Ppm Sulfur Research Articles

Preparation and oxidative desulfurization performances of modified SBA-15 supported polyacid metal oxolates

In this study, eight composite catalysts were prepared by loading (CTAB)3H3[PW9V3O40] (active components) onto amino-functionalized mesoporous titanium silicate Ti-SBA-15(supports). In order to study the effects of different Ti contents and different active components on the catalytic performances of the catalysts, 30 %(CTAB)3H3[PW9V3O40]/NH2–Ti-SBA-X (X = 0, 25, 50, 75, 100) and X%(CTAB)3H3[PW9V3O40]/NH2–Ti-SBA-50 (X = 20, 40, 50) were obtained and characterized. The oxidative desulfurization performances of the composite catalysts were explored. It was found that catalyst 40 %(CTAB)3H3[PW9V3O40]/NH2–Ti-SBA-50 exhibits the optimal oxidative desulfurization performance. This is because the incorporation of SBA-15 with an appropriate amount of Ti (n(Si)/n(Ti) = 50) can improve the acidity and stability of mesoporous silica. The successful substitution of CTAB (n(CTAB)/n(H6PW9V3O40) = 3) in the active component can reduce the mass transfer resistance and speed up the reaction rate. 3-Aminopropyltriethyl silane (APTES) acts as a silane coupling agent to graft amino groups onto mesoporous molecular sieve SBA-15, which can enhance the interaction between heteropolyacids and carriers. Under the synergistic effect of the active component and the support, the total removal rate of the optimal catalyst with a total concentration of 1000 ppm sulfur compounds in the simulated fuel was 94.44 %. After four cycles, the total desulfurization rate of the catalyst can reach 91.28 %.

The role of microwave radiation in extractive desulfurization of real diesel fuel for green environment: an experimental and computational investigation

The process of removing sulfur compounds and aromatic compounds to produce clean fuel is an important and effective contribution to the processes of mitigating and adapting to climate change. In contrast, it is necessary to find an innovative way to remove sulfur and carcinogenic aromatic compounds because clean, low-sulfur diesel is commonly used in all countries of the world at the present time. Therefore, in this work, we have studied the effect of the microwave radiation power and the irradiation time with the use of more than one type of organic solvent; methanol, acetonitrile and ethyl acetoacetate; as an extractant and solvent to feed ratio impact on the removal of sulfur and aromatic compounds of a real diesel fuel feed which has 450 ppm sulfur content and 16 wt% aromatic Content. The results showed that the best solvent used during this work was ethyl acetoacetate. According to the results, high sulfur removal (≈ 92%) was accomplished with microwave-assisted extractive desulfurization technique under the following ideal conditions: the irradiation time is 7 min, the solvent feed ratio is 3:1 and the microwave intensity is 180 W. To reveal the mechanism of microwave-assisted extractive desulfurization via different organic solvents, a theoretical study including structural examination and interaction energy analysis on the interaction between dibenzothiophene (DBT) or dimethyl dibenzothiophene (DMDBT) and the different organic solvents was also conducted.

Synergistic Palladium Single Sites and Nanoparticles Implanted Into a Novel Zr‐Based Metal–Organic Framework via Solvent‐Free Processing for Upgrading Oxidative Desulfurization Performance

AbstractDesulfurization is a significant approach to producing clean fuel. The design of novel host–guest catalysts with multiple active sites at atomic‐ and nano‐scales, opens a new door to gain an ultrahigh synergistic performance for targeted applications. Herein, an in situ solvent‐free approach is conducted for synchronously implanting Pd single sites (PdSS) and nanoparticles (PdNP) into a novel Zr‐based metal–organic framework (Zr‐MOF). The optimal catalyst exhibits ultrahigh oxidative desulfurization (ODS) performance that can oxidize 1 000 ppm sulfur with diluted oxidant at 40 °C within 5 min. The turnover frequency of the catalyst at 40 °C reaches 774.7 h−1 which is 47.4 times higher than host Zr‐MOF and surpasses the most reported ODS catalysts. A substantial synergistic effect between PdSS and PdNP is responsible for the upgradation of ODS performance. Experimental and theoretical results indicate that PdSS in Zr‐MOF can readily absorb H2O2, and synergistically decompose H2O2 with the assistance of PdNP for accelerated generation of •OH radicals that dominates the ODS performance. This work provides a new solvent‐free way for in situ implanting synergistic catalytic sites into MOFs to upgrade their catalytic performance in targeted reactions.

