Photocatalytic Degradation of Toluene and BTEX Compounds in Gas Reactor Modified by TiO2/Ti Net Nanotubes

Exposure to volatile organic compounds (VOCs), such as toluene and BTEX gas, may cause severe impacts on the environment and long-term health problems for the workers. Industry must place this issue as a priority in supporting occupational health and efforts to minimize the environmental effects. However, many industries still have not paid more attention to degrading their industrial waste containing these compounds. Several studies on VOCs degradation in liquid and aerial media were developed in line with the rapid progress of nanomaterial technology. In this work, we have successfully synthesized TiO2/Ti Net nanotubes thin film resulted from anodization of Ti plate at 25 V vs Ag pseudo-reference electrode for eight hours and physically characterized by SEM/EDX and XRD. The activity test of photocatalysis was performed to determine the TiO2/Ti Net Nanotube's performance to degrade toluene steam and BTEX standard gas. Under the optimum experimental condition, the results showed that approximately 70% of toluene and 60% of BTEX standard gas were degraded in 120 min under the optimum experimental condition. The gas reactor generated approximately 400 ppm CO2 as a byproduct.

On the Relation between the Gas-Permeability and the Pore Characteristics of Furan Sand

Furan sand is one of the most commonly used chemically bonded molding materials in foundries across the world. It consists of a furfuryl alcohol-based resin and an acid-based liquid catalyst. When the molding material comes in contact with the molten metal, it undergoes a thermal shock accompanied by a certain release of volatile gases. In order to evacuate these gases, molds and cores should have optimal gas permeability values and proper venting by design. If the volatile compounds are not appropriately evacuated, they are prone to enter the melt before the first layer of solidified metal is formed which can lead to the formation of gas-related casting defects. Standard gas permeability measurements are commercially available tools used in the industry to compare and to quality control different sands, however, they only provide reference numbers without actual units. Permeability in a standard unit, m2, provides uniformity and helps the comparison of results from difference sources. In this paper, a new method using Darcy’s law (prevalent in earth sciences), was adapted to measure the gas-permeability of furan samples made of silica sand with various grain size distributions. The effect of grain size distribution on the gas-permeability of furan sand samples was studied. Gas-permeability values in m2 were then correlated with mercury-porosity measurement results to bring new light on the relation between pore size, pore volume and the permeability of molding materials.

Applications of Vacuum Measurement Technology in China’s Space Programs

The significance of vacuum measurement technology is increasingly prominent in China’s thriving space industry. Lanzhou Institute of Physics (LIP) has been dedicated to the development of payloads and space-related vacuum technology for decades, and widely participated in China’s space programs. In this paper, we present several payloads carried on satellites, spaceships, and space stations; the methodologies of which covered the fields of total and partial pressure measurement, vacuum and pressure leak detection, and standard gas inlet technology. Then, we introduce the corresponding calibration standards developed in LIP, which guaranteed the detection precision of these payloads. This review also provides some suggestions and expectations for the future development and application of vacuum measurement technology in space exploration.

Space and laboratory observation of the deuterated cyanomethyl radical HDCCN

Our observations of TMC-1 with the Yebes 40 m radio telescope in the 31.0–50.3 GHz range allowed us to detect a group of unidentified lines, showing a complex line pattern indicative of an open-shell species. The observed frequencies of these lines and the similarity of the spectral pattern with that of the 20, 2–10, 1 rotational transition of H2CCN indicate that the lines arise from the deuterated cyanomethyl radical, HDCCN. Using Fourier transform microwave spectroscopy experiments combined with electric discharges, we succeeded in producing the radical HDCCN in the laboratory and observed its 10, 1–00, 0 and 20, 2–10, 1 rotational transitions. From our observations and assuming a rotational temperature of 5 K, we derive an abundance ratio H2CCN/HDCCN = 20 ± 4. The high abundance of the deuterated form of H2CCN is well accounted for by a standard gas-phase model, in which deuteration is driven by deuteron transfer from the H2D+ molecular ion.

