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Determinative Techniques to Measure Organics and Inorganics
Published in Paul R. Loconto, Trace Environmental Quantitative Analysis, 2020
A block diagram for the GC-AED is depicted in Figure 4.48. This schematic should convey the impression that operating the instrument properly requires a number of compressed gas sources. Note that the 6890 GC pneumatically controls the reagent gas pressure and flow rates via Agilent Technologies’ electronic pressure control (EPC). In the author’s experience, helium carrier gas and nitrogen purge gas are the two most frequently replaced compressed gases in practice. A N2 Dewar is the only practical source (short of a nitrogen generator) to use as the source for the N2 purge. Figure 4.49 depicts the relationships between the AED cavity that incorporates a WCOT column interfaced to a capillary discharge tube, the plasma itself, and the exit through a conical aperture through an optical lens and into the monochromator, where a fixed photodiode array with the established atomic emission wavelengths for the various elements is shown that scans from 690 down to 171 nm. This fixed photodiode array for the newer model stands in contrast to the earlier model design, whereby the grating was fixed and the array moved. It is important in practice to maintain a cavity pressure of ~1.5 psi, which leads to a stable plasma. Indeed, theMIP is quite stable, and this leads to a very stable AED in practice and, subsequently, a stable baseline in the chromatogram.
Gas Migration, Emissions and Safety Aspects
Published in T. H. Christensen, R. Cossu, R. Stegmann, Landfilling of Waste: Biogas, 2020
T. H. Christensen, R. Cossu, R. Stegmann
In the event of a combustion equipment malfunction or downtime due to maintenance, a number of operating modes are available, which should enable safety coverage of the site. These operating modes include: normal - landfill gas in, inert gas out;extraction only - both injector and collector mains under suction;external inert gas inlet (nitrogen generator or storage tank);standby and duty blowers operational.
Membrane Technology
Published in Shintaro Furusaki, John Garside, L.S. Fan, The Expanding World of Chemical Engineering, 2019
One of the applications of oxygen/nitrogen separation is to produce oxygen-enriched gas that is used in the medical field as a heart-lung oxygenator. In this application, relatively small-size gas separation modules are needed. Oxygen enriched gas is also used in a furnace to improve combustion. Injection of oxygen-enriched air, containing 25 to 35% oxygen, into a furnace leads to a higher flame temperature. Energy saving of 24 to 26% can be expected. Usually, membranes are preferentially permeable to oxygen gas, and nitrogen gas is concentrated in the feed stream. Nitrogen gas also finds applications in various sectors of the chemical process industries. For example, nitrogen is used as an inert purge gas in many processes throughout the chemical industry and is used also in the synthetic natural gas industry. Nitrogen can also be used for the purpose of enhanced oil recovery, instead of CO2. A nitrogen blanket is an effective method of preserving fruits and vegetables, in which nitrogen-enriched air can be used. Figure 15.9 shows a compact nitrogen generator.
Research on a Spontaneous Combustion Prevention System in Deep Mine: A Case Study of Dongtan Coal Mine
Published in Combustion Science and Technology, 2022
Biao Kong, Jiahui Li, Wei Lu, Wei Fu, Haizhou Song, Jifan Liu
According to the characteristics of the small space fire area, inert gas and water-based foam are used to prevent and control the fire area. For the fire extinguishing method, DT Coal Mine used PSA97–600 pressure swing adsorption nitrogen generator and MYQ-1500 liquid inert gas fire extinguishing system (Hou, Zhao, and Zhao 2020), and used underground mobile membrane separation nitrogen generator to successfully extinguish 14,307 fully mechanized mining face, 4308 West track along the channel fire area (Qin and Chen 2003), in the DT Coal Mine 14,308 West track along the channel fire area, the use of inert foam to block the air leakage, and achieved a good fire prevention effect. Subsequent fires occurred in gobs 1305 and 1306, after injection of CO2 and N2, the CO concentration continued to drop to 20~25 ppm, which reduced the O2 concentration in the high-temperature fire area, thereby reducing the secondary re-ignition of coal. The possibility of controlling the fire (Fu, Lu, and Feng 2013). The successful fire extinguishing in the field application shown that the injection of inert gas and water-based foam can effectively prevent and control the fire in the goaf and improve the efficiency of fire prevention and extinguishing.
Removal of copper (II) ions by eco-friendly raw eggshells and nano-sized eggshells: a comparative study
Published in Chemical Engineering Communications, 2022
Somaia G. Mohammad, Sahar M. Ahmed, Mayyada M. H. El-Sayed
Batch contact experiments were conducted using a fixed adsorbent dose of 0.5 g/100 mL, at different pHs (2–6), and initial copper concentrations (5–60 mg/L) and for several contact times (5–120 min). A 100 mL of copper solution was placed in a 250-mL Erlenmeyer flask and 0.5 g of the adsorbent were added to it, then it was left to shake at an agitation speed of 200 rpm. After adsorption, the solution was centrifuged for 5 min at 4000 rpm, then the supernatant was filtered through a membrane filter of 0.45 µm. The concentrations of copper ions in the solutions were determined using Agilent Microwave Plasma with Atomic Emission Spectrometry 4200 (MP-AES) having nitrogen gas plasma supplied with an Agilent 4107 nitrogen generator. The operating conditions for the instrument were as follows: pump rate: 15 rpm, sample uptake time: 15 s, wavelength: 324.75 nm, rinse time: 30 s, and stabilization time: 15 s. Samples were measured in triplicates.
Preparation and characterization of hydroxyapatite from Achatina achatina snail shells: effect of carbonate substitution and trace elements on defluoridation of water
Published in Journal of Asian Ceramic Societies, 2018
Bernard Owusu Asimeng, Joseph Richmond Fianko, Elsie Effah Kaufmann, Elvis Kwason Tiburu, Claude Fiifi Hayford, Prince Atsu Anani, Obed Korshie Dzikunu
Dionex ICS-90 IC was used to determine the concentration of the fluoride (F−). The IC is controlled by Chromeleon chromatography software v. 6.8 and Peak nitrogen generator. The IC performs isocratic ion analyses using suppressed conductivity detector, liquid eluent, a high-pressure pump, a sample injector AS14A-5 separator column, AG14A guard column, and Anion microMembrane Suppressor (AMMA 111). Supernatants were filtered using Sartorius polycarbonate filtering and 0.45 cellulose acetate membrane filters after which 20 of filtered liquids were injected into an anion exchange column for separation. The separated anions were detected and compared with a calibration curve.