One-Pot Preparation of Nitro-Functionalized Bimetallic UiO-66(Zr-Hf) with Hierarchical Porosity for Oxidative Desulfurization Performance.

Preparation of multifunctional metal-organic frameworks (MOFs) offers new opportunities to obtain ultrahigh synergistic catalytic performance for heterogeneous reactions; however, the application of a one-pot method for preparing multifunctional MOFs remains challenging. Herein, we develop a one-pot green route for synthesizing bimetallic nitro-functionalized UiO-66(Zr-Hf)-NO2 with hierarchical porosity under solvent-free conditions. The optimal UiO-66(Zr-Hf0.6)-NO2 shows an ultrahigh enhancement of oxidative desulfurization (ODS) efficiency to oxidize sulfur compounds (1000 ppm sulfur) in a model fuel at 40 °C within 12 min due to the introduction of more active Hf sites in the nodes, the increased Lewis acidity of Zr/Hf-O nodes by the electron-withdrawing NO2 group, and the enhanced diffusion rates by the mesopores. The turnover frequency (TOF) over UiO-66(Zr-Hf0.6)-NO2 at 40 or 50 °C reaches 145.3 or 217.0 h-1 that surpasses the TOF of most reported MOF-based catalysts in the ODS reaction. Quenching and electron paramagnetic resonance experiments confirm that the formed Hf-OH on the Zr/Hf-O nodes can easily decompose the oxidant (H2O2) for generating a Hf-OOH-active intermediate and dominate the ODS efficiency. This contribution provides a one-pot solvent-free avenue to synthesize multifunctional MOFs for enhancing their catalytic activities for targeted applications.

Synthesis of amorphous titanium isophthalic acid catalyst with hierarchical porosity for efficient oxidative desulfurization of model feed with minimum oxidant

Deep desulfurization is an indispensable technique for obtaining clean fuel and the preparation of novel materials for upgrading desulfurization efficiency is highly pursued. Herein, we develop a novel amorphous titanium isophthalic acid (Ti-IPA) catalyst with hierarchical porosity and highly dispersion of Ti-OH defect sites via solvothermal method. Ti-IPA is suitable for a variety of oxidant desulfurization (ODS) reaction systems due to its amphiphilic nature. The optimal Ti-IPA reveal extraordinary ODS performance for oxidizing 1000 ppm sulfur of dibenzothiophene-to-dibenzothiophene sulfone in model feed within 12 min at 40 ℃ with minimum oxidant/sulfur molar ratio of 2 (the sulfur oxidation efficiency reached 99.5 %), and the reaction time can be altered to 5 min at 50 ℃. The activity per unit mass of Ti-IPA reaches 52.2 mmol h−1g−1 at 50 ℃, outperforming all the reported Ti-based organic materials. Quenching and EPR tests indicate that Ti-IPA adopts non-free-radical ODS mechanism. Experimental and characterization results verify that the terminal OH capped on the Ti defect sites can easily react with oxidant to form peroxo-titanium intermediates, which manipulate the sulfur oxidation efficiency.

