Interfacial Tailoring of Polyether Sulfone-Modified Silica Mixed Matrix Membranes for CO2 Separation

In this work, in situ polymerization of modified sol-gel silica in a polyether sulfone matrix is presented to control the interfacial defects in organic-inorganic composite membranes. Polyether sulfone polymer and modified silica are used as organic and inorganic components of mixed matrix membranes (MMM). The membranes were prepared with different loadings (2, 4, 6, and 8 wt.%) of modified and unmodified silica. The synthesized membranes were characterized using Field emission electron scanning microscopy, energy dispersive X-ray, Fourier transform infrared spectroscopy, thermogravimetric analyzer, and differential scanning calorimetry. The performance of the membranes was evaluated using a permeation cell set up at a relatively higher-pressure range (5–30 bar). The membranes appear to display ideal morphology with uniform distribution of particles, defect-free structure, and absence of interfacial defects such as voids and particle accumulations. Additionally, the CO(2)/CH(4) selectivity of the membrane increased with the increase in the modified silica content. Further comparison of the performance indicates that PES/modified silica MMMs show a promising feature of commercially attractive membranes. Therefore, tailoring the interfacial morphology of the membrane results in enhanced properties and improved CO(2) separation performance

Synthesis and Purification of Carbon Nanotubes

In this chapter, we will evaluate the synthesis and purification of carbon nanotubes. Carbon nanotubes are cylindrical molecules that consists of graphene (rolled up of a single-layer carbon atom). A wide variety of synthesis techniques such as arc discharge synthesis, laser ablation of graphite/laser vaporization synthesis method, chemical vapor deposition (CVD), high pressure carbon monoxide synthesis and flame synthesis techniques, have been implemented to grow single and multi-walled carbon nanotubes for technological applications. All of the above methods exploit transition metals, like iron, cobalt, and nickel, as a catalyst. There are number of methods (filtering, chromatography and centrifugation) used to purify the carbon nanotubes, but the degree of purity remained questionable in these methods. In order to enhance the purification extent, alternate techniques such as Gas phase purification, Liquid phase purification and Purification by Intercalation are introduced. Here we will discuss the advantages and disadvantages of these purification routes. It will help researchers in selecting appropriate and effective method for synthesis and purification of carbon nanotubes

Sodium alginate-f-GO composite hydrogels for tissue regeneration and antitumor applications

Biopolymer-based composite hydrogels have attracted tremendous attention for tissue regeneration and antitumor applications. Since sodium alginate is a biopolymer, they offer excellent therapeutic options with long-term drug release and low side effects. To prepare multifunctional composite hydrogels with anticancer and tissue regeneration capabilities, sodium alginate (SA) and graphene oxide (GO) were covalently linked and crosslinked with tetraethyl orthosilicate (TEOS) by the solvothermal method. The structural and morphological results show that the hydrogels exhibit the desired functionality and porosity. The swelling of hydrogels in an aqueous and PBS medium was investigated. SGT-4 had the highest swelling in both aqueous and PBS media. Swelling and biodegradation of the hydrogel were inversely related. The drug release of SGT-4 was determined in different pH media (pH 6.4, 7.4, and 8.4) and the kinetics of drug release was determined according to the Higuchi model (R2 = 0.93587). Antibacterial activities were evaluated against severe infectious agents. Uppsala (U87) and osteoblast (MC3T3-E1) cell lines were used to determine the anticancer and biocompatibility of the composite hydrogels, respectively. These results suggest that the composite hydrogels could be used as potential biomaterials for tissue regeneration and antitumor applications

