Natural halloysite nanotubes (HNTs) were hybridized with metal – organic frameworks (MOFs) to prepare novel composites. MOFs were transformed into carbon by carbonization calcination, and palladium (Pd) nanoparticles were introduced to build an emerging ternary compound system for hydrogen adsorption. The hydrogen adsorption capacities of HNT-MOF composites were 0.23 and 0.24 wt%, while those of carbonized products were 0.24 and 0.27 wt% at 25 °C and 2.65 MPa, respectively. Al-based samples showed higher hydrogen adsorption capacities than Zn-based samples on account of different selectivity between metal and hydrogen and approximate porous characteristics. More pore structures are generated by the carbonization reaction from metal – organic frameworks into carbon; high specific surface area, uniform pore size, and largeporevolume benefited the hydrogen adsorption ability of composites. Moreover, it was also possible to promote hydrogen adsorption capacity by incorporating Pd. The hydrogen adsorption capacity of ternary compound, Pd-C-H3-MOFs(Al), reached 0.32 wt% at 25 °C and 2.65 MPa. Dissociation was assumed to take place on the Pd particles, then atomic and molecule hydrogen spilled over to the structure of carboxylated HNTs, MOFs, and the carbon products for enhancing the hydrogen adsorption capacity.
Fig.4 shows pore-size distribution of the prepared γ- alumina employing BJH model. It indicates relatively narrow and uniform distribution of micro and meso pores with 1–10 nanometer sizes in the sample, where related maximum peak is seen in 2.1 nm. Based on the previous researches, textural properties of materials including high specific surface area, largeporevolume and a narrow pore-size distribution in the range of 1 to 10 nm are of great interest for both adsorption and catalytic applications .
MSNs feature several advantageous properties including high surface area, largeporevolume, tunable pore size, stable frameworks, ease of surface modification and good biocompatibility that renders them suitable for drug delivery applications. Specifically, the high surface area and largeporevolume enables encapsulation of decent amounts of therapeutics; tunable pore size allows for immobilization of cargos in various sizes; the stable silica framework can protect cargos from enzymatic or chemical degradation; ease of surface modification enables the attachment of functional assemblies, e.g., targeting ligands and stimuli-responsive gatekeepers, etc.. MSNs have shown great success in the delivery of a variety of therapeutics including anti-cancer drugs, 40-44 oligonucleotides 25,32,39,44,45 and proteins 46-48 either in vitro or in vivo for disease treatment or for biological research. In addition to drug delivery, MSNs can also be used for imaging purposes 49 either at the cellular level for cell biology 34 studies or for disease diagnosis such as magnetic resonance imaging (MRI) 50-52 and positron emission tomography (PET). 53 Figure 1.7 demonstrates a multifunctional MSN model as an autonomous nanoagent for different biomedical applications. The integrated functions ideally include a porous framework for cargo loading, a gate keeper system for controlled cargo release, tracking markers for particle tracing, spacer molecules (e.g., polyethylene glycol, PEG) to enhance the solubility and biocompatibility, targeting ligands to enable a specific targeting delivery, and endosomal escape agents to trigger cargo release from trapped endosomes.
mesoporous silicas for protein analysis is a very interesting research field due to their attractive properties such as high surface area, uniform pore size, largeporevolume, controllable morphology, high thermal stability, and facile surface functionalization [21, 22]. Additionally, the shell is always chemically inert; thus, the encapsulated nanozyme could have good dispersion stability in PBS buffers or after the addition of chromogenic substrates [23, 24].