Magma recharge in persistently active basaltic–andesite systems and its geohazards implications: the case of Villarrica volcano, Chile

We report whole-rock chemistry, mineral chemistry, and volatile content from Villarrica volcano’s major recent paroxysms and background activity. Composition of the volcanic products are basalt to basaltic andesite with whole-rock SiO2 content between 50 and 56 wt%, and a mineralogy dominated by olivine (Fo71-80), clinopyroxene (Mg# ~ 50) and plagioclase (An60–80). Volatile contents in melt inclusions are up to 1.5 wt% H2O, 500 ppm CO2, 1230 ppm sulfur and 580 ppm chlorine. Regardless of the type of activity, there are no substantial variations in whole-rock composition or the volatile content when the activity switches from background activity to a major paroxysm, strongly suggesting that this shift does not just depend on the arrival of new magma in the shallow magmatic system. Geothermobarometry constrains crystallization of the major mineral phases at various depths between 3 and 12.7 km, suggesting that degassing of a volatile-rich recharge magma occurs deeper than 12 km, producing efficient mixing throughout the whole system, and sustaining the lava lake activity in Villarrica’s summit crater. The occurrence of a permanent lava lake also suggests that the magma recharge must be close to continuous and therefore sudden changes between background and paroxysmal volcanic activity are likely controlled by relatively small changes in the rate of recharge and/or the volatile release rate in the magmatic system. This has important implications for the understanding of eruption triggers and the forecasting of volcanic eruptions.Graphical abstract

Sulfide Inclusions in an Al‐Killed Nonoriented Electrical Steel with Lanthanum Addition

Herein, laboratory experiments are conducted to evaluate the effect of sulfur and lanthanum content in the steel on the modification of inclusions. The amount, composition, morphology, and size of nonmetallic inclusions in the steel are observed using an automatic scanning electron microscope. Results show that as the lanthanum content in the steel increased from 0 to 72 ppm, the inclusions in the steel with 12 ppm sulfur are modified in the following order: Al2O3–CaO–MgO → LaAlO3 → LaAlO3–La2O2S → La2O2S. Similarly, when the sulfur content is 27 ppm, inclusions transformed in the order of Al2O3–CaO–MgO → LaAlO3 → LaAlO3–La2O2S → La2O2S → La2O2S–LaxS → LaxS as the lanthanum content increases from 0 to 150 ppm. Thermodynamic analysis using FactSage based on a private database is employed to reveal the mechanism for the modification of inclusions. Additionally, a kinetic model is established to study the transformation rate of inclusions in the steel after the addition of lanthanum and sulfur. Liquid Al2O3–CaO–MgO inclusions disappear after 800 s when the steel contains 12 ppm sulfur and 12 ppm lanthanum. The composition of inclusions is 53%LaAlO3–47%La2O2S at 1800 s, while it is 100%La2O2S and 80%La2O2S–18%LaxS–2%CaS when the lanthanum content is 33 and 72 ppm, respectively.

Promotion of Rh-based La2Zr2O7 type catalysts with the transition metals to improve sulfur-tolerance in diesel reforming

Several Rh-based La2Zr2O7 type catalysts promoted by the transition metals (Mn, Fe, and Co respectively) were synthesized and used to reform n-hexadecane (a diesel surrogate) that contains 50 ppm dibenzothiophene for hydrogen production. Compared to Co-LaZrRh and Mn-LaZrRh, the Fe-LaZrRh catalyst exhibited the best hydrogen extraction capability and sulfur tolerance. This is probably due to the introduction of Fe, which not only enhances the Rh dispersion, but also facilitates the formation of electron-deficient Rh sites and the generation of oxygen vacancies. Additionally, electron-deficient Rh sites can hinder the formation of an irreversible sulfur-metal bond, thus resulting in better sulfur tolerance and thermal stability. Finally, the generated oxygen vacancies may also activate steam to form surface active oxygen species, which help remove the deposited carbon on the catalyst surface. In summary, the developed Fe-LaZrRh catalyst performed the best in the steam reforming of n-hexadecane containing 50 ppm sulfur, which deserves further exploration for future applications.

