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2 Separation from Natural Gas
Published in Zeinab Abbas Jawad, 2 Sequestration and Separation, 2019
A.K. Zulhairun, N. Yusof, W.N.W. Salleh, F. Aziz, A.F. Ismail
As previously discussed for polymer-based membranes, gas separation is achieved by solution-diffusion model due to its dense structure. In contrast, gas molecules cannot penetrate the densely packed structure of inorganic materials. Around the 1940s, porous glass material comprising homogeneous pores of 20 – 40 Å in diameter was fabricated by Corning Incorporation (Pandey and Chauhan 2001). Such porous material separates gas molecules based on a sieving action; the size of the pore is smaller than the gas to be excluded while large enough to permit the permeation of the desired gas component. Since CO2 kinetic diameter is very small (3.3 Å) and there is only a small size difference with CH4 (3.8 Å), microporous molecular sieve of narrow pore size distribution has to be tailored. The following section reviews some of the most attractive microporous materials recently studied for CO2 separation such as zeolite, carbon molecular sieves, graphene, carbon nanotubes (CNTs), and Metal Organic Frameworks (MOFs).
Gas Distribution
Published in Subrata Kumar Majumder, Hydrodynamics and Mass Transfer in Downflow Slurry Bubble Columns, 2019
The porous plates are generally made of stainless steel, copper, titanium, glass and alumina as shown in Figures 2.1a and 2.2a. The plates are prepared with pore sizes ranges 1–100 µm and with a porosity range of 0.25–0.75. For uniform gas flow, highly dispersion forms above the distributor, formation of little bubbles and emulsion, by coalescence bubbles rapidly move upward. Plates are furnished in a disc shape, rectangular shape or customer specified shape. Porous glasses with pore diameters ranging from some millimetres to around 20 µm can be obtained by sintering techniques. However, conventional sintering shows some disadvantages: the production of open pores with a diameter of only a few micrometre is difficult because such small pores can easily collapse caused by the viscous flow of the glasses during sintering. Before sintering, the glass powder is mixed with a salt of melting point (e.g. tricalcium phosphate, melting point at 1730°C) above the sintering temperature (between 1000 and 1520°C) of the glass and a high solubility in a solvent, in which the glass is insoluble. During the sintering process, the salt acts as a spacer. After cooling, it is leached and in dependence on the glass to salt ratio, porous glasses with an open porosity of up to 75% can be obtained. The diameters of the open pores depend on the grain size of the salt. Pyrogenic silicic acid (AEROSIL OX50) is used as a glassy phase in the salt sintering process.
Preparation Techniques
Published in Mihir Kumar Purkait, Randeep Singh, Membrane Technology in Separation Science, 2018
Mihir Kumar Purkait, Randeep Singh
Glass membranes are nothing but porous glass. Glass is formed of two phases: one the hot acid, water, or alcohol-soluble, alkali-rich borosilicate phase; and second, the silica phase. The porous glasses are phase-separated alkali borosilicates produced by leaching of alkali-rich borate phase. The pore size of a glass membrane ranges from 0.3 to 1000 nm. The pore size of a glass membrane mainly depends upon the glass constituents, phase separation time and temperature, and leaching conditions. The porous glasses are better in terms of thermal and chemical resistance or stability, optical transparency, and better access to the active sites present inside the pores. Glass membranes, due to their better properties, can be used as gas detectors, catalyst support, and gas separation.
Purification of lipase from Burkholderia metallica fermentation broth in a column chromatography using polymer impregnated resins
Published in Preparative Biochemistry & Biotechnology, 2023
Zhang Jin Ng, Sahar Abbasiliasi, Tam Yew Joon, Hui Suan Ng, Pongsathon Phapugrangkul, Joo Shun Tan
The effect of the binding solution’s flow rate on PF and yield (%) of purified lipase is presented in Figure 3. The highest concentration of lipase adsorbed to the impregnated porous glass beads was obtained at 1.0 mL/min. There was a decrease in lipase adsorption onto the impregnated porous glass beads when the flow rate of the mobile phase increased. The PF decreased from 2.8 to 1.67 with the increase in flow rate from 1.0 to 2.5 mL/min, respectively. The yield of lipase also decreased from 80% to 53%. This situation could be due to the inadequate contact time between the lipase molecules and the impregnated porous glass beads at a higher flow rate. In this respect, at a lower flow rate, the contact time is much higher. Thus, lipase molecules have more time to go through interconnected pores, diffuse to the pore walls of the beads, and bind to the PEG-impregnated glass beads, all of which lead to a better adsorption capacity.[23] The optimal flow rate was 1.0 mL/min, which was used for the rest of the study.
Highly selective sol-gel derived optical sensor using 2,6-dichlorophenolindophenol for the sensitive determination of aqueous iron(III)
Published in Instrumentation Science & Technology, 2023
Abdollah Yari, A. Shiravandi, S. Moradi
The sol-gel method has many applications in chemical and industrial fields. This approach is used to trap indicators in a glass matrix to produce sensitive, flexible, and selective optical sensors. Sol-gel membranes are physically controllable and mechanically stable. In addition, they are optically transparent, do not have adverse chemical reactions, and show high compatibility.[3,6–8] In the sol-gel process, a hydrolyzed metal alkoxide and a solvent are homogeneously mixed to produce a sol in which cross-linking of the particles leads to the formation of a gel that is dried to form a three-dimensional porous glass. Since all steps of the sol-gel process are performed at ambient temperature, this becomes an effective alternative to fabricating optical sensors with indicators that are temperature sensitive.[9–12]
Changes in the composition of heavy oil during thermolysis in the presence of molten sodium without hydrogen
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2022
Igor P. Kosachev, Dmitry N. Borisov, Dmitry V. Milordov, Nikolay A. Mironov, Svetlana G. Yakubova, Makhmut R. Yakubov, Airat I. Shamsullin, Tagir S. Aynullov
The composition and properties of the initial oil and its thermolysis products were analyzed. The density and kinematic viscosity were determined. The gas fraction was determined according to the weight difference of heavy oil before and after thermolysis. Coke was separated via filtration through the porous glass filter Schott. The precipitate was transferred to a flask, washed with isopropyl alcohol to remove sodium residues and, then, hydrochloric acid. The latter procedure was aimed at the qualitative determination of sodium sulfide, whose reaction with acids gives hydrogen sulfide. Hydrogen sulfide was detected both organoleptically according to rotten-egg odor and by the darkening of the filter paper soaked by lead (II) acetate solution according to the following reaction: