The microstructure of functionalized poLyacrylonitrile beads for bioseparations

1990 ◽  
Vol 48 (4) ◽  
pp. 1094-1095
Author(s):  
Eduardo A. Kamenetzky ◽  
David A. Ley
Keyword(s):  
Aqueous Solution ◽  
Affinity Chromatography ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Surface Coverage ◽  
Vacuum Impregnation ◽  
Thin Sections ◽  
Selective Staining ◽  
Low Viscosity ◽  
Diamond Knife

The microstructure of polyacrylonitrile (PAN) beads for affinity chromatography bioseparations was studied by TEM of stained ultramicrotomed thin-sections. Microstructural aspects such as overall pore size distribution, the distribution of pores within the beads, and surface coverage of functionalized beads affect performance properties. Stereological methods are used to quantify the internal structure of these chromatographic supports. Details of the process for making the PAN beads are given elsewhere. TEM specimens were obtained by vacuum impregnation with a low-viscosity epoxy and sectioning with a diamond knife. The beads can be observed unstained. However, different surface functionalities can be made evident by selective staining. Amide surface coverage was studied by staining in vapor of a 0.5.% RuO4 aqueous solution for 1 h. RuO4 does not stain PAN but stains, amongst many others, polymers containing an amide moiety.

Effects of Surface Properties and Solvent PH Values on the Adsorption/Desorption Abilities of Mesoporous SBA-15 to Methylene Blue Molecules

2012 ◽  
Vol 518-523 ◽  
pp. 352-355
Author(s):  
Hui Liu ◽  
Hong Liang Li ◽  
Meng Xue Wang ◽  
Jing Jing Sang ◽  
Xiu Song Zhao
Keyword(s):  
Aqueous Solution ◽  
Methylene Blue ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Surface Properties ◽  
Weak Base ◽  
Adsorption Ability ◽  
Ph Values ◽  
Model Molecule ◽  
Adsorption Desorption

Methylene blue (MB) was used as model molecule to investigate the effects of surface properties and solvent pH values on the adsorption and desorption (or release) behaviors of mesoporous SBA-15 materials. It was found that the treatment of SBA-15 with a pH 7.8 aqueous solution can enhance the adsorption rate and capacity in comparison with the pristine SBA-15. The effect of pH values on MB releasing from the weak base treated SBA-15 and the pristine one have been studied and been compared in pH values range from 0.5 to 7.0. Both of them showed a maximum releasing rate at about pH 2 and all of the treated SBA-15 samples showed a higher releasing quantity than the pristine ones. The influence mechanisms of base treatment on the adsorption ability and that of pH values on the releasing properties of SBA-15 samples have been analyzed and been discussed based on the composition, the morphology, the surface area and pore size distribution and adsorption/desorption measurements.

Properties and Structure of Micro Porous Mullite-Corundum Refractory with High Strength

2010 ◽  
Vol 105-106 ◽  
pp. 23-26
Author(s):  
Juan Wu ◽  
Dao Yuan Yang ◽  
Kai Zhu ◽  
Rui Zhang
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Raw Materials ◽  
High Strength ◽  
Casting Process ◽  
Solid Content ◽  
Apparent Porosity ◽  
Corundum Refractory ◽  
Low Viscosity

Mullite- corundum ceramic was fabricated using bauxite and silica fume as raw materials by gel-casting process. The fluidity of the slurry, as well as strength, apparent porosity, pore size distribution, phase composition and microstructure of sintered specimen were studied. The results showed that: the slurry had low viscosity, good fluidity for casting if pH=9, dispersant 0.33wt% and solid content 60vol%; the strength of material came up to 165MPa even if the apparent porosity was about 30%; the samples were characterized by mullite 70%, corundum 22%, rutile 3%, glass phase only 5%, the size of majority grains was about 2μm, and most crystals with high melting point bonded directly; the average aperture was 264nm, the pore size distribution were divided into 2~30nm, 45~60nm and 1500~4000nm three regions. The distribution probability of nano- aperture was the largest, the volume of micron -aperture was the maximum, but all pores were less than 4μm in diameter, which suggested that the materials had micro porous characteristics. The microcrystalline, crystals combined directly and micro porous structure leaded to high strength of the refractory materials together.

Pore Size and Surface Texture Modification of Silica Via Trialkylsilylation

1992 ◽  
Vol 271 ◽  
Author(s):  
Duen-Wu Hua ◽  
Douglas M. Smith
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Surface Texture ◽  
Surface Coverage ◽  
Total Pore Volume ◽  
Nitrogen Adsorption ◽  
Small Scale ◽  
Pore Surface ◽  
Texture Modification

ABSTRACTSurface modification of silica via silylation is often undertaken to change surface chemistry and hence, adsorption characteristics but little attention is paid to its use for pore morphology modification, the subject of this work. Modification of two silica samples was conducted by trimethylsilylation. The degree of silylation/ surface coverage was monitored by TGA and elemental analysis. Pore structure was studied by nitrogen adsorption and condensation, and small angle x-ray scattering (SAXS). Previously, we demonstrated that surface area, surface texture, pore size distribution, and total pore volume are indeed changed in a controlled fashion due to silylation of mesoporous silicas. Generally, the mean pore size is smaller, the pore size distribution is narrower, and the pore surface is smoother after silylation. However, questions remain concerning the effect of small-scale surface roughness and the fractional surface coverage on the effective pore size. This study concentrates on the silylation of smaller pore material (r < 40 Å). Significant pore size distribution narrowing and smoothing of the pore surface with increasing surface coverage was noted.