Kükürtlenmiş Kayısıların Raf Ömrünü Uzatmada Kükürtün Etkisinin Kinetik İncelenmesi

In this study, sulphurized apricots with different sulfur values were obtained from the factory in Malatya province. These apricot samples were kept at market temperature values (4, 26 and 40°C) in the package offered for sale, and their sulfur dioxide values were determined daily. As a result of the experimental periods, reduction rate and other data were determined by calculating the sulfur dioxide in the sample. Also, loss rate and kinetics of sulfur dioxide were determined from its change over time at different temperatures. From the results obtained, important findings such as shelf life of sulphurous apricots at different temperatures in the package, deterioration and effect of the sulfur dioxide value on the shelf life were obtained. According to the analysis results of apricots containing different amounts of sulfur, when the moisture and SO2 loss in dried apricot samples during their stay on the shelf were examined in the kinetic study, it was determined that it was suitable for the first order kinetic model for 4°C and the second order kinetic model for 26 and 40°C. From the experimental results, quite low sulfur removal values were obtained for the samples offered for sale after 980 hours at 4°C and 525 hours at 26°C. Moisture and SO2 losses accelerated after approximately 740 hours at a temperature of 40°C. In the sample containing 3280 ppm sulfur dioxide during shelf storage at 4°C, there was an 11% loss of sulfur dioxide after 980 hours. A 46% sulfur dioxide loss was determined in the same samples after 740 hours at 40°C. It has been determined that sulfur dioxide loss is greater at higher temperatures. When the storage conditions of the samples were examined in terms of humidity, it was observed that apricots lost their moisture in the range of 52-85% after 29 days at temperatures of 4 and 40 °C. Based on the fact that the water activity of the packaged sulfurized dried apricots offered for sale is 25%, in this study, an average shelf life of approximately 25 days was determined according to this value.

Sonochemical synthesis of heterostructured ZnO/Bi2O3 for photocatalytic desulfurization

In this study, metal oxides nanoparticles heterogeneous photocatalysts prepared by coprecipitation and ultrasonic techniques were used for diesel desulfurization. They were characterized by scanning electron microscope, powder X-ray diffraction, energy dispersive analysis, diffused reflectance spectra, photoluminescence analysis and BET surface area. The surface area of catalyst B is larger than catalyst A confirming its higher reactivity. X-ray reflectance spectroscopy was used to analyze the sulfur contents in feed. Thiophene was used as a model fuel to evaluate the photocatalytic activity of catalysts A and B. Using the Scherrer equation, sharp and intense signals suggesting their higher degrees of crystallinity, with average crystal sizes for ZnO, Bi2O3, catalysts A and B, respectively; of 18, 14.3, 29.7, and 23.8 nm. The operational parameters of the desulfurization process were optimized and have been studied and the maximum sulfur removal was achieved via a further solvent extraction step. A diesel fuel with a 24 and 19 ppm sulfur content and hence a total sulfur removal of 94.6% and 95.7% was acquired for catalysts A and B, respectively (sulfur compounds concentration in diesel fuel feedstock was 450 ppm). These findings demonstrated that photocatalysts A and B are good and effective catalysts for desulfurization of diesel fuel.

Upgrading the oxidative desulfurization performance of metal-organic frameworks with proton stimulation

The modification of metal-organic frameworks (MOFs) to achieve desirable performance is attracting extensive investigation in heterogeneous catalysis, however, exploring the potential peculiarity of pristine MOFs for targeted applications is often overlooked. In this work, we developed an efficient approach for upgrading the oxidative desulfurization (ODS) performance of Zr-MOFs with proton stimulation. The ODS performance of pristine Zr-MOFs prepared under solvothermal conditions was commonly very poor at ambient temperature but could be activated when protons were introduced. Moreover, the upgradation of ODS efficiency by protons exhibited a sharply increasing trend (from 0.05 to 17.5 mmol g−1 h−1) with the increased density of defects in Zr-MOFs. The most defective UiO-66(Zr) showed ultrahigh activity in model oil which removed 1000 ppm sulfur after 25 min at 30 °C or after 4 min at 50 °C upon proton stimulation that is better than the sample pre-treated with 1 M HCl, and in multicomponent model oil which removed 972 ppm sulfur after 20 min at 50 °C in the present of proton. The turnover frequency (TOF) could reach 211.6 h−1 at 50 °C, surpassing the most investigated ODS catalysts. Quenching experiments and EPR tests demonstrated that the reaction pathway of UiO-66(Zr) could be altered by protons from free radical (OH• and O2•-) into non-free-radical (Zr–OOH) that manipulate the sulfur removal efficiency. Experimental results indicated that the terminal Zr–OH/OH2 sites could decompose H2O2 with assistance of H+ to form Zr–OOH, which probably accounts for the enhancement of ODS activity. Our work reveals a facile and efficient strategy for upgrading the ODS performance of pristine MOFs.