DEVELOPMENT OF POLYMER BLEND MEMBRANE FOR GAS SEPARATION

The main objective of this work is to study the effect of solvents and polymer blending on the development of polymeric blend membrane (PBM). Polysulfone (PSU) and polyethersulfone (PES) were selected as glassy polymers and polyvinyl acetate (PVAc) was chosen as rubbery polymer. Pure polymeric membranes were prepared in N-Methyl-2-pyrrolidone (NMP) and N, N-Dimethylformamide (DMF) solvents in order to evaluate the effect of casting solvent. The glassy/rubbery polymer blend membranes were prepared by blending PSU-PVAc and PES-PVAc while the glassy/glassy polymer blend membranes were prepared by blending PSU-PES. The prepared pure and PBM membranes were characterized in terms of morphology, miscibility, chemical bonding and thermal stability and tested for permeation of carbon dioxide and methane gases

DEVELOPMENT OF POLYMER BLEND MEMBRANE FOR GAS SEPARATION

The main objective of this work is to study the effect of solvents and polymer blending on the development of polymeric blend membrane (PBM). Polysulfone (PSU) and polyethersulfone (PES) were selected as glassy polymers and polyvinyl acetate (PVAc) was chosen as rubbery polymer. Pure polymeric membranes were prepared in N-Methyl-2-pyrrolidone (NMP) and N, N-Dimethylformamide (DMF) solvents in order to evaluate the effect of casting solvent. The glassy/rubbery polymer blend membranes were prepared by blending PSU-PVAc and PES-PVAc while the glassy/glassy polymer blend membranes were prepared by blending PSU-PES. The prepared pure and PBM membranes were characterized in terms of morphology, miscibility, chemical bonding and thermal stability and tested for permeation of carbon dioxide and methane gases

DEVELOPMENT OF IONIC LIQUID NANOCOMPOSITE MEMBRANES (ILNCMS) FOR CO2/CH4 SEPARATION

Membrane technology has a potential to be used for CO2-rich offshore applications. However, mixed matrix membranes suffer from both interfacial defects and permeability-selectivity tradeoff

Fischer-Tropsch Synthesis in a Fixed Bed Tubular Reactor using Cobalt and Iron Catalysts

Fischer-Tropsch (FT) synthesis performance of cobalt and promoted iron catalyst prepared by incipient wetness impregnation method was investigated in a fixed bed tubular reactor at 7 bar and three different temperatures (493 K, 523 K and 563 K). Syngas with a composition of CO:H2 (1:2) was used for FT studies. Liquid products and tail gases were analyzed by gas chromatography. Alpha value for each run was measured and it was found that it decreases with increase in temperature. Selectivity of both catalysts was measured and it was observed that the probability of chain growth decreases with increase in temperature. The 493 K was found to be good operating temperature for cobalt catalyst to give high selectivity of diesel range. For iron catalyst gasoline production is more favoured at 563 K and presence of carbon dioxide in tail gases showed that water gas shift (WGS) reaction is favoured at high FT temperatures. Also methane selectivity was more pronounced at 563K for both catalysts. For the given temperature range, it was observed that promoted iron catalyst was less influenced by the reaction temperature as compared to unpromoted cobalt catalyst.&nbsp

A review on coatings through thermal spraying

Ceramic-coated metals with enhanced properties such as chemical and environmental deterioration resistance and high thermal stability have previously found widespread uses in various industries. However, their application was limited due to weak bonding at the interfaces of dissimilar materials. To achieve the necessary interfaces and bonding qualities, a variety of procedures, primarily mechanical treatments, were used. Interface structure and composition, transition temperature, and wettability are important characteristics. In this review, extensive study has been carried out for several thermal spray methods, such as flame spray, electric arc spray, and plasma spray technology. The study explores microstructural elements of plasma-sprayed coatings, including bonding mechanisms, pore creation, oxides formation, and other important process parameters. The study emphasizes how crucial wetness is to coating development. It looks at what affects wetting, how interfacial reactions affect reactive wetting, and how important additives or reactive materials are to encouraging wetting. In conclusion, the authors suggest the next studies and technological developments in coating technologies and thermal spray procedures. The study contributes to the continuous advancement of these processes and their applications by pointing out opportunities for more research and development.</p