Differences In Porous Structure Research Articles

Adhesion and morphology of mammalian cells on nanoporous and nonporous spherical carbon substrates

Three spherical activated carbons (SACs) were used as substrates for mammalian cell proliferation. SACs were obtained by carbonizing styrene-co-divinylbenzene ion exchangers 35WET, XAD4, or 1200H. The new materials (XAD_C, WET_C, and H_C) were characterized by adsorption–desorption nitrogen isotherms and mercury intrusion porosimetry. XAD_C and WET_C exhibited well-developed BET surface areas, similar total pore volumes, and highly different pore size distributions. H_C was nonporous spherical material—reference material. The XAD_C was meso-macroporous, but the WET_C was micro-mesoporous. All SACs were not cytotoxic toward Leydig TM3 cells. The differences in porous structure and morphology of the carbon scaffolds led to morphological differences in adhered cells. The monolayer of cells was distributed flat over the entire WET_C and H_C surfaces. Leydig TM3 cells adhered to nonporous SAC but were easily washed out due to weak adhesion. The cells adhered in clusters to XAD_C and proliferated in clusters. As microscopic techniques and viability tests demonstrated, only nanoporous carbons provided a good surface for the attachment and proliferation of eukaryotic cells.

Detailed modeling of sorptive and textural properties of CaO-based sorbents with various porous structures

In the current study, the volume-sintering model was implemented for the simulation of sorption/desorption and textural evolution of the set of CaO-based sorbents with broad differences in porous structure. The porous structure of the materials was modeled with the dense random packing of spheres using the Lubachevsky–Stillinger compression algorithm. The simulated packages were fitted to the parameters of the porous structure of real templated and non-templated CaO-based sorbents. The sintering of the packages during sorption/regeneration cycles was carried out based on the assumptions of the lattice diffusion mechanism and the sintering rate of CaCO3 being higher than that of CaO in the proposed model. The obtained model predicts well the dependence of textural changes and the recarbonation extent on the number of the sorption/regeneration cycles for the sorbents with different porosity and grain size.

열풍, 진공 및 동결건조가 눈개승마의 항산화 및 품질특성에 미치는 영향

The purpose of this study was to evaluate the effect of drying methods including freeze, hot-air, and vacuum drying on the nutritional properties, antioxidant activities, and drying properties of Aruncus dioicus var. kamtschaticus. The optimum temperature of hot-air drying was 100℃ based on the total phenolic and flavonoid content and antioxidant activities, which were altered as a function of drying temperatures of 60, 80, 100, and 120℃. In addition, based on the drying curve, the optimum condition of hot-air and vacuum drying was 100℃ for 10 min, whereas that of freeze drying was 210 min. Vacuum drying was most effective for removal of moisture compared with the other drying methods. The water activity and water solubility index of dried samples obtained by the different drying methods were not significantly different. The water absorption index and rehydration ratio increased in the order of freeze, vacuum, and hot-air drying because of differences in porous structure of A. dioicus. Thus, vacuum drying of A. dioicus leads to the highest total phenolic and flavonoid content and antioxidant activities, followed by hot-air, and freeze drying.

Effect of leaching concentration and time on the morphology of pores in porous glasses

Herein, porous glass was prepared by the acid leaching of phase-separated sodium borosilicate glass. The effects of hydrochloric acid (HCl) leaching concentrations varying from 0.1 to 3 M and of leaching times varying from 2 to 48 h on pore size and shape are reported here. The porous structure evolution was investigated through small angle X-rays scattering measurements and were compared to the classical nitrogen adsorption technique. We argue that the composition of these samples is not significantly modified with the acidic concentrations of the solution or with the leaching times tested. However, as expected a priori, we clearly show strong differences in porous structure. The investigation of different HCl leaching concentrations (from 0.1 to 3 M), with a small variation between each concentration, has enabled the observation of an interesting result. That is, we clearly show a non-linear effect of acidic concentration on the porous structure of these materials. At low acid concentrations, the specific area of these materials is relatively low. Increasing the HCl concentration to approximately 0.7 M leads to a strong increase in a specific BET area and total pore volume. However, further increasing of the acid concentration of the leaching solution leads to a decrease of both the specific surface area and the total pore volume. All of these results due to the presence of colloidal silica inside the pore structure can be explained by the well-known Zhdanov's model. These nanoparticles formed at an intermediate acid concentration seem to cluster when the acidity increases. The effect of the leaching time is less significant than the HCl concentration; however, this same assumption can be explained by the experimental results.

Influence of differences in porous structure within granules of activated carbon on adsorption of aromatics from aqueous solutions

The adsorption of organics from aqueous solutions on the activated carbon samples obtained by gradual abrasion of granules is studied. The nitrogen adsorption/desorption isotherms are applied to determine the parameters of porous structure of investigated carbon samples. The adsorption isotherms of four organic substances: nitrobenzene, phenol, 4-nitrophenol, and 4-chlorophenol from dilute aqueous solutions are also measured. The influence of porous structure changes inside of a carbon particle on organic solute adsorption from aqueous solutions is analyzed and discussed. It was stated that the carbon porosity was a function of the distance from granule surface, however, the properties of carbon micropore and mesopore walls were preserved. The similarity of adsorption mechanisms over the whole carbon granule were found for liquid systems.

Effect of precipitation and aging on porous structure of aluminium hydroxide. II. Changes in pore size distributions

Differences in porous structure of the dried aluminium hydroxide (containing sulphate ions) caused by changes in temperature and pH of precipitation, the time of aging and by additions of surfactants are documented and discussed. The aluminium hydroxide precipitated at low temperatures (30 – 50°C) and pH values (7 – 8) has bi-disperse porous structure with maxima in the region of large and medium pores. The increase of temperature and pH of precipitation limits or completely suppresses medium pores and increases large and small pores. Characteristic trend was the disappearance of medium pores which led to monodispersity in the region of large and small pores. The addition of surfactants suppressed the effect of short-time aging on pore size distributions. At moderate temperatures the effect of surfactants manifested itself in the broad pore size distributions and in the increase of the volume of large and medium pores. Qualitative and quantitative differences in porous structure caused by the action of surfactants were suppressed on increasing temperature and pH of precipitation.