Adsorption-catalytic method for reducing the content of sulphur compounds in gas condensate diesel fuel

Gas condensate diesel fuels, being an excellent resource base, often do not meet modern standards of the cetane number value and the content of sulfur compounds (SC). Currently, Euro 5 and Euro 6 (<10 ppm sulfur content) diesel motor fuels are produced worldwide. High-quality diesel fuels are produced using hydro desulfurization process. Analysis of scientific publications has shown that the adsorption is effective method of desulphurization, which can serve as a method of removing SC from fuels or refining oil and its fractions, which allows removing residual sulfur. The advantages of the adsorption method are: low level of capital costs; simplicity of equipment; carrying out the process under much milder conditions compared to hydro desulfurization. In this paper, an original adsorption-catalytic method of reducing the concentration of SC to <10 ppm using a nanoporous adsorbent-catalyst is proposed. The structure and content of complex sulfur compounds in gas condensate fuels obtained from the raw materials of two deposits – Yamburgsky and Zapolyarny – were determined by gas chromatography–mass spectrometry. The next SC substances were found: tert-hexadecanethiol (C16H34S); 4,4,6-trimethyl-5-phenyl-1,3-oxazinane-2-thione (C13H17NOS); 1,2-bis(2-methylundecan-2-yl)-disulfane (C24H50S2); 3-methyl-2,4a,9,9a-tetrahydro-1H-2λ4-indeno [2,1-c]thiopyran-2-carbonitrile (C14H15NS) and 2,3,4,5-pentamethylbenzene-sulfoneamide (C11H17NO2S). Three-dimensional images of SC molecules and their adsorption complexes with Al-Ni-Mo-O component of a complex adsorbent-catalyst were obtained by molecular modeling. The adsorption energies of SC on the Al-Ni-Mo-O catalyst are calculated. The obtained values of the adsorption energies are in the range of −99.17 ÷−231.66 kJ/mol. As a result of the conducted research, a cartridge with selected adsorbent catalysts has been developed, which must be activated by heating in an inert medium up to 350 ° C. The average life of the cartridge is 1.5 years, after which it needs restoration.

Adsorptive desulphurization of fuels by hypercrosslinked nanoporous polymers derived from polycyclic aromatic hydrocarbons

A sustainable method is employed to remove polycyclic aromatic sulphur heterocycles (PASHs) from fuels by using a series of high surface area nanoporous adsorbents synthesized from polycyclic aromatic hydrocarbons (PAHs). The hypercrosslinking of PAHs has been used to synthesize high surface area (SABET of 620–1565 m2 g−1) nanoporous polymeric materials via a microwave assisted method. The adsorbent poly-naph (highest SABET, i.e., 1565 m2 g−1) display best performance for desulphurization of fuels from batch to fixed bed column mode. In batch mode, the adsorption capacity of 12.1 (up to 9 ppm sulphur) and 8.9 mgS g−1 (up to 43 ppm sulphur), has been estimated for model (100 ppm sulphur) and real fuels (110 ppm sulphur), respectively. Furthermore, from ultra-low sulphur model (10 ppm sulphur) and real fuel (9 ppm sulphur), the adsorption capacity of 16.1 (up to 0.3 ppm sulphur) and 10 mgS g−1 (up to 3 ppm sulphur) has been estimated. In fixed-bed column mode, the high concentrated model and real fuel have been desulphurized to final concentration of 1 and 12 ppm, respectively. While, at low concentrations, the final concentration of 100 ppb and 1 ppm is achieved for model and real fuels, respectively. The adsorption mechanism revealed that π-electron density in the polymeric framework plays prominent role in the adsorption process apart from high surface area. This approach to control carcinogenic aromatic pollutants like PAHs and PASHs can be sustained over time through technological advancement, financial assistance and governmental regulation.