large amount mesopores, high BET surface area and largeporevolume. The electrochemical characterizations manifest that the optimal sample shows an exceptionally high specific capacitance of 1988.6, 1954.3, 1874.3, 1714.5 and 1491.4 F g -1 at discharge current densities of 1, 2, 5, 10 and 15 A g -1 , respectively, with excellent cycling stability (retain 94.0 % after 1500 cycles at 10 A g -1 ). The outstanding electrochemical performance is attributed to the desirable composition and the unique 3D hierarchical mesoporous flower-like architecture. The novel NiO-Co 3 O 4 composite could be a
Mesoporous alumina with high specific surface areas and narrow pore size distributions was synthesized for the used in the fine chemical purification, catalysts, catalyst support and adsorbents . Based on the value added property of the material, the unit price of mesoporous alumina has largely increases. For example, the mesoporous alumina absorbent for purifying liquid crystal (LC) is about 100 times higher than the unit price of alumina . Conventional γ-Al 2 O 3 , composed of a mixture of macro, meso, and micropores in irregular sizes has
granulated form, together with its binding properties, (Thoorens et al., 2014), are highly advantageous enabling manufacturing of tablets by direct compression. Furthermore, being cellulose, and thus of plant origin, its inert properties in-vivo make it an ideal material support. In MCC water can be absorbed into the inter-particle pore structure or diffuse into the cellulose inter-polymer space. The relative influence of these different physical liquid transport regimes 70
Sato et al carried out HCK reactions of diphenylmethane and tetralin over three different types of zeolites (USY, HY and mordenite) with or without NiW sulfide, to establish the roles of catalytic bifunctionality . Jessica et al prepared aluminosilicate-supported Pt-Ru for hydrogenation of toluene. When compared with their monometallic counterparts, the bimetallic catalysts displayed significantly high turnover frequencies due to the synergy between Pt and Ru. In another work involving a bimetallic catalyst system; zeolite-alumina composite supported NiMo catalyst was developed and used in hydro cracking of decalin and 1-methylnapthalene. To the best of our knowledge, no data are available on investigation of mixed oxides of Ni,Co and Mo on toluene hydrogenation reaction. There are still important questions regarding the effect of zeolite acidity, pore sizes and surface area on hydrogen insertion reactions. The role of the mixed metal oxides on the conversion and products distribution has not been categorically established. Therefore, the aim of this study was to prepare trimetallic zeolite-supported
Another way to manipulate the pore structure and the pore surface is to use mixed precursors. The attempts of using methylsilane as partial substituent for TEOS resulted in the increase of the surface area, to the significant decrease of the pore size and to the broadening of the pore size distribution. 9,10 Also, the materials stable over time toward water can be obtained due to the enhancement of the surface hydrophobicity induced by increased density of the surface methyl groups. 11 Under the acidic condition, the rate of MTES hydrolysis/polymerization
The FBP release from the FBP@MOFs showed two stages. This is related to the FBP location within the pores of MOFs, pore size, and kind of host–guest interaction. When the filled pores with FBP were located close to the surface of MOFs, FBP molecules release concerned only the weakly bonded molecules. The first stage was a fast stage of release (within 2 h), which can be regarded as zero-order kinetics because of drug concentration independence. The kinetics of FBP release from FBP@MOFs are empirically adjusted with regression factors of 0.99, 0.85, 0.77, and 0.78 for FBP@Fe-MIL-101, FBP@Fe-MIL-100, FBP@ Ca-MOF, and FBP@Fe-MIL-53, respectively, as shown in Figure S4. It can be defined to be a burst effect because of the porous structure and high solubility of FBP in PBS at pH 7.4 relating to ionization due to the acidic nature of FBP (pKa 4.6). The second stage of release can be defined as an erosion process due to the slow collapse of the MOFs in alkaline media. Frameworks collapsing in PBS are due to replacement of the carboxylate linkers by phosphate groups in the PBS solution and/or formation of iron oxide rendering less favourable formation of stable metal carboxylate bonds at pH values above the pKa of carboxylic functions ( ~ 4−5). 32
At a given wavelength InP and GaP have similar, but not identical, refractive indices. For example at a wavelength of 700 nm the refractive indices of InP and GaP are 3.48 and 3.23 respectively. The difference is relatively small, but it is still large enough to have an influence on the PBG effects of the infilled and inverted opals. The optical properties of the III-V opal composites and inverse structures gave broadly the same result (differences in overall intensity due to opal quality, shifts in position of the bands due to bare opal size and amount of infill). From the position of the Bragg stop band it is possible to estimate the extent of III-V infill within the opal. The higher the extent of infill the greater the wavelength shift from the bare opal.
Samarkand State University, 2,3 Samarkand Medical Institute Abstract. The sorption, textural, and physicochemical characteristics of bentonite and kaolin are studied. To determine the relative surface of the samples, the Brunauer-Emmett-Teller method (BET) was used, and the Barret-Joyner-Helend method (BLC) was used to determine the volume and size of pores. As a result of the research, a relationship was established between the volume of adsorbed gas and the relative pressure and pore radius. It has been established that at P/P 0 = 0-
for their role in drug delivery. The work also highlighted the use of citrate which brings with it a dual role of converting the dumb bell shaped hydroxyapatite to individual spheres and importantly a stimuli release mechanism. The reaction was done using one pot synthesis with vancomycin. In-vitro of the vancomycin was performed when 0.02g of sample in 20 ml of a media of phosphate buffer, stirring for 12h at room temperature. The group successfully prepared MHAp with a hierarchical porous structure with the thermodynamic treatment to bring with it a controlled release without burst release to make it a promising drug delivery vector. Summarized in their review about the basic idea behind the chemical design classical inorganic porous material: aerogel. The review passes through main heading of sol-gel chemistry, the structure of the gels, and the resulting properties of the light weight aerogel material. In the review, postulate of exchanging the pore liquid which is traditional method showed that it maintains the filigrane solid network. The various drying techniques such as supercritical drying and ambient pressure were elucidated. The versatility with which these aerogels can be used as aerogel films, carbon aerogels and hybrid inorganic-organic aerogels were also reported. The authors conclude that preparation of aerogels is “nanotechnology” which possesses unique optical, thermal, acoustic and mechanical properties. Ambient pressure drying brings new light in to this field as aerogels can be prepared in normal laboratory scale.
with strong adsorbability, and decomposed at high temperature. Metal oxides produced by pyrolysis are evenly loaded on the surface of activated carbon, so as to achieve the purpose of loading modification of activated carbon. However, as nitrate enters into the pore structure of activated carbon, the metal oxides produced by pyrolysis adsorb on the pore surface, which will lead to the decrease of pore size and the blockage of small pore structure. As a result, the specific surface area of activated carbon decreases, and the ability of pore structure to transport electrolyte ions decreases, resulting in the decrease of double layer capacitance of activated carbon. In order to load metal oxides on the pore structure surface of activated carbon, and reduce the influence of metal oxides on the pore structure at the same time. BNC was selected to load nickel oxide on sargassum-based activated carbon. The pyrolysis reaction of BNC at high temperature can be divided into two steps. The first step is the dehydration reaction of BNC, and the second step is the decomposition reaction of anhydrous salt. The specific reaction formula is as follows:
Dialysis is a membrane based separation process in which the concentration gradient across the membrane is the driving force resulting in a flow of material from one side of the membrane to the other. In this study membranes (Accurel, Celgard, GVHP, PM30 and PTHK) with different pore sizes were employed to characterise the transport of lithium ion in various (0.01, 0.1, 0.5, 1 and 2.5 w/v percent) initial feed concentrations via the dialysis process. This may be considered as a basis for wastewater treatment containing metal ions. The results show that low initial feed concentration causes less passage of ions through the membrane due to low driving force i.e. concentration gradient across the membrane. The investigation of the effect of membrane pore size on ion transport revealed that largepore size membranes provide less penetration of the metal ions through the membrane. These reproducible results, which are not expected, have been explained by the transport mechanism. Two types of mechanisms (extensive versus intensive) have been suggested for metal ion transport through different membranes. If the mechanism of ion transport is intensive, more ions pass through the membrane. Extensive mechanism results in lower ion transport through the membrane.
et al., 2016b; Mees et al., 2003; Behroozmand et al., 2015; Weller et al., 2015). The main aim of our paper is to integrate an electrical method in this study. Electrical conductivity and polarizability (or real and imaginary parts of electrical con- ductivity) are fundamental physical properties of porous ma- terials. The SIP method measures the low-frequency electric behavior of rocks and soil material that can be efficiently rep- resented by a complex electric conductivity (e.g., Slater and Lesmes, 2002). The electric properties of a porous material depend, to a large extent, on key parameters including the porosity, the grain and pore size distribution, the specific in- ternal surface, the tortuosity, the saturation, and the chemical composition of the pore-filling fluids. SIP is a nondestruc- tive method that can be applied to characterize the geometry of the pore system. Müller-Huber et al. (2018) proposed the integration of SIP in a combined interpretation with NMR and MIP measurements for carbonate rocks in order to use the partly complementary information of each method. The SIP method is used to explore correlations between parame- ters derived from complex conductivity spectra and specific pore space properties. We go a step further and directly com- pare the pore size distributions derived from the different methods. Procedures to derive pore size distributions from induced polarization (IP) data have been proposed only re- cently (Florsch et al., 2014; Revil et al., 2014; Niu and Zhang 2017; Zhang et al., 2017).
We propose a porosimetry-based method to characterize pores formed by carbon nanotubes (CNTs) in the CNT agglomerates for designing neat CNT-based materials and composites. CNT agglomerates contain pores between individual CNTs and/or CNT bundles (micropore < 2 nm, mesopores 2 – 50 nm, and macropores > 50 nm). We investigated these pores structured by CNTs with different diameters and number of walls, clarifying the broader size distribution and the larger volume with increased diameters and number of walls. Further, we demonstrated that CNT agglomerate structures with different bulk density were distinguished depending on the pore sizes. Our method also revealed that CNT dispersibility in solvent correlated with the pore sizes of CNT agglomerates. By making use of these knowledge on tailorable pores for CNT agglomerates, we successfully found the correlation between electrical conductivity for CNT rubber composites and pore sizes of CNT agglomerates. Therefore, our method can distinguish diverse CNT agglomerate structures and guide pore sizes of CNT agglomerates to give high electrical conductivity of CNT rubber composites.