk NiB alloy in the presence of nitrogen compound – carbazole. Before and after reaction the catalysts were characterized by X-ray diffraction (XRD), also by high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM) and differential scanning calorimetric analysis (DSC) and by X-ray photoelectron spectroscopy (XPS) – after HDS reaction. The surface and metallic phase were determined by N2 physisorption and CO chemisorption. During the HDS reaction partially formed Ni3S2, metallic Ni and Ni3B were observed. The activity of the catalyst was mainly attributed to the presence of Ni and Ni3B phases. In the absent of N-compound the main product was the 3-(3′-methylcyclohexyl)-toluene (MCHT) – formed via hydrogenation route (HYD route). At lower contribution of direct desulfurization route (DDS route), products like 3,3′-dimethylbiphenyl (3,3′-DMBPh) were also formed, but no fully hydrogenated product (3,3′-dimethylbicyclohexyl) was observed. In the presence of carbazole the distribution of HDS products was the same, but the activity was lower due to the HDN competition reaction. Based on these results and after calculated kinetics, it can be assumed that the rate of HDS of the 4,6-DMDBT, catalyzed by NiB alloy, is a first order reaction with respect to the substrate concentration for alone process of HDS, while for the same catalyst in case of simultaneous HDS/HDN reactions, this rate is independent of the 4,6-DMDBT concentration (zero-order) in the range of contact times studied.

A quantum chemical study on the molecular interaction between pyrrole and ionic liquids

Requirement to produce Ultra Low Sulphur Diesel is becoming more stringent with the target of zero emission. The presence of nitrogen compound in crude oil is undesirable because it inhibits the efficiency of desulphurisation process besides being environmentally hazardous when found in transportation fuels. Extractive denitrification with ionic liquids (ILs) as solvents has been found to be applicable for denitrification but more insights are required to explain the interaction between ILs and nitrogen compounds. In this study, the interaction between pyrrole as model nitrogen compound with 18 ILs built from 6 cations and 3 anions is investigated by means of quantum chemical calculation. Geometry optimisation was done for individual molecules of pyrrole, cations and anions, as well as complexes of ILs, pyrrole–cation, pyrrole–anion, pyrrole–IL at Hartree–Fock level and 6-31G* basis set. NBO analysis was performed from the optimised geometry for each molecule and complex. The interaction between pyrrole and ILs is investigated via HOMO and LUMO energy values and gaps, global scalar properties, interaction energies and partial charges. It was found that [EPY][EtSO4] is the most favourable IL for the removal of pyrrole.

Influence of Pyrrole Concentration on Cracking Activity of n-hexane in a Performance FCC Catalyst and Additives

To enhance the refinery margins there is always pressure to process different types of crude containing nitrogen and sulfur. Nitrogenous and sulfur compounds have adverse effects on the performance of catalytic processes. Studies on the effect of sulfur on catalyst and their removal through catalytic treatment have been reported. Whereas systematic study on the performance of FCC catalysts and additives in presence of nitrogenous compounds is not well understood. This topic deals with studies on effect of model nitrogen compounds like pyrrole (non-basic) on the performance of fluid catalytic cracking catalyst and additives. And we have also study the effect of concentration of nitrogen compounds on cracking activity of n-hexane and VGO, the reasons for the deactivation of the catalysts seems to be due to deactivation of active sites by the strong adsorption of nitrogen compounds Alkali-treated ZSM-5 zeolites produce higher yields of light olefins compared to either untreated zeolites or alkali-treatment introduces mesopores to the zeolites and improves their catalytic cracking ability.

Inorganic Nitrogen Compounds in Water Mains in Northern Poland and Their Implication for Health Risk

AbstractThe presence of nitrogen compounds significantly affects the quality of water intended for human consumption. The maximum contaminant level (MCL) of nitrogen in potable water in Poland was set up as follows: NO2−–0.5 and NO3––50 mg/L, NH4+–0.50 mg/L. For this reason, the objective of the study was to monitor the chemical composition of water as a priority basis for the water quality information system to provide consumers with water that meets the appropriate health and quality standards. The results of a multiyear study (1992–2003) carried out in four regions and at 12 monitoring sites in northern Poland showed NO2− and NO3− levels significantly below MCL limits. Low nitrate concentrations in water drawn from Quaternary water-bearing horizons indicate the absence of point sources of pollution. Ammonia levels exceeded MCL values at every monitoring site. Supernormal ammonia concentrations in raw water are indicative of the natural origin of ammonia ions. They are correlated with the depth of the...