Effect of Microchemistry Elements in Relation of Laser Welding Parameters on the Morphology 304 Stainless Steel Welds Using Response Surface Methodology

Small differences in the contents of surface active elements can change flow direction and thus heat transfer, even for different batches of a given alloy. This study aims to determine the effects of sulfur on weld bead morphology in the laser process. The paper presents the results related to the weld bead shape of two thin AISI 304 industrial stainless steel casts. One cast contains 80 ppm (0.008%) of sulfur, considered as a high sulfur content, and the other one contains 30 ppm (0.003%) sulfur, which can be considered low sulfur. The welds were executed using a CO2 laser. The effects of laser power (3.75, 3.67, 6 kW), welding speed (1.25, 2.40, 2.45, 3.6 m/min), focus point position (2, 7, 12 mm), and shield gas (Helium, mixed 40% helium + 60% argon and mixed 70% helium + 30% argon) with a flow rate of 10 L/min on the depth of the weld (D) and the aspect ratio (R = D/W) were investigated using RSM (response surface methodology). The experimental results show that the transfer of energy from the laser beam to the workpiece can be total in cases where the selected welding parameters prevent plasma formation. For the 304 HS cast, the focus point is the major factor in determining the depth of penetration, and its contribution is up to 52.35%. However, for 304 LS, the interaction between shield gas and focus point seems to play an important role, and the contribution of their interaction raises to 28% in relation to the laser depth of the weld. Moreover, the study shows that sulfur plays a surface-active role only in the case of partial penetration beads, so that a 56% partially penetrated weld supports the hypothesis of its surface-active role in the formation of the weld pool. However, a penetration of only 36% confirms the effects of a sulfur surface-active when the bead is fully penetrated.

Quantification of polycyclic aromatic sulfur heterocycles in fine airborne urban particles (PM2.5) after multivariate optimization of a green procedure

Polycyclic aromatic sulfur heterocycles (PASHs), such as benzothiophenes (BT), dibenzothiophenes (DBT) and benzonapthothiophenes (BNT), can be emitted from vehicular traffic and deposited in fine particles matter (PM2.5). The presence of these compounds in PM2.5 is an environmental concern due to air pollution and its toxic properties. In this study, a green microscale solid–liquid extraction method was developed to determine twenty-three PASHs in PM2.5. A simplex-centroid mixture design was applied to optimize the extraction solvent. A full factorial design was used for preliminary evaluation of the factors that influence the extraction process (extraction time, sample size, and solvent volume) and then a Doehlert design for the significant parameters. The optimal extraction conditions based on the experimental design were: sample size, 4.15 cm2; 450 μL of toluene:dichloromethane (80:20,v/v); and extraction duration, 24 min. High sensitivity (LOD < 0.66pg m−3 and LOQ < 2.21 pg m−3) and acceptable recovery (82.8–120 %), and precision (RSD 3.6–14.0 %) were obtained. The greenness of the method was demonstrated using the Analytical GREEnness (AGREE) tool. The method was applied for analyzing PASHs in PM2.5 samples collected in three time intervals per day from years with different sulfur contents in the diesel: S-500 (≤500 ppm sulfur) and S-50 (≤50 ppm sulfur). Fourteen PASHs were quantified with the highest concentrations observed for 2,8-DMDBT and 4,6-DMDBT, which are recalcitrant compounds. The ANOVA test indicated significant differences between sampling periods during the day. The reduction of diesel S-500 to S-50 corresponded to a 28 % decrease in the total sum of PASHs (∑PASHs) evaluated. Spearman's rank correlations allowed for verifying that BTs and DBTs were highly correlated, suggesting that they were derived from similar sources. A weak correlation of 2,1-BNT and 2,3-BNT with BTs and DBTs indicates that these compounds are a chemical proxy for the emission of diesel engines during the combustion process.