Oxidation of Gaseous Elemental Mercury in Acidified Water: Evaluation of Possible Sinking Pathway of Atmospheric Gaseous Mercury in Acid Cloud, Fog, and Rain Droplets

This is the first report investigating the transformation of gaseous elemental mercury (GEM), the major form of airborne mercury, into oxidized mercury in bulk liquid, a possible sinking pathway of atmospheric GEM in clouds, fog, rain droplets and ocean spray. A 100–150 ng m−3 GEM standard gas, a 50–150 times higher concentration than the typical atmospheric concentration, was introduced into a 2.5 L rectangular glass vessel, at the bottom of which a 0.5 L uptake solution of pure water (pH 6–7), weakly acidified pure water with sulfuric or nitric acid (pH 3.2–3.6) or seawater (pH 8) was resting. The standard gas was introduced into the space above the solution in the vessel at the rate of 0.82 L min−1 and exited from the opposite end of the vessel, which was open to the room’s pressure. After exposing the solution to the gas for 0.5–4 h, a portion of the uptake solution was sampled, and the dissolved elemental mercury (Hg0aq) and dissolved oxidized mercury (Hg2+aq) in the solution were analyzed by the conventional trapping method, followed by cold vapor atomic fluorescent spectrometer measurements. The results showed that the quantities of total dissolved mercury (THgaq = Hg0aq + Hg2+aq) in the pure water and seawater were compatible, but those were slightly lower than the equilibrated Hg0aq concentrations estimated from Henry’s law, suggesting non-equilibrium throughout the whole solution. In contrast, the quantity of Hg2+aq and THgaq in the acidified pure water with sulfuric acid was significantly enhanced. Over the 4 h exposure, the THgaq concentrations were two times higher than the equilibrated Hg0aq concentration. This was due to the slow oxidation reaction of Hg0aq by the sulfuric acid in the bulk phase. Using the collision rate of GEM with the surface of the solution and the observed uptake, the estimated uptake coefficient of GEM by this uptake was (5.5 ± 1.6) × 10−6. Under the typical atmospheric concentration, this magnitude results in an atmospheric lifetime of 4970 years, negligibly small compared with other atmospheric oxidation processes.

Significant production improvement using optimization of completion and artificial lift: case studies from South-West Iran

Productivity of wells in South-West Iran has decreased due to completion and production problems in recent decades. This is a large risk against sustainable production from the fields. To allow stable production, an important measure is completion and production optimization including artificial lift methods. This was investigated using simulations validated by pilot field tests. Several case studies were considered in terms of their completion and production. Five scenarios were investigated: natural production through annulus and tubing (scenario-1 and 2), artificial gas lift production through annulus (scenario-3), through tubing using non-standard gas lift (scenario-4) and using standard gas lift (scenario-5). Scenario-1 is currently the case in most wells of the field. To find the optimal scenario and completion/production parameters, simulations of 11 wells of an oilfield in the region were carried out using nodal and sensitivity analysis. The optimized parameters include wellhead pressures (WHPs), tubing dimensions, maximum tolerable water cuts and gas oil ratios and artificial gas injection rate. Simulation results were validated by pilot field tests. In addition, appropriately selected wellhead and Christmas trees for all scenarios were depicted. Simulations confirmed by field pilot tests showed that optimization of completion and production mode and parameters can contribute largely to production improvement. The results showed that the current scenario-1 is the worst of all. However, production through tubing (scenario-2) is optimal for wells which can produce with natural reservoir pressure, with an increase of 800 STB/Day rate per well compared with scenario-1. However, for wells requiring artificial gas lift, the average production rate increase (per well) from the annulus to tubing production was 1185 STB/Day. Next, using the standard gas lift (scenario-5) was found to be the optimal mode of gas lifting and is strongly recommended. WHPs in scenario-5 were the greatest of all, whereas scenario-1 gave the lowest WHPs. The optimal tubing diameter and length were determined. The greatest maximum tolerable water cut was obtained using scenario-5, whereas the lowest was with scenario-1. The maximum tolerable GOR was around 1900 scf/STB. Changing of scenarios did not have significant effect on maximum tolerable GOR. The optimal artificial gas injection rates were found. This validated simulation work proved that completion and production optimization of mode and parameters had considerable contribution to production improvement in South-West Iran. This sequential comprehensive work can be applied in any other field or region.