Elimination of the negative effect of nitrogen compounds by CO2–water in the hydrocracking of anthracene

Development of green and efficient methods to eliminate the negative effect of the nitrogen compounds in the hydrocracking of heavy oils is of great importance, and model compounds (e.g. anthracene) are often used to get the related chemical knowledge. In this work, we studied the effect of CO2 and/or water on the hydrocracking of anthracene catalyzed by NiFe + HZSM-5 in the presence of nitrogen compounds. Using 2-methylimidazole as the nitrogen compound, the influences of different factors, such as the amount of water, amount of the nitrogen compound, and the Si/Al molar ratio of HZSM-5 on the reaction were investigated. It was demonstrated that without water and CO2 the nitrogen compound had significant negative effect on the hydrocracking by poisoning the catalyst. Water or CO2 could reduce the negative effect to a considerable degree. Interestingly, CO2–water mixture could eliminate the negative effect completely, and the yields of the products could be even higher than that in the absence of the nitrogen compound. Further study indicated that some other nitrogen compounds like pyrrole, pyridine and 2-methylpyrazine also had a positive effect on the hydrocracking in the presence of CO2–water mixture. The reason for this phenomenon was discussed.

Inhibition of δ-aminolevulinic acid dehydratase activity by cadmium in excised etiolated maize leaf segments during greening

Supply of 0.1–0.5 mmol CdCl<sub>2</sub> inhibited δ-aminolevulinic acid dehydratase (EC 4.2.1.24, ALAD) activity and total chlorophylls in excised etiolated segments of maize leaves during greening. Due to cadmium supply δ-aminolevulinic acid (ALA) content was reduced significantly at 0.5 mmol Cd only. Also the Cd treatment decreased the protein content and accumulated significantly the Cd in the tissue. Significant correlation between Cd accumulation in the leaves and various parameters measured is observed, with the R-squared values being 0.727 with ALAD activity, 0.885 with ALA content, 0.902 with total chlorophylls and 1.00 with proteins. The % inhibition of ALAD activity by Cd was decreased in the presence of nitrogenous compounds, glutamine and NH<sub>4</sub>NO<sub>3</sub> and the observed inhibition was 25% and 16%, respectively. More substantial reduction in % inhibition of enzyme activity by Cd was observed during treatment with glutathione, a ubiquitous thiol and levulinic acid, a competitive inhibitor of ALAD, with the inhibition being only 2% and 4%, respectively. Supply of some essential metal ions, such as Mg, Zn, and Mn, also reduced the % inhibition of enzyme activity by Cd. Inclusion of varying concentrations of ALA during assay also affected the % inhibition of enzyme activity by Cd showing an increased inhibition from 17% to 53% with increasing ALA concentration. It is suggested that Cd inhibits ALAD activity by affecting the ALA binding to the enzyme and/or disrupting thiol interaction.

Soluble, semivolatile phenol and nitrogen compounds in milk-processing wastewaters

Potable water is an essential and major input in processing our food supplies, and the continued growth in food manufacturing is placing increased pressure on this limited resource. Recycling and reuse of factory wastewater can lessen potable water use but requires a detailed understanding of wastewater properties. This study uses solid-phase extraction techniques with gas chromatography-mass spectrometry analysis to investigate trace-level semivolatile organic species in various waste and reference waters associated with the Burra Foods milk-processing plant located in Southeastern Australia. Our focus was on contaminants containing phenolic and heterocyclic nitrogen functional groups, which, because of their toxicity and persistence, may limit options for water recycling and reuse. Effluent from the wastewater treatment plant of the factory showed both the highest soluble carbon burden (47 mg/kg) and concentrations of target compounds. The target species found in these effluents included methyl phenol (13 mg/kg), hydroxy indole (9.8 mg/kg), synthetic tolyltriazoles (5.1 mg/kg) and alkyl phenol ethoxylates (0.2 mg/kg). Given the environmental stability of the tolyltriazoles, they may act as chemical markers where these effluents are used for purposes such as irrigation. Milk evaporator condensate waters, in contrast to the effluent, contained very few target species, with only low levels of pyrrolidine and piperidine derivatives such as ethylglutarimide (450 μg/L) detected. Although there were fewer target microcontaminants overall in the potable and creek reference waters, these samples had characteristic profiles. The potable water analysis revealed hydroxy cineole (2.1 μg/L) and the creek analysis revealed dichlorohydroxyacetophenone (0.3 μg/L), which were not detected in other waters. The compounds found in the wastewaters are likely to have been derived from milk or synthetic chemicals used in factory operations. The presence of nitrogen compounds in all the different milk-processing waters suggest their likely source was milk, probably milk phosphoproteins subjected to thermal, chemical, or microbial degradation. Our benign results for the condensates suggest it may be possible to substitute condensate for potable water with minimal pretreatment, both within the plant and in other applications, such as irrigation of recreation turf.