Laser Weld Aspect Optimization of Thin AISI 316 SS Using RSM in Relation with Welding Parameters and Sulfur Content

A quantitative and qualitative study of the effect of laser (light amplification by stimulated emissions of radiation) welding parameters, such as focus point, welding speed, power beam and shield gas on bead profile in relation with microchemistry compositions differences of two thin AISI 316 industrial stainless steel casts have been studied. One cast contains 60 ppm (0.006%) of sulfur considered as high sulfur content and the other one contains 10 ppm (0.001 %) sulfur which can be considered as low sulfur content. A set of 27 tests were carried out by combining three welding speeds (1500, 3000, and 4500 mm/min), three shield gases (helium (He), mixture of 40% helium and 60% argon (Ar) and mixture of 70% helium and 30% argon) with flow rate of 15 L/min, and three focal lengths (+2, +7, and +12 mm). The depth, aspect ratio (the ratio between the penetration depth weld and the weld width) and the bead cross section profile are investigated using response surface methodology (RSM). Linear and quadratic polynomial models for predicting the weld bead geometry were developed. The results of the preliminary validation indicated that the proposed models predict the responses adequately. The geometry of the welded area was analyzed using optical microscopy, and correlations between weld morphology (depth, weld aspect parameter and weld area) and welding parameters were performed. For the cast 316 HS (high sulfur content), the main input factor influencing the depth weld (Yd) is the focus point with a contribution up to 19.32. On the other hand, the main input factor affecting the depth weld (Yd) of the cast 316 LS (low sulfur content) is the combination effect of focus point and power input energy with contribution up to 10.65%. Sulfur as the surfactant element contributes to determining the laser weld bead shape up to 71% when the welds are partially penetrated and diminishes to 50% when the welds are fully penetrated with the occurrence of the keyhole mechanism.

Spectral Features Differentiate Aging-Induced Changes in Parchment-A Combined Approach of UV/VIS, µ-ATR/FTIR and µ-Raman Spectroscopy with Multivariate Data Analysis.

From the moment of production, artworks are constantly exposed to changing environmental factors potentially inducing degradation. Therefore, detailed knowledge of natural degradation phenomena is essential for proper damage assessment and preservation. With special focus on written cultural heritage, we present a study on the degradation of sheep parchment employing accelerated aging with light (295-3000 nm) for one month, 30/50/80% relative humidity (RH) and 50 ppm sulfur dioxide with 30/50/80%RH for one week. UV/VIS spectroscopy detected changes in the sample surface appearance, showing browning after light-aging and increased brightness after SO2-aging. Band deconvolution of ATR/FTIR and Raman spectra and factor analysis of mixed data (FAMD) revealed characteristic changes of the main parchment components. Spectral features for degradation-induced structural changes of collagen and lipids turned out to be different for the employed aging parameters. All aging conditions induced denaturation (of different degrees) indicated by changes in the secondary structure of collagen. Light treatment resulted in the most pronounced changes for collagen fibrils in addition to backbone cleavage and side chain oxidations. Additional increased disorder for lipids was observed. Despite shorter exposure times, SO2-aging led to a weakening of protein structures induced by transitions of stabilizing disulfide bonds and side chain oxidations.