Investigation of CPE/PVC morphology via STEM

1988 ◽  
Vol 46 ◽  
pp. 932-933
Author(s):  
E. G. Rightor ◽  
E. I. Garcia-Meitin ◽  
D. W. Liou
Keyword(s):  
Scanning Transmission Electron Microscopy ◽  
Staining Technique ◽  
Light Phase ◽  
Thin Sections ◽  
Chlorinated Polyethylene ◽  
Selective Staining ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Diamond Knife

Microscopic characterization of the phase morphology of poly(vinyl chloride) (PVC) modified with chlorinated polyethylene (CPE) is vital to understanding the blend physical properties. A 2-3 week CPE selective staining technique, developed by Fleischner et al., has been the mainstay for recent TEM investigations of CPE/PVC. Several researchers employing this method have reported a network structure of CPE surrounding primary PVC particles.Rapid electron beam-induced dehydrochlorination of chlorinated polymers prohibits TEM examination of unstained sections. Chemical changes resulting from such dehydrochlorination of polymers was addressed recently by Vesely and Finch. In this study we investigated unstained thin sections, obtained at ambient temperature with a diamond knife, by scanning transmission electron microscopy (STEM) on a JEOL 2000 FX.As the STEM micrographs show (Figs. 1-3), sufficient contrast was available to distinguish CPE (light phase) from the PVC matrix (dark). Differences in initial chlorine concentration and rates of beam-induced mass loss most likely account for the contrast between phases.

Quantitative stereological analysis of the pore-size distribution in a colloidal silica sol-gel

1990 ◽  
Vol 48 (4) ◽  
pp. 1078-1079
Author(s):  
Helen M. Kerch ◽  
Rosario Gerhardt
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Pore Diameter ◽  
Sol Gel ◽  
Image Analyzer ◽  
Average Pore ◽  
Thin Sections ◽  
Stereological Analysis ◽  
Colloidal Gel

The pore size distribution of an unsintered colloidal gel has been determined by stereological analysis of ultramicrotomed thin sections (70 nm) of the gel. This is a novel use of the ultramicrotomy technique as the epoxy represents the porous phase of the microstructure rather than just the medium used to maintain a coherent structure during thinning. In order to obtain statistically significant pore size information a nested sampling scheme was carried out, and a total of 36 two-dimensional fields taken at 19,000 X were examined. Pore diameters were measured with a digital image analyzer which measured 15 projected diameters every 12° from the center of the feature. Stereological quantities obtained were average pore diameter (Davg), number of pores per unit area (NA), and number of pores per unit volume (NV).

scholarly journals Three-dimensional hierarchical porous carbon derived from natural resources for highly efficient treatment of polluted water

2021 ◽  
Vol 33 (1) ◽  
Author(s):  
Jiaxin Li ◽  
Rudolf Holze ◽  
Simbarashe Moyo ◽  
Song Wang ◽  
Sanxi Li ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Porous Carbon ◽  
Low Cost ◽  
Polluted Water ◽  
Hierarchical Porous Carbon ◽  
Adsorption Performance ◽  
Hierarchical Porous

Abstract Background Dealing with the ever-increasing water pollution has become an urgent global problem, especially the organic containing polluted water. Physical adsorption has become one of the most popular ways for removal of organic dyes from wastewater due to its low cost as well as high efficiency. However, the adsorption performance is still limited by the low specific surface area (SSA) and unsuitable pore size. Hence, it is still a challenge to synthesize active carbon (AC) with high SSA, suitable pore size distribution as well as low cost for polluted water treatment. Here, we report an efficient method to prepare AC with large SSA from jujube for removal of both cationic dye and anionic dye from aqueous solution. The present results demonstrate that biomass-derived hierarchical porous carbon has a real potential application for wastewater treatment. Results The as-prepared hierarchical porous structure carbon material (PC-500-6) shows a high specific surface area (3203 m2/g) and pore size distribution in the range 0.8 to 3.0 nm, while exhibiting an enhanced adsorption performance for both methylene blue (MB) and methylene orange (MO) from an aqueous solution. The maximum adsorption capacity even reaches 925.93 mg/g and 1281.39 mg/g for MB and MO, which was calculated from Langmuir model. Through analysis of the adsorption data, it was found that the corresponding adsorption kinetic fits the pseudo-second-order model very well. Conclusions It can be concluded that the adsorption of MB has a strong correlation with SSA, pore size distribution as well as the pore volume. The present study paved a practical way for wastewater treatment by using biomass-derived hierarchical porous carbon.

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