Study of Asphaltenes Adsorption on Metallic Surface Using XPS and TOF-SIMS

X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectroscopy (ToF-SIMS) were used to characterize an adsorbed layer of four different asphaltenes on a stainless steel surface. Surface composition indicated different atomic concentrations of C, S, N, and O with similar chemical nature of their functional group as aromatic and aliphatic hydrocarbon. The presence of nitrogen compounds as pyrrolic and pyridinic, sulfur as thiophenic and carbon as carboxylic and hydrogenated (C−O) were confirmed by both XPS high-resolution binding energies and the high sensitive ToF-SIMS analysis of the detected negative fragments of nitrogen and sulfur. Depth profiling showed a carbidic nature on surface after surface sputtering with no surface sulfur and nitrogen. The optimum sputtering rate needs to be identified to allow studying and characterizing the asphaltene metallic interface.

Adsorption structures of heterocyclic nitrogen compounds over Cu(I)Y zeolite: A first principle study on mechanism of the denitrogenation and the effect of nitrogen compounds on adsorptive desulfurization

The adsorption configurations of quinoline, acridine, indole and carbazole over Cu(I)Y zeolite were studied by the density functional theory (DFT) method. The η 2 adsorption mode has been found to be energetically preferred for neutral nitrogen compounds, i.e. indole and carbazole; while for basic ones, quinoline and acridine, the η 1N adsorption mode is the most preferential one, implying that in the competitive adsorption aromatics show a strong preference over neutral nitrogen compounds than over basic ones. The adsorption energies of the adsorbate over Cu(I)Y zeolite decrease as follows: basic heterocyclic nitrogen compounds > neutral heterocyclic nitrogen compounds > thiophenic compounds, suggesting that deep denitrogenation and desulfurization could be carried out simultaneously over Cu(I)Y zeolite under ambient temperature, while for Cu(I)Y zeolite the adsorption of nitrogen compounds is preferable to that of sulfur compounds, and good selectivity will be shown for the basic nitrogen compounds during denitrogenation. Meanwhile, when the adsorbent is used for selective deep desulfurization, the presence of nitrogen compounds can greatly retard sulfur removal.

The ignition, combustion and flame structure of carbon monoxide/hydrogen mixtures. Note 2: Fluid dynamics and kinetic aspects of syngas combustion

The kinetic characterization of the H 2/CO system in presence of nitrogen components was systematically revised in the first note of this work [Frassoldati A, Faravelli T, Ranzi E. The ignition, combustion and flame structure of carbon monoxide/hydrogen mixtures. Note 1: detailed kinetic modeling of syngas combustion also in presence of nitrogen compounds. Int J Hydrogen Energy; 2007, in press]. This second note analyses three different turbulent non-premixed syngas flames by using different approaches such as the Eddy dissipation (ED) the Eddy dissipation concept (EDC) and steady laminar flamelets (SLF) model. Detailed kinetic schemes are too large and computationally expensive to be directly applied to CFD codes. Pollutants marginally affect the main combustion process and consequently it is feasible to post-process the CFD results with large detailed kinetic schemes, capable of accurately predicting the formation of pollutants, such as NO x , CO, PAH and soot. Thus, in order to predict NO x formation in these flames, a detailed kinetic scheme is applied by means of a newly conceived numerical tool: the kinetic post-processor (KPP). The successful prediction of flame structures and NO x formation supports the proposed approach and makes the KPP code a useful tool for optimizing the design of new burners.