ROAD TRAFFIC INDUCED ENVIRONMENTAL AIR CONDITIONS ON STREET-ENTREPRENEURS IN AKURE-SOUTH LGA. ONDO STATE, NIGERIA

Roadside corridor serves as a major hub for street entrepreneurs to display their items and carry out their business in most African city. The major objective of this research is to be carried out roadside analysis of the surrounding air along street corridor in other to determine the amount of Carbon monoxide (CO), Sulphur dioxide (SO2), Nitrogen dioxide (NO2) and Particulate Matter (PM10) which are by-product of automobile on the street entrepreneurs on the selected street in Akure, Ondo State, Nigeria. Likewise, both Survey and experiment analysis was deployed to obtain the real state of some of the common air pollutant in the corridor of study. Results shows that these informal entrepreneurs are greatly affected by road traffic air pollutant; as 12.45% of the respondents have high nasal discharge, 12.21% of the respondents reported high throat irritation, 12.21% of the respondents cough often, 4.72% reported high level of breathlessness and 4.11% reported high asthmatic condition. While it was observed that between 13.943ppm to 3.225ppm of carbon monoxide, 0.025 ppm to 0.007 ppm sulphur dioxide, 0.071 ppm to 0.016ppm of Nitrogen dioxide and 1156.000 µg/m3 to 328.260µg/m3 of Particulate matter 10 (PM10) is generated along the corridors of study. The study recommends that entrepreneurs in the informal sectors operating along road corridors should carry out their business at least 150m away from major road traffic path to avoid over exposure to automobile generated air pollutions as this will lead to a decrease in health hazard occasioned by over-exposure.

Anhydrite solubility enhanced by CaO in silicate melts: Implications for sulfur cycling in subduction zones

The capacity of slab-derived melt in mobilizing sulfur from the slab to the mantle wedge is essential for understanding global S cycling in subduction zones of the present or ancient Earth. The promotive role of the CaO constituent in the silicate melts, provided chiefly by subducting sediments, in anhydrite dissolution in silicate melts has been noted before. Nevertheless, the dependence of SCAS, sulfur concentration in the melt at anhydrite saturation, on melt CaO concentration and the underlying dissolution mechanism have yet to be well constrained. Using a piston-cylinder apparatus, we carried out five series of phase equilibrium experiments between anhydrite and felsic melts to obtain constraints on the effect of melt CaO concentration, water concentration, temperature (T), and Ca/(Ca+Mg) ratios on SCAS at 1–3 GPa and 1050–1350 °C. Electron probe microanalyses of quenched products confirmed that the dissolved sulfur was predominantly present as SO42−. The experimental results show that SCAS increased significantly with increasing melt CaO and Ca/(Ca+Mg) ratios at a fixed degree of silicate melt polymerization (NBO/T = 0.43 ± 0.01). The SCAS also increased with increasing T and dissolved water concentration, and the effect of water was non-linear. Previous SCAS models could not capture well enough our new experimental data, therefore a new SCAS parameterization was developed using previous and our new experimental data. With our new results and model, we find that slab melts with high CaO concentration could efficiently transport S from the slab to the mantle wedge in the Archean. Slab melts in modern hot subduction zones can carry more than 1800 ppm sulfur, raising S concentration in the mantle wedge to the lower end of the observed level by metasomatism. In modern intermediate or colder subduction zones, however, slab melt is not an effective agent of sulfur transfer even at CaO concentration >10 wt%.

Boosting Catalytic Performance of MOF-808(Zr) by Direct Generation of Rich Defective Zr Nodes via a Solvent-Free Approach.

Creation of rich open metal sites (defect) on the nodes of metal-organic frameworks (MOFs) is an efficient approach to enhance their catalytic performance in heterogeneous reactions; however, direct generation of such defects remains challenging. In this contribution, we developed an in situ green route for rapid fabrication of defective MOF-808(Zr) with rich Zr-OH/OH2 sites (occupying 25% Zr coordination sites) and hierarchical porosity without the assistance of formic acid and solvent. The optimal MOF-808(Zr) not only displayed superior activity in oxidative desulfurization (ODS) for removing 1000 ppm sulfur at ambient temperature within 20 min but also could convert 3.8 mmol of benzaldehyde to (dimethoxymethyl)benzene within 90 s at 30 °C. The turnover frequencies reached 45.4 h-1 for ODS and 3451 h-1 for acetalization, outperforming the most reported MOF-based catalysts. Theoretical calculation and experimental results show that the formed Zr-OH/OH2 can react with H2O2 to generate peroxo-zirconium species, which readily oxidize the sulfur compound. Our work provides a new approach to the synthesis of defect-rich MOF-808(Zr) with the accessibility of active sites for target reactions.