Influence of chrome electroplating on fatigue strength of parts

The article is devoted to the results of studies, which have been conducted on parts with electrolytic chromium in order to determine the effect of the coating on fatigue strength of their. The work was performed in observance of standards, which are fixed in GOST RV 2840-001-2008. Samples for the tests were made from standard gas turbine engine compressor blades. We used a VEDS- 1500 electrodynamic vibration stand with an UMK-12K power amplifier to excite vibrations. It has been shown that the minimum endurance limit of 46 kgf/mm2 based on 2 ∙ 107 cycles, established on uncoated parts, didn't decrease during fatigue tests of compressor blades with an electroplated chrome layer. It should be stressed that the influence of the geometry of the chrome-plated part on the reduction of the endurance limit has been established.

Sniffing Methanol in Hand Sanitizers

The COVID-19 pandemic has increased dramatically the demand for hand sanitizers. A major concern is their adulteration with methanol that caused more than 700 fatalities in Iran and U.S.A. (since Feb. 2020). In response, the U.S. Food and Drug Administration (FDA) has restricted the methanol content in hand sanitizers to 0.063 vol% and blacklisted 194 products (as of Oct. 1, 2020). Here, we present a low-cost, handheld and smartphone-assisted device that detects methanol selectively in hand sanitizers between 0.01-100 vol% within two minutes by headspace analysis. It features a nanoporous polymer column that separates methanol from confounders by adsorption (i.e. van-der-Waals forces) rendering it selective. A chemoresistive gas sensor detects the methanol. When tested on seven pure and spiked commercial sanitizers (total 76 samples), methanol was quantified accurately, in excellent (R² = 0.99) agreement to "gold standard" gas chromatography. Most importantly, methanol quantification was hardly interfered by different sanitizer compositions (e.g. 2-propanol, ethanol, butanone, glycerin, aloe vera essence, various odorants and colorants) and gel-like viscosity while other potential contaminants (e.g. 1-propanol) were recognized as well. This device meets an urgent need for distributed and on-site methanol screening by authorities (e.g. customs, police), health product distributers and even laymen. <br>

Sniffing Methanol in Hand Sanitizers

The COVID-19 pandemic has increased dramatically the demand for hand sanitizers. A major concern is their adulteration with methanol that caused more than 700 fatalities in Iran and U.S.A. (since Feb. 2020). In response, the U.S. Food and Drug Administration (FDA) has restricted the methanol content in hand sanitizers to 0.063 vol% and blacklisted 194 products (as of Oct. 1, 2020). Here, we present a low-cost, handheld and smartphone-assisted device that detects methanol selectively in hand sanitizers between 0.01-100 vol% within two minutes by headspace analysis. It features a nanoporous polymer column that separates methanol from confounders by adsorption (i.e. van-der-Waals forces) rendering it selective. A chemoresistive gas sensor detects the methanol. When tested on seven pure and spiked commercial sanitizers (total 76 samples), methanol was quantified accurately, in excellent (R² = 0.99) agreement to "gold standard" gas chromatography. Most importantly, methanol quantification was hardly interfered by different sanitizer compositions (e.g. 2-propanol, ethanol, butanone, glycerin, aloe vera essence, various odorants and colorants) and gel-like viscosity while other potential contaminants (e.g. 1-propanol) were recognized as well. This device meets an urgent need for distributed and on-site methanol screening by authorities (e.g. customs, police), health product distributers and even laymen. <br>